Delrin Cross Slide Nut

Plastics like Delrin work extremely well for lead screw nuts in applications where the atmospheric conditions are clean, free of crud, dust, etc. They have to be run against a lead screw that has a ground and polished thread. They can be run dry or lubricated with mineral oils or hydraulic oils or PTF base silicone grease. This is why you see them used in the food industry with the proper food grade lubricants. As for putting a Delrin nut on a lathe, its a toss up which way to go on this. If your lead screw can be kept cleaned and lubricated and not heavily used, it will probably be fine. This is only good if your lead screw is in good shape and not worn. You practically have to use a new screw with polished thread flanks to get good life from a Delrin nut. Delrin can only handle about half the load of a bronze nut, so no heavy feeding! Most of us don't have to worry about this in our H-M environments. I would say there is a size limitation on how big of a lathe to try this on. In my opinion, don't try on anything bigger than a 12" or 14" lathe. Ken
 
Delrin is used extensively in small engines, as, for 1, camshaft lobes, (in a well lubricated enviroment), and could be used in manual mill tables as a feed nut. However I question its application in, "a hobby machinist" application on a lathe.

Cheers Phil
 
Just to try it I got a cutting board from Walmart and cut two pieces and put them in vise and drilled a hole too the miner size of a 3/8 threaded shaft. Then I put in bench vise and heated shaft and formed the thread around the shaft. It took about half hour to make the whole thing. It seemed to work good but the thread was tight.
I think it would get looser with use. And the stock was cheap about 2 bucks. Fun to try.
Jimsehr
 
willthedancer said:
I would not use plastic. It adds another layer of potential tool pressure deflection. Bronze.

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I've live in Great Britain & have been following a UK engineering forum for a long while .

We have lots of precision engineering machinists who have day jobs playing with lathes & CNC machinery . Their threads about Delrin for bearings & guide nuts that used to be brass or phosphor bronze are numerous .
The latest commercial & some hobby lathes & CNC machines apparently use all manner of Delrin type plastics for nuts , bearings , some machine threads & flat or grooved locating low friction surfaces as it keeps its tightness due to being almost self lubricating at low speeds & temps below 150 oC or so . It can also allow a little bit of metal dust /swarf to embed in the plastic with out much problem to the machine .

From another site I use ( All about circuits ) there are also weekly presentations of the very latest innovations & advances that have been revealed to the world plus some great insights as to where things are heading .

As the parts can be easily & very cheaply injection moulded or printed on a 3D printer to within a few microns almost any where in the world remote from the CNC draughtman / designers , watch out for zillions of traditionally made metal parts including those above changing over to Delrin type plastics etc .

New plastics will soon be made commercially from home grown bio materials instead of oil from the Middle East ..... I guess that will hasten the changes tremendously within a couple of years .
 
My old Tida lathe has a horrendous amount of backlash in the cross slide screw. I can grab it and slop it forth and back. It makes turning risky because sometimes the rake angle pulls it into the cut and makes it hard to hold a diameter. Facing cuts end up a weird series of circles instead of a smooth face. It is not worn just poorly made. I have seen the Evanut and plan to put one on my machine.

From what I've read there are some pretty substantial machine tools that use acetal nuts. From what I've seen of the material it is plenty strong. My attempts have not been all that successful. But I'll keep at it. Any results will be posted. If I ever get the time to get back to it.
 
Would I need to make a new lead screw or just mold the nut onto my current one?
 
Round in circles said:
............snip...............
New plastics will soon be made commercially from home grown bio materials instead of oil from the Middle East ..... I guess that will hasten the changes tremendously within a couple of years .
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I have a chunk of thermoset plastic here in my garage that I watched being mixed from liquids made from corn, poured into a large coffee cup, and in about 1 hour it was harden solid ready to machine. Of course, the chemical reaction created so much heat, took about a day for it to cool down to handle it. The tensile strength of the material is just as equivalent or better that most thermoset plastics out there. And there is no petroleum products used in the process. Right now, it's only available in 55 gallon drums for commercial use for now. Ken
 
ddickey it"s so easy to try I would just make nut and try it on your old lead screw.
If you do make it read the whole evenut post . A hell of a lot of people have tried it and are happy.
jimsehr
 
Dickey, I bought a length of left hand threaded rod from Enco when the were till around. MSC and others probably still have it. What I did wash cut a "gash in the rod to help cut clearance on the nut. The one trial I made came out pretty tight. That way I have no fear of damaging the original lead screw.

As you can see in the second picture the nut did not stay entered. My plan on the second try will be to use a one piece nut that is slit on only one side.

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