12" I3V Build

[printbus]

The 11A input will also need 12V going to it in order for the heat bed output to have any voltage to drive the SSR. You won't need much current. It's fine to run some light gauge jumpers from the other 12V input over to the 11A input.

EDIT: The power input for the heat bed is kept separate in order to support those people who run a different voltage heat bed, like 24V.

[Dustin B]

And is thermal paste really necessary between the SSR and heatsink. Isn't the SSR pretty big overkill for the DC the heat bed will be running?

SSR
Heatsink

[printbus]

Hopefully someone with an SSR and heatsink used with a 12-inch heat bed will chime in. How hot the SSR gets depends on the current rating and the quality of the MOSFET inside it. IIRC some have reported their SSR getting pretty warm. If the MOSFET is only rated for around the 40-amp limit on the SSR, there could be enough on-resistance that it'll dissipate noticeable heat with a 12-inch bed hanging off it. Some that have built their own MOSFET board have used up to like a 200-amp MOSFET in order to ensure a very low on-resistance. Those would dissipate very little heat. There's also so much counterfeit and knock-off stuff out there that you don't know what you're really getting these days, especially from sources like eBay and Amazon.

You could always try it without the heatsink grease and see how warm it gets.

[BLKKROW]

I have an SSR and used TIM (thermal interface material). My heatsink barely gets warm after printing for 18+ hours.

[Dustin B]

I'll try it without and keep an eye on it's temp. Any thoughts on what range would be concerning?

[BLKKROW]

I'll try it without and keep an eye on it's temp. Any thoughts on what range would be concerning?

If I were you I would use TIM. The fact is the heat sink and SSR are not perfectly flat, so they will not have a lot of contact without the TIM. This means you might have thermal runaway that might burn something.

[Dustin B]

Can you test the movement direction and homing of the axis from the marlin lcd menus?

[printbus]

You can do basic movements from the LCD, yes. It's been a year since I ran Marlin, but I think you can only home all three axis, not each axis selectively. You can also move each axis by fixed increments of distance. Rotating the knob CW should give you "positive" movement, rotating CCW will give you negative movement. Until you do a homing action, "zero" is where ever the nozzle is when the printer is first turned on, which can make it easy to slam against a mechanical stop with large movements from the LCD.

Note that in at least legacy versions of Marlin, Z can only be commanded to move in 0.1mm or 1.0mm steps. For some reason the developer(s) didn't want to allow 10mm steps on Z. In other words, the option to move Z won't show up when you've selected 10mm incremental movements. This is a common area of confusion for those starting out.

This is a more thorough Marlin menu tree than the one that Colin at least used to provide in the build guides - http://mauk.cc/mediawiki/images/LCDmenu.pdf Home all axis is the Auto Home under the prepare menu. Axis movements are under the Move Axis item also on the prepare menu.

EDIT: Extruder motor movement is also possible on the move axis submenu tree. Just note that protections built into Marlin won't let you move the extruder motor if the hot end is not above a low temp threshold. The intent is to keep you from trying to move the motor when the filament is "frozen" in the hot end.

[Dustin B]

Got the wiring finished. And using the menus I've verified all the steppers are working and moving in the right directions. All the end stops are working. Both thermistors give readings. The hot end fan runs and both the hotend and the heat bed will heat up. So tomorrow or saturday I'll fine tune the end stops and level the bed. Run the auto tune on the hotend and heatbed and verify the thermistors are reading in the right ball park. Get the extruder steps per mm configured (unless it's really off this will just be using the multipler from the slicer). Then print some test bars to verify x and y steps per mm. Then print benchy

Anything I'm missing in this list?

[Dustin B]

Oh and the pointometers or whatever they're called on the stepper controllers. How likely am I to need to adjust them. What should I be looking for to tell if a motor is skipping steps. And I assume just watch temp to decide if they are running too hot? There's some way to measure them isn't there, but unless you have a really steady hand and the right equipment is it advisable?