How I fixed Z banding on my 12" i3v. AL Y bed and solid state heat bed relay/PID

I would say you have a power supply issue then.

Are your stock rods bent at all? Do you have anything trying to constrain the top of the rod? Did you change the wooden Y axis bed for an aluminum one?

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Originally Posted by tsteever

I am measuring at the power supply. I read a fair bit more on wire gauge from all my text books, online, etc... I am sure that the 14 gauge wire is more than adequate from the job here. I still need to check the connections. I am getting even more convinced that the cheap power supply is just not up to the job of a 12" bed. It is a 30 amp model. I only paid $28 or so from Amazon. I think I may go with this one as it has a higher output and reads to be of better quality. I think a more stable power source may help with my Z banding issues.

My next step in getting rid of Z banding is to replace the M5 screws with M6 lead screws. I'm not really sure what gains that will give me as the 5mm screw has pretty good resolution. I think the biggest gains may be had by a backlash nut of sorts.

Do you guys see the M5 rods as a possible source of Z banding? I was thinking of getting a pair of these.

PS - sorry for seemingly hijacking the OP's thread. Trying to keep this as close to getting rid of Z banding so people can use this thread to serve as a resource.

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I have nothing holding the top of the rods and yes, I have upgraded to the Aluminum bed.

I don't think Z backlash is a problem, because the weight of the X always pushes down on the Z nut.

Agreed, I have not had any issues with Z backlash either.

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Originally Posted by 3DPBuser

I don't think Z backlash is a problem, because the weight of the X always pushes down on the Z nut.

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I ordered the relay and heatsink. looking forward to trying this out. how likely is the relay to fail if using a heatsink?

My relay doesn't get hot at all. I did order the heatsink and was a bit concerned by the size. It seems to be working fine. A review on Tom's youtube page suggests that adjusting the frequency could help but I haven't figured that part out yet.

I ordered the heatsink and some thermal paste as well. I have the whole thing attached to my enclosure and it's never been remotely warm. Not sure how warm it would be without it.

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Originally Posted by adamfilip

I ordered the relay and heatsink. looking forward to trying this out. how likely is the relay to fail if using a heatsink?

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Not sure but I wouldn't want to find out. If the relay fails there is a chance that it would stick in the on position and since it is wired directly to your power supply your bed temp would run away. Not that this is any different than the mechanical relay because it would do the same thing if the contacts stuck on with the relay.

You can turn on the Thermal Runaway protection in Marlin.

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Originally Posted by tsteever

You can turn on the Thermal Runaway protection in Marlin.

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Not really. Thermal runaway protection still depends on the heater control circuit working properly.

EDIT: I should qualify this. IIRC, if the printer is wired so that the printer power supply can be controlled by gcode commands, the thermal runaway protection will shut the printer off and turn off the heater. Otherwise, a stuck heater circuit is a stuck heater circuit and the heater will stay on. BTW, both mechanical relays and MOSFET-type solid state relays tend to fail in the "ON" state. Mechanical due to contact arcing and MOSFET because of the substrate nature of the device.