How much play in Z axis gantry

I tested by drilling and milling a simple hole in a 2mm aluminum plate. The z gantry starts to wobble and then kicks horribly ending up with a relative large ugly cut.

I use a spindle from Ali about 11000rpm and a 4mm 2flute end mill.

It seems the bearings in z gantry are good and tight, as they all “run” when moving the gantry up and down! I also feel resistance when I hold the bearings tight when moving, but when I push the bit x/y direction I have a lot of play (I think)!

Looking at the gantry it seems the xyz-part is a little soft and moves with the z metal tube when I push the bit. I printed the whole thing in PETG fresh from the store, should I try printing it in PLA instead?

Here are some videos explaining the issue. I have some cracks in the xyz parts, this happened recently when I tried tightening to see if it solved the issue. It did not.

Bit play

Xyz play

Drill test(0.1mm steps)

Mill test (0.1mm steps)


Hard to say but start bu mounting the spindle up higher. the collet should be plush with the bottom of the Z axis, and the mount should be as wide as you can make it.

Another thing to consider is most end mills are not made to plunge very well, even in wood. They are made to have a flat end, and there for not flutes to clear material. You can spot drill, and ramp into other cuts.

Look for a different end mill or a short drill bit if you want to pop a bunch of holes.

That is one spec that I don’t recall coming across. Looking through the documentation there doesn’t seem to be any illustration of mounting a spindle. I guess using the standard Dewalt and mounting setup it all falls into place. Will need to look at my custom mount and see if I can bring it up just a hair. I haven’t had issues with wood but I don’t push the feeds too much.

If you have your spindle sticking out 3" that just means your machine can be 3" shorter, that means it can be a lot more rigid.

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Thank you for the inputs! i will lift the spindle, and shorten the vertical feet’s. The machine has a build space of 390x390! Any input on petg vs pla? I will have to print some new parts, should I go for pla?

I prefer PLA unless maybe the spindle mount if it gets really really hot.

Noted! Thank you again:ok_hand: