Making a Cross Feed Screw for a Lathe or Mill

petertha said:
So pardon my dumb questions, but I'm so impressed with this:
- when I hear people making the lead screw nut & having to buy an expensive reverse thread tap, did you alter the tool orientation & cutting direction on like a boring bar style tool?
- on the lead screw threading, when you said you went to either side a bit for a smaller progressive bite, does that mean the threading tool advances straight in, or the compound still has some angle?
- what type of insert holder/tool did you use for both ID & OD operations
- what do you recommend for an anti-backlash arrangement on the nut, do you have a pic of that
Click to expand...
I'll post a picture of the threading tools I used.
And no, I don't use any kind of anti-back lash mechanism on the nut. I always lived with slop in the screws and nuts over the years. It don't bother me unless it's really bad.
 
RandyM said:
So Ken, do you use a thread gage? And if so, what kind? I see there are the individual blades and the plate style. Any pros or cons to either?
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No gages. I make the screw first, getting it correct to measurement over wires. Next, I thread nut and use the freshly made cross feed screw as a gage for a snug fit to the nut. I single point the thread in the nut. No tap used to finish the thread.
Ken
 
gi_984 said:
http://www.greenbaymfgco.com/ACME-nuts.php
Anybody use Greenbay manufacturing for ACME nuts?
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Nope. I find it easier to make your own. Most of the ones they list don't even come close to working out for the ones I've ever replaced over the years. Plus, an 3/4"-10 Acme is not a standard size anyone carries. Now, I may have to eat my words.
Ken

Edit: Green Bay does carry 3/4-10 Acme left hand. But you got to remember, it is a class 2G fit thread. That means it could have as little as .0069" to as much as .0363" of pitch diameter slop in the two threads. In my book, that is too much slop in a cross feed screw to have. GB will only offer closer fit threads upon special order. And you know what special order means, $$$$ to get something made to much tighter tolerances. In the home shop, a good snug fitting screw and nut can be achieved easily by careful planning. (I forgot to take pictures of the threading tools I use and post.)
Ken
 
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Hi Ken,
Thanks for the update. I expected the tolerances to be a bit on the loose side. Please post any pictures of the milling set up, etc for the nut.
 
gi_984 said:
Hi Ken,
Thanks for the update. I expected the tolerances to be a bit on the loose side. Please post any pictures of the milling set up, etc for the nut.
Click to expand...
Will do. Probably be after Christmas, maybe even New Years. I've got a full plate right now. Ken
 
Here's a picture of the threading tools I used as requested.
DSCN3848.JPG
 
I found the carbide threading inserts had to be run at a higher speed than you would usually thread at with HSS to get a decent finish. It certainly sharpened the reflexes! One could run upside down and backwards like Joe Pie (youtube - advanced innovations) advocates. You cut from left to right so you don't have to rush to disengage before you crash. Nice work here. I will refer back to it if I ever decide to make a lead screw. Any idea what metal alloy the original ones are?
 
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