lead screw nut making ?

[max_imum2000]

i have a very nice scew with 4 starts, the problem is that i dont have a nut for it, some people here here made a nut out of derlin or similar plastic product, i tried to make the screw go inside the delrin but its not cutting anything at all even after i made a pilot hole.
i tride to heat a part of the screw then forced to enter the derlin, and it did and worked but it was so firm and not running freely
any suggestions ?

[ger21]

You have to cut or grind flutes into the screw to cut the threads, so it looks like a tap. Like this.
http://www.cnczone.com/forums/attach...achmentid=1039

[max_imum2000]

any idea how can i cut these flutes ?

[Dman]

When I made my tap I used a dremel with a cutoff/grinding wheel to put the flutes into the threaded rod.

[ger21]

I used a dremel as well, first cutting a slot with a cutoff wheel and then enlarging it with a chainsaw sharpening stone. It takes a little while, so be patient.

[Geof]

Has anyone ever tried casting a nut around the acme thread. Babbit bearings can be cast around the shaft that will run in them. It should be possible to do the same for a nut; and get very little backlash. An alternative could be something like graphite filled epoxy but making sure it did not stick to the metal, as it is designed to do, could be a bit tricky.

[ger21]

Originally Posted by Geof Has anyone ever tried casting a nut around the acme thread. Babbit bearings can be cast around the shaft that will run in them. It should be possible to do the same for a nut; and get very little backlash. An alternative could be something like graphite filled epoxy but making sure it did not stick to the metal, as it is designed to do, could be a bit tricky.

Yes, it's been done. This is what's usually used.
http://www.moglice.com/

[max_imum2000]

actually i have also made it, using alumilite, polyester and epoxy, the problem is that these all has a shrinkage factor after beeing cured , so they become so so tight on the screw.

[ger21]

I've heard you need to lap the nut on the screw to relieve some of the tightness. And try to put a couple heavy coats of release agent on the screw too.

[erase42]

i tried something similar once, and used a few coats of car wax as a space filling release agent. I might have just gotten lucky, but the resulting epoxy filled nut worked really smoothly on the threads.

ed

[badillion]

What kind of epoxy are you talking about and where can one get it?

[dertsap]

fibreglass body filler makes pretty sweet molds , strong easy to find and cheap ,just use a thin film of axle greese