3 point leveling not cutting it in the first pass.

[Steve Lynch]

I was wondering.... my Railcores “true level” the bed in the first pass, and really don’t do much the 2 and third time around. I built this new machine for fun, as I wanted a ginormous corexy. It’s not totally done, as I didn’t have the 1/2” aluminum to mill my Carriage parts. I kind of appropriated the Railcore style for the Y carriage for now, but I designed a more rigid gantry using a 15mm linear guide. It’s a mosh mash if my FT-5 upgrade parts I designed a few years ago, a little Railcore, and a whole lot of last minute changes. 550mm of Mic6 goodness! I milled all the parts the other night.

Anyhow, when I do a “true level”, , I have to throw a round bubble level in the bed to get it close before it’ll complete. Otherwise I get one corner that doesn’t trigger the BL touch. I assume this is just due to the fact that the bed is longer, so a variation in height compounds. But here’s the deal. When it levels, it’s still way off after the first adjustment. Then it gets better for the second, and pulls it flat on the third pass. Is that normal? Or should it try to fix it in the first pass?

Either way, it works, but my correction is progressive, rather than immediate!

Thanks guys!!!

[Phaedrux]

For a large bed that is pretty normal I think.

[droftarts]

@Steve-Lynch impossible to say without your config.g and firmware version. most likely either your leadscrew positions aren’t accurate in M671, or your probe isn’t set up correctly (offset or not repeatable accurate).

Edit: do you get any error? Maybe it’s beyond the max deviation for bed levelling.

Ian

[Steve Lynch]

Thanks guys... I kind of figured it was just the size of the bed... 1 degree tilt on a 220mm bed is big... double that, and I guess you're right... it's exceeding the max correction value... raising that value almost always leads to a bed crash. I've learned that.. Nothing I can't live with... I just wondered if I needed to set up the maths or something.

I appreciate the reply!

[Szwalkiewicz]

I'm kind of new to duet but at the top of the bed.g after the G28 but before the leadscrew G30's a you could add a m558 with a larger (H) dive height and then after the G30's but before the G29 change the m558 back to what you have in the config.g
then the m671 larger S parameter will work?

[dc42]

@Steve-Lynch said in 3 point leveling not cutting it in the first pass.:

Anyhow, when I do a “true level”, , I have to throw a round bubble level in the bed to get it close before it’ll complete. Otherwise I get one corner that doesn’t trigger the BL touch.

Increase the dive height, that's the M558 H parameter.