Acme threading

[HSS]

This is another fine mess I've gotten meself into, Ollie. How would you thread a nut 3 inches long when the threading tool only has a depth of thread length of 2 inches?
Someone had previously repaired this by brazing and recutting. I'm thinking of making a new one out of brass (because I have the brass) and have already ordered a new acme rod this morning. This is the X lead screw on my mill and is 1" 5 tpi. Thanks

Pat

 

[8ntsane]

I would take the old rod ACME shaft, and cut a piece of unused section. You can make this into a longer cutting tool. Machine a slight taper, much the same as a starter tap. Cut flutes in the length with a slitting saw. Basicly your making a tap with a unused section of the old screw. Or you could form a new nut from acetal, and you dont need to tap/thread the brass.

 

[HSS]

Thanks for the replies. How strong is acetal? That table is one heavy sucker.
I have no problem single pointing that nut, but can I find an acme insert for the boring bar or would I have to grind one?
I'm afraid the other problem will be in aligning the nut to the table. It has to be precise in 3 different planes and I'm not used to that kind of precision.
I guess I'll have to figure out some kind of setup that will work for me.

Pat

 

[Tony Wells]

That's some extreme brazing. Taps are notoriously expensive, and single pointing that would be awkward at best. You'll have to build a fixture of some sort that will chuck in a 4 jaw chuck. Mimic the anchor point on the mill. Of course, if that's your only mill, you're in trouble on that one.

 

[TOOLNUT]

Different approach

This is another fine mess I've gotten meself into, Ollie. How would you thread a nut 3 inches long when the threading tool only has a depth of thread length of 2 inches?
Someone had previously repaired this by brazing and recutting. I'm thinking of making a new one out of brass (because I have the brass) and have already ordered a new acme rod this morning. This is the X lead screw on my mill and is 1" 5 tpi. Thanks

Pat

Hi Pat,
A possibllity for you to consider might be to make a stub shaft ( true with the thread) that would screw into the partial tapped hole and then mount the assembly on the lathe using the shaft an a guide. Indicate the shaft stub and then remove it so that the inner thread can be extended by normal ID thread cutting with a boring bar.


I once worked for a man who often said, " there are no bad ideas" because one idea often generates another.
Jerry

 

[HSS]

Using both Jerry's and 1200's idea would work. Mount the nut to a faceplate using an angle plate and dial it in with a stub shaft. That sounds doable. Thanks guys.

Pat

 

[TOOLNUT]

On Second Thought....

A tap that large should be able to tap right on through the hole as long as it has a long enough "handle". Can you come up with an extension so that you can continue past the length of the tap?.? Don't know offhand just what the size of the square end is but sometimes the extensions in your socket wrench set will suffice. May have to be a 3/4 " drive and then you may have to borrow one from a neighbor.
Just a thought
Jerry .

 

[HSS]

Well, part of the X travel is finished. We were slow at work today, so I told the guys I was going home after lunch and I went to my shop and turned out the X screw. The nut is being machined by a friend that works in the machine shop with my wife. So far so good, next will be the 4 gear, gear cluster that will have to be made. Time is on my side, yes it is.

Pat

 

[HSS]

Well, the nut is finished and thanks to my 2 friends where my wife works, it looks really good. They made the nut from bronze. Now all I have to do is get every thing back together, except for the GB. Still waiting on the gears for that.

 

[HSS]

Well the wait is over for the gearbox gear cluster, I got it back last night. Now I just have to put everything back together and finish cleaning it up so's I can paint it. This is the old cluster and you can see the 2 worn teeth on the bottom. The one on the right is the new one.