Making Acetal leadscrew nuts the easy way

[Evan]

The nut may be removed from the screw by chucking up the nut and and clamping the screw with vise grips, then turning it off in back gear. Use some oil on the screw and take it in small stages to avoid overheating the acetal from friction. After removal the nut may be chased out slightly by grinding a small slot on the end of the screw a couple of threads long. Put the nut in the fridge to shrink it a thou or two and then chase it with the screw while cold.

[taydin]

Hi Evan,

In the picture where the leadscrew is chucked to the lathe, how do the two halves of the plastic hold together? Is it the heating that bonds the two?

[Evan]

The melted acetal squeezes out into the kerf and heat welds the pieces together. I wouldn't depend on it in use so it would be a good idea to make a sleeve either from acetal or metal and press the nut into that.

This worked beautifully for me on the very first attempt so that tells me that it should be very easy to replicate.

[taydin]

Thanks for sharing this method. While converting my mini Proxxon mill for CNC PCB drilling, I had a real hard time making the delrin leadscrew nuts tight. I used left and right thread taps, but the left tap ended up making a loose thread. This method should allow me to make the delrin nuts quite tight.

[Evan]

I forgot to mention that the nut and screw should be left to cool until both can be comfortably touched for a few seconds by bare hand. Then it may be water quenched the rest of the way to cold before attempting to remove the nut.

[strokersix]

Nice method. Thanks for sharing.

[Your Old Dog]

That's pretty neat Evan. Thanks for taking the time. Hopefully I'll be able to find the thread when I need it! Once depicted, it looks pretty simple and easy to remember.

I am a little unclear on the polishing the thread part. How polished and how did you do that?

[Evan]

Just a quick touch up on a buffer with red rouge. Then clean thoroughly to make sure no crud remains in the threads.

[Tony Ennis]

That's a cool tip, Evan.

[Bill Pace]

Good 'kiss' engineering!

What is your method of drilling the hole - A common drill bit?

I can have a problem with the drill wanting to 'dig' in and also want to wander off, and also to leave an undersized hole...

[Evan]

There is nothing very critical about the hole. The material will flow into place and when it is machined in place on the screw concentricity is automatically achieved. This is basically injection molding turned inside out. Or is it outside in?

[wierdscience]

Neat idea,if that doesn't ditch backlash nothing will.

[A.K. Boomer]

That's pretty clever, I can see bending the rules some about the initial bore and leaving it larger than you would for tapping as its not like your removing material but more like displacing it.

By the looks of the minimal amount of material that popped out of the ends you maybe already doing that ------- ?

[Evan]

The kerf assures that there will be enough material to completely fill the threads and at the same time it gives any excess material a place to escape. The cool thing is all these things just fall out of the method without requiring any special treatment or process.

[DICKEYBIRD]

Now that's what I call thinking outside of the box! I reckon I'll be using that one.