# Unwanted Taper ?



## Danuzzo (Apr 28, 2020)

I am at my wit's end trying to figure out why I consistently get a taper on the three 7x mini lathes that I have tried. I am now on a third 7x mini. I was getting a taper in all 3. The taper always the same; that is, the chuck end always thicker than the tailstock end. All pieces were turned *without a tailstock*.

This is my thinking at this point. The common denominator on all 3 lathes is *Me*. I am now reluctant to think that all 3 headstocks were out of alignment, and all in the same direction. The 1st one had a significant taper of about .001 per inch. The second one was a little better, especially after I bolted it to a bench with a shim on the tailstock end away from me.However, the next day, I went back to cutting a taper with the same lathe that did so well the day before.

Now on my 3rd one. At first, it was cutting a taper; but, I think it has improved because I shimmed the bench's foot at the tailstock end way from me. The lathe itself sits on the bench on the rubber feet. The lighter the cut (e.g. .001 for a total removal of .002), the greater the taper. The current piece I am testing is aluminum 1" stock sticking out about 3" from the chuck. The taper has been reduced to about less than .0015" over the 3"; except the last piece where I said "one last try for the night", and I took a cut of about .010 (actually .020 taken off) and I got much less taper. In fact, the first 2" from the tailstock end measured about .0005 off only at the first 1/4" or so. After that, it was probably less than .0001 off. But; then I get to the last inch and it tapers about .00075.

This was all yesterday, I haven't gone out to see what happens today. Help would be greatly appreciated.


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## Danuzzo (Apr 28, 2020)

Okay, went and tried again. Taking a cut depth of about .013" (total of .026"), the 2" measured from the tailstock end are pretty good varying about .00025". Still, when I get to around the last 1" closest to the chuck, it is about a .001" thicker than the other 2 inches.

Please help me figure this out .


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## Smokey Joe (Apr 28, 2020)

I had the same problem with mine. I ended up shimming the head of the machine  .003 to straighten it out.


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## Danuzzo (Apr 28, 2020)

Smokey, where did you place the shim? Was it for the height or from side to side? Thank's.


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## Smokey Joe (Apr 28, 2020)

The raised part of the bed that locates everything.  On the far left side on the front of the raised part I had to put a .003 shim about 1/2 long to shift the head CCW when your looking at the top. Mine had three bolts holding the head on. Two in the front and one in the back.  I hope this is understandable. I'm not real good at describing things. I took the covers off and took a picture so you can see what I'm talking about.


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## fcheslop (Apr 28, 2020)

When bolting the machine down the bed could be twisting
In the ML7 Manuel it shows a simple way to level /wind the machine in
I would try this before shimming the head
A link to the book 


			http://vintagemachinery.org/pubs/4654/9521.pdf


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## Danuzzo (Apr 28, 2020)

Thank's for the replies. Still at it; once, I got lucky and minimal taper. I think I will bolt it to the bench and try the shims on the far side of the tail stock end. Not quite ready yet to take it all apart to try to shim the headstock.


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## Danuzzo (Apr 28, 2020)

Okay. Got the taper down to a repeatable .00025" with lathe bolted to bench and a .007" shim on the tailstock end away from me. Several different shims sizes were used. If I recall correctly, the 1st shim was .016", and the taper was about .002", but with the narrow end at the chuck (opposite of what had been going on). Tried several different shim sizes until I went with the .007".

Done for the day. That 1" aluminum stock is down to around .70" diameter now. Will try again tomorrow, hoping for the same results.


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## goldstar31 (Apr 29, 2020)

Danuzzo said:


> Okay. Got the taper down to a repeatable .00025" with lathe bolted to bench
> 
> This is 'a. quarter of a tenth of a thous' but  it does raise the questions of
> 1. Over what distance the measurement was taken
> ...



Being a Doubting Thomas of almost 90 now,  I hae me doots

Norman


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## bluejets (Apr 29, 2020)

Worth watching.........


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## teeleevs (Apr 29, 2020)

Danuzzo said:


> Okay. Got the taper down to a repeatable .00025" with lathe bolted to bench and a .007" shim on the tailstock end away from me. Several different shims sizes were used. If I recall correctly, the 1st shim was .016", and the taper was about .002", but with the narrow end at the chuck (opposite of what had been going on). Tried several different shim sizes until I went with the .007".
> 
> Done for the day. That 1" aluminum stock is down to around .70" diameter now. Will try again tomorrow, hoping for the same results.


Just a couple of observations, a lathe, especially a small one should never be bolted down to rubber as you can distort the bed even bolted to timber can be a problem as timber will move with changes of the weather. I have used shems to rectify problems with a very old lathe but before resorting to this you need to check the between centres accuracy.  An over hanging cut can bend the job away from the toolpost, a very light lathe can even bend the mandrel but between centres it should be straight.


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## David Shealey (Apr 29, 2020)

Danuzzo said:


> Okay. Got the taper down to a repeatable .00025" with lathe bolted to bench and a .007" shim on the tailstock end away from me. Several different shims sizes were used. If I recall correctly, the 1st shim was .016", and the taper was about .002", but with the narrow end at the chuck (opposite of what had been going on). Tried several different shim sizes until I went with the .007".
> 
> Done for the day. That 1" aluminum stock is down to around .70" diameter now. Will try again tomorrow, hoping for the same results.


You should also put a dial indicator on the carriage and run it up and down the TOP of a straight piece of rod in the chuck.  If the head is pointed up or down relative to the bed that will also give you a taper.  Not as pronounced as side to side, but still needs to be right.


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## goldstar31 (Apr 29, 2020)

Sorry but the chuck is not sufficiently accurate to be of use.

A 3 Jaw chuck on a 7x14 is not exactly my idea of something conforming to Schlesinger's `Limits


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## Danuzzo (Apr 29, 2020)

goldstar31 said:


> Being a Doubting Thomas of almost 90 now,  I hae me doots
> 
> Norman



Piece of aluminum sticking out about 3" from chuck, was used. Micrometer was used. The test used was "trial and error". I don't have fancy measuring equipment or a known true rod. Will see if it is repeatable later today, as soon as I can get back to it. I am hopeful that it will repeat. I will also try a piece of 1" mild steel.


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## Danuzzo (Apr 29, 2020)

Bluejets, thank's for the video link.

Teeleevs, no rubber used. The bench is a formica covered one. The movement should be limited. Was not turned between centers.

David, I do have a 3/8 round drill rod; will that work, or is it to small in diameter, resulting in droop?

Thank's for all the responses.


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## goldstar31 (Apr 29, 2020)

Danuzzo said:


> Piece of aluminum sticking out about 3" from chuck, was used. Micrometer was used. The test used was "trial and error". I don't have fancy measuring equipment or a known true rod. Will see if it is repeatable later today, as soon as I can get back to it. I am hopeful that it will repeat. I will also try a piece of 1" mild steel.



I think that 'Boxford' lathes amongst other reputable lathe firms used to supply a test report using the Georg Schlesinger book on testing machine tools. It gave the abbreviated 'précis' of Connolly's Machine Tool Reconditioning.

This was ALL published in this fora years ago - and included how to get the standard book by Connolly from the 'internet.
Again, I wrote up how I restored a 'basket case' of a friend's Myford ML7 in Model Engineer. 

I'll continue  settle for what was  tried and tested- and accepted.


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## Danuzzo (Apr 29, 2020)

Goldstar, I wish I could get a hold of a Boxford or Myford.


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## goldstar31 (Apr 29, 2020)

Danuzzo said:


> Goldstar, I wish I could get a hold of a Boxford or Myford.



I think that I got £300 for a ML10-  it was basic as I kept the accessories which went onto a Super7 with gear box and power cross feed at £3000- which was basic. Reconditioned from Myford and still very basic would have been £7500 to which accessories will- go sky high.
So my Sieg4 secondhand cost £350 and I added £350 for a new mill attachment but then I had to add- a lot- for accessories. 

OK, I'm nudging 90 and a widower and have donated enough monies to see my grandchildren(4) through university when I'm dead and gone.  With job problems with the coronavirus, both my kids are sort of unemployed and need a handout and , along with equally kind mates, we are donating to help people working for less fortunate people.

Model engineering simply limps along as a game that I've had- for 81 years or more!

I wish you the same good fortune

Norman


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## peterl95124 (Apr 29, 2020)

I would definitely not use bolting the lathe to the workbench with shims,
distorting the bed isn't a good way to counter a misaligned head.

I definitely feel for you though, when I tighten the bolts that hold the head to the bed
on my mini-lathe the tightening changes the alignment, so it's really hard to get it to
the correct offset such that it will come out straight after tightening.  I've never gotten
better than a couple thou per 6" of length. If I need more accuracy I use the tail-stock.

Another problem, once you do get things all aligned, since you say the piece comes out 
thicker at the chuck end and thinner at the far end is this, chucks (especially 3-jaw) are 
not nearly as rigid as you'd think, the farther away from the chuck the cutter is the more 
leverage it has to deflect the work, and the closer to the chuck the cutter is the less leverage 
it has.  on small diam soft material we all know it is the material that bends, but on thick diam 
hard material other things, including the chuck, can distort.  Something to remember for 
the future even if it doesn't apply here.

and if that weren't enough possible problems, the preload on the spindle bearings might be
too light, allowing the spindle itself to shift even while the head stays perfectly aligned.

above all have patience, alignment can take forever...


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## BaronJ (Apr 29, 2020)

Hi Guys,

I haven't found any comment in this thread that mentions chuck run out !  Apart from the fact that three jaws chucks very rarely repeat accurately and can have several thou runout to add into the mix.

Head tilt will also play a large part in producing a taper even if the head is perfectly in line with the bed.  Turning between centers is one way of getting parallelism but it tells you nothing about bed twist.


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## Cogsy (Apr 29, 2020)

I wouldn't think chuck run out would be an issue on a turned piece unless it's an absolute junk chuck and the bore through the jaws is crooked. Now if a test bar is simply being chucked up and measured that's a different story, but the way I read the original post it was after taking cuts so 'normal' run out disappears.


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## Danuzzo (Apr 29, 2020)

Thanks for the posts. Tried it again this morning and was repeating minimal taper. Actually, the ends are about the same; but, some spots away from the ends are about .00003" to .0004" off. what would be the explanation for this?

Now I am working on aligning the tailstock. Back to working on it.


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## goldstar31 (Apr 29, 2020)

Cogsy said:


> I wouldn't think chuck run out would be an issue on a turned piece unless it's an absolute junk chuck and the bore through the jaws is crooked. Now if a test bar is simply being chucked up and measured that's a different story, but the way I read the original post it was after taking cuts so 'normal' run out disappears.



You may be right but the only way that parallelism can be achieved in a worn or mis-aligned lathes is with a boring bar- and used  'between centres'. Well, this is the way that I have machined to accommodate parallel round PGMS bars in  say  'Quorn' Tool and cutter grinder. Professor Chaddock and George H Thomas in the MoModel Engineers Workshop Manual report. As a mere amateur, I have to agree.

A ga in, taking what is said to be 'a normal cut' if the lathe is worn or incorrectly aligned. Mathematically, my experience suggests that wear or mis-alignment can cause an error of THREE  times the measured error/wear.
This, is Pi but it gets worse when the actual wear is about 6 inches from the spindle and or the chuck jaws.
This is why a lot of so called measurement is done now with laser alignment. Earlier it was done with a wire and clock gauges, running between centers and clocked using the carriage.

Clears throat a bit and would mention a failed machine tool factory-- and obviously worthless share certificates. 
Actually there were 3 but - the rst of the shares in 'other factories' are still a success.

However, I am 'Connolly Man' but note that others may not share my views.

Digressing further, I have 'special equipment' and  several of my lathes over the years have been mounted - without twist, using cheap studding, penny washers and cheap nuts. My surface plate was nothing more than a piece of plate glass and I scrapped with a worn out old file using engineers blue.  Initially, I got 'near' using strips of cigarette rolling papers.  Years before I made wartime models with used single bladed safety razor blades honed on the inside of glass tumblers.

My experiences- but my I found my late wife's ruler yesterday.  It was a 6" wooden one and despite having a list of degrees working down from a Fellowship, that is what she still used from when she was- a school girl.
I have Dad's folding 2 foot brass rule. My son has still my slide rule. Such is Life.
I digressed- sorry

Normani


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## awake (Apr 29, 2020)

Chuck run-out is immaterial once a piece is turned. At that point, the results depend on the alignment of the spindle to the bed, and vice versa.

Danuzzo, look up "Rollie's Dad's" method - much better than taking a continuous cut.


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## goldstar31 (Apr 29, 2020)

Danuzzo said:


> Thanks for the posts. Tried it again this morning and was repeating minimal taper. Actually, the ends are about the same; but, some spots away from the ends are about .00003" to .0004" off. what would be the explanation for this?



Any number of reasons, but the most obvious( to me) is 'Flex' from any numbers of reasons.

This, as you will find- is a very big and detailed  subject.


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## Danuzzo (Apr 29, 2020)

Got the tailstock lined up; but, still have not used it.

I tried turning the 1" mild steel about 2.5" long. No significant taper. I am pleased with the current result.

Thanks for all the input.


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## goldstar31 (Apr 30, 2020)

Danuzzo said:


> Got the tailstock lined up; but, still have not used it.
> 
> I tried turning the 1" mild steel about 2.5" long. No significant taper. I am pleased with the current result.
> 
> Thanks for all the input.



Respectfully, you  should have a projection of 6" and as my good friend Frazer mentions, cutting two rings and then compare results. 
FYI I had several Myfords over the years I stripped the headstocks off the lathes and had them 'Blancharded' to get a 'reference'. So far no one has mentioned this practice. I then  scraped a piece of mild steel as long as the lathes and proceeded to scrape the number 1 shear which wears 6 inches from the chuck end. I then scraped and blued the saddle etc so close that little strips of cigarette papers were held.
When all was saisfactory,  I could hold a Number 2 Morse. taper test bar which when clocked near the spindle end and then 6" from the free end only deflected when tested with a tenths of an inch dial gauge by less than half a thous.

This is where you should be going.  Connoly talks about tests made to 'references' and never mentions these these 'itty bitty funny practices' in more than 500 pages of text.

If you have to remove 'metal' you scrape to a minimum of 25  'spots' in a square inch. This is what the old restorers normally worked to whilst blueing and scraping 'cycles'


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## Tim1974 (Apr 30, 2020)

what brand and type of Micrometer are you useing ? i with i could reliably get to .00005


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## Danuzzo (Apr 30, 2020)

Tim1974 said:


> what brand and type of Micrometer are you useing ? i with i could reliably get to .00005



I have an old Brown & Sharpe that I have to estimate the 10ths, and I do take more than one reading. In addition, I also use a Harbor Freight digital that does go to tenths, and again, I must take more than one reading to make sure I am getting consistent results. I have never actually tested either mic to confirm they are accurate, as far as the actual measurement; but, they appear to be accurate at least as far as checking the difference of the diameter from one spot to another.


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## goldstar31 (Apr 30, 2020)

Check your decimals, they appear pretty dismal


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## Danuzzo (Apr 30, 2020)

goldstar31 said:


> Check your decimals, they appear pretty dismal



Whoops. I can't measure in .00000 (5 digits past the decimal). So, anywhere I stated .00000, I mean't 10ths, as in .0000 (4 digits past the decimal). I wish I could get tolerances in the .00000 range .


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## goldstar31 (Apr 30, 2020)

Danuzzo said:


> Whoops. I can't measure in .00000 (5 digits past the decimal). So, anywhere I stated .00000, I mean't 10ths, as in .0000 (4 digits past the decimal). I wish I could get tolerances in the .00000 range .


Try Statistical Quality Control from McGraw-Hill and if it is no good you can always keep it to prop the broken leg on the chair!


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## Danuzzo (Apr 30, 2020)

Still having fits over trying to figure out why I am getting a smaller diameter on the aluminum in the center of the piece. The two ends are pretty darn close. Now, i have variance of up to .00065" for a distance of about 1" around the center of the cut. Tried different tool angle on 2 different HSS bits , speeds, carbide insert tool. Appears to be in the same area all the time.  

Help!


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## goldstar31 (Apr 30, 2020)

0.00065".  Come on-- digitum extractum If you are still playing about with a cob end, and getting unexpected answers- heaven help you.  Project out a decent 6 inches or more and let us know what the result is.


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## TonyM (May 1, 2020)

Danuzzo said:


> Still having fits over trying to figure out why I am getting a smaller diameter on the aluminum in the center of the piece. The two ends are pretty darn close.


That suggests the headstock/testpiece is pointing up or down in relation to the bed. If this is the case a longer test piece would prove the theory. The low point would remain in the same position distanced from the chuck as this would be the point where the tool is on centre of the test piece. With a longer test piece the diameter would increase the further away from the chuck you get. The tool needs to be perfectly sharp, large diameter piece and very small cuts to minimise deflection.


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## goldstar31 (May 1, 2020)

Deleted


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## TonyM (May 1, 2020)

I don't know if there is any point in progressing this but lowering the tool height should change the position of the small diameter. If you lower the tool and the small diameter moves away from the chuck the head is pointing down. If the lowpoint moves nearer the chuck the head is pointing up. It just sounds like an alignment problem. The head is bolted rigid and the tail has bowed either down under its own weight and that of the saddle and tailstock. Or up if the table is not flat.  When installing a lathe you really need to level the bed and the spindle with a high resolution engineers level.  
Without one of those remove the tailstock and wind the saddle as near the chuck as possible. Take a couple of pieces of thick felt (4-5mm) the size of the mounts and soak them in shellack.  Place them in position where the feet of the lathe go and gently lower the lathe onto the pads leave to dry out. No need for bolting down and the resultant possibility of distortion. They used to be available on a roll for industrial equipment but I cant remember what they were called.


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## goldstar31 (May 1, 2020)

Deleted


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## Badhippie (May 2, 2020)

What about wear in the ways has this been checked. If you are worried about a taper in the .0000 then you should be worried about wear in the ways. Another possibility is all the backlash taken up when the cut is being made


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## Danuzzo (May 2, 2020)

No wear in the ways. Brand new.


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## retailer (May 2, 2020)

> Okay, went and tried again. Taking a cut depth of about .013" (total of .026"), the 2" measured from the tailstock end are pretty good varying about .00025". Still, when I get to around the last 1" closest to the chuck, it is about a .001" thicker than the other 2 inches



That .013" cut seems like quite a lot to me, I may be wrong but I always believed that when doing this type of check the smallest depth cut is used to minimise any tool spring, work spring etc. which will affect the results, I would have thought that a few tenths of a thou per cut would be used.


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## fcheslop (May 3, 2020)

More chance of the tool just rubbing and not cutting .


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## Danuzzo (May 3, 2020)

Thank's for the input.


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## retailer (May 3, 2020)

If the tool is properly sharpened it will cut not rub, with material that is not hard or tough ie 1020 mild steel I have found it easy to take  .001"  cut.


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## goldstar31 (May 4, 2020)

retailer said:


> If the tool is properly sharpened it will cut not rub, with material that is not hard or tough ie 1020 mild steel I have found it easy to take  .001"  cut.



This conflicts with the views of non other than  Leonard Sparey in  his book the Amateurs Lathe. Sparey designed many of the engine designs which are still followed today. Martin Cleeve( Kenneth C Hart) author of Screwcutting in the Lathe and also the designer of the Swing Tool and many articles in Model Engineer and other mags wrote about taking virtually imperceptible cuts in steel. In other. In other words, creating steel wool so fine that it would crumbled as dust between the fingers- and merely dirty them.
Suffice to say that I have suggested the existence of such gems seemingly without anyone noticing.
Again, screeds have been written about stting a lathe tool to the correct cutting height to cut correctly.

John Moran as GadgetBuider.com writes freely on  his 7 X14 lathe etc. Again, it is excellent-- and free of copyright


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## fcheslop (May 4, 2020)

We live and learn
I will stick by my original comment
cheers


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## goldstar31 (May 4, 2020)

fcheslop said:


> We live and learn
> I will stick by my original comment
> cheers



Greetings Frazer

From Sparey's book, he was using a knife tool--

At centre height
with an approach 'cut' or rub at less than 3 degrees.

In other words, not much different to your comment.

However, with sufficient power- and that excludes low powered Myford and certainly these 7x14 variety, you can literally push metal off. Negative carbides and brute force on rigid machines!

Digressing a touch, even the recommended positive carbides with chip breakers are relatively blunt compared with those sharpened with progressive grades of diamond dust/paste

Clearly, YOU know all this but I'm adding this for others who cannot distinguish between the need of metal removal and only precise metal removal for 'measurement'

As you know, and I know, there is one helluva problem using a light lathe where really removal to prese limits should be carried out by grinding.  another interesting ball game, eh?

Meantime, best wishes

Norman


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## retailer (May 4, 2020)

Goldstar31 and fcheslop our ideas seem to differ and that's fine we have all had different experiences and are all entitled to our own opinions. 
I guess I must work differently to you, and you are probably better machinists than me, I don't think I could have made a decent job of my my Quorn grinder build if I wasn't able to take small depth cuts - I haven't had much success taking the last 10 or 15 thou in one cut and getting it bang on, I usually take deeper cuts until the last 3 or 4 thou and then go a thou or so at a time, I get a feel for the amount of tool and work spring at this stage and feed in accordingly, sometimes I'll take the last 2 or 3 passes without increasing the depth of cut, each pass takes 0.5 thou or so and I can usually get to my target diameter + or - 1/2 thou.


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## Danuzzo (May 4, 2020)

The lighter the cut on my taper issue, the greater the taper issue. Don't know what it means. Just my personal observation. Even after the shim, it went back to a taper on the aluminum. By the way, I took a Bridge City straight edge to the bed length wise, and I found a small gap between the ends. This was with the shim. I didn't measure without the shim. Don't know the significance of this; but, I did not think it was a good thing.


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## fcheslop (May 4, 2020)

Retailer, I dont doubt that youre machine will do as you say and often do the same myself
As to better machinists Im only a toy maker and have illusions on that matter
The thing I doubt is that you can dial in 0.0001 cut on a machine  like this and it will give a constant cut and I wonder why the machines owner is so concerned about 0.0001 ..
If in the past I wanted to work to that level it would have gone on to a grinder either cylindrical or otherwise .
Keep well and safe
kind regards
frazer


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## retailer (May 4, 2020)

I think you are misunderstanding me - when I say a thou I am referring to 1/1000 of an inch or 0.001 inches this is one division on the cross slide so it is do able, I see you are thinking 0.0001  which is a tenth of a thou and you are right  I know I couldn't dial in 0.0001.


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## goldstar31 (May 4, 2020)

Retailer
Building a Quorn involves a lot of boring. I followed Chaddock and George Thomas by making two 'between centre boring bars.  In pother words for the two 1" bed bars have to be a tight fit for 3 holes, dead parallel and +0.003" for the split one. Then being a cast iron casting, one has to ensure that once cutting the casting, it doesn't spring shut. Thomas found out( and so did I).  He found it on the Mark1 castings on the the Versatile Dividing Head whilst I found it on making the original Westbury mill drill.  But this is light years from someone who is writing here for assistance- and seemingly not taking a blind bit of notice.
Chaddock refers to a half thous cut on the grinder as a whopping cut.
ALL my tool and cutter grinders apart from the Clarkson have mere 1/6th HP 2880 rpm motors

Danuuzzo

Might I suggest that you seek professional advice- anf have your - new?- lathe returned to what is was on leaving the factory


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## retailer (May 4, 2020)

Danuzzo:  just thinking are you having issues with aluminium ? I noticed in an earlier post you mentioned turning a piece of steel with acceptable results, aluminium can be strange stuff and is known to 'gall' easily I always give aluminium a good squirt with WD40 when machining.


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## Steamchick (May 5, 2020)

Danuzzo said:


> Thanks for the posts. Tried it again this morning and was repeating minimal taper. Actually, the ends are about the same; but, some spots away from the ends are about .00003" to .0004" off. what would be the explanation for this?
> 
> Now I am working on aligning the tailstock. Back to working on it.


Just trying to glean anything useful that I can learn from this. But in doing so, I reckon that maybe you have a wrong starting point? A regular 3-jaw chuck is - at least when I was taught in the 60s - a "jobbing" centre: I.E. Ok to grip something approaching round while you machine the part "to drawing". But as it is made from a series of components - aligned with sliding clearances - it can never be "truly accurate". To work with something "true", you need a collet chuck, high precision chuck or mandrel, work between centres, etc. And any machined length needs to be supported, as during the cut the side pressure from the tool will cause distortion in the part that you can measure with high precision measuring tools. Incidentally, how you hold the micrometer and operate it, can (WILL) give you variation. Measure a single diameter 30 times and then do the stats to see how accurate (Repeatable) you are? Put the mic on the bench, rub your hands together and clap once before each measurement. Have you run a clock (DTI) along the length of the machined bar? (stationary of course), after a "finish" cut? - Incidentally, for lathe work I never expect to work to within 0.001" That needs a precision grinder... Do you control all the temperatures to 20 degrees C. for machining and measuring? When auditing Car component suppliers, we would sack them if they didn't control everything when measuring. Plus or minus 2 degrees C. in the calibration lab was DISASTER!


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## retailer (May 6, 2020)

I should have mentioned I usually set the compound rest over to 30deg, so If I need to advance the cutting tool 0.0005" (1/2 thou) for a fine cut I advance the compound rest 0.001", this moves the cutting tool just under 0.0009"  towards the head stock and also 0.0005" (1/2 thou) in towards the work piece, this is nothing new and I don't doubt that it is used by some forum members.


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## goldstar31 (May 6, 2020)

I'll check again-- Sorry

Yes, G H Thomas could remove  a 1/5th of a thous   with a top slide advance of 4 thous


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## Tim1974 (May 7, 2020)

Your chasing your tale get a better lathe if you expect that sort of tolerance


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## ALEX1952 (May 7, 2020)

Unless you spend major money on a lathe or mill and have a very good maintenance schedule (not just giving it a clean and a squirt of oil) I dought you will achieve the accuaracy you are chasing, in fact I would be suprised if the average machine could achieve that given the variables in manufacture. Far better is to get to know your machine recognise its limitation and work around them, if it is still a problem then do as someeone has allready suggested get a grinder, and deep pockets.


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## IanN (May 8, 2020)

OK, I'll bite.

Why are you trying to achieve such high levels of accuracy and precision?

What are you actually trying to make on the machine?  I'm struggling to think of a reason for trying to gain the standards of accuracy and precision that you specify

All the best,
Ian


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## Danuzzo (May 8, 2020)

Those who are asking me (OP) why I am looking for less than .0005" taper in 2" or even 1", I was under the impression, maybe mistaken, that any lathe, without tailstock assistance, should be able to achieve this kind of tolerance. Please educate me if my expectations are too high.


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## fcheslop (May 8, 2020)

I think a tighter tolerance should be achievable to what level on those machines I have no idea
The approach needs to be methodical 
My preference would be to use two test bars one that fits in the machines spindle and the other between centres and then do some measuring making notes as you go . So that you are starting from a known point
Level the machine in with the first with the machine bolted down or you a peeing into the wind
Set the tailstock with the second and it should also show if the bed is bellied 
To check the head use a parallel and clock  
Bogstandard did a very good write up on this and other forums about remachining one of youre lathes and detailed 
My two lathes one a ML7R the other a Schaublin 70 TO will do what I want but as the temp and humidity changes they go out of whack. Both machines have cost as much as a medium SUV but have in the past made my daily crust
Chasing tenths can and is frustrating and often not needed depending what you want to make
Sadly precision costs both for the machines and the machines environment
Only you can decide to what level you want the machine to perform
If in the past I was machining below 0.001 then it would be a grinder jobby now if Im at 0.0003 Im a happy bunny
Im a little dyslexic so deliberately dont post often  as it takes me far to long and life is to short
Other more wise will have better advice
cheers


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## BaronJ (May 9, 2020)

fcheslop said:


> More chance of the tool just rubbing and not cutting .



I don't know, I can easily take a tenth thou cut in most materials !


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## BaronJ (May 9, 2020)

retailer said:


> I think you are misunderstanding me - when I say a thou I am referring to 1/1000 of an inch or 0.001 inches this is one division on the cross slide so it is do able, I see you are thinking 0.0001  which is a tenth of a thou and you are right  I know I couldn't dial in 0.0001.



A lot of getting fine cuts is down to technique !  The sine method will easily allow a tenth cut.  The real question is can the machine achieve that level !


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## BaronJ (May 9, 2020)

Danuzzo said:


> Those who are asking me (OP) why I am looking for less than .0005" taper in 2" or even 1", I was under the impression, maybe mistaken, that any lathe, without tailstock assistance, should be able to achieve this kind of tolerance. Please educate me if my expectations are too high.



You are talking about a Chinese lathe, by your own admission the lathe has a slight upward bow in the bed.  Whilst old iron can achieve what you are looking for quite easily, they were made and built to do actual work to precise standards.  Not like the toys coming out of the far East.


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## goldstar31 (May 9, 2020)

JohnB And Frazer- and I assume myself are perfectly capable of both removing 'barely perceptible swarf' and ' making such fine steel wool that it can be crumbled in the fingers. I have no doubt that we could all do it on a 7 x14 lathe. I can do it on a 8x16 which I have in addition to what I could do on the old Super7B and I have no qualms or doubts about it once I refit the 'funny ' motor on my nearly new Super7B PXF.

The common denominator in such things is that we all follow a classical professional approach-- and not try to  to re-invent the wheel. 
As John mentions,  he and i are quite familiar the sine and a lot more of the many propositions of Euclid- and can instinctively apply our learning to something as trivial as has raised so much 'hot air'. I have no doubt that our good Frazer will have no problems either.

It does require getting things which are appropriate to the task in hand and not trying to use the wrong micrometer that will only measure at best half a thous when n appropriate one will measure in 'tenths'.

In other words, the right tool for the right job- to have the wit to blame ourselves when things go wrong- and not the tool.

My thoughts but the world may be full of people who disagree. 

Norman


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## IanN (May 9, 2020)

Danuzzo said:


> Those who are asking me (OP) why I am looking for less than .0005" taper in 2" or even 1", I was under the impression, maybe mistaken, that any lathe, without tailstock assistance, should be able to achieve this kind of tolerance. Please educate me if my expectations are too high.



Hi Danuzzo,

Nothing wrong with expectations!

There are two types of machine tool (in this case lathe) owner:

1) The person who uses their lathe to actually make stuff.

If you are this sort of user, there is no point in wasting time, money and effort making your machine any more accurate than you actually need - if your most demanding task only require a tolerance of +/- 5 thou then there is no point in chasing tenths

This is the sort of person who goes down the pub, shows off their latest beautifully finished steam engine and expects everyone to be impressed and buy them a pint

2) The type of owner who never actually makes anything and has “ownership of the tool” as their hobby

There is absolutely nothing wrong with this - if you get pleasure and a sense of achievement through making incremental improvements in machine accuracy then go ahead and enjoy yourself

Such an owner may never have any manufactured artifact to show off, but they do gain “bragging rights” allowing them to walk in to the pub and demand “My lathe can repeatable turn to one tenth over a two inch length - now buy me a pint!”

Personally I make stuff, and everything I make is a “one off” - the actual dimensions are not that critical as long as parts have a “good fit” with each other.  Nothing has to be interchangeable with parts from a second item.

My lathe is over a hundred years old and is quite sloppy in a number of places - it is quite possible to produce very accurate and consistent parts on it, you just have to know what you are doing

Whatever sort of user you are, and whatever you do - just have fun and enjoy yourself 

All the best,
Ian


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## terryd (May 9, 2020)

retailer said:


> I think you are misunderstanding me - when I say a thou I am referring to 1/1000 of an inch or 0.001 inches this is one division on the cross slide so it is do able, I see you are thinking 0.0001  which is a tenth of a thou and you are right  I know I couldn't dial in 0.0001.



Hi,

 If you set the compound slide to a fraction under 6° (actually 5° 44') then use the compound slide to feed in, each division is divided by 10.  So if I feed in 0.001" on the cross slide dial the tool advances by 0.0001".  a bit ott perhaps given all of the variables in lathe condition, material being cut, tool sharpness etc but it is actually very useful if you have backlash in your cross slide.  e.g. if you need an accurate 5 thou' cut you dial in 50 thou' on the cross slide when offset as above and the tool advances by exactly 5 thou'.  That perhaps may be a useful tip to stow away for future reference?  So in the discussion above if you dial in 10 thou' (0.010") on the cross slide the tool advances by 1 thou' (0.001") - that can make for better accuracy - and all the better if you can lock the saddle and cross slides on your lathe.

And I understand that in the USA what we call a thou' (0.001") you call a mil.  Is that correct?  In the UK a 'mil' is short for a millimetre.

Regards

TerryD


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## retailer (May 9, 2020)

terryd - thanks for the info on the compound slide setover I was aware that there was an angle somewhere between 2 and 10 that gave 1/10 thou feed on the cutting tool, but never got around to trying it out , I do believe it is a very useful thing to know, I might put up a small note on my splashback reminding me, I've had my lathe from new since the early 1980's and made a few steam engines etc but it is only since I machined the Quorn grinder that I became serious about working to fixed dimensions with in tolerances,I used to just machine parts to fit each other but it didn't occur to me that once the first part is machined the second part must be machined to a fixed dimension with a set tolerance so why not do it all of the time.
I'm in Oz and work in metric for just about everything except the model engineering where it is imperial and thou's, I can't quite seem to get my head around the metric engineering stuff 1/10mm is too coarse and 1/100mm is less than 1/2 thou and quite close tolerance, 1 thou seems just right.  I've got an air spindle build in the pipeline perhaps I'll bite the bullet and try working in metric the closer tolerances can only help with the air spindle.


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## ALEX1952 (May 9, 2020)

I second IanN last post, the machine only needs to be good enough for the job in hand, yes you could strive for perfection but to maintain that perfection would be a nightmare, as mentioned previously a change in temperature or atmosphere would be enough to cause an issue. when I was working anything of the accuracy you are seeking was in a shop with controlled temp and atmosphere, some of the machines were never turned of so that they were allways at working temp, shafts would settle because the oil film would drain away, CNC machines had a cycle that would keep all the axis moving. This was to achieve what you are seeking, stop obsesing and enjoy your hobby get to know your machines failings, and work round them, as IanN says "mostly you are looking for a fit nothing needs to be interchangeble", which is why if something you buy requiring such accuracy you invariable buy it as an assembly or, they are made undersize for you to match and fit.


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## minh-thanh (May 9, 2020)

Hi All !
Danuzzo !



Danuzzo said:


> This is my thinking at this point. The common denominator on all 3 lathes is *Me*. I am now reluctant to think that all 3 headstocks were out of alignment, and all in the same direction. The 1st one had a significant taper of about .001 per inch. The second one was a little better, especially after I bolted it to a bench with a shim on the tailstock end away from me.However, the next day, I went back to cutting a taper with the same lathe that did so well the day before.
> 
> Now on my 3rd one. At first, it was cutting a taper; but, I think it has improved because I shimmed the bench's foot at the tailstock end way from me. The lathe itself sits on the bench on the rubber feet. The lighter the cut (e.g. .001 for a total removal of .002), the greater the taper. The current piece I am testing is aluminum 1" stock sticking out about 3" from the chuck. The taper has been reduced to about less than .0015" over the 3"; except the last piece where I said "one last try for the night", and I took a cut of about .010 (actually .020 taken off) and I got much less taper. In fact, the first 2" from the tailstock end measured about .0005 off only at the first 1/4" or so. After that, it was probably less than .0001 off. But; then I get to the last inch and it tapers about .00075.
> 
> This was all yesterday, I haven't gone out to see what happens today. Help would be greatly appreciated.



 All data you give are my dream !
Exact perfection is always desired, but if you are too focused on it you have to spend a lot of time and money ...
Focus on the projects you are going to do and adapt to your machines !


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## goldstar31 (May 9, 2020)

Danuzzo said:


> The lighter the cut on my taper issue, the greater the taper issue. Don't know what it means. Just my personal observation. Even after the shim, it went back to a taper on the aluminum. By the way, I took a Bridge City straight edge to the bed length wise, and I found a small gap between the ends. This was with the shim. I didn't measure without the shim. Don't know the significance of this; but, I did not think it was a good thing.



I missed this remark originally. Enough to question whether the lathe is bolted down or not when the straight edge is used. Of course the straight edge could warp as well


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## SpringHollow (May 9, 2020)

My South Bend 10L is within around 0.001 over 36" after appropriate leveling.


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## Cogsy (May 9, 2020)

I'm with the OP on this one (and it sounds like we're in the minority) but I would be quite upset if my lathe was delivering a taper of 1/2 a thou per inch as he describes. Relating that to making I.C. valve, that means my valve stem would be 0.025mm thicker at one end than the other, when I like to maintain a tolerance of half that (and that's on a very flexible part). Relating it to a crankshaft with 3" of shaft each side of the webs, there would be 0.05mm difference between the end of the crank and the web with the chuck end thinner than the tailstock . So to get the shaft end small enough to get a bearing to press on it would be sloppy and loose in it's running position.

Now expecting to cut on-size to a tolerance of 0.0005 thou might be a bit extreme (not that I think he was suggesting that), but in my opinion, expecting to have less than that amount of taper per inch of travel is certainly justified. I'd be interested to hear why I'm wrong though - change my mind!

Edit: I re-read the original post and I see that the taper is the opposite to what I remembered it, with the thicker end of the shaft being the chuck end, so my crank example means I would get the shaft small enough to get the bearing on then it would freeze part-way down the shaft. Still not ideal in my opinion.


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## TonyM (May 10, 2020)

I have levelled and bolted down more high precision machines than I care to remember. Every machine was levelled before bolting.  Bolting down, if required, was always done gradually checking levels as you go.  I realise that many here have not had the benefit of experience and no real instructions are given when you buy a small lathe.
These chinese lathes are as flimsy as you like and invariably placed on a wooden bench. They only have two mounting holes and no adjustment other than shimming. This does not allow for any 'out of flatness' of the mounting surface. Bolting down tight to an out of flat surface will distort the bed in whatever direction regardless of how level it is lengthwise.

The head should be leveled in both directions  then the bed should be leveled in both directions rechecking the head as you go.

If you want to ensure best chance of accuracy make some mounting pads with jacking screws on each corner and one holding bolt between these.  Bolt one plate to the table and the plate with the jacking screws to the lathe using the jacking screws to adjust instead of shimming


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## BaronJ (May 10, 2020)

Hi Cogsy,



Cogsy said:


> I'm with the OP on this one (and it sounds like we're in the minority) but I would be quite upset if my lathe was delivering a taper of 1/2 a thou per inch as he describes.



Me too !  I have just less than half a thou over 6 inches. Around 0.0003"  I'm quite happy with that.  Particularly with bearing fits.  I'm currently making a grinding spindle, so bearing fits are particularly important.



> Now expecting to cut on-size to a tolerance of 0.0005 thou might be a bit extreme (not that I think he was suggesting that), but in my opinion, expecting to have less than that amount of taper per inch of travel is certainly justified. I'd be interested to hear why I'm wrong though - change my mind!
> 
> Edit: I re-read the original post and I see that the taper is the opposite to what I remembered it, with the thicker end of the shaft being the chuck end, so my crank example means I would get the shaft small enough to get the bearing on then it would freeze part-way down the shaft. Still not ideal in my opinion.



No I agree with you !  There are so many variables involved here you can spend weeks or months chasing your tail !


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## IanN (May 10, 2020)

Cogsy said:


> ..... a taper of 1/2 a thou per inch as he describes. Relating that to making I.C. valve, that means my valve stem would be 0.025mm thicker at one end than the other,
> :
> Relating it to a crankshaft with 3" of shaft each side of the webs, there would be 0.05mm difference between the end of the crank and the web with the chuck end thinner than the tailstock.



Hi,

Let’s get real here.  addressing the above points in order:

1) Your example of machining a valve stem with 1/2 thou/inch taper and a total end-to-end discrepancy of 0.025mm (1 thou) suggests a machined stem length of 2 inches - a full sized I.C. engine valve.  If you are intending to make critical engine components for your car, holding a taper over 2 inches is the least of your problems (in real a production environment such items would be rough turned on a lathe then ground to size - much quicker, easier and more precise)

2) Your second point above considers two bearing journals 3 inches apart.  As I’m sure you already know, no-one would ever seriously attempt to make a shaft to the journal diameter along its entire length - you would machine one journal to size, move along and machine the second journal to size then machine the shaft in between to about 10-20 thou under the journal size (and leave it rough turned - don’t waste time, effort and money putting fine finishes where they are not required)

The issue with machine accuracy breaks down in to two sets of criteria:  Accuracy over short distances, and accuracy over long distances.  For most of us, accuracy over short distances (less than 1/2 inch) covers 99% (often 100%) of a hobby user’s requirements.  Unless you make full sized pistons for 3 litre car engines, I cannot imagine anyone actually needing to hold 1/2 thou over 3 inches

All the best
Ian


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## goldstar31 (May 10, 2020)

I sort of go along with the suggestions of TonyM. The difficulty is that the OP is not following a recognised test procedure. The only hint of proper measurement is the use of a straight edge.  Whether the lathe when checked was 'bolted down' or not has yet to be answered. My own SiegC4- the slightly larger version at 8 x 16 is as good or perhaps better than most would admit. It's Chinese, it's crap, and so on. Mine has a powered milling attachment- and true to form- the motor was crap but replaced under warrantee. At the price- second hand for the lathe itself, it is surprisingly good value.

However the complaint of the present poster is not unknown. It was answered here and as far as I can recall, was only resolved with obtaining a new lathe bed. Again, I vaguely recall someone with a 'blued' straight edge discovering a shear which had literally sagged- after it was machined. 
Whether our OP's machine is something similar is unknown. 
More years than I wish to recall, my father would 'normalise' warped steel. He had little to do with castings but that was raised by a then apprentice who found mountains of part machined castings left out in the open to rust and weather before being brought in for final machining. Both he and the factory are- long gone.

All of this is nothing new. I can - or could shrink or otherwise normal sheet steels but I would be loathe to attempt this on high strength low alloyed steels. 

So it remains with the OP.  to actually correctly determine the situation before anyone attempts to find a cure for it


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## goldstar31 (May 10, 2020)

John
          Lathe beds etc aside, I have written using your 'other' e-mail address.

Still trying to snow so I'm going to do my tax return-- in the warm

From one Grumpy Old Git to another

Best Wishes

N


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## terryd (May 10, 2020)

retailer said:


> terryd - thanks for the info on the compound slide setover I was aware that there was an angle somewhere between 2 and 10 that gave 1/10 thou feed on the cutting tool, but never got around to trying it out , I do believe it is a very useful thing to know, I might put up a small note on my splashback reminding me, I've had my lathe from new since the early 1980's and made a few steam engines etc but it is only since I machined the Quorn grinder that I became serious about working to fixed dimensions with in tolerances,I used to just machine parts to fit each other but it didn't occur to me that once the first part is machined the second part must be machined to a fixed dimension with a set tolerance so why not do it all of the time.
> I'm in Oz and work in metric for just about everything except the model engineering where it is imperial and thou's, I can't quite seem to get my head around the metric engineering stuff 1/10mm is too coarse and 1/100mm is less than 1/2 thou and quite close tolerance, 1 thou seems just right.  I've got an air spindle build in the pipeline perhaps I'll bite the bullet and try working in metric the closer tolerances can only help with the air spindle.


Hi,
I also work in metric and have mostly metric tooling with a little imperial stuff that I sometimes pick up from car boot sales but on the whole I tend to convert drawings to closely matching metric sizes.  I realise that 0.1 mm is 0.004 thou' and therefore 0.01mm is 0.0004 so I can use 10ths mm to get reasonably accurate and let's face it, if you're making steam models as we say here 'half a gnat's cock' is close enough.  Of couse if miniature pulse jets are your thing that's a different matter.  After all the very early Newcomen atmospheric engines had large cast iron cylinders hand scraped and filed and the piston was sealed with a leather flap around the circumference and a layer of water on top to complete the seal.  As you probably know the piston was only powered on the downstroke as the partial vacuum created by the condensation of the low pressure steam below the piston pulled it down.  In those circumstances tolerances were measured in large fractions of an inch.  James Watt's achievement was to improve the efficiency of Newcomen type atmospheric engines.

TerryD


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## IanN (May 10, 2020)

goldstar31 said:


> :
> The difficulty is that the OP is not following a recognised test procedure.



This is, of course, the root of the problem.  There is a proven path to follow when testing and trueing a lathe and any omissions or deviations from the sequence will result in uncertain test conclusions and, therefore, the likelihood of faulty corrective actions

There is a motto in engineering:  “Check everything, assume nothing”

Until the bed is proved straight and true against a surface plate, there is little point in doing any further corrective work

All the best,
Ian


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## Danuzzo (May 10, 2020)

Thank's for all the input. To answer goldstar's question. Yes the lathe was bolted down.

I cannot financially or wisely spend the money to buy fancy measuring equipment, so I cannot level a bed properly. Plus I would not know the proper methods for doing so. However, I do like Tony's idea of mounting pads with jack screws.

Another question. With these 7x mini lathes, would the chances of having an warped bed be less with a 7x10 vs a 7x16 (less chance for error??) Just curious.


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## peterl95124 (May 10, 2020)

at least here on the west coast 0.001" is called a "thou" and 0.0001" is called a "tenth" (!)
I've never heard a machinist use the term "mil", you do see it used in some specifications
outside of machining, for example "10 mil" plastic sheeting is 0.010", but never in machining
so 0.010" shim stock is "10 thou", not "10 mil".

I've never been able to get the head perfectly aligned with my lathe bed (tightening the bolts
changes the alignment, argh!!!), so for critical parts, e.g. a shaft that has to fit a ball-bearing, 
I use very fine wet-or-dry paper to get a perfect fit over the length it has to slide over.  
Fortunately I'm always building one-off model engine parts as a hobby, otherwise I'd have 
to get a better lathe !!!

the only model engine part for which this tedium is an issue for me is valve stems,
but in that case I want a 2000-grit mirror polish finish in the end, so while using coarser
grits to approach the final diameter I monitor the taper (with a 0.0001" vernier mic)
and eliminate it that way.

HTH, YMMV, etc...


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## goldstar31 (May 10, 2020)

Danuzzo said:


> Thank's for all the input. To answer goldstar's question. Yes the lathe was bolted down.
> 
> I cannot financially or wisely spend the money to buy fancy measuring equipment, so I cannot level a bed properly. Plus I would not know the proper methods for doing so. However, I do like Tony's idea of mounting pads with jack screws.
> 
> Another question. With these 7x mini lathes, would the chances of having an warped bed be less with a 7x10 vs a 7x16 (less chance for error??) Just curious.



It doesn't do to bolt a lathe down- on a unknown surface. Unbolt it and use TWO sprit levels - one length ways one crossways. At least you will get somewhere - cheaply.  Again, use a cheap laser pointer- through the spindle and also therough the tailstock after removing the poppet.  I think the Model Engineer article 'Microscope on the Lathe is still on the net. Written by Exactus which was propably 'Ned' Westbury.

You should get some idea of what it is all about. 
Again, get Georg Schlesinger's Measurement of Machine Tools- rather than inventing your own rather doubtful ways


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## goldstar31 (May 10, 2020)

peterl95124 said:


> at least here on the west coast 0.001" is called a "thou" and 0.0001" is called a "tenth" (!)
> I've never heard a machinist use the term "mil", you do see it used in some specifications
> outside of machining, for example "10 mil" plastic sheeting is 0.010", but never in machining
> so 0.010" shim stock is "10 thou", not "10 mil".
> ...



The only time that abrasive paper should be used is at the end of a scraping cycle when one papers the arris is raised creating the spots which should eventually gt 25 points/spots per  square inch.

Thous? I also refere to gnat's cocks and midgie whiskers


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## BaronJ (May 10, 2020)

Hi Peter,



peterl95124 said:


> I've never been able to get the head perfectly aligned with my lathe bed (tightening the bolts changes the alignment, argh!!!)



Assuming that your lathe is properly mounted on a rigid surface that cannot move or warp, the easiest way to set the lathe up is to use the two collar method, and use shims or jacking screws at the tailstock end to very slightly twist the bed so that each of the collars measure the same diameter.

This is done by taking a fine cut, a couple of thou, across both collars without altering the cross slide in any way.

My two collar test bar is an 8" inch (200 mm) length of 20 mm diameter hydraulic piston rod with two 20 mm thick aluminum rings, 40 mm in diameter locktited onto it 6" inches (150 mm) apart.


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## fcheslop (May 10, 2020)

An often overlooked problem with the OP machine is that the bolting down pads (feet) are not machined correctly by the factory and if you merrily go bolting it down without at least giving them a cursory looking at it twists the machine
Iv skimmed a couple in the past for people when I had the facilities to do so and they were 0.025 or there abouts out
There are many ways to skin a cat my preference is to use test bars although Im lucky and made them when I had the equipment to do so on a cylindrical grinder
Again look at Bogstandards Darrens lathe write up the pics may well be missing but the methodical approach still holds true
The two collar method is in the Myford book I posted a link to  although Iv not seen any acknowledgement that he/she has looked into it
Horses and water 
cheers


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## goldstar31 (May 10, 2020)

From my shenanigans with my  Myford Motor problem- now solved- I am  setting the lathe up again.
The Myford  manuals for ALL the 7 series are available on the net to down load.  The 2 ring thing is there.

Taking Frazer's comments about skimming lathe feet, it may not be practical for some workers.
I must, however, agree with both him and John Baron about 'getting the bed' level, out of twist and probably suggest that dear old Tom Walshaw's book - writing as Tubal Cain in Simple Workshop Devices has a technique to hold his lathe on  penny washers and nuts and studding.  He lived in the English Lake District and the level of his lathes etc in his workshop actually moved.  

I did A Level Physical Geography  and was a member of a mountain rescue team! My home dates to Anglo Saxon times and Roman times as well as being undermined in later times. So it is on a concrete float and so is my newer worksop. So one CAN drop a slurry of concrete which automatically levels itself. So my lathe is going back to a reasonably level and solid base. Isn't education useful

Of course, the  lathe and stand are really too heavy to move at my age and I'm using steel rollers and a pinch bar made from a pneumatic drill end.  Brute force and bloody ignorance ?


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## Cogsy (May 10, 2020)

IanN said:


> Hi,
> 
> Let’s get real here.  addressing the above points in order:
> 
> 1) Your example of machining a valve stem with 1/2 thou/inch taper and a total end-to-end discrepancy of 0.025mm (1 thou) suggests a machined stem length of 2 inches - a full sized I.C. engine valve.  If you are intending to make critical engine components for your car, holding a taper over 2 inches is the least of your problems (in real a production environment such items would be rough turned on a lathe then ground to size - much quicker, easier and more precise)



Ok, 1-1/2" stem then, which takes the difference in stem diameter down to almost 0.02mm, still well outside the tolerance I like for my valve stems (to be honest I look for < 0.01mm variance over the entire stem length on valves). I would think a 2" valve stem would be a Brigss and Stratton size, maybe a motorbike, but certainly far from full size 'normal' I.C. for a car. At least all the ones I've ever worked on.



IanN said:


> 2) Your second point above considers two bearing journals 3 inches apart.  As I’m sure you already know, no-one would ever seriously attempt to make a shaft to the journal diameter along its entire length - you would machine one journal to size, move along and machine the second journal to size then machine the shaft in between to about 10-20 thou under the journal size (and leave it rough turned - don’t waste time, effort and money putting fine finishes where they are not required)


 What I was meaning here was a single cylinder (say a hit and miss) style crankshaft, not a multi-throw. One that uses ball bearings as main bearings. The bearing needs to be pressed onto the shaft and at least be a 'good' fit along the entire length, while things like gears, flywheels and even outboard bearings (for some designs) get placed along the 3" shaft-end so it needs to be on-size for it's entire length.  



IanN said:


> The issue with machine accuracy breaks down in to two sets of criteria:  Accuracy over short distances, and accuracy over long distances.  For most of us, accuracy over short distances (less than 1/2 inch) covers 99% (often 100%) of a hobby user’s requirements.  Unless you make full sized pistons for 3 litre car engines, I cannot imagine anyone actually needing to hold 1/2 thou over 3 inches
> 
> All the best
> Ian



Obviously I disagree with this (as you can see above) and I have a theory that the measuring system we use might have something to do with it. To imperial users,  a thou seems like a tiny amount but to metric users that's more than 2 full graduations on our measuring tools. When I'm machining for a critical dimension, like a bearing fit for example, I'm aiming to hit my number spot on but I will normally tolerate +/- one hundredth of a millimetre. So my 'normal' working tolerance on a precision part is within about 0.0004". So having each crankshaft half of a hit and miss to 1/2 a thou along it's length seems perfectly reasonable to me.


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## goldstar31 (May 11, 2020)

Today's gripping episode is the installation of my 'new' Myford and its ort of desecrated metal stand by cutting the floor of my wooden workshop floor. The concrete screed is   fairly level- if one ignores the   great circle sailing or whatever.  I did it in about 1945 and gues that it still applies

The deivery guys had sort of plopped the original metal stand and the  new Myford onto the  4 studs which I had earlier screwed down with nothing more that studding, nuts and penny washers.
Chucking a decent spirit level along the bed indicated  that it was pointing almost due North but as a basis to turn things-- I could forget it! So I unbolted the top holding bolts and sang 'I;m forever Blowing bubbles' because it was dead easy to crank up with a spanner underneath the feet- and in a few minutes, the bubble was spot on in 4 directions. I simply bolted the feet down.
Frankly, is that all there is to it, please? I'd forgotten.


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## IanN (May 11, 2020)

goldstar31 said:


> Today's gripping episode is the installation of my 'new' Myford
> :
> Frankly, is that all there is to it, please? I'd forgotten.



I believe you should have had a glass of Bushmills between achieving a level state and the final tightening

All the best,
Ian


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## IanN (May 11, 2020)

Cogsy said:


> :
> to be honest I look for < 0.01mm variance over the entire stem length on valves
> :
> What I was meaning here was a single cylinder (say a hit and miss) style crankshaft, not a multi-throw. One that uses ball bearings as main bearings. The bearing needs to be pressed onto the shaft and at least be a 'good' fit along the entire length, while things like gears, flywheels and even outboard bearings (for some designs) get placed along the 3" shaft-end so it needs to be on-size for it's entire length.
> ...



Hi Cogsy,

Thanks for taking the time to reply - as you point out, we probably work in two different environments and have different expectations and histories and so have differing points of view.  My view point:

I was taught to use a mill and a lathe in 1969 and my first employer (while paying lip service to SI units) manufactured everything in Imperial units - during my time there I purchased a full set of Imperial measuring equipment and tooling.  My next employer was "metric".  I purchased a full set of SI unit measuring equipment and tooling.  I just work better in thous than mils and to this day resent having to buy every "tool of the trade" twice 

I am past retirement age but I still teach engineering apprentices (and lecture in engineering at a university) and so my view point is purely practical, so answering your points:

1) Why on earth would you turn the entire length of a valve stem to such tight tolerances when only half of the stem actually runs in the valve guide?

I based my comment on valve stems on many years experience of Mr Weslake's beautiful BLMC A series engine which had valve guides around an inch long (depending on engine version) - the critical fit of a valve stem is over less than half its length, the rest of the stem is surrounded by spring or manifold gas.  I agree that if you are in industrial manufacture you would grind the stem to size along its entire length, but as a "Home Model Engine Machinist" this target is quite unnecessary

2)  I agree with you entirely that bearings, journals, etc require accurate diameter shafts, but gears, eccentrics, etc are always fitted with collets, cotters, keys, or grub/set screws.  Please don't tell me you press fit everything along a shaft machined to a single dimension!

Finally, the units we work in have absolutely no relevance - it is the physical distance that matters

I hope we may agree to differ on these points.  As I said in an earlier post, there are two types of lathe owner, the sort who makes stuff and has a machine capable of doing what they want, and the sort who pursues accuracy and precision as a goal in itself.  As a hobby, both are perfectly acceptable.

All the best,
Ian


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## peterl95124 (May 11, 2020)

BaronJ said:


> Hi Peter,
> 
> 
> 
> Assuming that your lathe is properly mounted on a rigid surface that cannot move or warp, the easiest way to set the lathe up is to use the two collar method, and use shims or jacking screws at the tailstock end to very slightly twist the bed so that each of the collars measure the same diameter.



thanks BaronJ, but what i wan't able to communicate correctly is that it is the bolts that hold the lathe
head to the lathe bed that I can't tighten without upsetting the alignment of the head. I have to set the head
at an unaligned angle, then tighten the bolts, then re-measure the taper, lather-rinse-repeat, it's awful.
I'm pretty sure my lathe bed is too short and stocky to bend.


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## goldstar31 (May 12, 2020)

The question  which has rattled through what might pass as a brain is 'Why do people in their ( hopefully) right minds. disturb the setting of the headstock and spindle.

It is only when I have had to strip the lathe down to correct a worn bed.  Then, in the care of a Myford 7 Series, the settings were set in the factory NOT to be disturbed by us lesser mortals.

Would someone explain why?

Again, there is no reason to have a bed truly horizontal other than the ease of setting up.  A  lathe on a ship goes with the waves like the rest of us

Cheers


Norman


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## BaronJ (May 12, 2020)

Hi Peter,



peterl95124 said:


> thanks BaronJ, but what i wan't able to communicate correctly is that it is the bolts that hold the lathe
> head to the lathe bed that I can't tighten without upsetting the alignment of the head. I have to set the head
> at an unaligned angle, then tighten the bolts, then re-measure the taper, lather-rinse-repeat, it's awful.
> I'm pretty sure my lathe bed is too short and stocky to bend.



Sorry I misunderstood !
In that case I would remove the head and make sure that the underside that contacts the bed was clean and flat, doing the same for the bed surface where the head sits.  No shims or anything else under there unless the manufacturer put it there.

Align the head using a known straight bar in the chuck to the tailstock. Nip the head down. That should get you in the ball park.

From here its very much measure and adjust as needed to get everything as near true as you can.

As far as the bed bending, don't kid yourself !  I've seen cast iron cylinder heads bend without too much effort !

Good luck, it won't be easy but patience wins.


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## goldstar31 (May 12, 2020)

Of course Baron is right, it actually needs a test bar which in this case is either a No2 or 3 Morse taper.
However, mine is 6" long so that I can detect a deflection of half a thous. If however we all go back to the Propositions of Euclid( which all remember, adding a length of piping to extend the levverage we can move the spindle minutely. If course. we all know this and we can do  this minute compensation that Myford does to allow for the pressure exerted by the lathe tool.
No it ain't the book but that is what happens.

And the Best of Luck

Norman


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## JCSteam (May 12, 2020)

Frazer, Norman, and indeed John (Bogstandards, how is his health by the way? anyone know?). This thread is a bit of da-ja-vu for me. The three mentioned members, have been at the receiving end of me chasing my tail with incorrect technique and measuring equipment. I currently have my lathe in pieces as it needed a good clean an repaint, plus there were a number of issues that needed to be addressed, (me half nuts for one). A recent house move was a prime opportunity to "Start again", and do it right this time. Though before with Frazers assistance and fettling, the now +80 year old lathe could still hold a 1thou taper over 4" length, through summer and winter, and could be dialled in even more accurately if I wished, (for a day before the humidity changed and say goodbye settings). 
The Myford ML4 was bolted to a wooden kitchen worktop (not ideal), on M8 threaded bar cut to length. and bolted to the wooden top, with washer and nut under and above the mounting feet. The lathe could be slightly twisted to level the bed, then subsequent test cuts taken on a piece of solid bar prodruding unsupported 4" from the chuck., As already mentioned, cuts of only a thou or less a time, and when close to desired tolerance a spring cut is taken, whereby the lathe turned off, the saddle retracted, then another cut taken at the same setting, (ie don't move the handle for the cross slide or the compound). 

This eliminates any spring in the material your cutting or the tool, the heavy cuts you are taking will be compounding the taper effect, ease off and go slow. 

The same should be doable with the mini lathe so long as you are not planning on it been moved often. remove the rubber pads, and bolt directly to studding fixed to the workbench. get the bed as level as possible even by crude means such as a builders level. check and check again. Then begin your cutting, take a 10thou cut 1" from the end of the bar, and stop 1" from near the chuck. now your material will be less likely to spring when you take your 1thou cut, do a spring cut as described above after the initial cut then measure both ends with a micrometer. 

Report back what you find after you do the above, this is working to a tolerance of 0.0005" which unless you have to achieve something of greater accuracy for whatever your machining will suffice for most machining applications, it certainly did for me for......blimey that's going back two years now. The lathe set up has made parts that have paid for the lathe in full so the only cost to me now are the additional tooling, rotary table, fixed vertical slide, myford milling vice, lots of rusty hammers and files ect ect that I bought for £80. Even then some of it was sold to recover the cost. levelling me with some tool restoration to do and hadn't cost me a penny. BUT!!! Do spend money on good measuring equipment that will measure down to half the tolerance you want, or learn to live with the tolerance you can measure, ie micrometer only measures to 0.0005" then you can only realistically set up to a 0.001" tolerance.

Don't disturb your headstock unless you really have to, it'll never just bolt straight back on perfect, how do I know.....3nights in my garage says that haha

I hope this is of some help to you, and take it from someone who HAS been in your shoes a few years ago you will get there, just need to be realistic with the tool you have, and the tolerance you want to achieve.

Regards

Jon.


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## goldstar31 (May 12, 2020)

Thanks JCSteam for the mention.
I'm glad that you are trying to start up again after your move.
Me? I'm in lockdown and unable to get out of my bungalow and gardens- for the future.
Being a widower, it is quite boring. So really, part of the family gets my food and my daughter in Leeds keeps in telephone contact.

With the help of John Baron and a friend from Sunderland, I have been able to get the sort of new Myford working. It's aligned now and the motor- a split phase one- is running.  My Sieg C4 is stagnating now that I can find my shed warmer. I've just fitted the George Thomas ratchet 4 way tool post and next is the rear inverted tool post.  Where my chuck spanners are now are missing so I'll have to make a new set.  I can cobble one up to make a decent set. I've got the Quorn going and the Stent will soon be employed.

The difficulty now is getting metal. There is Argoshield gas in the Mig and that's about it. I'm or was a certifield welder after I retired and it solves a lot of almost insoluble problems at this difficult time.
Keep well and keep safe


Cheers

Norman


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## JCSteam (May 12, 2020)

Well Norm, if your bored up there I have some castings for a dividing head, sat under the bench that need finishing off, and I can get the extra materials from work (yes still working making plastic sheet, and Perspex face shields). Ill drop them at your doorstep next time i'm passing haha. 

Keep safe old friend.

Jon

PS I was told Noggin end are still selling mail order.


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## goldstar31 (May 12, 2020)

Thanks John but I already have 2 Dividing heads and 2 rotary tables.

Actually I can use my one hole dividing plate to get ANY number. Using TWO acme threads!

Thanks again

Norman


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## terryd (May 13, 2020)

peterl95124 said:


> at least here on the west coast 0.001" is called a "thou" and 0.0001" is called a "tenth" (!)
> I've never heard a machinist use the term "mil", you do see it used in some specifications
> outside of machining, for example "10 mil" plastic sheeting is 0.010", but never in machining
> so 0.010" shim stock is "10 thou", not "10 mil".
> ...



Hi Roger,

 glad to hear that about your terminology,  but I've heard serveral machinists in The US use those terms (mil) on Youtube videos so I assumed that it as always thus the case

TerryD


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## goldstar31 (May 13, 2020)

I'm deaf, part blind and cannot hear the phone or doorbell except very close. There is a present coming from my daughter and I'm indoors.

So time to find a lathe alignment chart- to get rid of all these confusions.
Lathes. co uk has a Colchester lathe set of test charts which should show how things should be conducted.

Again, Boxbord Lathes( a South Bend clone) also has a chart.  You may be luckier than me but I hope that the foregoing is of use.

I had to use an illuminated magnifying glass - but that's old age

Norman


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## IanN (May 13, 2020)

goldstar31 said:


> The question  which has rattled through what might pass as a brain is 'Why do people in their ( hopefully) right minds. disturb the setting of the headstock and spindle.
> 
> Would someone explain why?



Hi Norman,

OK - I'm willing to take you on.

My lathe is designed to allow the headstock to be rotated to allow short work to be cut to a steep taper.

The pic below shows my lathe.  The headstock is designed to rotate around the stud/nut just to the left of the belt round the spindle and the headstock is locked by the stud/nut on the radius "arm" next to the front headstock spindle bearing







What is the big deal with checking and setting the spindle of a machine?

As I have said before, I teach apprentices.  I teach them to check the alignment of their machine, the "tram" of their mill, before ever doing any work.  You never know what "raving loony" was on the machine before you...

Aligning a machine is a very simple and very straight forward procedure - people have been doing it for a couple of centuries 

The rreal issue is that it takes five years of college and employment - 40+ hours a week for five years - to qualify as a machinist.  If an "enthusiastic amateur" were to spend an hour a day and a few hours over the weekend on learning to use machine tools and reading text books (say 10 hours a week) it would take them 20 years to get to the point where they were as competent as a newly qualified apprentice....

People expect to be "experts" immediately.  I would advise an inexperienced new comer to the hobby to join a club, learn while an experienced mentor looks over your shoulder and accept that it takes time and effort to achieve your goals.

All the best, hope you stay safe and well,
Ian


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## goldstar31 (May 13, 2020)

Hi Ian

Sorry, I don;t think that I come into either of your categories.
I sort of appear near the edge of the 3 Standard Deviations from the Mean but still don't quite understand how I got an IQ of 135.


The way that I worked it was how to retire for the last 36 years

Whimsically

Norman


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## awake (May 13, 2020)

Ian, I've never seen a lathe like that. What is the make & model?


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## BaronJ (May 13, 2020)

Hi Andy,

As a guess, a very early Myford with the bolt on headstock, probably an ML1 or ML2.  Quite a rare lathe.


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## goldstar31 (May 13, 2020)

I've overhauled a ML2 so no!

I'd gamble on a Myford Drummond but I haven't seen one since seen one since ???? 1944

I'd been making a simple athodyd jet engine from Cpl Henwood's articles in Aeromodeller- amd I wanted  metering jet.
We did daft things like that at 14 in war time


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## goldstar31 (May 13, 2020)

This is the time of the Plague. At 90 and with a heap of physical problems, I thought it sensible to update my little workshop as I am unable- in law NOT to venture out- nor have vistors except those bringing food.

So why not make a profit out of my hobby? I can't go to the Working men's club, or the Conservative Club or the Masons where I'm a Provincial Office, mentor, auditor and 'something in the Charity.

Surprisingly, my last two bank statements indicate a rather large 'growth' after making sensible payments for nursing home staff and such.

So the over used TV blew up and the two printers- didn't print and my white dinner tux is new except that it has the price labels removed


So the 'new' price of a Super7- without anything in tooling etc is £3000 and again adding a motor( Oh Yes) and the gearbox , PXF and stand are nudging £7 to 8K. Again, without even chucks or faceplate or whatever.

And the bank rate after tax and allowing for inflation or 'devaluation' is a vast depreciation like giving money to a millionaire beggar.  So I bought to enjoy and as an investment when I'm 9 minute puff of smoke at the crematorium.

That's what I did when all these other people where 'going to the pub'

Verb Sap

Norman


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## IanN (May 13, 2020)

Hi,

My lathe is a Drummond - according to the makers, it was catalogued as the "3 1/2-inch Centre Back Geared, Self-acting Sliding, Boring, and Screwcutting Lathe" - not a very snappy title, and after drummond introduced a lathe called the"A Type" it was referred to as the "B Type"

My model dates from about 1910 (from the serial number).  Based on the motor rating plate the conversion to electric motor was done around late 1950s, long before I took custodianship of it so I do not have the original stand, flywheel and treadle.  On her 100th birthday I sat in the workshop and shared a couple of beers with her - I told her about all the future project I would be building on her, and she told me a few things too.

For illustrations of far better examples and more info, see Tony's site:





__





						Archive: lathes.co.uk
					

Machine Tool Archive, lathes.co.uk, Tony Griffiths



					www.lathes.co.uk
				




All the best,
Ian


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## JCSteam (May 14, 2020)

Ian, the bolting arrangement on your Drummond B is similar to the myford ML4 I have, (from 1938, I managed to date it) Whereby the headstock has a single bolt where the pulley is, and can pivot (only slightly for the ML4, and also ML2) around this pivot point, and two studs and nuts go from underneath into the headstock. So the head can be dialled in (I use rollies dads method), and then secured to the bed with all bolts tightened.

As it happened a new saddle and cross slide turned up for my ML4 with only 3thou backlash on the leadscrew, a vast improvement to my 20thou I had before with the old one. Looking at the serial number stamped under the castings, it was built around the same time as mine, wish I could have found the rest of the lathe and not just a few bits from it. Just need a new gib strip for it for the saddle and to redrill for the thread dial indicator on the front. But it also gets rid of a 10thou error when traversing the cross slide, from someones previous attempts to re-machine it and set it up wrong.

As for the Drummond been rare, a friend has three B's sat in his garage he hopes to make one good one from the bits for himself, and sell the other ones as spares, one as complete. I may end up doing it for him simply for the pleasure of it.

I believe i've managed to get my headstock somewhere near true for now, and ill proceed to bolt the lathe back together, then check from there using rollies dads method and also a MT1 to MT2 socket adaptor in the spindle, it prodrudes 6" from the chuck and measures within 0.00005" at both ends. test bar would be better but it will work for me. as long as what I make is within +/-0.0005" then I will be happy with that and it'll work for what I need.

Jon


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## goldstar31 (May 14, 2020)

A zillion years ago, I bought a Round Bed Drummond Lathe and a Drummond shaper.  If I recall it was £9 for the RB.

Not an  earth shattering event then and only a couple of Chinese beers now- or before the virus struck the Chinese New Year!
aS far as lathes are concerned Drummond Bros were taken over by Myford, Then it was Raglan and then Myford went into administration and the name was bought by RDG who are now restoringMyfords from £3000 to-- well, astronomical figures. All that I have dome is too buy ' one of the last of the many' at a price more or less at the bottom of the present prices and a fraction of the price of a cruise that did not happen.

In the middle of this crisis, I am  still going further and further into the black- sitting watching the dismal news on the telly- and bored rigid like most and almost ready to take my little bag across the park to adjoining mental hospital.

So Drummonds and taking a 7 x12 to bits and not knowing how to get it back again? No, not realy.

Have a nice day


Norman


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