[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]

....., 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]

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]

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]

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.

[ger21]

Actually I think UHMW is slicker.

Slicker, but softer.

[sdantonio]

JGRO on his second machine used oil impregnated bronze bushings. They slide well and range from about 6 to 30 each depending on whether you want grease groves on the inner surface or not (http://mcmaster.com). They seemed to work for John, but unless you align your rods prefectly they will have a binding problem.

Joe, on his 2006a machine used UHMWPE for his z-axis bearings (pretty much the only close to non-weight bearing axis). Nice and slick, a little soft as Gerry pointed out, cheep as Phil pointed out and easy to machine. He also had a binding problem and went back to skate bearings.

Steven

[djastram]

Check out the bearings that Igus sells. I used them in my router, and they work awesome. Check my gallery for pictures.

http://www.igus.com/dryr/dryrji.asp

[posix]

Is it me or are people finding out that delrin isn't an end-all be-all material that everyone seemed to think?

I'm just asking because I got this huge big 50mm delrin rod that cost me a small fortune, well $50, and it seems that silly drawer mechanisms might be a better linear slide than steel rod/delrin bearing combo? And for $50 I could've bought a truck load of those silly drawer mechanisms...

[pminmo]

Well I can't speak for durability over thousands of cycles. But having an axis drill rod and umhw and an axis drawer slides. The drill rod axis is more precise, less play.

[posix]

less play you say huh?

how about friction? big differences? appreciable differences? ok you're running choppers so you're probably in the 50v arena whereas I'm still down with 12v so it all matters...

[High Seas]

This a bit of a sideways look:
http://www.cenece.com/eng/index.htm (go to Catalog page 2)
INA Linear Bearing 20 mm -- not Delrin BUT a very interesting alternative.
Won't say cheap - but, nice balled-races for the matching guide holders and calibrated guide rails.
You'll note the self lubricated bearings are available in 20mm too.
:cheers: Jim

This may have been covered elsewhere? Maybe not - but seems like it fits here too..

[Vaughan Sage]

I would try ACETAL blocks as bed bearings relieved at the top so you get a pait of VEE supports off ONE rail & just bear on top only of your other plate-supported round bar, then the two rods can't fight against each other if not straight or aligned. Acetal is more slippery than any other plastic I'ved checked, & is as "hard as hobs" you only need small blocks bedded onto your round bars. Anti-lift Fingers fitted under will avoid huge slide bed lift-off if the uplift forces form a cutter exceed the weight of your bed table. Sharp edges on the bearings will scrape off any dust, rounded edges not reqd for dry bearings, & silicone spray make even slicker.