Cheap sliding ways

[chuckknigh]

Well, on my last trip to Dallas, I had to stop in one of my favorite stores. Woodcraft. Anyone who is a woodworker knows this is the best toy store for woodworking tools and gizmos.

While I was there, I looked for ways to make sliding fixtures, jigs, etc. And, came up with an idea that might work for sliding ways for our CNC machines.

OK, we all know about UHMW plastic, and how it makes good bushings. They had a grab bag of assorted pieces for $9.99, which seems good till you look in the bag, and realize a whole 1 piece would be suitable...maybe 2 if you got lucky, or creative.

So, I kept thinking. Eureka! They have this stuff called "slick strips" which is essentially self adhesive plastic tape, made from UHMW! It's designed to let wood slide along the fence on your router table, or table saw.

It's thin (fewer dimensional problems than with thick pieces of plastic) and fairly cheap at only $5.99 or $18.99 per roll, depending on the width you get. The cheaper one is 3/4 inch wide.

I was thinking that someone could use this to make DryLin style bushings, or maybe even just line both halves of sliding ways, and use it as a bearing surface.

The price is definitely right, and it should be easy to handle. Has anyone used this stuff, before? Surely I can't be the first person to find this stuff!

-- Chuck Knight

[fyffe555]

I use this stuff on my table saw and router table for jigs and the like. Mine came from Rockler because it was cheaper but it's the same manufacturer.

Here's the deal; it has a contact adhesive backing that moves a lot under the indirect pressure of use during woodworking mounted with a wood or Al. backing material. While fine for the purpose - that of improving slide between two surfaces with little load - I don't think it will take any significant direct pressure. I've removed it from all but a few jigs. The material itself is relatively soft. Reasonable use noticably scores the materials face - again remember that's with no direct pressure or load. I've also had movement when used in a fence saddle jig where either the glue, the material or a combination of the two were sufficiently soft to allow enough movement to misalign and bind the jig. Tightening the jig fit made the slide too hard to move with the material so it got tossed out - now just use hardwood on Al. with a bit of wax.

So, interesting idea, maybe it would be ok for a wrapped style bearing on a ground rod or what ever so maybe its worth an experiment, but it would still not be sufficiently stiff for a small cnc I think.

In contrast the Delrin often used in these pages is significantly more strong and resiliant than UHMW and the Igus material is many many times more so that Delrin.

Chuck, I noticed your machine from way back and your ideas on hexapod style machines, how are they running? Maybe you could cnc up some carriers to try this uhmv tape and let us know how it goes.

[chuckknigh]

Mine isn't running. The gantry style machine was built as a proof of concept machine, only, and was never actually used. Then I got busy, it got put on the back burner, etc, etc, etc... We all know what happened next.

Since it was only intended as a proof of concept, I never sealed the MDF...it's now sagged noticably, and needs to be rebuilt anyway, so I'll just redesign while I'm at it. This time I'm going to use metal ways on a sealed MDF frame.

I've got some aluminum window-frame extrusion in the trunk of my car, and I intend to do a Kleinbauer-inspired moving table machine, next. Heck, building the machines is the fun part! :-) Of course, I'll reuse most of it, probably. I picked up some offcuts of vinyl from the "venetian blinds" section at Home Depot, which I'll probably use for slides...slick, and free. They slide really well on the aluminum.

One of these days I might even learn CAD! ;-)

A few other ideas I had for slides, the same day, came from wandering Home Depot. The nail-on plastic tips made for the bottoms of chair legs seem to be a very hard plastic, and fairly cheap. Shouldn't be too hard to press them into service, as glides on a hard (aluminum?) way...and there is a very thick "felt" material, also made for furniture slides, which seems to be extremely dense. I wonder how it would hold up? Seems like it'd slide very easily, too...and be relatively immune to dust and shavings. It is designed as a glide, after all.

-- Chuck Knight

P.S. The hexabot stuff was a thought experiment...nothing more, at this stage. I would sincerely like to build one, one day, but not now. However, I did find some extendable square tubing, with U-joints on each end, at an electronics surplus place. Guess what I was thinking?

[Ken_Shea]

Chuck, going through some old scrap I thought of you and your hexapod idea when I ran across 3 old inner tie rod ends from rack and pinion steering boxes. They are about 13.5" long with a very nice swivel ball on the end. I thought that might give you some additional options when it comes to your hexabot arms.

Here is a picture of a ford version, GM have a female threading on the large end.

Well, cannot figure how to insert picture so here is a link to one.

http://cgi.ebay.com/ebaymotors/ws/eB...tem=7908371144


Ken

[chuckknigh]

Well, the ones I found at the surplus store were a heck of a lot shorter than that. More like 4 or 5 inches long, extendable to maybe 8 or 9 inches. Perfect for a tiny, desktop machine.

Anyway, back to bearing/bushing materials. Is anyone interested in trying this idea? I'd be interested, but I'm using a totally different design for my next machine.

-- Chuck Knight

[High Seas]

This seemed like a good thread to ask in - so here goes:

Does anyone have a good - online source to order some Moglice. I can call the company I suppose - but thought if I could just order a convienent size - I'd do that and have it on the way. Been down the Reid Tools/McMaster path and several other - but no joy.

I want to build some slide prototypes for the 80/20 rail and Moglice seems like might be a good start for the insert - and maybe some of Chuck's find for the surface. Keep the cost down so you wouldn't mind doing a replacement as wear becomes a problem.

Any hints for sources? TIA - Cheers - Jim

[Steinie]

Originally Posted by chuckknigh I've got some aluminum window-frame extrusion in the trunk of my car, and I intend to do a Kleinbauer-inspired moving table machine, next. Heck, building the machines is the fun part! :-) Of course, I'll reuse most of it, probably. I picked up some offcuts of vinyl from the "venetian blinds" section at Home Depot, which I'll probably use for slides...slick, and free. They slide really well on the aluminum. One of these days I might even learn CAD! ;-) A few other ideas I had for slides, the same day, came from wandering Home Depot. The nail-on plastic tips made for the bottoms of chair legs seem to be a very hard plastic, and fairly cheap. Shouldn't be too hard to press them into service, as glides on a hard (aluminum?) way...and there is a very thick "felt" material, also made for furniture slides, which seems to be extremely dense. I wonder how it would hold up? Seems like it'd slide very easily, too...and be relatively immune to dust and shavings. It is designed as a glide, after all. -- Chuck Knight

I have seen a sheet of plexiglass used between grooved wood strips for a Z axes slide. See:
http://www.hobbycnc.com/products/cnc-router-plans/

I have worked with Aluminum and wood slides with good results.
You must oil the wood first, let it soak, then, after 24hrs, a light coat of axel greese. Polish the Aluminum tongue first. Make the wood gibs adjustiable.