Joe's 1000x600x200 steel and aluminium router started

[Nealieboyee]

I would either bolt down some thinnish alu plate on each member and then skim them all level, or pour more epoxy on the members so they self level. But that means making a framework for the epoxy to travel between members.

[Kitwn]

Epoxy sounds a bit too complicated for something so simple and you'd have to confirm the frame was adjusted to make the plane of the rails orthogonal to local gravity or it becomes pointless.
I'd go with the shim and skim. That cannot fail to put the plane of the base parallel in all directions to the plane which the spindle moves which is what you really want and will minimise the thickness of material you need to skim off the final, sacrificial surface.

[JAZZCNC]

I would use epoxy metal paste. Use levelling grub screws in the bed and adjust until planer, then remove and skim all the surfaces with a lite coating of epoxy putty then put plate back on and tweak it out any error from lifting etc.
Tape the bed where it meets the epoxy and when dry you will be able to remove bed.

[JAZZCNC]

I'd go with the shim and skim. That cannot fail to put the plane of the base parallel in all directions to the plane which the spindle moves which is what you really want and will minimise the thickness of material you need to skim off the final, sacrificial surface.

It's not possible to skim the whole surface using the machine because plate is the full size of the base so cannot skim the portion under the gantry.!! Only way this could work is if the plate was the actual cutting size.

[Kitwn]

It's not possible to skim the whole surface using the machine because plate is the full size of the base so cannot skim the portion under the gantry.!! Only way this could work is if the plate was the actual cutting size.

Obvious when you point it out!

I like the grub screws and epoxy putty idea, but might it be better to use ordinary bolts instead? It would mean a slightly thicker layer of putty but it would allow you to adjust each bolt with an open spanner while the gauge is on it's head rather than have to measure, move the gantry away to adjust, move it back to measure, move it away to adjust again etc.

[JAZZCNC]

I like the grub screws and epoxy putty idea, but might it be better to use ordinary bolts instead? It would mean a slightly thicker layer of putty but it would allow you to adjust each bolt with an open spanner while the gauge is on it's head rather than have to measure, move the gantry away to adjust, move it back to measure, move it away to adjust again etc.

No point really and you want to be measuring off the bed not the bolt head. A M3 or M4 socket cap grub screw is easily adjusted thru the hole and is small enough not affect the bed too much.

There are several ways to do the same thing and it depends on how your planning on using the bed regards fixtures etc. The main point was Epoxy putty works good for this application, it could easily be car body filler(Bondo to you upside downers) if your on a budget...Lol

[Kitwn]

I was thinking the grub screws would be in the frame, not holes drilled in the base board. Slowly but surely the lights come on.

[devmonkey]

Thanks for the ideas guys. I went ahead and epoxied some 2" x 1/8th aluminium strip to the 3 cross members that are machinable from the gantry. There is around 60mm outside each of these which will be shimmed manually. The rear cross member cannot be machined as it is under/behind the gantry as Jazz says, so this will get manually shimmed as well. Quite easy to do with a DTI n the Z as 90% of the bed plate is supported by the milled strips,



So the exciting bit was getting the machine to machine itself, first time it has cut anything:


Finish was superb for chewing gum grade aluminium, thickness of thinnest final shim is ~1mm.



I used an 8mm 2 flute carbide bit, there is no scalloping which means the head is in pretty good tram (I can't tram it until the bed is on). I ran the tool path twice, initially to bring all 3 strips down to height then dropped the Z 0.1mm for a finish pass.

[devmonkey]

Time to fix the bed down. I want to finalise the work holding at the same time. I have a few choices,

1. Drill and tap a grid of holes in the plate and bring these holes up through the spoil board,
2. Just drill and tap the spoil board (pvc foam) creating blind holes.
3. Cut t-slots into the plate and create narrow planks of spoil board between them (I would need to get a special bit to cut the t-slot),
4. Create t-slots from planks of spoil board, not sure how strong they will be.

T-slots are probably more work but less tapping, what do people think?

[JAZZCNC]

I'd go with a mixture of T-Slot Track in the Spoil board around the outer edges and a matrix of Tapped holes.
The T-slot allows quick and easy clamping of large pieces.
The Matrix of holes allows you to clamp small parts easily and just about any where on the bed and nearly always means you can find a place on your part to clamp.

The pain of tapping all those holes is worth the effort IME.!! . . .