[Todd Zuercher]

We are mainly a woodworking shop. So most of my experience is setting up cnc routing with wood and MDF sheet material.

However I need to mill a spacer fo mounting a new spindle on one of our larger CNC routers (18hp). The spacer needs to be 4.5mm thick and about 200mm x 230mm with 8 13mm through holes.

Of course we don't have any stock material 4.5mm thick. So at this point I plan to try to mill down some 1/4" aluminum plate we have. I'll probably do this on an old Lagunmatic VMC we have. We may not have much suitable tooling though. Could a fly cutter we use for surfacing MDF fallboards be pressed into service for this? (with flood coolant.)
https://www.vortextool.com/catalog/product/view/id/1732/s/7040-kit/category/79/

2nd question is how in the world should I go about fixturing this so it will lay and stay flat while machining it?

[peteeng]

Hi Todd - I would start with an oversize plate and cut some of the 13mm holes to allow you to check the thickness. This would be edge clamped. Then mill the top down to the required thickness missing the clamps. Also include some smaller holes to use to hold the part to the bed or wasteboard. Once your happy with the thickness you can profile it ( use holes for holding part with screws and remove the clamps). Then finish the 13mm holes with a 13mm drill in a drill press or once profiled you can replace the edge clamps and finish the 13mm holes in situ....Peter

[pippin88]

Material is important. Some aluminium has a lot of stress and will warp if you machine off one side.

[Todd Zuercher]

That is what I'm afraid of. The plate stock I was going to use is 6061 (I think). I was considering clamping on one side, surfacing half of it, then moving the clamps to the other side to finish, but I'm afraid that it won't stay flat and screw up the thickness and surface finish.

[CNCMAN172]

Just use the 1/4” aluminum and get slightly longer mounting screws

[Todd Zuercher]

Just use the 1/4” aluminum and get slightly longer mounting screws

I need the spacer keep the spindle centerline in the same position as the old spindle. So that I don't have to reinvent the toolchanger and dust shroud systems.

[CNCMAN172]

I need the spacer keep the spindle centerline in the same position as the old spindle. So that I don't have to reinvent the toolchanger and dust shroud systems.

If that is the case, I would recommend you surface with a 1/2” carbide two flute endmill. It will cut aluminum like butter, especially 6061 which is easily machined