Zero Backlash LH Trapezoidal Thread Cross Slide Nut, From Delrin

Very cool Doc. Do you have the ultimate test in mind yet? Like pressure knurling?

It's interesting to hear the different properties. Like you would think Delrin being stiffer/harder sounding would be better, but that is pure WAG.
 
All very cool stuff. I learned something new....the burn test for plastics. I have accumulated a few big chunks of supposed to be “delrin” from eBay estate sales. I have always been suspect of a few of them just because the colors don’t quite mesh with what I know to be real delrin from McMaster.
Anyway...a quick google turned up this page.
Burn test identification of plastics
 
C-Bag said:
Very cool Doc. Do you have the ultimate test in mind yet? Like pressure knurling?

It's interesting to hear the different properties. Like you would think Delrin being stiffer/harder sounding would be better, but that is pure WAG.
Click to expand...
thank you @C-Bag!
i don't pressure knurl often since i got my clamp type knurler, but that would be an excellent test!

i would think a general comparison, in different materials, in common turning scenarios would be best for a month or better

i'm considering using delrin for my lathe at the shop at work and using the ertalyte nut on my more worn home machine and see the difference

i turn a lot of 303 and 304 at the shop at work, but turn a fair amount of delrin and aluminum too
in my home shop, i'll turn anything from brass to plastics to aluminum to cast iron to stainless steels

i look forward to see the test!
 
I think that would be an interesting test having the different materials on two different machines. I would have a hard time remembering exactly how much I used each one. Swapping out on the same machine would be a pain I would think and also hard to keep track of unless through like a Hobbs meter or something. But that's probably silly. Doing a lot of stainless is probably a good test. I guess I was just trying to think of some ultimate quick test.

I've already learned a lot in that I always wondered about Delrin or UHMW as a nut, learned of a new plastic and never heard of a trapezoidal thread.
 
I am going to take this route with my Van Norman. I'll possibly grind the tap required. I'll also add an anti backlash component to it.

In the VN there are two bronze nuts when I was cleaning mine I cut finger on an ACME thread to give you idea of the condition of the nuts. With Delrin its cheap and I'll be able to cut the threads and test easily.
 
Scra99tch said:
I am going to take this route with my Van Norman. I'll possibly grind the tap required. I'll also add an anti backlash component to it.

In the VN there are two bronze nuts when I was cleaning mine I cut finger on an ACME thread to give you idea of the condition of the nuts. With Delrin its cheap and I'll be able to cut the threads and test easily.
Click to expand...
anti backlash component?
 
Scra99tch said:
The nut itself is split towards one end and a sleeve with a spring keeps pressure on the fingers of the nut. So as it wears the fingers keep engaged on the threads.

View attachment 304971
Click to expand...
Hmm, it's kinda hard for me to get how it works without some kind of break down.

I was thinking more traditional way where the nut has a cut through it with a screw set through cut side and you tighten the screw to tighten the cut part to the body squeezing the thread together and taking out the play. That's the way the X&Y nuts are on my RF30 mill/drill.
 
here are my final thoughts on the nuts...

Ertalyte is very springy.
the material stretches when bolts are torqued into place , you never feel like the bolt is tight enough
i also felt like the nut would give when i applied pressure for cutting

Ertalyte is a decent material, but i felt Delrin was superior in almost every way for use as a cross slide nut

Delrin doesn't stretch to the same degree, bolt torque feels positive
i didn't get a springy feel to my cuts
Delrin drilled and tapped better and held dimensions closer to the tooling used\
Ertalyte holes come out small so you must oversize tooling to get the desired bore
both materials are easy to machine.

this was a wonderful experiment, i wish to thank everyone involved!
 
Big thumbs up Doc. This is a great experiment. I hope you update us as to how it wears over time.
 
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