steps per mm for Z axis
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hello all
i am in the final stages of setting up a printer for work, and i am having an issue getting the correct steps per mm to provide the correct distance to be moved, spec of the printer is
corexy 300x300x300
Duet 6HC
firmware is the latest 3.4
x3 z axis lead screws (the lead screws are single start "T10") which move the leadscrew nut up/down by 2mm per revolutionthe motors are nema 32 23HM22-2804S from stepper-online they are listed as a 0.9 degree motor which is a step value of 400 per revolution
i used the config tool to make a config file and added the extra z axis motors its came out with a setting of 6400 at x16 micro steps for the Z axis
my problem is when i ask the printer to move the Z axis with those settings the motors only emit a high pitched whine and dont move, if i change M350 & M92 to
M350 X16 Y16 E16 Z32 I1
M92 Z3200with those settings i can get the Z axis to actually move in the correct directions just not by the desired distances, any ideas as to what i am doing wrong ? as its driving me up the wall.
one thing i also noticed is that the config tool put X & Y steps/mm at 160 (same motors 20 tooth pulleys) but those steps per mm did work either i played with those steps/mm and measured travel moves until i reached a figure of 128.5 steps/mm which seems odd im wondering if my motors are not what the sticker says they are.
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@bertie-basset said in steps per mm for Z axis:
23HM22-2804S
looking at the specs for those motors there are 2.8 amps so your string in the M906 should I think be around 2000 and not the 800 you have set.
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@bertie-basset I have almost the same settings you do for the same hardware (other than I've got 1.8 motors), other than the current. If correcting the max current doesn't work you might check and make sure each Z motor is actually moving in the direction you think (you can move them individually to test). If one Z motor is going the other direction...
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@dougal1957 said in steps per mm for Z axis:
@bertie-basset said in steps per mm for Z axis:
23HM22-2804S
looking at the specs for those motors there are 2.8 amps so your string in the M906 should I think be around 2000 and not the 800 you have set.
@Dougal1957 Yes as @Arnold_R_Clark said i forgot to add i did try putting the amps up
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thanks good point, i though i had checked that, as everything appeared to move in the right direct when i changed the steps per/mm but i will re-check.
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@markz said in steps per mm for Z axis:
@bertie-basset I have almost the same settings you do for the same hardware (other than I've got 1.8 motors), other than the current. If correcting the max current doesn't work you might check and make sure each Z motor is actually moving in the direction you think (you can move them individually to test). If one Z motor is going the other direction...
I re-checked they all run in the correct direction....
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Well if they are moving satisfactorily other than the distance moved you merely need to adjust the Z value in the appropriate M92.
Issue a command to move Z by 100mm. Measure how far it actually moved. Then compute the new Z value using the ratio of the two distances.
New Z Value = Current Z value * (100 / distance actually moved) .
Repeat as needed until satisfied.
Frederick
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@fcwilt said in steps per mm for Z axis:
Well if they are moving satisfactorily other than the distance moved you merely need to adjust the Z value in the appropriate M92.
Issue a command to move Z by 100mm. Measure how far it actually moved. Then compute the new Z value using the ratio of the two distances.
New Z Value = Current Z value * (100 / distance actually moved) .
Repeat as needed until satisfied.
Frederick
In theory yes, in reality NO.
As i said in my original post when you put the required number to get the amount of travel required, the motors dont move they just sit and whine, slowly bring the number down until you get the motors to move (even over 2amps) and the distance traveled is less than the amount requested. I know the math its just not doing what its should be doing which is why im scratching my head.
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@bertie-basset Your motor config:
; Drives M671 X-30:150:330 Y-10:350:-10 S15 ; pivot points M569 P0.0 S1 ; physical drive 0.0 goes forwards M569 P0.1 S1 ; physical drive 0.1 goes forwards M569 P0.2 S1 ; physical drive 0.2 goes forwards M569 P0.3 S1 ; physical drive 0.3 goes forwards M569 P0.4 S1 ; physical drive 0.4 goes forwards M569 P0.5 S1 ; physical drive 0.5 goes forwards M584 X0.0 Y0.1 E0.2 ; set drive mapping M584 Z0.3:0.4:0.5 ; ser drive mappiing for z axis M350 X16 Y16 Z16 E16 I1 ; configure microstepping with interpolation M92 X128.50 Y128.50 Z3200.00 E395.00 ; set steps per mm M566 X900.00 Y900.00 Z60.00 E120.00 ; set maximum instantaneous speed changes (mm/min) M203 X6000.00 Y6000.00 Z180.00 E1200.00 ; set maximum speeds (mm/min) M201 X500.00 Y500.00 Z20.00 E250.00 ; set accelerations (mm/s^2) M906 X800 Y800 Z800 E800 I30 ; set motor currents (mA) and motor idle factor in per cent M84 S30 ; Set idle timeoutI'd say
M566 Z60is your problem. You are trying to start the motors too fast, and larger motors have more inertia, so can't spin that fast straight away. The high number of steps per mm doesn't help either. TryM566 Z10and work up from there.Ian
Bed-slinger - Mini5+ WiFi/1LC | RRP Fisher v1 - D2 WiFi | Polargraph - D2 WiFi | TronXY X5S - 6HC/Roto | CNC router - 6HC | Tractus3D T1250 - D2 Eth
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thank you that is a great spot. i didnt think of it as that is just what the config tool spat out.
i will test now and report thank you again.
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@bertie-basset said in steps per mm for Z axis:
As i said in my original post when you put the required number to get the amount of travel required, the motors dont move they just sit and whine, slowly bring the number down until you get the motors to move (even over 2amps) and the distance traveled is less than the amount requested. I know the math its just not doing what its should be doing which is why im scratching my head.
Well the 0.9 steppers are contributing a bit to the the problem, having a bit less torque and requiring twice the steps/mm.
The suggesting regarding acceleration may be spot on.
Frederick
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thank you for the pointers I dropped the acceleration down to 10 then 5 and still no joy.
i fitted a set of T8 leadscrews that are not long enough but everything works just fine with them...
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@bertie-basset said in steps per mm for Z axis:
thank you for the pointers I dropped the acceleration down to 10 then 5 and still no joy.
i fitted a set of T8 leadscrews that are not long enough but everything works just fine with them...
So you were able to drop the steps/mm from 3200 to 800?
I've never used 0.9 steppers but I have, in the past, used T2 lead screws without issue other then a slower max speed.
Were you trying to move at max speed? If so did you try any slower moves?
Frederick
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yes i was able to drop to 800 and i tried running them very slowly that didnt help, i will see if i can get a full set of T8 leadscrew via Amazon
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And i just this minute got it to finally work
I Think i had a combination of issues, while messing about with M203 I had at some point set the max speed of the Z axis to 1800.00 instead of 180.00 and I hadn't noticed, that in conjunction with M566 being too set too high compounded the problem.
i have managed to get it working with the following
M203 Z180.00 ; set maximum speeds (mm/min)
M566 Z10 ; set maximum instantaneous speed changes (mm/min)
M350 Z32 ; configure microstepping
M92 Z 6400 ; set steps per mm
M201 Z20 ; set accelerations (mm/s^2)
M906 Z2000 ; set motor currents (mA)Thank you to everyone for their input i will mark this as solved
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