Joe's 1000x600x200 steel and aluminium router started

[devmonkey]

I see you have maximised the distance between your x rails, by placing them top and bottom of the Gantry.
Did that make things excessively more difficult?

Steve

Not really no. If you want the rails to sit flat then you have to mill the extrusion anyway particularly with 15mm rail on 8mm slot.

When you set the rail you will need a setting tool to offset the reference edge of the rail from the edge of the profile, I am making the assumption that the extrusion itself is straight. The setting tool with be a pair of L shapes milled together so they are identical with a hole so they can be bolted to the T slot. The short part of the L will then form a reference surface to locate the rail.

Note I'm referring to the rails on the gantry as the Y rails.

To get the separation of the Y bearing plates perfect is a little more involved since it is very hard to accurately measure the extrusion depth, again this is a nominal dimension when you purchase the profile, mine is nominally 160mm but is infact around 159.8mm, and now a bit less after I milled the flat for the rail.

So I slot joined the lower Y bearing plate to the rear Z plate but I didn't slot joint the upper Y bearing plate, I think this would have been impossible. Rather, with the Y bearings on the rails and bolted to their plates, I assembled the lower plate onto the Z axis and tightened. I then clamped the upper plate with a long clamp across the back of the gantry tensioning it against the lower plate and slightly pre-loading the bearings, then spot drilled through the holes in the Z plate into the upper Y bearing plate.

This means you only have to locate the holes in the rear Z plate to around 0.5mm accuracy...also should note that I'm using M6 bolts for these joints and I drilled 6mm holes, the 0.2 or so play of an M6 bolt in a 6mm hole is generally sufficient to align things if you are milling accurately, you don't need 6.5mm holes for M6 as is usual, although I could only do this as I counterbored with a 12mm endmill in the milling machine rather than an M6 counterbore which would have required 6.5mm holes.

I think it is much better with the rails top and bottom not just because of the increased distance between them but because of the reduced spindle overhang. My last machine which was much larger than this had the rails on the gantry face and although it was very simple to mount them it was less stiff due to the overhang.