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Heavy 10 crossfeed screw upgrade to 1/2-10 TPI ACME

atwatterkent

Cast Iron
Joined
Nov 3, 2006
Location
Kankakee, Illinois
Because of the lack of availability of 7/16-10 screw stock I thought it an easy upgrade to the readily available 1/2-10 TPI. I've been trying to find info from others on the pitfalls of this seemingly simple job without any success so I'm open to suggestions. I already have the 1/2-10 ACME tap to modify the nut.
 
Just wondering why you would perform this operation when precision and professionally made screws are cheap and readily available. Just seems like a waste of time and a project that might end up requiring you to change the dials on this lead screw to be able to accurately tell your depth of cut.

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Why would he have to change dials?
It's still 10tpi.
But is it a Precision manufactured screw? What class of thread is it? just because it's 10 threads per inch doesn't mean it's a very precise one

Brian at Miller Machine make excelent replacement parts for your machine at reasonable prices...

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I was thinking of modifying my 9" lathe to 3/8-10 and filling the nut with something like epoxy, rather than making a new one. I'm down to knife edges in the middle of the screw, and probably not the original nut.

if you have enough material on the nut to open it up, i don't see why it wont work. theoretically the nut could be so worn, that even after you open it up, you won't have a full thread engagement.
 
I would not go down in diameter.
Not only would it be getting pretty flexible,the increase the helix angle would invite even more instability.
 
I have a call in to Miller Machine but haven't heard back from them. There's no need to change the dials because the TPI is the same. It would be great if I could just buy about 3 ft of the 7/16 size from Miller. I also emailed Steve Wells but haven't heard back from him either. I would expect that ACME threaded rod from MSC would be usable. The college that I am fixing this heavy 10 for won't allow reimbursement for Ebay purchases.
 
I made a new screw and nut. 1144SP screw, delrin nut. Project was mildly challenging, mainly because I had to make my own 7/8-4LH Acme tap.

It's not precision ground, the lead error is about .001"/1", but its a damn sight better than what I had.
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Maybe this is an appropriate place for this. I replaced the crossfeed nut on my 10L and now the crossfeed travel tends to bind at the inward end of travel unless I leave the crossfeed mounting screw a bit slack. Are these sometimes shimmed for alignment or something? I haven't pulled the nut back out to compare the measurements on the shoulder. I was thinking of just adding a shim washer up there to space it down but stay snug to reduce the lash I get from the mounting screw being loose.

Unless its an alignment problem with the taper attachment? The crossfeed screw does run through that.
 








 
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