2024-07-16

Last modified: 2024-07-16 14:05:41

Machine building

Status was:

• The table rises at the left by 0.58mm over 230mm.
• X and Y are perpendicular enough to each other to satisfy me.
• The gantry should be shimmed forwards at the top, with a shim of about 0.20mm.
• The top of the Z axis leans to the right by 0.35mm over 90mm.

I've unbolted and adjusted and rebolted the Z axis, and now measuring that it leans to the right by 0.075mm over 90mm, which is an improvement - except I forgot to make the cylindrical square stand up level.

Still leans to the right by 0.30mm over 90mm.

I loosened the bolts holding the X carriage plate to the carriage bearings, and pulled the Z axis part to the left at the top, and now it's showing 0.05mm over 90mm, which is 0.03 degrees. I might be able to tap it with a mallet and get a small improvement.

Got it to within 0.03mm over 90mm, or 0.02 degrees away from vertical. That'll do for now.

I've also bumped up the max. feed rate in LinuxCNC to 3000 mm/min. I think it will be able to do more with grblHal, but I'm running into LinuxCNC's loop frequency limit.

So current status is:

• X/Y is square
• X/Z is square
• Y/Z needs the shim

And how are we doing for spindle tram? How do I check that?

I think put a shaft in the spindle and put an indicator on it, and move the Z axis up and down and see that the indicator stays still?

The runout is quite bad, this might not work.

With the spindle aligned for "maximum" runout reading, I get a variation of 0.30mm over 53mm of Z travel. Rotating the spindle 180 degrees away from there, I get 0.45mm of variation, TIR at the tip of the shaft is 0.25mm.

If we assume it is running out by sweeping a cone around the spindle axis, and I position the spindle halfway between the minimum and maximum reading, then can I expect the point on the shaft that the indicator is touching to be parallel to the spindle axis? I think so, let's measure that.

It changes by 0.44mm over 62mm of Z travel. It's moving to the left when Z is at the top, which means the spindle axis is leaning to the right at the top.

Now got it to 0.07mm over 60mm of Z travel, that'll do for making the spindle axis square to the X axis. I'm not going to worry about making it square to Y just yet. It will need shimming if I do need to adjust it.

I'm having some trouble getting these green circles into the linear rails:

They don't fit very well, so I'm having to hammer them in with a drift, but it's proving difficult. Seems like they should be rubbery instead of hard plastic.

So now we've got:

• gantry needs shimming forwards at the top by 0.20mm, probably use coke can material
• the extra bolts and green circles all need putting in
• then make a fast circle-moving demo or something
• then spindle wiring
• and why does the spindle run out so badly? is it because of bad collets?