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threedee
21-06-2019, 08:47 PM
Planning on reworking my laser cutter.
Trying to figure out how to increase Y rigidity, essentially requiring full rework.
Need to put down reinforced thicker rod, at present measly 12mm for 750mm of length.
Way too flexy.
Machine travel is about 600mm.

This aluminium extrusion capturing bearing and carrying gantry, i cant figure it out where do i get something like this for bigger, and maybe open, bearing (16mm? 20mm?). What is it and where i can get some.

Alternatively, any ideas on how to proceed ?

Wal
21-06-2019, 10:01 PM
That's an oddball bit of extrusion, for sure.

Hey, why not ditch the idea of trying to track something like that down and simply buy linear bearings already housed in blocks and then use a plate as the interface between the bearing block and whatever you need it to attach to. See my highly technical illustration below.

25965

All you'll need to do is layout and drill a few holes. If you can't get the plate at the exact thickness you need it then I'm sure someone on here could skim it down for you - alternatively buy the plate a little thinner than it needs to be and shim it.

Just a couple of ideas. Might help.

Wal.

EDIT - you'll probably want open type linear bearings to ride on supported rail (SBR or the like) my hasty drawing alludes to closed type bearings which ride on unsupported rail - if you want better rigidity then, of course, ditch your current unsupported rail system.

threedee
21-06-2019, 10:58 PM
Sadly, i have no means of machining anything of use.
I'd like to disturb current "design" as little as possible, because any sort of disturbing comes with angle grinder action.
Too little space to work with as is. Hence me looking for the extrusion to fit bigger bearing.

routercnc
22-06-2019, 08:55 PM
As Wal was eluding to it sounds like you are looking for a source of linear rail. For this application these sort of rails would work fine:
https://www.ebay.co.uk/itm/142713036010

You should be able to find the right length, if not you can cut them down with a thin inox disc on the grinder, but do it in stages to avoid getting it too hot and loosing the case hardness.

Search for SBR16 for the rail and SBR16UU for the carraige blocks. These are 16 mm size, if you want 12 mm size change the numbers to 12.

The dimensions of these family of rails are here, just measure from the gap between the lower surface (if that is where you want to mount them) to the gantry and get something which is close. If you are lucky the gap is a nice thickness that you can just order from aluminium warehouse (who will also cut to size). If not, as Wal says, get the next thickness up, get it cut to size and delivered, and some kind soul on here would probably skim in down on the lathe or mill for postage and coffee/beer fund money. I can't offer this service myself as every workshop minute is required to get my daughter's kart finished before she is too old to care (!)

25966

Take some measurements, mock up some cardboard, whatever you need, and see if this works.

You then need to link it down to the belt drive. A bit of angle aluminium/iron off the edge of the shim plate on top of the carriage should do it.