What lube on acme w/delrin nuts?

[WoodSpinner]

What lube do you use on acme screws with delrin nuts? I started out using a light machine oil but starting to wonder if I should be using more of a grease or what?

John

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[LouF]

John here you go...

http://www.thomsonlinear.com/website...ication_en.pdf
Lithium grease will work wipe it on..

Lou

[Geof]

My company made adjustable tables using acme screws in Delrin nuts and just used Vaseline for lubrication. Very little is needed because Delrin is very slippery.

[ger21]

I use pneumatic tool oil. Just a few drops every 2-3 months.

[louieatienza]

Like Gerry, I've been using pneumatic tool oil. I actually do it more to protect the screws rather than as lubrication. I apply very little, spread it with a stiff nylon brush, then wipe it off.

[LouF]

Louie so the pneumatic tool oil is better than the Lithium grease I was spraying it on a rag and wiping it on the the screws?



Lou

[louieatienza]

Louie so the pneumatic tool oil is better than the Lithium grease I was spraying it on a rag and wiping it on the the screws?



Lou

Lou, I couldn't tell you since I've never used lithium grease on my leadscrws. Then again, I'm using high lead (8tpi) leadscrews, so they're pretty efficient to begin with. But like I mentioned, I only use the oil as preventive maintenance, not necessarily as a lubricant.

Thinking about this more, lubricating the screw could be self-defeating, as the delrin nut could probably deposit microscopic amounts of delrin onto the screw, which would make it "self-lubricaing" so to speak.

edit- I should add that Roton does recommend EP (extreme pressure) grease for their higher-lead plastic nuts. Then again, my machine does not run continuously, but if your's does, it might be a good thing to look into.

[LouF]

Lou, I couldn't tell you since I've never used lithium grease on my leadscrws. Then again, I'm using high lead (8tpi) leadscrews, so they're pretty efficient to begin with. But like I mentioned, I only use the oil as preventive maintenance, not necessarily as a lubricant.

Thinking about this more, lubricating the screw could be self-defeating, as the delrin nut could probably deposit microscopic amounts of delrin onto the screw, which would make it "self-lubricaing" so to speak.

Louie, thanks this is food for thought thinking about it I was looking at lubricating side my lead screws are the ones that came with my FLA-100 me being a newbie any help is always welcome..


Lou

[Joe S.]

Hi Lou,
I think you should check the MSDS sheet on any lube you are considering, for it's ability to "polymerize" or in other words, solidify. Many years ago, I greased some tool box slides and now it's tough to get them open If I used anything on Delrin, i suspect it would be silicone spray, though I would test to be sure it would not dissolve it first.

[ger21]

From my experience, Delrin by itself isn't nearly as slippery as it is on an oiled screw. On my "underpowered" machine, the pneumatic oil increased performance by at least 30%.
Even more on cold days.

I think you'll find that it's much neater than any grease. Add a few drops, jog back and forth, then run a rag over the screw and it's pretty clean, compared to grease.

And I don't think it ever thickens, as that would tend to have a bad effect on pneumatic tools.

[LouF]

Gerry & Louie, Thanks I will start using the oil on my leadscrews.

Lou

[WoodSpinner]

thanks to everyone who replied, I believe I'll be going with pneumatic tool oil as a lubricant, even if all it does is prevent rust to the screw.

John

[RomanLini]

Silicone lubricant is excellent with delrin on steel. It even embeds a bit in the delrin.

Just watch out if you use spray lubricant once spray gets on something you won't ever be able to paint it! Fortunately you can get simple liquid silicone lubes. I've used "Armor all" in a pinch, it works very well as a silicone lubricant.

[WoodSpinner]

Silicone lubricant is excellent with delrin on steel. It even embeds a bit in the delrin.

Just watch out if you use spray lubricant once spray gets on something you won't ever be able to paint it! Fortunately you can get simple liquid silicone lubes. I've used "Armor all" in a pinch, it works very well as a silicone lubricant.

Thank you RomanLini. That sounds like a good idea.

John

[WoodSpinner]

I've come back to this thread as I have run into a problem. I bought a 36" acme rod with delrin nut from a different supplier on ebay and the nut is exceptionally tight and when I run the screw it makes a horrible shuddering sound.

I've tried light oil, no good, motor oil, no joy, white lithium grease, helped some but not enough, next I tried something called tri flow, has teflon in it, and it did make the noise go away but its only a temporary solution as after several runs back and forth the noise comes back and I have to reapply, in fact if I wait overnight its almost like I never put any on. I've been hesitant to use silicon as I'm still in building stage and have several parts I still need to paint.

any more suggestions?

John

[RomanLini]

You could hacksaw a fine slot in the nut allowing it to flex and reduce the clamp force. I suggest not cutting too much, as they will settle in over time.

Another suggestion would be to heat the nut and screw in an oven etc to get it up near the Thd (temperature of heat deformation) of the Delrin, this will allow the Delrin to reform slightly around the screw so it is not so tight. That method can risk damaging the nut if you get it too hot.

Probably the first thing I would try is some silicone lube and "running in" the nut (just as it is) with a power drill, you don't have to do that anywhere near your paint. If it starts to run in ok you don't need the other methods. Running in a tight nut with a power drill causes the heat right at the thread surface, so it tends to reform plastic nuts quite well to be a good fit.

I hope somehting there helps.

[microcarve]

any more suggestions?

John

I always polish my home made taps before I make them....so the nuts
are usually a little tight...(better a bit tight than a bit loose...)

But my secret for making "perfect" fitting nuts is that I also make a secondary
follower tap.

These are all variations and are for different screw makers/batches/whatever
causes the screws to be different from one time to the next...
but you can see the follower tap with the handle for one of them.

What that does is removes the tiniest bit of material each time you pass it
through the nut. A couple times and a nut can be made nearly perfect.

Mine was made with a grinder and has a fairly good sized notch in the end,
but all it really takes is a small notch in the end of a scrap of acme...from
the same screw you want to use...and it'll work perfectly.

Worse case....a notch can be made even on a screw that there's no
extra scrap of with a dremel cut-off wheel. Then if it's polished out
really well after it's done it's job, it won't hurt anything.

http://www.microcarve.com/forum001/taps/

Maybe you can get an idea from that....


John

[WoodSpinner]

You could hacksaw a fine slot in the nut allowing it to flex and reduce the clamp force. I suggest not cutting too much, as they will settle in over time.

Another suggestion would be to heat the nut and screw in an oven etc to get it up near the Thd (temperature of heat deformation) of the Delrin, this will allow the Delrin to reform slightly around the screw so it is not so tight. That method can risk damaging the nut if you get it too hot.

Probably the first thing I would try is some silicone lube and "running in" the nut (just as it is) with a power drill, you don't have to do that anywhere near your paint. If it starts to run in ok you don't need the other methods. Running in a tight nut with a power drill causes the heat right at the thread surface, so it tends to reform plastic nuts quite well to be a good fit.

I hope somehting there helps.

I'll probably try your last suggestion first, I'm a bit nervous about trying anything that could mess it up and end up with horrid backlash in it or just destroying it as with most builders I'm on a budget.

I'll try running it in with silicone lube, I am going to write a small g-code to run that axis back and forth at speeds varying from 500 rpm to 1k rpm (50ipm, 100ipm) and hopefully that will do it. I've run it an hour or two with the Teflon but that hasn't eliminated it as of yet.

I always polish my home made taps before I make them....so the nuts
are usually a little tight...(better a bit tight than a bit loose...)

But my secret for making "perfect" fitting nuts is that I also make a secondary
follower tap.

These are all variations and are for different screw makers/batches/whatever
causes the screws to be different from one time to the next...
but you can see the follower tap with the handle for one of them.

What that does is removes the tiniest bit of material each time you pass it
through the nut. A couple times and a nut can be made nearly perfect.

Mine was made with a grinder and has a fairly good sized notch in the end,
but all it really takes is a small notch in the end of a scrap of acme...from
the same screw you want to use...and it'll work perfectly.

Worse case....a notch can be made even on a screw that there's no
extra scrap of with a dremel cut-off wheel. Then if it's polished out
really well after it's done it's job, it won't hurt anything.

http://www.microcarve.com/forum001/taps/

Maybe you can get an idea from that....


John

I have a screw from another vendor that is a bit rough in spots(has spots that look like it was starting to corrode) and perhaps if running it in doesn't work, I'll run that one through the nut a few times, I dont have any extra screw at present to attempt to make a tap. I do eventually intend to replace the corroded one so will have that to work with eventually.


Thanks to both of you for your help, I truly appreciate it.

John

[WoodSpinner]

well, I've been running a "break in"/Wear in routine about a hour a day utilizing the silicon, so far so good, still getting noise at high speeds but I think in part thats because my screw is wobbling at those speeds. I'm going to find someone with a lathe around here to extend the bearing areas on the ends of the screws so I can use self locking nuts to secure the screws, as it is they are held by bearing pressure in from the ends placing the screws in compression which I believe is a large part of the screw whip I'm experiencing. So I'm hoping by locking the bearings to the shaft I will be able to put the screws in tension (just a little) in the hopes it will reduce the problems.

Speaking of speeds, I went from using 5/16 18 tpi screws to 1/2 10 single start screws, I thought the difference in speed would be dramatic, like doublt what I was doing before but not the case..I'm curious, what speeds are others getting using acme screws like mine?

I'll probably try your last suggestion first, I'm a bit nervous about trying anything that could mess it up and end up with horrid backlash in it or just destroying it as with most builders I'm on a budget.

I'll try running it in with silicone lube, I am going to write a small g-code to run that axis back and forth at speeds varying from 500 rpm to 1k rpm (50ipm, 100ipm) and hopefully that will do it. I've run it an hour or two with the Teflon but that hasn't eliminated it as of yet.



I have a screw from another vendor that is a bit rough in spots(has spots that look like it was starting to corrode) and perhaps if running it in doesn't work, I'll run that one through the nut a few times, I dont have any extra screw at present to attempt to make a tap. I do eventually intend to replace the corroded one so will have that to work with eventually.


Thanks to both of you for your help, I truly appreciate it.

John

[ger21]

75-100ipm is about the max you'll see from 1/2-10 single start.

I get between 150-195ipm with 1/2-8 2 start, and a lot of people get 300-400ipm with 1/2-10 5 start.