delrin as linear bearing?

[phantomcow2]

I recall seeing a guy on this forum make his CNC router using delrin as linear bearings. Just delrin bored perfectly to size, sliding over drill rod or whatever other shafting. Well i cant find that again, so i thought i would ask;
Is this a good idea?

I am in the process of making a CNC router and was going to go the skate bearing route, but if this has been known to work well, i will use delrin instead.

It would be sliding on 2.25" diameter shafting, and 1.25" shafting

[Geof]

Originally Posted by phantomcow2 ....., i will use delrin instead. It would be sliding on 2.25" diameter shafting, and 1.25" shafting

For 2.25" diameter shaft you will need Delrin 2.5" if you mount the Delrin inside some type of housing. If you just want to use Delrin and bolt it to your frame or carriage then you will need something larger; maybe something around 3" diameter. Have you priced Delrin in these sizes? This might be the expensive route.

[phantomcow2]

Had not looked at prices until a few minutes ago. I think for that cost i might as well go for linear bearings! Looks like the old skate bearing route is the way im going then.
Plus ive already machined many parts for my skate bearing setup, so i suppose its for the best.

[mvaughn]

Originally Posted by phantomcow2 I recall seeing a guy on this forum make his CNC router using delrin as linear bearings. Just delrin bored perfectly to size, sliding over drill rod or whatever other shafting. Well i cant find that again, so i thought i would ask;

Is this what you were referring to?
http://www.cnczone.com/forums/showpo...1&postcount=74

[phantomcow2]

Actually no, but that is a fantastic job you did there. Instead of using round stock, you use plates of it, i like that. And you say with some silicone lube it works even better? Why did you not simply bore the hole perfectly to fit the shafting?

what i was reffering to was a picture, it was in one of the galleries. This guy used round delrin stock and bored them out

[mvaughn]

Originally Posted by phantomcow2 And you say with some silicone lube it works even better? Why did you not simply bore the hole perfectly to fit the shafting?

Yes, silicon spray reduces the friction considerably and doesn't pick up dust.

I cut the reliefs to reduce surface contact area to reduce the friction as well.

[phantomcow2]

And are you getting any play/chatter with this setup?

[mvaughn]

I don't get any play or chatter from the bearings. The only problem I had was getting them aligned so they didnt' bind on the round stock. I'm sure this wouldn't be a problem if I had machined these bearings but I used hand tools when I made them.

I should mention that for my next design I will be switching to using skate bearings. There is just too much friction as far as I'm concerned. I know I'm wasting a lot of energy from my steppers just overcoming the friction of these bearings. Although, they DO work.

[phantomcow2]

Yea it sounds like skate bearings is my best bet. On one hand i would not want a lot of surface area to reduce friction, but on the other i would want more to increase surface contact for less chatter.

[Pat2000]

I'm still 'playing with the idea' of using Delrin bearings, I'm torn between skate bearings and Delrin, lucky for me there is stacks of spare Delrin Blocks at work that I'm allowed to use, I've got 1 1/2 inch stainless bar for one axis (supported on the underside) and the other is 20mm probably silver steel (I've yet to purchse it)

I thought of broaching or maching out about 50% of the bearing surface also.

a big kinda problem for me tho is that both designs are 'open bearing' designs ie the bars I have are all supported with a plate on the underside of the bar, but maybe that will allow me to effectively adjust the bore size??

I'm honestly unsure still which way to go. my steppers are on the small side (I expect I'll have to cough up and buy bigger ones tho anyway). Delrin for me is free !! and I don't want swarf/dust in skate bearings?

I'd pondered an air feed to the delrin blocks - rather like an air-bearing? umm got no compressor and it may be noisy !

nice n simple mind... maybe I'll go down that route after all?

[tpworks]

Originally Posted by phantomcow2 I recall seeing a guy on this forum make his CNC router using delrin as linear bearings. Just delrin bored perfectly to size, sliding over drill rod or whatever other shafting. Well i cant find that again, so i thought i would ask; Is this a good idea? I am in the process of making a CNC router and was going to go the skate bearing route, but if this has been known to work well, i will use delrin instead. It would be sliding on 2.25" diameter shafting, and 1.25" shafting

Maybe this is the one you were looking for, posted in Nov. 2003, built in Jan 2001
http://www.cnczone.com/forums/showpo...1&postcount=53

[pminmo]

Actually I think UHMW is slicker. Cheap on ebay, drills and machines nice and easy.