Adding linear rails

A project log for OpenBuilds C-Beamâ„¢ Machine Build

C-Beam Machine is a CNC machine design based on the popular V-Slot linear guide system.

charliexcharliex 09/06/2015 at 18:520 Comments

Fixed the google+ image links, thanks google+ for changing that under me...

I've noted before there is a lot of flex in the y axis/work holding gantry. So what to do about it?

Well looking around the shop, earlier this year I'd picked up an NSK LH25 linear rail up from fleabay with the assurance it was a good rail and the usual "like new". Upon arrival it had a nasty scratch on the upper surface but worse on the bearing race there was dent, pretty much in the middle of it, so i'd discarded it into the ever growing pile o things, it moved around but there was a definite click and stall at that spot.

So when looking at options for the C-Beam I realised i could chop that rail in half and put a truck under near side

of the build plate, bolt it to the build plate and the front and rear extrusions, so a quick check and the overall height of the rail was just about perfect for it to ride on. So chris chopped the linear rail into two halves and discarded the part with the dent

hmm, this might not be right!

some adjustments were made... it's important to keep the hardened rails cooler so take time cutting them. tape off the rest of the rail.

onto the build plate, remove the old one, mine has the tool plate. So i flipped it over, and bolted it back into the plate so i could position the holes for the delrin nut properly.

grabbed the right size transfer punch

used my tap guide to keep it straighter

marked off the two punched holes for easy to see on the drill press.

and drilled with 4.2mm drills.

broke the edges of the holes

tapped with an M5 tap and tap magic,. useful tap guide again

test fit of the bolts

still needs the spacers

mounted the nut

and back on the machine

measuring and laying out the guides

I decided to over board and pick up another two trucks so i could put one at each corner, back to fleabay for that.

very solid so far, slight shim needed of 1-2mm haven't decided yet, and i'll put the shims on top of the trucks then bolt them in.

we did cut out some steel on this before this mod, and once i'd realised i'd left a HSS bit instead of the carbide, it went pretty well, kept hitting Z bottom so need to install that limit switch or just improve the travel, took a bit to realise what was going on since it was about 4mm off each time, thought the bit was slipping.