Bed levelling - just z probe, or 2 indep. motors with G32?
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Hi,
Bed Leveling (BL), be it automatic or manual, and Mesh Bed Compensation (MBC) are aimed at two different problems.
While MBC can help cope with a bed in need of leveling it is not an ideal solution.
MBC is best suited to coping with bed irregularities.
If you wish BL to be Automatic you need at least 2 independent Z steppers but 3 are much better.
You can get by with the Manual Bed Leveling Assistant (MBLA) which requires 3 or 4 bed leveling screws that you can turn by hand in response to the required adjustments reported by the MBLA.
I have 1 printer equipped with 3 Z Steppers and 2 with bed leveling "thumb" screws.
Being able to auto level the bed is a joy.
Frederick
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@fcwilt I think then it was the bed leveling that I actually need
Yes I have 2 indep. Z stepper motors - I am building a heavy modified Folgertech FT-5 and it will have 3 z steppers - so too my MGN BLV Cube that is still in pieces! -
@Reefwarrior said in Bed levelling - just z probe, or 2 indep. motors with G32?:
@fcwilt I think then it was the bed leveling that I actually need
Yes I have 2 indep. Z stepper motors - I am building a heavy modified Folgertech FT-5 and it will have 3 z steppers - so too my MGN BLV Cube that is still in pieces! The FT5 would be a good candidate for converting to 3 Z steppers.
I have one but it is still equipped with the 3 bed leveling "thumb" screw adjustements.
The printer equipped with 3 Z steppers is one of my own design and I could not be happier with it.
Frederick
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@fcwilt Ok, so I did a few changes in my configuration files:
config.g
M671 X:32.5:202.5 Y:32.5:202.5 P0.5
bed.g
G28
M401
G30 P0 X32.5 Y32.5 Z-99999
G30 P1 X202.5 Y32.5 Z-99999
G30 P2 X32.5 Y202.5 Z-99999
G30 P3 X202.5 Y202.5 Z-99999 S3
M402After running G32, I get:
G32
Error: Calibration failed, computed corrections: nan nan nanBoard: Duet 2 WiFi (2WiFi)
Firmware: RepRapFirmware for Duet 2 WiFi/Ethernet 3.2.2 (2021-02-11)
Duet WiFi Server Version: 1.25Note: You can install updates on the System page.
Tinus
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think I may have found the problem - the 'S' in the last G30 must be S4; as there are 4 screws, not 3....
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@fcwilt The P is for the thread pitch ....
I got this: Error: Number of calibration factors (4) not equal to number of leadscrews (3)
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@Reefwarrior said in Bed levelling - just z probe, or 2 indep. motors with G32?:
@fcwilt The P is for the thread pitch ....
I got this: Error: Number of calibration factors (4) not equal to number of leadscrews (3)
Arggggg.....
My bad - I confused the S and P parameters.
When am I going to learn to not trust to memory....
Frederick
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@fcwilt hahahaha no stress
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Can't seem to sort out the 'Number of calibration factors....' error.....
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Eureka!
G32
Manual corrections required: 0.00 turn up (0.00mm) 0.00 turn down (0.00mm) 0.76 turn up (-0.38mm) 0.81 turn up (-0.41mm)The M671 I used to define the springs positions was not correct.
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@Reefwarrior said in Bed levelling - just z probe, or 2 indep. motors with G32?:
Eureka!
G32
Manual corrections required: 0.00 turn up (0.00mm) 0.00 turn down (0.00mm) 0.76 turn up (-0.38mm) 0.81 turn up (-0.41mm)The M671 I used to define the springs positions was not correct.
The : character after the X and Y?
Frederick
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@Reefwarrior said in Bed levelling - just z probe, or 2 indep. motors with G32?:
This setup is basically on an Ender3 with a DuetWifi.
I wouldn't bother changing the Ender3 to a dual Z axis setup. It's not necessary. When assembled properly the design is adequate for keeping the X gantry level. The bed can be manually leveled pretty easily, and mesh compensation can take care of the rest.
There's something to be said for simplicity. Once you add a second Z axis motor you have to calibrate it because it won't stay in sync over time.
Also, 2 Z motors will only give you tilt correction along a single axis. You need 3 motors to do a 3 point plane. So you'd still be using mesh compensation and manual leveling anyway.
So I say avoid a second z axis motor if the printer design allows for it.
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@Phaedrux Hi, thank you for the reply. I have extended my Z and my X axis and noticed drooping on the one side if the Z raises... hence the reason now for the second motor
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@Phaedrux I'm probably going too complicated now, but won't it help to have 2 indep. motors, have it correct tilt and then bed level assistant for the rest? If I read it correctly, I can not have both 2 indep and MBLA at the same time, or have I misunderstood something?
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@Reefwarrior said in Bed levelling - just z probe, or 2 indep. motors with G32?:
If I read it correctly, I can not have both 2 indep and MBLA at the same time, or have I misunderstood something?
Yes you can use both, but there needs to be a reference somewhere. If you do the tilt correction based on the bed surface, but then change the bed surface itself with MBLA your tilt correction is now changed as well.
Maybe a better solution would be to correct for gantry tilt with 2 endstops at the top of the frame so that you're leveled to the frame as a reference. Then you can adjust the plane of the bed to match the frame.
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@Phaedrux Awesome, thanx!
