# Aligning a lathe to turn parallel



## pete (Jan 15, 2011)

Ok,
Andrews thread about "Lathe recommendations in Canada" started to go a bit off track and we were approching a hijack. Please see the last few posts about lathe alignment on page 3. Does anybody here have anything to add. Whats your approach to aligning a lathe to turn parallel? Methods? Even links to some specialized ways of doing it?
IMO, It's a subject that is really not stessed enough in regards to importance.


Pete


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## Ken I (Jan 15, 2011)

Pete,
    I presume you are talking of a lathe that does not turn paralell from the carriage - ie the headstock is out of line with the lathe bed.

Any realignment method is dependent on how the manufacturer attached the headstock to the bed.

In the case of a Colchester it is via tapered pins. I whacked one out of line when I was an apprentice (left the chuck key in - damn fool) - to straighten it out I had to pull the pins (replacing them did not entirely correct the error) and via a process of running a dial gauge up and down a precision shaft (a bottle square with precision centres) between centres and then whacking the (lightly bolted but not pinned) headstock with a mallet and measuring with a dial gauge to get it back into line. I then had to re-ream the tapered pin holes and re-install the pins.

The whole process required several methods - shaft in 4 jaw - check tailstock - precison shaft between centres and the final proof was an accurately turned up piece of bar by the best turner in the shop who had to "sign it off" - I remember the tongue lashing I got for buggering the lathe up in the first place as well as a few more each timed he deemed my realignment "not good enough".

My mini lathe has a headstock profile that matches the lathe bed so any error here could only be corrected by scraping the underside of the headstock (horrors) or reboring / sleeving the main bearing holes in the headstock.

etc. etc.

You need to first measure to determine where the error lies and then figure the best way of correcting it.

So I don't think there is any specific way to fix this problem as each machine design will have its own peculiarities.

Question - How did the lathe get out of whack ?

Ken


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## pete (Jan 15, 2011)

Ken,
Nope my lathe is just fine, I have my own methods for lathe alignment and think I get pretty good results. I started this thread as maybe a way to show guys that just bought their first lathe that there's more to it than just bolting a lathe to a bench top and then thinking their good to go.

Pete


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## lazylathe (Jan 15, 2011)

I would like some more info on this if possible!

For example:
The lathe is on a sturdy bench that is level to the concrete floor.
The lathe is bolted to the table.
I would need to check the lathe bed with an engineers level to get it perfectly level.(?)
If all that is good, how does one tell if the headstock or tailstock is out of alignment?
Do you require a precision cut bar to ensure it is in alignment?
I have read of bars that you can buy that have morse tapers cut at each end to fit the headstock and tailstock,
is this the ideal method?
Or would using a D.I. be sufficient?

Sorry for all the noob questions, but that is what i am!
I am reading to try and gain more understanding of techniques and methods.

Andrew


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## Ken I (Jan 15, 2011)

Pete,
    Yes - I read the original thread - jumped to the (erroneous) conclusion that it was something more fundamental.

Lathes can get twisted out of shape by injudicous bolting.

Most of the larger industrial size lathes I have had mounted on anti-vibration mounts so simple leveling generally sets them up right.
When rigidly bolting to a foundation you shim so that it is standing firmly before bolting - during bolting place a long shaft in the chuck and a dial gauge in the toolpost about halfway down the carriage - if the dial gauge starts moving as you tighten down - check your shimming - some movement is normal but the dial gauge should be where it started once fully tightened.
Some machines have jacking bolts adjacent to the hold down holes and you can work them against each other so as not to "bend" the lathe.

Agreed it is never a simple bolt it and forget it - that can get you a permanently twisted lathe.

Andrew - leveling is always good practice but I wouldn't lose too much sleep over it - I'd be more concerned with ensuring that my bolting is not twisting the lathe.

Ken


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## bambuko (Jan 15, 2011)

As Pete says, we were discussing ways of securing lathe bed to bench.

1 - our small lathes are very light, our benches are often not as solid as they should be and workshop floor is often flimsy timber. However much effort you out into securing the lathe without distorting it, it is often all in vain because everything moves, twists and distorts.

2 - all the lathes with more than three fixing points - by default it is difficult to achieve flat plane that avoids distortion. If you have one fixing point (like on watchmakers lathe with pedestal under headstock) you cannot distort it by fixing to bench. Similarly with two fixing points (again mostly small lathes) you are not twisting the bed (as long as you discount the width of the pedestals). With three fixing points - you achieve flat plane by default. And yet most of the lathes have at least four and often more bolt downs.

3 - however carefully you adjust all the multitude of legs/fixing points, unless you leave one end of the bed free, you will be affected by thermal expansion distorting the bed fixed rigidly to bench

Solutions:

Some people fix the lathe to something substantially stronger and heavier than the lathe (eg granite block). 
I was in turn extolling virtues of the idea used by Hardinge in their HLV-H lathe. Three point support (two under headstock, one under tailstock), tailstock end allowed to expand as well as preventing bed from twisting (single point). All three points sprung loaded. One could adapt similar idea (using intermediate plates between lathe and bench) to our little lathes. 
Advantage of this arrangement - it is impervious to flimsy floor, weak bench, not affected by thermal distortion and not bothered by owners adjustment. 

Chris

ps mine is *Prazimat DLZ*


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## bambuko (Jan 15, 2011)

lazylathe  said:
			
		

> ...I would need to check the lathe bed with an engineers level to get it perfectly level.(?) ...


Doesn't matter at all whether it is level or not - levelling is simply an easy way to make sure that the bed is not twisted i.e. if both ends are level than it means that both are the same (not twisted), but you can incline the bed towards you (for example) and providing that both ends are inclined by the same angle - you are fine.
Of course you will find both internet and hobby magazines full of people who will tell that it will never work unless you have it absolutely level. 
:big:
Don't let them fool you 

Chris


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## pete (Jan 15, 2011)

My last hour of single finger typing about this has apparently disappeared, Till I cool off I'll sit back and read all your points.

Pete


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## bambuko (Jan 16, 2011)

I am sorry to hear about your misfortune Pete.
I am sure it has happened to all of us at some time, usually after some long typing session 
My trick to prevent this disaster, is to select just typed text and "copy" it, before using either "preview" or "post" buttons - this way if anything goes pear shaped, I simply use "paste" to recreate my lost posting.

Chris


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## pete (Jan 16, 2011)

Chris,
Thanks, That's what I get for trusting the computer gods. 

Pete


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## pete (Jan 16, 2011)

OK, Let's try this one more time.

Andrew, Yeah those accurate test bars with the Morse taper on one end do work, But won't do everything. Your headstock and tail stock tapers must be spotlessly clean, Properly ground, and undamaged. A .0001 reading DTI would probably be the best to use, As a .001 reading dial indicator IMO doesn't give you a fine enough resolution.Slide the test bar into the headstock M/T and give it a fair tap to seat it into the taper. Fixture your DTI so the probe tip is really close to the C/L of the test bar. Use your carrige travel to run back and forth on the straight portion of the test bar. Reset the probe tip to the top of the test bars C/L and repete the above test. Do the same testing setup for the tailstock. This will show just how well both the headstock and tailstock are aligned with the lathe bedways. But it won't show how well the headstock and tailstock are aligned to each other.

All the postings about lathe leveling are ok, But a dead level lathe is just an easier way to get your lathe real close to what you really want. Those postings forget that this is a static condition. Due to various tollerance stacking ect. you want to test your lathe under cutting conditions. It's a lot better to have a lathe that turns parallel end to end than one that's just level. You could set the lathe up to be 45 degrees out of level and if the lathe is well aligned it will still turn parallel.

To do this I use a 2" diameter bar of even scrap material around the same length as your lathe will take between centers. I turn between centers so in the future I can do testing by lightly machining the bar again. Far faster to set up than to accuratly set up the bar in a 4 jaw chuck. Once your scrap bar is machined end to end so it's fully cleaned up you make a light depth of cut pass the full length of the bar. Measure each end with a accurate micrometer. Any differances in size, Then your lathe needs aligning. Since my Emco lathe has a tailstock that can't be adjusted to turn tapers, Then what needs to be done if the test bar isn't parallel is twist the tailstock end to match the headstock end. You do this by using shims or jacking bolts. Say if your test bar was slightly smaller at the tailstock end. You need to twist the lathe bed AWAY from the cutting tool tip. I'm not 100% sure of the exact order lathe alignment is done with a lathe that has a tailstock that can be adjusted side to side for tapers. So I'm hoping that someone who does will post that here.

There's a lot more to aligning a lathe than I've posted here, I didn't even mention what to do with shims or jacking bolts, scraping ect. if your headstock is missaligned with the lathe ways, but this is getting long enough. Obviously when your getting down to .000? tollerances then EVERYTHING you do has a effect somewhere. If your next part you want to machine on the lathe is a harder material, Different material, Larger depth of cut ect. Then this can and will show up to greater or lesser extent when trying to turn truly parallel. The bench the lathe is bolted to, Method of bolting it down as mentioned by Chris, How to let the lathe compensate for temperature fluctuations ect,ect,ect. Needs to be addressed too. This is why I started this thread because it's a lot more complicated than a lot of people think. Is it nessisary to align a lathe to .000? tollerance? Only the user can make up their own mind about that.

Oh yeah, I forgot to add that I think it's a good idea to test any lathe. If you don't test it then you don't really know just what your actually able to achieve as far as tollerances for any machined part.

Pete


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## pete (Jan 17, 2011)

Hm-mm, Over 450 views and nobody wants to add to this. I was hoping I could learn something too. Will have to check this thread when I get back from work in a couple of weeks.

Pete


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## ttrikalin (Jan 17, 2011)

Pete,
Most times I use the shave the bar method, as you describe above. 
But a very neat alternative is Rollie's dad method. A lot written on it, so I give links.

igor.chudov.com/manuals/Rollies-Dads-Method-of-Lathe-Alignment.pdf

And if you like video

[ame]www.youtube.com/watch?v=ZaIuHNFIFNw[/ame]


Take care, 

tom in MA


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## lazylathe (Jan 17, 2011)

There is a lot of info in this post for me to try and digest!
I hope there is more to come!

A lot to contemplate and figure out.

I can see the ladder in the distance but i am so far from the first rung it is not even funny! ;D

Andrew


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## Blogwitch (Jan 18, 2011)

When I refurbed my old Myford ML2 or 3, it was just a matter of slackening the head hold down bolts, and gently tapping the head into correct alignment.

The Atlas on the other hand was brought into alignment using a cold chisel and a file on the guide that sat in the bed channel. By careful manipulation, you gradually 'kicked' the head around until you got it turning perfectly parallel.

When I came to fix a mini lathe, I actually used cooking foil shims on the bedways under the head to achieve the same thing. Bottom part of this post.

http://madmodder.net/index.php?topic=627.msg5193#msg5193

On the new lathe I have now, there are jacking bolts that can be used to kick the geared head around if ever it starts to turn tapered.


Bogs


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## lazylathe (Jan 18, 2011)

Thanks Bogs!
I had read through the whole posting on fixing Darren's lathe and it was an excellent read!
That was some amazing work and very logical thinking of how to progress with such a fix!

Andrew


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## ChrisB (Jan 18, 2011)

I am very tempted to try out the Rollie's dad method on my Mini Lathe, but rather scared to find out what the results would be. I already know it turns a slight taper, but not knowing a value almost makes it easier to ignore. 

Seems to me that having a value attached to it is going to get me down a dark path of chasing my own tail forever :.


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## bambuko (Jan 18, 2011)

Getting it adjusted to perform best is one thing, keeping it this way without constant tweaking of your jacking screws and bolt downs is completely another ...
So if you start with timber floor, timber bench etc you are might as well not bother - all these things are affected by both humidity and temperature, constantly twisting, bending and changing.
You are better off with concrete slab for a floor, solid metal or granite for a bench etc.
But ... (yes I know I am boring ;D) why confront the problem instead of avoiding it - let me repeat here (because it's the best place for it I think) what I have already described in *Andrew's thread* - arrange three point spring loaded boltdown and you will never worry about twisting your bed or needing to adjust it. 

Chris


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## mu38&Bg# (Jan 18, 2011)

I used the dad's method to initially set up my lathe. This got it close but seemed difficult to zero in and wasn't perfect. I recently readjusted it, this time turning a 9" long piece of 2" diameter aluminum and measuring taper with a 10th's mic. I was able to bring it true like this. My Clausing 4900 stands on 4 anti-vibration pads with adjusters on concrete. I didn't have access to a machinist level so I'm not sure how close mine is to being level.

Greg


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## GWRdriver (Jan 18, 2011)

bambuko  said:
			
		

> Of course you will find both internet and hobby magazines full of people who will tell that it will never work unless you have it absolutely level. Don't let them fool you


Never work? I doubt it, . . work better maybe. One of the things I've done since I entered the hobby is read. Read read read read read - everything I could get my hands on going back before the turn of the previous century. I've also talked with many people with years of machine tool experience and read dozens of accounts or specifications for equipment installation. I was involved in design and construction of two automotive plants in the South (Nissan, Saturn) including the construction of concrete machinery foundations and subsequent machinery installations and absolute LEVEL was of primary concern. I was also similarly involved with the foundations for a major MRI installation at Vanderbilt Univ Hospital where there was even more concern with absolute level and elimination of vibration. Nowhere have I ever read, or heard, even once that leveling didn't matter, even for the garage guy, until today so you'll have a lot of 'splainin' to do to convince me otherwise. Personally I doubt if all those people and sources are wrong but then, what could it hurt? The problem for most of us is that a level of the level of precision necessary to be of any benefit is very difficult to borrow (and very expensive to buy.) We can't just run over to the tool crib and check one out so we do without.


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## bambuko (Jan 18, 2011)

Hi Harry, 
I am not out to convince anybody  
I am not one of these types frequenting interweb forums, who will argue to death, because they are right :big:
Forum format is not the easiest to conduct discussion anyway, so I am perfectly happy to agree to disagree and walk away 
I have nothing against levelling. By all means do so, to the best of your available equipment, your ability and your desires.
Just give me one rational reason why a lathe with bed at an angle of 1 deg to horizontal will perform worse than the one at an angle of 0 deg  and I might listen :bow:
Of course, within reason - I would not expect lathe with a bed designed for horizontal operation to perform well, when turned into slanted bed version...

BTW this subject has been done to death on other machining forums ... and it never lead anywhere apart from a lot of heat being created.

Chris


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## Ken I (Jan 19, 2011)

O.K. let's throw some gas on the fire.

As an engineer responsible for the installation of hundreds of machines as well as the design and construction of dozens - as a person who was raised on the "level it - level it - level it" gospel - a gospel I practice simply because it IS good practice.

Machine builders build with their machines dead level - so that is how you should site them. Siting them otherwise might introduce stresses that will "change" the machine slightly - so for really precision work - it's mandatory.

Having said all that it (in most - not all) cases it doesn't matter if your machine is out of level slightly - most lathes would work fine if you bolted them to a wall. On a mill you might want to use an inclinometer or autocollimator - in which case the ground plane is your reference and it better be right.

You need to be more concerned about introducing a twisting moment into your equipment - by following good leveling pratice - you are less likely to screw it up.

So yeah - its really important - maybe.

Ken


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## bambuko (Jan 19, 2011)

OK 
Put three legged stool on the floor and it will be stress free, without you having to adjust any of the legs to prevent bending and twisting.
Put four (or more) legged stool on the floor and the chances are that without careful adjustment of the legs it will be bending and twisting introducing stress.
Now - you can adjust the legs to take out the stresses, without making the top level. It can be done, but it's not easy and it's difficult to know when you have adjusted it just right. On the other hand if you use levelling as a means of testing the adjustment - it's easy to do and you know when you have got the job done.
There may also be other, practical reasons why keeping things level is advantageous. 
So, I am not against levelling - it makes perfect sense to use it, but it doesn't matter "per se". If you had means of accurate measuring of angles you could have lathe bed at an angle (providing it is not ridiculous) without stressing it, as long as this angle is the same along bed length 

This discussion reminds me similar argument about wheel quartering on the steam locos - there will be some people who will tell you that "it has to be" at 90 deg exactly. B******s - anything close enough will do, as long as it is the same for all the axles.

So, as Ken says "...You need to be more concerned about introducing a twisting moment into your equipment..." How you achieve this is up to you - I prefer three legged stool, somebody else might prefer to adjust their many legged stool 

Chris

and just to lighten up


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## mu38&Bg# (Jan 19, 2011)

With all this said, does anyone inspect their hobby parts to the .0001"? I recently checked a paying part after that above mentioned alignment process and found it was ±.0001" on the OD and maybe ±.0002 on the ID over 5.5" length. Elsewhere, I posted I had a problem with the ID being tapered, but found after I parted it off, a ridge at the bottom of the bore where I measured about .002" smaller ID. I'm not sure if I got distracted and didn't finish boring. It pays to check alignment if you need to do accurate work. If you can't, or more likely the shop doesn't give you time in a production environment, you put in a 12" reinforced foundation and spend the money to have a machine installer to put in your machine so it doesn't need to be checked often. There is a difference between a production environment and hobby shop. Every individual has their taste in what they desire to enjoy the hobby, whether it meets ISO specs or not. An individual who desires accurate parts will listen when they need help. Had I access to a machinist level, my lathe would get the treatment. Even without one, I am happy with the parts.


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## Ken I (Jan 19, 2011)

dieselpilot  said:
			
		

> There is a difference between a production environment and hobby shop. Every individual has their taste in what they desire to enjoy the hobby, whether it meets ISO specs or not. An individual who desires accurate parts will listen when they need help. Had I access to a machinist level, my lathe would get the treatment. Even without one, I am happy with the parts.



Couldn't agree more - well put.

Ken


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## ieezitin (Jan 19, 2011)

Im gonna be the asxxxle here.
If anyone who thinks there worth a shot the machine would not be the weakest link, just peruse the net and other hobby forums and see some of the most beautiful creations made on machines such as a craftsman 618  6 lathe and other temperamental small equipment including the Asian clan.

Getting your equipment dialed and zeroed in for business does not necessarily mean your work will reflect your machine capabilities, its you the operator who is responsible and to know its incongruities.

I have a 12 Atlas that I have used for 12 years now, its level and not twisted! But she cuts a slight taper, I know this and I build it in or I avoid cutting tapers on it, it heaves on knurling duties so I slightly angle the tool and dog it down on the tool post, 4 away from the headstock she rises .002 I accommodate that, it will not cut a 050 cut under power it will burst the half nut!, my Logan on the other hand will handle all of the above with no quirks with accuracy but!! Vibrates at high speed and everything turns to crap.

Machining is an art and knowing your boundaries is a part of the knowledge, we are hobby machinists our environments will not compare to industrial standards but saying that there are people out there who produce first class parts with simple practical tooling why because they are machinists and realists . know your frontiers and be in harmony with them.

If I have offended anyone so be it!.   God bless   Anthony.


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## pete (Feb 2, 2011)

I just got home from work and thought there was some interesting points raised. I'll have to reread them in the morning when I'm not dragging my butt.

Pete


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## Ken I (Feb 2, 2011)

ieezitin  said:
			
		

> its you the operator who is responsible and to know its incongruities.



Well put - I once turned in a substandard part and blamed the machine for it - did I get a roasting - I was then tasked with doing it again on the "worst" machine in the shop - and no excuses would be accepted - it might take a little longer - but no excuses - guess what - I did it - lesson learned - I have never blamed the machine since.

If you can't fix your machine errors - you should at least know what they are.

Ken


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## pete (Feb 2, 2011)

Ken,
"If you can't fix your machines errors - you should at least know what they are." Very well said. It's pretty well impossible to compensate for something you don't know about. That's the main reason I started this thread. I have no industrial machining experience other than talking with various machinist's on different job sites. But in industry with their heavy, rigid equipment the first thing they do after getting a new machine is level it, Then bolt it down in a unstressed condition. Then do final alignments. Yet we hobbiests expect to take a really lightly built machine, Bolt it down to whatever surface is handy and expect it to perform dead true. It took me a lot of years of reading, thinking, checking my equipment, to figure out even some of this. The majority of hobby type lathe manufacturers do a pretty poor job about educating their customers in my opinion.

Pete


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## dwentz (May 16, 2011)

So my buddy down the street has an old South Bend that came off a ship. I wonder if they kept it level?

Even my big lathe on concrete moves, and twists and bends under load. I have put an indicator on the bed while taking a heavy cut, and the bed does warp during the cut.

I was taught to align the lathe bed for square, and to do it use small wires from the left back to the right front of the bed, and from the left from to the right rear, Let them cross. If the wires touch both ways it is good enough. If they do not you have too much warp in the bed. The wire is very fine strands from multi strand wire. It gets the twist within a few thousands on a 3 or 4 foot lathe. I learned this from my buddy down the street with the South Bend. He was a Navy machinist, and the old South Bend in his basement is the same lathe he used in the Navy on board a ship. Looks like it just came off of the showroom floor too, he takes real good care of his stuff.

Dale


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## Ken I (May 17, 2011)

That's a cute trick I've never heard of - make mental note for future reference.

Thanks.


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## lordedmond (May 17, 2011)

they used the wire method to align the bearings on steam turbines before lasers were invented, stretch it tight between the end ones and take readings 


Stuart


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## pete (May 24, 2011)

Dwentz,
I've been away at work so just read this, I'd certainly agree with Ken. That's a new one for me and very clever.

Pete


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