Comments sought on new build: A CNC Router for RC Gliders and Planes

[njhussey]

Depends on whether you have a gantry to use as a gauge? I had built the structure of my gantry in advance for this purpose, so I bolted down one rail along the box section centre line, placed the second rail on its box section, and attached the carriages to use to align the rails. I think, in essence, you are doing the same thing but you will then pick off the rail spacing dimension to finalise the gantry. Hiwin recommend aligning the rail against a machined step but where this is not possible you align the second rail from the first. My only reservation is how you guarantee the straightness of the first rail but I think you can finally adjust this by test cutting. I hope so, anyway!

Looks a nice epoxy job.
To fit the first rail I clamped a good wide straight edge on top of the beam then butted the Hiwin rail up to it, like Neale said about the machined step. Then I mounted the gantry and used the bearings themselves to line the second rail, just nipping the bolts up slightly. Before fully tightening the second rail down I put the straight edge up to it to make sure there were no kinks. After that I also checked the distrance between them at points along the length just too make sure they were parallel.

Thanks guys.....

I'm going to do a similar thing to both of you. I don't have a good straight edge that I can butt the rail up to so I'm going to use the first rail as a reference and use the dummy gantry to get the second rail square to the first. Regarding striaghtness of the rails I might look at using a small laser pointer that I have to shine along the length to check for any bend in the rail, not sure if this will work but don't see why not in principle?

Got some more cutting discs (and G clamps to clamp the rails) on the way in to work this morning so I can cut the second rail to length. Looks like it's going to be lots of drilling and tapping today, hope there's not too much proper work to get in the way of doing this...!