Steel rail upgrade ideas

discussion of design changes / improvements / suggestions
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orangezero
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Joined: Sun May 12, 2013 8:35 pm

Steel rail upgrade ideas

Post by orangezero » Mon May 04, 2015 6:12 pm

I'm curious as to what other have found for steel rails. I know mcmaster has them in 3ft and 6ft lengths.

http://www.zoro.com/pbc-linear-linear-r ... /G0753672/

This is the most cost effective I've seen. Only the aluminum openrail is cheaper. I was going to eventually pair them with some rs2zz steel v-groove bearings. Is there something with the PBC linear rails I'm missing, or would those pair with the rs2zz without issue? I'll be attaching them to some standard extrusion.

Hans
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Re: Steel rail upgrade ideas

Post by Hans » Mon May 04, 2015 6:28 pm

Do the holes in the track you linked line up with the slot in a regular extrusion? I know openrail is designed to install that way, but I think for the cold rolled steel rails you're expected to drill a matching hole pattern in your frame.
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orangezero
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Re: Steel rail upgrade ideas

Post by orangezero » Mon May 04, 2015 7:21 pm

I doubt they would. I believe openrail is designed for 20mm extrusion. I have 30mm-size extrusion (60x90). My idea was to get an aluminum or steel piece around 60-70mm wide (perhaps 3-4mm thick) which would attach to side of the rails, and then the rails would attach to the top and bottom of those. That wide piece could be attached to the extrusion via t-nuts. Otherwise, those steel rails would need to be screwed in very close to the corner of the extrusion, which would probably not be ideal.

My other thought was to use a cold rolled 60-75mm wide "rail" which could be used as the rail for the steel wheels, perhaps 0.125in thick. The top bearings would run along the top and the bottom on the bottom, so one single piece for top and bottom. I'd still need a shorter "spacer" piece to move the tom/bottom edge away from the side of the extrusion. I haven't seen too many do that, probably because if you spend that much you might as well do it correctly using a piece designed for precision (as the v-rails are). It does seem as if there are several examples using steel angle, but I've always tired to avoid drilling 100+ holes in steel...

It seems perhaps easier to use the 12in length v-rails they sell to upgrade the z-axis, as those are only $7-10 per piece.

bharbour
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Re: Steel rail upgrade ideas

Post by bharbour » Wed May 13, 2015 1:06 pm

A steel rail, steel wheel system would, I think, be best but those steel rails don't have pre drilled holes and I'm afraid I'd screw that up trying to drill holes.
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orangezero
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Re: Steel rail upgrade ideas

Post by orangezero » Wed May 13, 2015 4:49 pm

If you search through the zoro tools website, they do have some with predrilled holes for the identical price. I may have linked to the undrilled ones.

For those interested:
http://www.pbclinear.com/V-Guide-Rail-f ... r-Bearings and then click on the specifications tab to see some photos and # of holes.

Reading through, it does say the non-V part of the rail is not hardened, so that would make drilling easier.

fasteddy
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Re: Steel rail upgrade ideas

Post by fasteddy » Thu May 14, 2015 1:34 pm

Looking at the pre-drilled specs on the PBC site, it looks like even on the (largest) 60mm rail, the pre-drilled holes would be off by 0.5mm (if using standard 2040 aluminum extrusion). 2040 requires a hole centered 10mm down, but the options for PBC are 4mm (20mm rail), 5.6mm (30mm rail) , 8mm (45mm rail) , 9.5mm (60mm).

orangezero
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Re: Steel rail upgrade ideas

Post by orangezero » Thu May 14, 2015 11:07 pm

Thanks for the input. Here is an example of hard work screwing you. I was out digging and pulling out old stumps all day, only to come inside at 6pm to find the 30% off zoro tools coupon had expired at 4pm. You have to spend over $200, which wouldn't be hard with these rails. Oh well.

Your measurements are the ones that matter. I have 30mm style extrusion. My plan, if I were to get them, would be to use a piece of 2.5in or 3in metal flat bar to attach the rails, so I could put holes wherever they are needed. It adds work.

I'm still leaning heavily towards using the ends of 1/8th cold rolled steel as a rail, with those rm2zz or rm2-2rs bearings. Still not sure which way I'll go there, I believe the rubber seal may work better, but I hope to have my bearings mostly shielded from the debris.

My local fablab has a cnc using those bearings and aluminum angle, but I figure I might as well get something that will last as long as possible.. My plan was to wait until I found a good coupon for onlinemetals, as they seem to have decent prices on the cold rolled stuff while my local metal shops tend to not want to bother with my questions about quoting for less than 20ft of steel.

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