Dual Z bed leveling question.

TLeTourneau

I have bed leveling setup and the command runs however I receive a "G32 Error: Some computed corrections exceed configured limit of 0.50mm: -0.415 -1.223" error when attempting to use it. I removed the S0.5 from the M671 and got a "G32 Error: Some computed corrections exceed configured limit of 1.00mm: -0.255 -1.060". I'm using a dc42 Mini Differential IR Sensor.

My config.g entries for it are:
M584 X0 Y1 Z2:4 ; Assign stepper motors to axis
M671 X10:485 Y275:275 ; leadscrews at left side center and right side center removed S0.5 from end for a test

and my bed.g is:
G28 ; home
G30 P0 X10 Y275 Z-99999 ; probe near a leadscrew
G30 P1 X485 Y275 Z-99999 S2 ; probe near a leadscrew and calibrate 2 motors

Any thoughts on the errors? I searched and I can't seem to find anything. The printer is a TronXY X5S-500 (500x500x600mm) CoreXY.

Thanks!

Tom

TLeTourneau

This post is deleted!

dc42

The message means what it says. In order to guard against damaging your Z axis if the probing gives incorrect results, there is a maximum amount of individual leadscrew correction that the firmware will apply. This limit defaults to 1mm if you don't specify it.

TLeTourneau

That makes sense. I manually adjusted the bed and ran the G32 again and was able to get it to work repeatedly however the adjustment apparantly did not survive a power cycle as after doing power cycle I started receiving the error again. It doesn't look like the lead screws are moving when I power down so I'm not sure what is happening to cause the problem.

dc42

@tletourneau said in Dual Z bed leveling question.:

That makes sense. I manually adjusted the bed and ran the G32 again and was able to get it to work repeatedly however the adjustment apparantly did not survive a power cycle as after doing power cycle I started receiving the error again. It doesn't look like the lead screws are moving when I power down so I'm not sure what is happening to cause the problem.

Stepper motors are more or less guaranteed to move when you power down, typically by 1 to 2 full steps. But that probably isn't enough to account for the imbalance you are seeing.

TLeTourneau

It seems this thing can drop the bed a fair amount when powered down. I think it may just be weight related, it's a 500*500mm build surface with a 6.35mm thick piece of glass on it. I'm still investigating a bit but that may be it.

The next thing I'm trying to figure out is how to use both automatic bed leveling and mesh compensation. When I define the area and points for the mesh it just does the ABL points.

On a completely unrelated note I was able to get the mini IR sensor to work by putting parchment paper between the glass/silicone and the heat bed. I thought I'd add that for anyone looking far an interface to use that can't bake high temp paint onto the plate.

dc42

@tletourneau said in Dual Z bed leveling question.:

The next thing I'm trying to figure out is how to use both automatic bed leveling and mesh compensation. When I define the area and points for the mesh it just does the ABL points.

Use G32 for bed levelling using the leadscrews. Use G29 for mesh bed compensation. In Duet Web Control v1.x, to run mesh bed probing, press the arrow next to the Bed Compensation button, and select Mesh Probing from the drop-down list.

TLeTourneau

@dc42 said in Dual Z bed leveling question.:

@tletourneau said in Dual Z bed leveling question.:

The next thing I'm trying to figure out is how to use both automatic bed leveling and mesh compensation. When I define the area and points for the mesh it just does the ABL points.

Use G32 for bed levelling using the leadscrews. Use G29 for mesh bed compensation. In Duet Web Control v1.x, to run mesh bed probing, press the arrow next to the Bed Compensation button, and select Mesh Probing from the drop-down list.

Thanks, I'll give that a try. I've noticed that the bed will drop even with the power on prior to homing. I've got 1.5 amps going to Z now and I'm not sure how much these motors are rated for as they are TronXY branded PN:SL43STH60-1684A. Does the system assign each driver the configured power in a parallel axis configuration or does that need to be specified per driver in the config.g somewhere?

Also, could someone recommend a decent 60mm NEMA 17 motor for a 600mm Z axis?

Thanks for all the help!

Phaedrux

@tletourneau said in Dual Z bed leveling question.:

Also, could someone recommend a decent 60mm NEMA 17 motor for a 600mm Z axis?

There's this beast: https://www.omc-stepperonline.com/nema-17-stepper-motor/nema-17-bipolar-18deg-65ncm-92ozin-21a-336v-42x42x60mm-4-wires-17hs24-2104s.html

I use this one to lift my 10Lb bed with 2:1 gearing: https://www.omc-stepperonline.com/nema-17-stepper-motor/nema-17-bipolar-59ncm-84ozin-2a-42x48mm-4wires-w-1m-cable-and-connector-17hs19-2004s1.html

TLeTourneau

@phaedrux said in Dual Z bed leveling question.:

@tletourneau said in Dual Z bed leveling question.:

Also, could someone recommend a decent 60mm NEMA 17 motor for a 600mm Z axis?

There's this beast: https://www.omc-stepperonline.com/nema-17-stepper-motor/nema-17-bipolar-18deg-65ncm-92ozin-21a-336v-42x42x60mm-4-wires-17hs24-2104s.html

I use this one to lift my 10Lb bed with 2:1 gearing: https://www.omc-stepperonline.com/nema-17-stepper-motor/nema-17-bipolar-59ncm-84ozin-2a-42x48mm-4wires-w-1m-cable-and-connector-17hs19-2004s1.html

Thanks! I guess I could go with a shorter motor and build a bracket. Gear reduction, I hadn't thought of that. Do you think it could help with the Z drop I'm experiencing?

Phaedrux

@tletourneau I used lead screws with a smaller pitch to reduce the bed drop potential. Tr88 is rather steep. I chose Tr81 which has a much flatter thread profile. The torque required is also reduced.

I'm not sure if the gearing would help reduce bed drop. I'd have to think about that. if 2:1 reduces the torque to drive it one way, does it increase the torque to drive it the opposite way?

TLeTourneau

@phaedrux I hadn't considered the pitch of the lead screws. The change to compensate for the change in pitch is to change steps per rotation, correct? Can you point me in the direction of a supplier? If I'm changing the lead screws I may look at ball screws as well rather than use the anti-backlash buts I use now. I'm also replacing the LM12's it came with for ones that are about twice as long hope that will help stabilize the front to rear tilting. I have some videos showing some of the challenges.

https://youtu.be/sUU4BBBJDbs

https://youtu.be/A3I0xM53tHI

Phaedrux

@tletourneau https://www.aliexpress.com/store/product/T8-100-150-200-250-300-350-400M-T8-Pitch-2mm-lead-12mm-Lead-Screw-8mm/2882163_32826081042.html If you scroll down the page there are link to other lengths. Buy twice as may as you need incase they come bent

TLeTourneau

@phaedrux said in Dual Z bed leveling question.:

@tletourneau https://www.aliexpress.com/store/product/T8-100-150-200-250-300-350-400M-T8-Pitch-2mm-lead-12mm-Lead-Screw-8mm/2882163_32826081042.html If you scroll down the page there are link to other lengths. Buy twice as may as you need incase they come bent

Thanks, I've been looking at them, bangood, and Amazon and haven't had any luck finding single start 1 or 2mm t8's 675mm or longer (I can have it cut if needed).

What about a 5/16" 18tpi threaded rod? I can get those locally in 304 stainless steel with a flange nut. 18tpi is about a 1.411mm thread pitch.

wilriker

@tletourneau said in Dual Z bed leveling question.:

Thanks, I've been looking at them, bangood, and Amazon and haven't had any luck finding single start 1 or 2mm t8's 675mm or longer (I can have it cut if needed).

I've ordered my lead screw from this shop. The following link leads you to 750mm long ones. They do have shorter and also longer ones (1500mm was the longest I spotted so far):

304 stainless steel T8 screw length 750mm lead 1mm 2mm 3mm 4mm 8mm 10mm 12mm 14mm 16mm trapezoidal spindle screw 1pcs

TLeTourneau

@wilriker said in Dual Z bed leveling question.:

@tletourneau said in Dual Z bed leveling question.:

Thanks, I've been looking at them, bangood, and Amazon and haven't had any luck finding single start 1 or 2mm t8's 675mm or longer (I can have it cut if needed).

I've ordered my lead screw from this shop. The following link leads you to 750mm long ones. They do have shorter and also longer ones (1500mm was the longest I spotted so far):

304 stainless steel T8 screw length 750mm lead 1mm 2mm 3mm 4mm 8mm 10mm 12mm 14mm 16mm trapezoidal spindle screw 1pcs

Thanks! I don't know why I couldn't find it, maybe getting search burn out. Next question, 1mm or 2mm single start T8?

wilriker

@tletourneau I do use 2mm single start. But since you have a huge bed and obviously issues with keeping it at where it is, 1mm might be the best solution. But then again they are so cheap you could just order both types. Advantage of 2mm would be double the speed compared to 1mm which might be helpful for long movements after a tall print.

TLeTourneau

@wilriker said in Dual Z bed leveling question.:

@tletourneau I do use 2mm single start. But since you have a huge bed and obviously issues with keeping it at where it is, 1mm might be the best solution. But then again they are so cheap you could just order both types. Advantage of 2mm would be double the speed compared to 1mm which might be helpful for long movements after a tall print.

That's a thought, get each to try. Would anti-backlash buts be recommended as well?

Stephen6309

@tletourneau The weight of the bed removes backlash, those nuts aren't need. Misspelled words sure do change things.

TLeTourneau

@stephen6309 ha, oops!