I have two of the 70mm diameter bearings and one of the 62mm.
Milling Machine - $950 - Mississauga
- Thread starter boilerhouse
- Start date
I guess there is nothing left to do but wait and see what I get. I think it should work though. Thanks for the help.
Ok the mill is up and running now using a Teknic SDHP servo motor. It seems to be working ok. Only got it working yesterday. I am turning my attention to a bent X-axis lead screw. It turns fine, but the end is bent to the point where I don't think a power feed would be able to work on it. I tried jacking it up at the end, but the machine started lifting and wasn't enough force to bend it back. Would heating it at the bend be out of the question? Anyone had this problem? Thanks
I don't know where it's bent or even if it matters. But my inclination would be to pull the screw and straighten it in a big press. I would not be inclined to heat it up because I'd be afraid of changing its metallurgy. But I don't even know if that matters. I guess I'd just rather play it safe.
I think I would agree. Just what I needed, an excuse to get a hydraulic press.
Former Member
Guest
Interesting video. I think I'll need to do the hydraulic press as it is pretty bent.
Different thing, taking the warps and bends out of a round shaft.
Just sayin'!
@Maker Mike, I would suggest a couple copper pads and a brass or copper block to use as pads and the pusher on the press. I would also suggest that you not get too emotionally attached to the idea of saving it, but rather, that you 'might' save it, and have a useful screw out of the deal at the end. EDIT TO ADD: If the bend is a larger radius and smooth, it stands a pretty high chance to straighten. If it is sharp and tight radius (like a kink) you will need to have the supports far closer in and use more pressure, and even then, you will have to be lucky, or be willing to file clean the warped threads. Still worth trying, esp is you have a press handy!
As an side, it was bent cold when it was bent, so cold will likely have the best results getting it back to straight.
And remember that lengths of almost any size and pitch Acme thread can be grafted to the original ends, if it is a less than straightforward lathe job to make the ends on new stock!
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I could care less about a video or you rubbing me wrong. No worries at all. My hide is old, full of battle scars, and quite impervious to smelly stuff slung at me. My nose doesn't work anymore anyway.
I fully qualified my recommendation based on lack of knowledge of the full details of the situation. I did not say that heating was a bad idea. I simply said that bending it back without heat was a safer approach in my opinion. It didn't get bent by application of heat, it got bent by exceeding its ultimate strength. Bending it back to its original shape does work the material a bit, but for a leadscrew it won't really matter. On the other hand, heating it enough to easily bend it will undoubtedly change the metallurgy. Whether this matters or not is also unknown.
I support @Maker Mike 's current plan and @trevj s comments about it. It sounds to me like he will do it correctly, and that the outcome is about as certain as can be reasonably expected.
I especially liked @trevj comments about attitude and emotional attachment. That was AWESOME advice.
historicalarms
Ultra Member
You will never regret adding a hyd press to your tool room I have a 20 T bought for one critical repair job on a machine, that was 15 yrs ago and i use it very regularly to bend or un-bend something or other. Jobs continually come up that you might not think of using a press for until it comes up... just a couple days ago I was trying to securely mount a Malcolm scope mount into a dovetail but the dovetail was over-sized for the mount. I took the barrel to the press and lay'd a 3" round bar across the cut and pressed that bar into the cut with precision that the regular method of a hammer blow to the lips could never give me.
Former Member
Guest
More or less the response I expected.
I guess some are doomed not to learn anything new and improve their knowledge base by being so set in ignoring the knowledge of others.
Again I wasn't saying it is "THE" solution, but a solution or part of a combined solution.
Thank you both for you input. Hopefully things will come out fine, and if they don't then I might have to buy a new lead screw.
Dabbler
ersatz engineer
@Maker Mike I have done quite a bit of improvised fixes over the years, but when I was asked if I could straighten a lead screw, I declined. This was because it was for a lathe for which replacement parts were either unavailable or punishing, so wrecking it was not an option. But this was a custom part for a specific lathe.
Keith actually straightened the lead screw I declined to fix. He did NOT use heat. You never use heat to straighten a threaded rod of any kind. It is nice when people are trying to be helpful, but sometimes suggestions are just that: a possible direction without any context or even applicability to your situation.
Because mill lead screws are far less difficult to obtain (or make), your risk factors are lessened. For a mill, I'd be happy to give it a shot. But you are probably not any where near Calgary, so there's that.
Keith actually straightened the lead screw I declined to fix. He did NOT use heat. You never use heat to straighten a threaded rod of any kind. It is nice when people are trying to be helpful, but sometimes suggestions are just that: a possible direction without any context or even applicability to your situation.
Because mill lead screws are far less difficult to obtain (or make), your risk factors are lessened. For a mill, I'd be happy to give it a shot. But you are probably not any where near Calgary, so there's that.
Tom Kitta
Ultra Member
I still think just getting ball screws for a mill would be a possible direction - they are easy to get - yes metric but either get new dials or just use DRO.
Yes, I know ball screws behave differently etc. BUT last time I checked X axis for a mill was around $1000 brand new for a BP machine.
Yes, one could cut this on a lathe. Would be an interesting project.
Also, you can check threaded rods available from US - you may get correct threaded rod you need to machine the ends of for say 300 - 400 CAD for both X and Y.
I am unsure I could make the rod straight enough - I don't even know how straight it needs to be - i.e. tolerances needed. If the rod is worn maybe its better just to replace. Lathe leads screws are different - like I never actually saw a worn out one.
Yes, I know ball screws behave differently etc. BUT last time I checked X axis for a mill was around $1000 brand new for a BP machine.
Yes, one could cut this on a lathe. Would be an interesting project.
Also, you can check threaded rods available from US - you may get correct threaded rod you need to machine the ends of for say 300 - 400 CAD for both X and Y.
I am unsure I could make the rod straight enough - I don't even know how straight it needs to be - i.e. tolerances needed. If the rod is worn maybe its better just to replace. Lathe leads screws are different - like I never actually saw a worn out one.
Tom Kitta
Ultra Member
Wait - only the end is bent? I have fixed a mill like that few years ago.
Dabbler
ersatz engineer
about .130 over 4" starting at the step between the nonthreaded cylinder the bearing runs on and the much thinner part that goes to the handwheel. He has detailed instructions on straightening it in a bench vise, and how to check it on v blocks.
Rauce
Ultra Member
Cheaper than that! On my last mill I replaced worn lead screws and nuts. The bronze nuts were the expensive part.
Precision ACME threaded rod (rolled) in 1018 steel is quite cheap, for example a 6ft piece of 1-1/4”-5 is $80 USD from McMaster-Carr.
The next step up in terms of precision are ground leadscrews but on a mill with a DRO there’s no point. For a leadscrew on a lathe that will get used for cutting threads a ground leadscrew is the way to go.