Help requested with original EvaNut® thread

[darryl]

I believe that one of Evans innovations involved getting the hole diameter in the plastic material just right so the plastic would fully fill the threads when crushed onto the lead screw, at the same time the nut halves came together. I don't recall the details, but if you subtract the minor diameter from the major diameter of the lead screw, then take about 1/3 of that figure and subtract that from the major diameter, you come up with a figure for the hole diameter in the plastic.

Things change if you bore the hole, then saw the future nut in half lengthwise. Might be better to start with two pieces, clamp them together, then bore the hole. If you want to bore first, then saw in half, you might want to bore the hole a bit larger than the figures would show.

During my experiments with casting the nut around the lead screw using some kind of epoxy, I ended up using a home made tap to open up the nut enough for free movement. This is not ideal as it chews up the plastic and leaves less area contact with the lead screw. In turn this allows play to develop. Better to be able to split the nut and adjust the amount of closure for the right fit, leaving the 'as cast' plastic surfaces untouched.

The epoxy material I used does not make the best nut, though I've never had any issues with the minimal uses I've put the machines to. Heat forming a slippery material makes a better nut, but as noted it becomes too tight when cool. I quit experimenting with this, but I had come to the conclusion that two 'third' nuts would have been the way to go. This won't fully surround the lead screw, but does give an adjustability factor that doesn't require any messing with the formed threads.

[Doc Nickel]

When I rebuilt my Exacto, the bronze X-axis nuts were badly worn, but the screw was in fine shape. I opted to fab replacements from Delrin- machined, not heat molded.



I asked over on PM what they thought about it, and it was pretty much as you'd expect: While a few of the notable loudmouths exclaimed that the Gods had bequeathed bronze upon us specifically for leadscrew nuts so using anything else is wrong and evil and blasphemous and probably immoral and fattening too, most said it'll be just fine and should last for years, especially considering the machine's only a 2HP R8 model, not a 5HP or 10HP CAT-40 spindle or something.

Several people noted that more than a few modern machines come from the factory with "plastic" nuts- and in my case, I have some 6" of contact between two nuts, on a 30mm screw. I'm not sure I'd be able to apply enough leverage on one of the handwheels to be able to damage those without getting out a cheater bar or something.

And we know that "injectable plastics" like Moglice are recommended as an easy leadscrew nut repair, so I have no doubts that a decent nut, either machined or molded from Delrin, would be perfectly adequate for 90% of us.

Doc.

[DennisCA]

I do like the idea of delrin nuts and will be replacing some in my lathe, cross slide most notably. Of course as important is finding out the shape of my lead screws, how have they worn over time...

[dian]

op, i dont know the machine, but i would try to split the nut. experiments like this take much more time than one would have thought with an uncertain outcome. and that stuff is not free either.

[Mike Burdick]

.... but then I remembered Evan's brilliant idea for an acetyl nut replacement and since I already have it torn down and cleaned, I figured now was the time to give that a try.

Now to my problem. I went back to Evan's original EvaNut®

So when Evan took credit for another members idea it now gets trademarked.

[tomato coupe]

So when Evan took credit for another members idea it now gets trademarked.

That seems to be the case ...

[elf]

That seems to be the case ...

Not exactly. Evan didn't coin the name and didn't add the ®.

[tomato coupe]

Not exactly. Evan didn't coin the name and didn't add the ®.

Actually, he did.

Hey, I like it! I was trying to think of a name for it. It is officially the EvaNut®.

[Magicniner]

Actually, he did.

and my favourite -

More to the point what has it got to do with the Daryllnut ?

BTW Evan's CircleCalc (link in my sig) is still available, presumably he instructed that be left available as it doesn't compromise his Tinfoil Hat.

[elf]

Actually, he did.

Actually, the author of the post before the one you quoted is the first to call it an Evanut. All Evan did was change the ™ to ®

[lugnut]

What ever Evan contributed to this forum, it should be considered a gift to us all. The sad part is for what ever Evan is doing now I hope he is OK. THANKS Evan.