Linear slides

I've been trying to figure out what to use for linear slides. While this doesn't really suit my end goals, it makes so much sense to me that I can't pass it by; someone might be able to make good use of it.

Why not use drawer rails as linear slides?

These look nigh-on perfect:
[www.leevalley.com]

The ones I have played with have lateral play. I think if you mounted one on its side and one vertical for each axis it would work.

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[www.hydraraptor.blogspot.com]

Drawer rails?
Like this?
[youtube.com]
[www.instructables.com]

Personally, I wanna use magnets:
[youtube.com]
[youtube.com]

there are pretty good drawer rails, most likely those for full opening the drawer,
or in somewhat heftier size for sliding doors.
unfortunately those are not cheap; around 40 Euros per pair.
To be on the safe side you'll need 4 per axis
So look twice.

Sometimes there are linear slides at ebay for ... well ...yes cheap'ish.
And if you're lucky enough cheaper than 4 per axis of really good drawer slides.

But may I ask why not use high quality steel rods and matching linear bearings?
Let's say you'll need a travel of 30cm, it's 4 linear bearing (6 each) and two rods (less than 5 each) and you'll only spend 34 Euros instead of 40 and have a better result.
( @ rod diameter of 10mm)
true for longer travels you should use bigger diamter rods.
And for perfect guidance four instead of two rods and eight instead of four bearings, but who needs something like that at all?

'sid

Eh, I'm going for aluminum C channels with skate bearings. I need the flat aluminum surface for position tracking and maybe drive.

I have used Draw slides on RepStrap Bertha. I was not able to feel any play with two slides on each axis. I will be using draw slides again on a larger CNC machine

Draw slides however are not so sutible for short axis movement like the Z axis for that I will use right angle alumininum with roller bearings.

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Bodge It [reprap.org]
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nophead Wrote:
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> The ones I have played with have lateral play. I
> think if you mounted one on its side and one
> vertical for each axis it would work.


Just got a pair of slides from Lee Valley (like those linked above). I cannot feel any play at all. The bearings are held in very tight.

My repstrap uses a ball bearing slide from a small home-office type photocopier (the kind that moves a glass platen with the original on it). The slide looks very much like some kinds of drawer slides. It gives good results except for a subtle feature. It has a metal and plastic "ball cage" that holds the ball bearings in place. This moves back and forth about half the distance that the platen does. Sometimes after many (hundreds?, thousands?) of back and forth movements it moves to one extreme and starts running into the end of the slide. It doesn't come out or anything, but the force necessary to move it goes up dramatically. This exceeds what the stepper that I use for that axis can do, and my print job gets messed up. The cure is to move the platen from one extreme to the other and back (by hand) before any long prints.

You may well see this with drawer slides. It took me a long time to figure out, so I hope that this message saves someone some time.

Frank Davies