thoughts on increasing rigidity of x2 mill? (besides coulmn brace)

[davesharps]

Hey all,
I converted my lms minimill to cnc, added a heavy duty bracing column and made an entire welded and dampened stand for the mill. all of which helps a ton! However, if i take too heavy of a cut, the z axis gibs become loose. Even on semi heavy cuts, its clear that where the spindle head meets the column is its weak point.

Has anyone found any good solutions to improving that area? Would swapping out the stock gibs to something like brass help? If we went crazy and swapped out the dovetails for linear rails would that work? I'm wondering how much further i could push this little mill while still using the same castings.

Thanks!

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[CL_MotoTech]

If the Z axis carriage is opening at it’s ways during cut you are probably nearing the maximum capabilities of the machine. That said you could build a girdle of sorts where you run plates off the carriage and tie them together off the back of this column. This would effectively places the carriage ways in double shear and should reduce any deflection you have at those points. I don’t own an X2 though, so I am guessing a bit. I have however considered this arrangement for my g0704.

[109jb]

If your gibs are loosening it could be that you have a crack in the Z axis slide.

[cncuser1]

I think you should look further into why the Z axis gibs are coming loose.
Cracks, as mentioned.
is it not tight enough to begin with? That would cause a lot of vibrations.

If the gib is tight but cocked at an angle in the gap it may work it's way loose.

Also make sure the gib is in contact with a flat face of the way and not rubbing improperly into the corner of the ways.

[dazp1976]

Sounds similar issue to mine. Mine has given a horrible finish since I stalled and broke an 8mm cutter. My head is vibrating badly in the exact same place. I've got the solid column conversion and it's rigid as anything in that respect.
Looking as though my head back end has spread at the ways.
I've literally replaced everything else including AC bearings and R8 spindle upgrade and got the same results.

I've gave up and have been converting a new PM25 over the last few months using the X2 to make the parts before end of life.
I have got another X2 purely for drilling purposes so I'll swap the parts over to see once the PM is running.

The X2's Z gib area is awful imo.

[CL_MotoTech]

If the ways are spread on the carriage then a girdle as I described with solve your issues.

My G0705 Z carriage was spread from what I believe was an issue from getting a gib strip stuck in the way during disassembly (previous owner). I solved the issue by replacing the carriage, but a girdle would be really easy to build and install.

[cncuser1]

CL, I am having trouble understanding your idea, could you post a picture or sketch?