Heater Question for Electrical Engineers and Other Knowledgeable on the Subject

[mykepredko]

@MicroFarmModels

So each “pulse” is 8 sec with marlin, correct? Or is the period a time in which the board is sending short pulses? Sorry if I am being dense.

No, each pulse takes place within the 8s (or whatever the Marlin) PWM period and is the period multiplied by the power level. 10% power would have a 0.8s pulse, 50% power would have a 4s pulse, etc.

My plan for the bed mount is to do what @Jason said the Modix printers they sell have. That is have bolts from the bed to the mounting brackets, but instead of a spring between the bracket and and bed, there is another nut on top of the bracket. The nuts are snugged up enough to be secure, but still allow the bolt to slide in it’s slotted hole. The very center bolt in the bed would have the nuts tightened so there would be one fixed mount on the bed. That way the end bolts would only need to move around half a mm, and the bolts in between some fraction of that.

Fastening down at one point, I use the lower left (0, 0) corner, seems to be the way that people are doing it now.

You are right that the best test will be building and testing it in real life. I still want to do due diligence though.

There’s “due diligence” and there’s appropriately prioritizing which I’m trying to push you towards. As I said in my last response, you have a basic plan for the heated bed (big aluminum plate that is heated by adhesive pads powered by a DC source). You have a huge and somewhat unusual build area that I would think you should be concentrating more on things like how to build the frame and jig it so that it is accurate and your rails are straight and parallel, both to each other as well as the print bed.

The heated bed is meaningless unless you have the moving parts running down very accurately placed rails with no chance of binding or cables being snagged as the gantry goes from one end of the printer to the other.