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Achievable tolerances on a hobby lathe

Arcadium

Plastic
Joined
Dec 26, 2020
Hello,
I want to buy a lathe with some parts in mind.
I was looking at Holzman ED400 FD lathe.
I need to turn a 8mm in diameter 40mm stickout brass shaft with h8 tolerance (+0; -0.022 mm)
Also I need to ream a 8mm hole in a 10mm brass rod(same stickout), also with a H8 tolerances.

My question is if you profesonals could adjust such level machine to achieve these results? The work amount to achieve the result is not that important, that kind of work is enjoyable for me :)
 
Hello,
I want to buy a lathe with some parts in mind.
I was looking at Holzman ED400 FD lathe.
I need to turn a 8mm in diameter 40mm stickout brass shaft with h8 tolerance (+0; -0.022 mm)
Also I need to ream a 8mm hole in a 10mm brass rod(same stickout), also with a H8 tolerances.

My question is if you profesonals could adjust such level machine to achieve these results? The work amount to achieve the result is not that important, that kind of work is enjoyable for me :)

Good luck with that. I think you are asking to much from a toy.
 
Need another piece of info....trying to turn the entire 40mm length to +0/ -0.00086", (which I see as +0/-0.001" due to lack of any good way to measure less than steps of 0.0005"), is likely your biggest issue, even with center support.

Without center support I don't think it matters what lathe you have, the issue will be with the base material.
 
Yes, i want to turn all the 40mm to this tolerance. I want to get a quote precise sliding fit. Could you elaborate a bit about why brass is so terrible for this?

I know I lack basic knowledge about machining but please bare with me, i appreciate all the help.
 
That looks like what is commonly called a 7 x 12 mini lathe. It is made in China. It is a low quality machine. That means it will fight you.

Can I or one of the others here use it to produce those parts to those tolerances. Probably. But not easily.

Can YOU do that. Well, the fact that you need to ask the question tells me probably not. At least not without getting past a learning curve. The real precision is in the hands of the machinist, not the machine. So, how steep that learning curve is depends on you.

Producing that reamed hole to that diameter with your desired tolerance is somewhat easy with the proper reamer. It is not the diameter that will be difficult to control, it is the location of the hole that will be difficult and there is where a better lathe would be a lot of help. In other words, getting it well centered will be the problem.

Reamers are THE tool for making holes with precision diameters but you have to use a drill bit to start that hole first.

You would be better off with a better quality lathe, perhaps a used one. Or just a better quality hobby lathe.



Hello,
I want to buy a lathe with some parts in mind.
I was looking at Holzman ED400 FD lathe.
I need to turn a 8mm in diameter 40mm stickout brass shaft with h8 tolerance (+0; -0.022 mm)
Also I need to ream a 8mm hole in a 10mm brass rod(same stickout), also with a H8 tolerances.

My question is if you profesonals could adjust such level machine to achieve these results? The work amount to achieve the result is not that important, that kind of work is enjoyable for me :)
 
Thanks, i will consider a different material then.
And for the turning part. Do you think that lathe itself will be too losely built that the tool would move more than 25microns?
 
The location of the hole is not of a big importance, the most important is the fit without a wobble.
I was thinking about the used lathe but I'm a bit scared because I'm lacking knowledge and could buy a beaten up one.
Im going to look for a better lathe then
 
Ok, i will try to outsource this part somewhere. But probably I'll buy a lathe as well, i just really itching to try metal turning and looking for an escuse to buy one :D and I think that practice will make all the reading 100 times better
 
I know McMaster, but I'm in Europe and kinda jealous because we don't have similar thing in Europe, or at least i don't know about it.

I was considering a ground rod, but this part will have other features and it will be hot and in contact with wood, so sharp steel point will oxidize quite fast.

I know that for this project I'm over engineer a lot of things, but if I knew better I wouldn't. I have seen some serious machines and I'm surprised by ingenuity and know that you who work with mechanical things have made them. I wish to surpasse you someday :D
 
What exactly are you trying to make ?

I think you seen a stipple art somewhere and there also a thing like wood burning (pyrography).
So I want to stipple on wood. Just like wood engraving with laser. But I have found that laser can't produce high contrast on wood, i don't know if they just blast away coal particles or it's some kind of another phenomenal.

I have made a simple CNC for tests and shows promise. The only problem is that it takes ages, so I want to increase the number of heads and reduce the dot size for better results.
 
I like the idea of your dot matrix wood burner. That's cool.

You're right that using a lathe will make all the reading easier. It's a catch-22 for the purchase: don't know what you can do until you get a lathe, don't know know what lathe to get until you know what you can do.

Turning is fun and useful. I'm sure you'll have other, less precise, parts to make that are more suitable for a learner and can be used to justify a lathe purchase.
 
Hello,
I want to buy a lathe with some parts in mind.
I was looking at Holzman ED400 FD lathe.
I need to turn a 8mm in diameter 40mm stickout brass shaft with h8 tolerance (+0; -0.022 mm)
Also I need to ream a 8mm hole in a 10mm brass rod(same stickout), also with a H8 tolerances.

My question is if you profesonals could adjust such level machine to achieve these results? The work amount to achieve the result is not that important, that kind of work is enjoyable for me :)

If work is no issue, you can achieve any tolerance you want. As an American, I am more accustom to imperial measurements. Having said that, I have hit dimensions with +/- .0002 of an inch on a bench lablonde lathe. I would leave .001 and file/ sand the part into tolerance. It took a lot of time and practice, but I made a few pins like that out of various metals.
 
HOBBY ALERT!
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You might want to look at one of the smaller used Emco machines:

Emco Lathes & Millers

Fairly available around Europe and you should have no problem hitting those tolerances with one. You could even get a mill/drill attachment to do simple milling.

There's a fairly active group at:

[email protected] | Topics

This thread will probably be closed shortly, don't be offended, check the discussion guideline sticky at the top.
 
Of course you can, it’s a one off, not a batch run, it’s like pancakes the first is always a throw away, hitting H8 with a little shaft is just as hard with a bloody big pacemaker or monarch ( I ince saw a 1/2” shaft in a craven 72” swing lathe, Chuck in a Chuck in a Chuck in a Chuck it was funny seeing this bloody monster lathe with a tiny thing in it, done for a laugh btw) just take your time, HSS tool, stoned, ( oilstone not whacky baccy) don’t bother with insert tools,
I’d certainly think of getting a better lathe but your pockets determine that, bout ml7 size or box Ford
Mark
 
You can generally hit any tolerance you want with handwork (filing, polishing, honing, lapping etc.) if you know what you're doing. But turning/tooling directly to that tolerance with the cutting tool is a whole 'nother ballgame.

For the purposes of the pin you've mentioned, I might be inclined to purchase something as suggested by thermite and modify it to suit.

As regards the lathe, I think you should get one. It sounds like you have the right mindset to enjoy the machine and learning how to use it better. If you want to buy a cheap import as a first machine and learn to use it, that is up to you - if you begin to appreciate the work and machinery you will probably want to upgrade to something better later. The cheap machines can do that level of work IF you do the precision part using one of the "by hand" methods I mentioned earlier. A nicer machine ought to be able to cut the part right to that tolerance.
 
Fear not. EVERYBODY on the planet surpasses ever' body else at SOMETHING.

Even our wind-up-toy Pretezelbent knows better than the "geniuses" as advise him if he needs to check his watch to see if it is time to go pee?
....

And your surpassing skill is....?

Probably sticking your nose up the former guy's ass....

And HIS surpassing skill, is whining and blubbering about unfair life is all of a sudden.
 
If you have an access to purchasing a used industrial lathe made in the USSR, I highly recommend it instead of investing your money into the Chinese toy (to put it politely). I'm sure you can find a local machinist who will help you check a used lathe or even find one.

I'm a strong believer in starting with better tools to learn right habits, enjoy the process and avoid bitter disappointment in the machining (or any other) field. Besides, you have to understand that tooling for any machinery will always be another sizable investment, and you don't want to waste money on something that you will DEFINITELY dislike shortly after trying.
 
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Turning small shafts with a high L/D ratio doesn't have much to do with the lathe, which can be a piece of junk. The reason is that a moderately sane person would use a box tool of some sort, putting the burden of precision on the box tool, not the lathe. A completely sane person would just order centerless ground material of the correct size and not mess with it. The 6x12 hobby lathes vary, but most are going to drive you crazy. Drive? Probably more like a short walk.
 
Hello,
I want to buy a lathe with some parts in mind.
I was looking at Holzman ED400 FD lathe.
I need to turn a 8mm in diameter 40mm stickout brass shaft with h8 tolerance (+0; -0.022 mm)
Also I need to ream a 8mm hole in a 10mm brass rod(same stickout), also with a H8 tolerances.

My question is if you profesonals could adjust such level machine to achieve these results? The work amount to achieve the result is not that important, that kind of work is enjoyable for me :)
"Its not the machine its the machine behind to machine".

Roger
 








 
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