Levelling the honeycomb

Any advice on how to level the honeycomb? After many months of problems with uneven power across the bed, I’ve finally noticed that the bed is about 3mm higher on one side than the other, and differs by about 1mm between front and back. That would seem to explain a great deal!

I’ve tried rotating the table supports but a full revolution makes too big a change.

I’m thinking that I’ll have to loosen the belt somehow, and turn the screws just a little at a time to get the heights equal. Has anyone else done this already?

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Yep, just did it about 3 hours ago. I loosened/removed the right front non-cog bearing (its a tightening bearing) and loosened the bolt sufficiently to allow it to lean over about 45 degrees.
Then, armed with a flat table vernier (something like this… but not this: Mini Digital Height Gauge Fence Rule Repeat Setting Measure Slot Flat with Three Measurement Modes Large Digital Display for Woodworking (Black) https://www.amazon.com/dp/B07TBXRRNJ/ref=cm_sw_r_cp_api_i_7220Eb8987P8Y) I set them all to the same height, within 0.05 mm. Yes, you have to turn each cog and seldom does full turns do it. Ensure adjusting one does not turn the others. Then, ensure the belt is around each cog (mine had slipped down and I had to backtrack), put the two nuts loosely, large washer, and two bearings on and likely out the top but on, but barely on with the belt in place… then tighten the bottom nut until the bolt stand s vertical (I had to tighten the 2nd and 3rd nuts against the bearings and each other to hold the bolt from spinning with a wrench on the top while I tightened the bottom nut/bolt. Loosen the top two nuts, spin and tighten the second one down. Ensure the belt is where it should be and then place the large washer and nut on top of the bolt and tighten away. Based on measurements from the bottom I had everything within .05mm of 45mm. Put the tray back in and check and because of variance in the tray and those back two supports being cut out and not solid or even, my final result measured from the bottom of the lens focal tip I was about 1mm off from level. 3mm is unacceptable. I’m workingWith it now and the 1mm doesn’t seem to make much difference. Most of my stuff is 9” x 9” or smaller so my actual variance is probably 1/2 mm max. If you find a better way holler out.

How did I guess that good advice would soon come from you?

Thanks for the suggestions, especially about the tensioning pulley. I was looking at those last night and wondering whether I’d ever get the thing back on again after loosening it.

I didn’t know about these gauges, and will see if I can make do with a stack of wooden blocks.

Stack of blocks will work. When you measure/compare the height of the two back tray supports consider if you should measure to the top of the two vertical fingers or the larger cutout area that is maybe 3/16" lower. I started thinking the fingers actually was inside the aluminum margin around the tray and so the tray would settle on the lower, cut-out area. Then I got to studying it and convinced myself that the tray will not settle down onto the lower cutout but would always ride on the higher smaller fingers. Let me know hat you conclude. cheers, Jim

This may be a bit of a brute way to do it, but I checked for level on the honeycomb, then took it out and manually turned the posts it was resting on, put the honeycomb back and repeated until it was level. Im not sure if there is an official way to do it, but im sure there are prettier ways.

If you are leveling with full turns off the corner posts I’m surprised they ever balance as a full turn is a couple mms. I removed one of the chain/belt tensions in the very front, dropped down the belt/chain, and then leveled each of the 4 corner platforms. Much easier and more accurate. But then… getting the chain/belt around all the cogs/tensions and tightening that tensioner back up is difficult. Just take it slowly and a third hand would be helpful.

I went the woodworker’s path to leveling my honeycomb. Shims! A little bit of veneer and some blue tape in the right places got me pretty darn close.
I still have some issues with the laser cutting through material when it is in the lower right hand corner of the machine thought. Still working on that one. Is that a leveling issue?

Shims it was for me, too.

If the beam is very wide and not quite parallel enough, that would be one explanation, as beam expansion results in less and less energy reaching the final mirrors. (Lasers are typically made so that the beam waist — the narrowest part — is right at the laser tube’s exit hole.) I doubt very much that this is the case, however, because the burn holes are so much smaller than the apertures.

Aside from that and a wonky honeycomb, I haven’t managed to think of what might make the beam lose noticeable cutting power over such a short distance.