# Observations on machining---The things I find most difficult---



## Brian Rupnow (Aug 29, 2008)

Well, I've been "machining" now for about 5 months. I bought my 10" x 18" Craftex lathe in March of 2008, and my CT129 Craftex mill in mid June. I must say that I like the machines very much, and that they perform very well from this novices point of view. I have just completed my third running model steam engine, and although I have for all intents and purposes not machined much of anything before this year, here is what I find:#1-Probably the most difficult thing I have tried to do is to cut threads. I know the theory, my machine does have a thread dial, and I was able to solve the mystery of what "change gears" are and how to use them. Did I succesfully cut threads???---No!!! I only tried a couple of times, but since it was one of many "lets try this and see what happens" exercises, I left it and went on to other things---(a note here--the slowest my machine will go is 115 RPM---some feel that even that is too fast for thread cutting.). I have mastered the secrets of turning to a finished diameter, boring to a finished inner diameter, drilling with the tailstock mounted chuck, and reaming. I have pretty well sorted out the "feeds and speeds" thing, and can with some degree of success measure a part in the lathe, subtract the amount (diameter) that I want to end up with, and divide it by the number of thousandths that my cutting tool will remove from the diameter of a peice being turned when I advance the tool by one "unit" as marked on the feed dials. I have used the 3 jaw chuck a lot, the 4 jaw chuck a bit, and turned between centers with a faceplate and lathe dog. As for milling, well, I have found out that 4 flute end mills don't plunge cut worth a darn (just as everone told me)---that trying to cut with the endmill revolving the wrong way can result in some spectacular and startling crashes, and that even when the machine is turned off, to quit reaching in with my hand under the cutter (and I have the scars on my knuckles to prove it.)---I have found that if you dare to ask an opinion about what type of milling vice to use you will get 600 opinions and probably start a range war. I did buy a rather horribly expensive rotary table and a bed mounted tailstock to go with it, and have used it once.---It works exactly as the machining books say it will, and some day I may find more use for it. My battery operated edge finder does work, and works very well, but without a digital read out system on the bed of my mill, you end up doing most things "by guess or by God" anyways, which renders the edge finder rather useless.--I do really like and use the digital readout on the quill travel. The most difficult thing that I deal with is trying to keep things square and parallel in the mill. I do have a good set of parallels, but they are almost always a bit too wide or a bit too narrow for the part I am milling. I always give whatever is in the milling vice a whack with a small dead blow hammer to set it down tight against the parallels after the vice is tightened, but even so, some of my parts are pretty "fishy" when it comes to parallelism of two opposing sides. I use the mill mounted chuck a fair fit for drilling and reaming, and other than the fact that the chuck is kind of a cheap darn thing, I haven't experienced any problems with it.---My mill really doesn't like drilling anything much with a drill larger than 1/2" diameter---I have a box full of blown fuses to prove that!!!---Brian


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## Bogstandard (Aug 29, 2008)

Brian,

You are going thu a massive learning curve, just like everyone else and his dog have been thru, maybe in your case a little quicker.

IT NEVER STOPS.

Old or young, experienced or no, we learn all the time in our quest to get material cut to how we want, it just gets a little easier over time.

Welcome to the club.

John


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## SmoggyTurnip (Aug 29, 2008)

I loved reading this post because I can relate to it so well. I have hade my machines for about 1.5 years but they sat in the basement for about a year before I had a chance to really use them. I have been playing with them for the last 6 months and have learned alot so far. The biggest surprise is just how difficult the hobby is compared to what I thought it would be, but that makes it so much more fun. Thank god it is only a hobby because I would starve real fast if I had to make money at it. I agree that threading was tough to get down and I haven't done alot of it but i have alot more confidence in it now. One thing you didn't put on your list is parting off - it is still a big question mark for me - broke lots of parting tools - pulled parts out of the chuck etc. but the last 2 times I did it everything went OK. Another observation is the amount of stuff you need to do a job - I am always missing some tool or attachment that would make the job easier. It doesn't matter what the job I have in mine it always takes 10 times longer than I thought. Now I know why it costs so much to get some machining done. Anyway thanks for the post and keep at it - I am watching you.


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## mklotz (Aug 29, 2008)

> I do have a good set of parallels, but they are almost always a bit too wide or a bit too narrow for the part I am milling.



Make your own parallels to suit. I've made dozens of special purpose parallels and, while they aren't up to metrology standards, they're plenty good enough for model making.

And Bogs is right about the learning curve. It's further complicated by the fact that it's a different learning curve for each individual; none of us are doing the same things, have the same tools, nor puzzle out the same personal methods for accomplishing something.

Console yourself by asking yourself the following question, "If there were a hobby I could completely master in six months, would I want to pursue it?"


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## Metal Mickey (Aug 29, 2008)

Brian, as someone only a few weeks ahead of you there is one thing that you didn't mention regarding screwcutting that caused me trouble initially and that is setting the topslide over to the correct angle. For what its worth (not a lot I expect) I made an aide memoire that I printed out and laminated. This stands next to the lathe and I have had few problems since....I did make a crankshaft nut for a vintage BSA 500 for a friend..(Link if you want to visit is http://www.mikes-models.com/ccbsanut.html.

The download can be found here http://www.mikes-models.com/downloads.html Usual disclaimers apply, its what I use for my screwcutting and it is from a novice, please bear that in mind.

Its good fun though eh!


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## Metal Mickey (Aug 29, 2008)

Oooopppppsssss..... sorry, something else I forgot.......the biggest aide to improving my relatively new skills, above all else by miles is..........DRO's! I bought a new variable speed Chinese lathe and specified DRO's. When working with them I immediately sourced a 3 output set up for my milling machine (a firm in Hong Kong suppled everything and a lot cheaper than UK - including shipping!) and they work fine, its just me that don't..... :big:

So if you were to invest in ANYTHING buy and fit DRO's. They also have the advantage of imperial/metric readouts and backlash, whilst still there, is much much less of a problem. I just wish I had them sooner......


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## pelallito (Aug 29, 2008)

MM,
Can you post where you got the DROs from? I would like to add some to my lathe.
Thanks,
Fred


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## Metal Mickey (Aug 29, 2008)

I will look out the address and post it back to you via private email if I can.....


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## Metal Mickey (Aug 29, 2008)

The company I used supply everything and the shipping is included (arrived quickly as well) and their communications were excellent for me. After they arrived I emailed them a couple of questions and they were very helpful. There may be other cheaper solutions now but at the time of my purchase these were the cheapest. You may want to test that out though now. I thought it was Hong Kong but it was Singapore after all.

Either enter ebay item number 330264121487 or I think this link should work http://cgi.ebay.co.uk/Meister-TOP10-3-Axis-Digital-Readout-Mill-DRO-FP1-FP2_W0QQitemZ330264121487QQcmdZViewItem?hash=item330264121487&_trkparms=72%3A984%7C39%3A1%7C66%3A2%7C65%3A12%7C240%3A1318&_trksid=p3286.c0.m14

I do not have any relationship to the company involved. I only bought once from them. Although I will be buying another set for a Myford ML7 I have bought and refurbishing, which will replace my little Myford ML10 (a great machine....)

Hope this helps.

Mike


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## pelallito (Aug 29, 2008)

Mike,
Thank you for the link. I would like to get one for my Atlas 12". I will not be getting it now, but hopefully soon. I need to finish some other projects before getting involved in new ones.
Regards,
Fred


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## rake60 (Aug 29, 2008)

Well Brian I'd have to label you as a NORMAL BEGINING MACHINIST.

If anyone tells you they didn't have a bit of trouble learning to single point thread,
They are either lying to you, or they have never actually done it.

I have a video posted on YouTube cutting a 10-32 thread in brass at 600RPM.
One comment posted to that video called me insane! LOL
In reality it isn't insane at all. A 10-32 is a very good thread to practice on.
It's major diameter is .190" so a 3/16" piece of brass is already to size.

Cut thread relief groove .050" deep where you want the thread to end, and go for it.
It's an even number thread, so pick any number on the thread dial as a start point.
Even at high speeds a 32 thread per inch doesn't have the carriage moving all that fast.
If you do happen to miss disengaging the half nut at the relief groove, SO WHAT?
The thread is only about .050" deep and your practicing with brass.
The tool will just make that relief groove a little wider. 

If your interested this is the video that caused me to be called insane. 

[ame]http://www.youtube.com/watch?v=pAwy6CUnzJ8[/ame]

It's a real good thread to practice on using 3/16 brass.
The only way to cause damage to the machine would be if you'd fall asleep after 
engaging the half nut.

Rick


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## Brian Rupnow (Aug 29, 2008)

Rick---All I can say is---"You're a far braver man than I am!!!"---Brian


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## baldrocker (Aug 29, 2008)

Screw cutting? Screwcutting? Watsit?
Paul


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## rake60 (Aug 29, 2008)

Brian Rupnow  said:
			
		

> Rick---All I can say is---"You're a far braver man than I am!!!"---Brian



Not at all!

Slow that down to your lathes slowest speed and try it on brass.
As I've said if you miss the exit groove it won't damage anything.
A slight miss might have you checking your pants.
A bad miss may cause a change of socks!  :big:
It won't have enough bite to do any damage.

Rick


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## greenie (Aug 29, 2008)

rake60  said:
			
		

> I have a video posted on YouTube cutting a 10-32 thread in brass at 600RPM.
> One comment posted to that video called me insane! LOL
> In reality it isn't insane at all. A 10-32 is a very good thread to practice on.
> It's major diameter is .190" so a 3/16" piece of brass is already to size.
> ...



Insane, INSANE, what IS this TOTAL garbage that your talking about, if anybody has called you that, for what your doin', well, they better look and learn.

You aren't insane AT ALL, those speeds are quite alright for what your doing, you DO NOT have to be brave to work like that, just think quick, that's all.

I noticed that you chucked that old wives B**L S**T story away as well, no stupid bloody 30 degrees on your top slide, just straight into it, AND IT BLOODY WELL WORKS, eh.

Nice work with the thread, quick and easy, that's the way to do it.

regards greenie


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## Circlip (Aug 30, 2008)

Perhaps you should say what you mean more directly Greenie and not beat about the bush. An old wives tale is one that has grown from a myth and is proven to be wrong, But one or two pivot pins with the locking pin threads cut at M42 x 4mm pitch on earth moving machinery using the "B4ll Sh4t set over method" can hardly be classed as "Unproven" It might not work for you but don't class your inabilities as the "Wrong" way to do it,there are MANY roads to Rome,we all pick the one we are most comfortable with. 8)
  Regards Ian


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## Tin Falcon (Aug 30, 2008)

> Well, I've been "machining" now for about 5 months. I bought my 10" x 18" Craftex lathe in March of 2008, and my CT129 Craftex mill in mid June. I must say that I like the machines very much, and that they perform very well from this novices point of view. I have just completed my third running model steam engine, and although I have for all intents and purposes not machined much of anything before this year



IMHO three engines completed in 5 months is fantastic. A great
 start.


> here is what I find:#1-Probably the most difficult thing I have tried to do is to cut threads. I know the theory, my machine does have a thread dial, and I was able to solve the mystery of what "change gears" are and how to use them. Did I succesfully cut threads???-


Another accomplishment. Many folks are hesitant to try threading. As ricks video proves low rpm is not needed another method is turn the rpm upside down reverse the sindle and feed away from the chuck. 

sounds like you are learning a lot and having fun

My biggest problem is getting my but in gear and spending time in the shop. 
Tin


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## Mcgyver (Aug 30, 2008)

> I have a video posted on YouTube cutting a 10-32 thread in brass at 600RPM.
> One comment posted to that video called me insane! LOL



Currently around my house 'sick' is the epitome of approval, perhaps this was a great and special compliment from a youngster learning the language


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## kvom (Aug 30, 2008)

It's interesting what people find hard and others "easy". My first project at school involved grinding a 60 degree threading bit and cutting 3/8-16 threads. Having been shown good technique by the instructor plus the proper way to set up the lathe, I found it pretty straightforward. Had I needed to self-teach, as Brian has been doing, I think it would have been more intimidating.

I also used a lathe that has a low speed of 52 RPM, which was a good "training" speed. After the first screw I did the other three at 80 RPM, which was comfortable. I suppose tinier threads at higher RPMs would be more difficult.

I have found the mill more intuitive to work with in most respects. Since it has a DRO on the x & y, plus a knee, I have almost never used to spindle for adjusting doc.

For a beginner like myself, I have also found participating in the team builds to be an excellent way to get started. I have goals for some parts and will get a couple of engines out of it in the end.

Once I get my own shop/machinery set upo, I think my first project will be Brian's scaled up plan.


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## BobWarfield (Aug 30, 2008)

Threading is where my variable speed DC treadmill motor is particularly handy on my lathe. When I first started threading, and whenever I haven't done any for a while, I follow this routing:

- Position the cross slide quite a ways away from where the threading begins and set up your threading tool.

- Turn the speed control all the way down to dead slow and start the spindle.

- It's going slow and there is a long way to travel, so you have 3 or 4 attempts to engage at the proper position on the threading dial. Heck, if you don't like and of those you can just crank it back out and try some more.

- Once engaged and happy with the point of engagement, I crank the speed control all the way up. Carbide threading tool, you know.

- Disengaging at the right point had never bothered me much.

It's really nice to be able to take your time on the engagement so everything comes out just right. Also, keep in mind, each successive cut should be shallower because the profile of the tool means it is cutting a wider area the deeper it goes. I tend to be pretty tame on the depth of cut when single point threading.

Try some more, Bryan. There is nothing quite like the sense of threading. That and welding (along with your normal turning and milling skills) kind of complete the sense that you can build anything anytime.

Cheers,

BW


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## Brian Rupnow (Aug 30, 2008)

Bob---I have been a ticketed welder for many years---no, let me rephrase that---I had my 2 position ticket many years ago. There, thats better. I have my own Lincoln stick welder and an oxy acetylene rig that are both old enough to vote, (by a large margin) and a new mig that I bought 5 years ago when I was building my current hotrod.


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## steamer (Aug 30, 2008)

Brian,

"There are many roads to Rome"  That is a very true statement.
If your get what you want out of your lathe or mill, avoid shrapnel and still have enough fingers to play the piano, how ever you did it is OK.  As time and experience progress.....so will you. Your techniques will improve and get more sophisticated, and your intimidation will transform into respect for the equipment and confidence in your own ability.

It's no differant than getting your welding ticket or your drivers license.....after twenty years of turning cranks, I learn something every time I turn the lathe on.  Just be a sponge and keep asking "Why?"

Best to you.
Dave


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## zeeprogrammer (Mar 17, 2009)

What a great thread! I'd be happy to take 3 times as long and accomplish half as much as you all did.

The video was great. But I have to tell you...I wasn't looking at the part...I was trying to see as as much of the hands making the part as I could. That's where the experience, knowledge, and art is.

If there's one thing you all could do for the newbie...it's to show more of your hands...the manipulation of the tools...the how...not the what.

Thanks.


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## rake60 (Mar 17, 2009)

For my threading video this might help.

[ame]http://www.youtube.com/watch?v=UjUfWq9j6fA[/ame]

It takes a soft touch on the controls and a deliberate execution
of engagement and disengagement. Nothing that any average 
split personality isn't capable of. 
 :big:

Rick


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## zeeprogrammer (Mar 18, 2009)

Very helpful. Exactly what I'm looking for. It explained a lot of things to me. Thanks very much.


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## Cliff (Mar 18, 2009)

I was working in a machine shop back in the early 70's and I ran across a job that showed me what threading was all about now I had did a lot of different threading job's so I was pretty comfortable with threading every thing from brass to fiberglass pipe ( always wash your hands before you go to the restroom or you will know it ) but I had to make a water valve stem it had 6 double acme threads on a 3/4" brass shaft. To cut the threads you had to cut three threads and go back and split the threads that you just cut and cut threads again. The only lathe that the shop I worked in had that would cut 3 threads per inch was a 24" Lodge and Shipley that was older than Noah and wouldn't run very slow along with the slop in the lathe and the huge 3-jaw chuck it got pretty harry but I got it made without destroying the shaft or killing my self. Cliff


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## BobWarfield (Mar 18, 2009)

Excellent instructional video!

BW


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## bentprop (Mar 18, 2009)

Brian,one little tip I picked up along the way somewhere:When you mount your "to be made parallel"
piece in the vise,put a piece of round stock horizontally between the work and the moving jaw.Then tap the work with the knockchrometer,and you will find it sits nice and flat.


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## mu38&Bg# (Mar 19, 2009)

bentprop  said:
			
		

> knockchrometer



That's a new one on me. ;D Filed for later use.


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