Cross Slide Screw Material

[YYCHM]

I can't picture how one would deploy a follower rest to cut threads. Anyone care to enlighten me?

 

[YotaBota]

Seeing is believing, do a search on "using a follow rest". There are a lot of videos on the subject.

 

[YYCHM]

Seeing is believing, do a search on "using a follow rest". There are a lot of videos on the subject.

This is not your typical follower rest?

 

[YotaBota]

Not typical but the concept is the same for all follow rests. It just keeps the part from deflecting away from the bit as you're cutting.
If you check this video, the follow rest starts at 36 minutes and he shows cutting a long bar.

 

[YYCHM]

It just keeps the part from deflecting away from the bit as you're cutting.

I've used a follower, but not in a threading operation. I just can't picture your typical follower bumping along on the tops of threads.

 

[YotaBota]

The pads are wide enough to cover a few threads so there's no bounce.

 

[PeterT]

This method is used quite a bit on slender parts, turning or threading to mitigate deflection. Joe.P video shows with/without. Depending on your lathe the travelling assembly it can be adapted to be mounted in different ways. I've even seen it incorporated on the tool post for smaller diameters.

 

[DavidR8]

@YotaBota I was think more about sourcing stock for the lead screw.
What about O-1 drill rod? KBC has 36" of 1/2" for $20. Likely $10 shipping would apply
My research says that it has a machineabilty rating of 95%. You have torches so heat treating after cutting should be possible.

 

[YotaBota]

That's probably the most viable solution yet, thanks for the tip. I may not even need to harden the rod. I'm going through the web site seeing what else I think I need.
What's goofy is that they have a store in Delta but the rod would ship from Ontario, there must be some logic there somewhere.

 

[DavidR8]

@YotaBota, when first loaded into my cart it said Mississauga also but then changed to Delta when I actually went to the cart.

 

[PeterT]

I'd be interested to know if stock conventional cross slide lead screws are hardened. You could do a rudimentary file test on the end just to see. I think ballscrew assemblies are hard(er) but suspect they are ground? I've had a tough time locating hardness of annealed O1 but guessing maybe 90 RB? If typical phosphor bronze is say 65 RB, the O1 will be ~40% harder.
The other issue with heat treating something long & skinny aspect ratio like a shaft is potential warping in the quench no matter how you dip it. You go air hardening but that's a different animal again.

I suspect there is more to 'wear' when it comes to dissimilar materials. You often hear a steel part will wear running inside a nylon or UHMW bushing, yet the plastic is much softer. Micro lapping maybe? I'm curious by the time a lead screw is clapped out, has it gone through 2 bronze nuts? Or maybe if replaced same time its because the bronze nut is being progressively tightened over time via anti-backlash adjustment so is kind of consuming itself like a lapping element?

 

[YotaBota]

a rudimentary file test on the end j

This one actually files quite easy, just about like mild steel. I would guess that the wear particles of the brass and steel mix with oil to form a lapping type compound and over time both wear.

 

[RobinHood]

Here is some info on lead screw material by a manufacturer:

http://www.barnesballscrew.com/acme-lead-screws/

Stressproof or 4140 / 4150 seem to be the material of choice.

 

[YotaBota]

I'm going to go with the Stressproof, drill rod has a tighter tolerance but I'm a bit leery that it may work harden even if it is O1.
Barnes makes some big screws, wow.
Thanks to all for the feedback.