extruder works but print not starting

dc42

You have all 4 Z motor currents set to 2.55A, which is more than the 2.4A maximum of the Duet. So it will reduce them to 2.4A. However, with 4 drivers running at 2.4A you need to provide very good fan cooling to prevent the drivers overheating. The most important area to cool is the underside of the PCB underneath the drivers. Best is if you put a fan at the edge of the PCB to blow air along the line of drivers on both sides of the Duet. Similarly for the X5.

The optimum way of driving 4 high current motors will be one of the following:

Connect all 4 of them to outputs on the DueX5. This means that you will only needed to fan cool the DueX5, also the Duex5 has a larger heatsinking area of PCB per driver chip than the Duet does, so it can better get rid of the heat.
Connect 2 of them to outputs on the Duet, and 2 to outputs on the X5. On each of the Duet and the DueX5, choose a pair of drivers that are not adjacent, so that they don't heat each other up as much.

You could also try using a lower motor current. What type of motors are they?

deckingman

Looking at the steps per mm for the Z axis, 640 seems to be an odd number to use. At 16X micro-stepping (which is what is being used) 640 micro-steps translate to 40 full steps. Assuming 1.8 degree motors which have 200 steps per revolution, then 40 full steps is 1/5th of a revolution which would imply the lead of the screw is 5mm which is a very strange number. It's possible but I've only ever seen 5mm lead screws in 22 or 28mm diameter.

If the motors are 0.9 degree (400 steps per revolution) , then 40 full steps would 1/10th of a revolution which would imply a 10mm lead on the screw which is very coarse and would likely be 30 to 40 mm in diameter.

Is there some gearing arrangement between the motors and shafts? i.e are there asymmetric pulley sizes? Can you post details of the screws and drive arrangement?

If the steps per mm are indeed correct, then driving them directly will require a lot of torque, so high power motors. A finer lead or gearing will reduce the torque requirement and allow lower motor current to be used.

Marine85

@dc42 I am using this motors https://www.aliexpress.com/item/NEMA23-stepper-motor-57x112mm-4-lead-3A-3N-m-Nema-23-motor-112mm-428Oz-in-for/1781700551.html+i am using duex 2 I will get duex5 and reduce the current.

I had a weird behavior for z when assigning the Z to 2 ,4 and 5 the macro not working!
when assigning to 2,3,4 and 5 works well , this with duex2 i will try with duex5

Marine85

@deckingman said in extruder works but print not starting:

the motors are 0.9 degree (400 steps per revolution) , then 40 full steps would 1/10th of a revolution which would imply a 10mm lead on the screw which is very coarse and would likely be 30 to 40 mm in dia

the motors are 1.8 degree and the pitch for the pull screw is 5mm,diameter is 16mm
the problem i the bed is abit heavy and requires these motors to lift and lower and they are working well now
the problem when trying to print now , driver 3 giving overheating warning and acting independently after x and y homed for printing

dc42

As well as cooling the drivers better, you should use the P parameter in the M584 command to hide the additional axes when you are not using them, and un-hide them when you need to move them independently. That should make them all work together.

deckingman

@marine85 said in extruder works but print not starting:

@deckingman said in extruder works but print not starting:

the motors are 0.9 degree (400 steps per revolution) , then 40 full steps would 1/10th of a revolution which would imply a 10mm lead on the screw which is very coarse and would likely be 30 to 40 mm in dia

the motors are 1.8 degree and the pitch for the pull screw is 5mm,diameter is 16mm
the problem i the bed is abit heavy and requires these motors to lift and lower and they are working well now
the problem when trying to print now , driver 3 giving overheating warning and acting independently after x and y homed for printing

Ahh, OK. As I said earlier in my post (which you haven't included in your quote) , I've never seen 5mm lead in anything other than 22mm diameter. Out of curiosity, what are the dimensions of the bed and how much does it weigh?

Marine85

Bed is 1300x1300 and used 25mm hiwin rails which they are really heavy and aluminum profiles 60x60 i would say it is about 35g i have a plan to make it lighter less than the half but now with these motors lifting is very smooth apart from the overheating issue
I will reduce the supply amps into 1350 amps and keep the duetwifi and duex in air-conditioned room and check
Hopefully it will print

Marine85

Bed is 1300x1300 and used 25mm hiwin rails which they are really heavy and aluminum profiles 60x60 i would say it is about 35g i have a plan to make it lighter less than the half but now with these motors lifting is very smooth apart from the overheating issue
I will reduce the supply amps into 1350 amps and keep the duetwifi and duex in air-conditioned room and check
Hopefully it will print

deckingman

@marine85 Yes, that's pretty big. I think if it were me, and if it's possible to fit, I'd look at using small pulleys on the motors and a large ones on the screws to give some gearing. That would reduce the torque requirement for the motors. Basically if you had 2:1 gearing, you halve the torque required. But on te other hand, you do have 4 motors so if you can drive the bed OK with lower current, then there is no need.

Marine85

Many Thanks all for great support , I got it working
but when I use the hide parameter P3 in M584 stops the macro for independent Z endstops?

dc42

Use M584 P5 within that macro to un-hide the U and V axes before you move them, and M584 P3 again afterwards.