[tomasonazo]

Hi everyone, semi-new here, I´m surfacing the bed on my home made cnc router, and after what feels like an eternity with a few steps to finish, has no got me in a mess. I´m surfacing (trying to) the bed of my cnc router but it´s really weird that both sides have high spots and the middles are flat. My objective here is using a 10 mm end mill with 90 overlap to check for any crookedness, but I just cant seem to understand how this could physically happen. Help please!

[difalkner]

Machine flex? Got any photos of your machine? I surface my 2x4 machine with a 1.5" bit; sems like 10mm is too small for surfacing. Is your bit upcut or downcut? What are your feeds and speeds?

[CNCMAN172]

Machine flex? Got any photos of your machine? I surface my 2x4 machine with a 1.5" bit; sems like 10mm is too small for surfacing. Is your bit upcut or downcut? What are your feeds and speeds?

Your spindle is not trammed. Thirty is what causes the ridges when surfacing, search on trimming

[tomasonazo]

Hi again and thanks for the answers, I know it´s not trammed, that´s why I´m trying to correct it, but it makes no sense that it would lift on one side and half way across to the other, the 10 mm end mill is only to check for nod or side to side compensation so as to not get any ridges when I use my 45 mm surface bit. There should be no play, it is aluminium and linear rails and bearings and steel structure bolted to the ground.
So I haven´t played around too much with the machine but it definitely didn´t do this before.

[tomasonazo]

photo of structure:

[routalot]

- - - Updated - - -

My guess is flexing and tramming.The tramming can be brought to a fair level of accuracy without too much drama and further refined when the spoilboard is true.Locating the source of any flexing can be a big challenge and I suspect you have it occurring with movement in both X and Y.The source may well be the Z axis,gantry flexing or spindle mount.Your best friend will be a dial gauge and a dependable way to mount it.

Begin by locating the gauge on the collet nut and apply a force opposite the probe to see what the outcome is along the X axis and then repeat in the direction of the Y axis.Keep a record of the numbers so that you can monitor improvements.Do the same with the movable plate of the Z axis and then the inside of the gantry uprights.I would be very surprised if they all gave zero movement and not surprised if one was giving a number a good deal higher than the others.

[Vlod]

I think you need more support of the bed and material you tried to surface.

[davida1234]

I agree with Vlod.

If the bed is held in place with just four clamps at each corner and has only three cross braces underneath for support, all kinds of sags and distortions of the bed should be expected. The piece of wooden spreader strip over the middle cross brace/under the bed can tilt, the unsupported portion of the bed can sag and so forth.

My suggestion would be to either add more cross braces or install stringers over the existing cross braces every 6-8 inches and then install a full-size 2-3 layer bed over those.

David

[tomasonazo]

Thanks so much for the replies, it ended up being the dust boots bristles being compressed( shallow surfacing bit) and it can flex the alu beam along the x axis. I thought the alu extrusion 30x90mm would be stronger but anyways, i just lifted the dust boot and I now have a lovely level bed.
One problem solved another million are born . I´m starting a new thread with a gcode problem I can´t understand