Prusa firmware for RAMPS Prusa i3 clones with MK42 beds

3D Modelling, Slicing, Hosts and Management
IanC
Posts: 20
Joined: Sat Aug 12, 2017 11:55 pm

Re: Prusa firmware for RAMPS Prusa i3 clones with MK42 beds

Post by IanC » Sun Aug 13, 2017 8:12 pm

Thank you :).

I've got some wire ferrules I can crimp on the end, so I should be able to get a good contact. Really pleased to hear it'll work straight off the MKS Gen without any need for separate MOSFETs :).

IanC
Posts: 20
Joined: Sat Aug 12, 2017 11:55 pm

Re: Prusa firmware for RAMPS Prusa i3 clones with MK42 beds

Post by IanC » Mon Aug 21, 2017 7:15 pm

This may be a silly question...

If I used a aluminium headbed (i.e. the cheap ones you see everywhere), am I still able to use the Prusa firmware and use the mesh levelling on an aluminium bed? I guess it's only skew detection that the MK42 points are needed for, whereas mesh levelling can just pick up the aluminium PCB? If that's the case, can the XYZ skew part be disabled in this firmware?

slippyr4
Posts: 224
Joined: Thu Jun 15, 2017 10:24 am

Re: Prusa firmware for RAMPS Prusa i3 clones with MK42 beds

Post by slippyr4 » Mon Aug 21, 2017 7:20 pm

The calibration definitely wouldn't work with an aluminium bed. With some hacking, the levelling might.

But I don't see the point really. Beyond the calibration, there are only a few real features that are worth having (notably the easily accessible "live z adjust" and the filament load/unload menus.

If you've not got a MK42 you'd be better off with marlin (i used marlin before i got my mk42 - and before that i had a smoothieboard in it).
Self-built Prusa i3 MK2 clone
My things: https://www.thingiverse.com/slippyr4/designs
My Prusa firmware port for ramps & MKS : https://github.com/slippyr4/Prusa-Firmware

IanC
Posts: 20
Joined: Sat Aug 12, 2017 11:55 pm

Re: Prusa firmware for RAMPS Prusa i3 clones with MK42 beds

Post by IanC » Mon Aug 21, 2017 7:27 pm

It's those little features that I'd miss :lol:

I might get an MK3 and see if I can get levelling working, as it would be interesting to see how it performs.

slippyr4
Posts: 224
Joined: Thu Jun 15, 2017 10:24 am

Re: Prusa firmware for RAMPS Prusa i3 clones with MK42 beds

Post by slippyr4 » Mon Aug 21, 2017 8:57 pm

I don't think it'd be that hard to get it working.

Fundamentally, the calibration data is a skew correction matrix which is stored in EEPROM. The calibration state of the printer is also stored in EEPROM. So you'd need to "fix" the functions that check the calibration state of the printer to tell the firmware that it's calibrated already, and then have the functions that return the matrix just return an identity matrix.
Self-built Prusa i3 MK2 clone
My things: https://www.thingiverse.com/slippyr4/designs
My Prusa firmware port for ramps & MKS : https://github.com/slippyr4/Prusa-Firmware

IanC
Posts: 20
Joined: Sat Aug 12, 2017 11:55 pm

Re: Prusa firmware for RAMPS Prusa i3 clones with MK42 beds

Post by IanC » Mon Aug 21, 2017 9:05 pm

Thanks, I'll give it a go and see what I can do :). I'm not much of a coder, but if it's primarily commenting lines out, I can do that :lol:.

Just need to find an MK3 bed that is the same size, which is more difficult than I thought!

slippyr4
Posts: 224
Joined: Thu Jun 15, 2017 10:24 am

Re: Prusa firmware for RAMPS Prusa i3 clones with MK42 beds

Post by slippyr4 » Mon Aug 21, 2017 9:30 pm

I used an MKS MK3 220mm before I had the MK42, a bit small in the x axis but it works quite well.
Self-built Prusa i3 MK2 clone
My things: https://www.thingiverse.com/slippyr4/designs
My Prusa firmware port for ramps & MKS : https://github.com/slippyr4/Prusa-Firmware

IanC
Posts: 20
Joined: Sat Aug 12, 2017 11:55 pm

Re: Prusa firmware for RAMPS Prusa i3 clones with MK42 beds

Post by IanC » Tue Aug 22, 2017 7:14 pm

Cheers, I'll take a look at that variant. All these parts are taking ages to arive from China :lol:.

How did you wire your Z steppers on your board? My MKS Gen 1.4 only has 1 header for Z - should I just add a splitter?

edit: Just found your answer on Github:
The firmware is setup for Dual Z steppers using the E1 driver

IanC
Posts: 20
Joined: Sat Aug 12, 2017 11:55 pm

Re: Prusa firmware for RAMPS Prusa i3 clones with MK42 beds

Post by IanC » Sat Aug 26, 2017 10:57 am

The parts have finally arrived and I'll be assembling it this weekend :).

I noticed that the MKS Gen board only has one MOSFET header (but two for extruders). How did you wire yours up in the firmware (for the part fan and heatsink fan)? I didn't understand what the explanation on GitHub meant, as I'm quite unfamiliar with these boards - so thought I should check before blowing something!

edit:

Ah, I see from this diagram (http://reprap.org/mediawiki/images/0/0d/MKS_GEN-PIN.PNG) that D7 is the E1 MOSFET header. So I connect the extruder cooling fan here and the part fan to the "fan" header (D9) and I'm all set? :D

slippyr4
Posts: 224
Joined: Thu Jun 15, 2017 10:24 am

Re: Prusa firmware for RAMPS Prusa i3 clones with MK42 beds

Post by slippyr4 » Sat Aug 26, 2017 12:42 pm

Yep that's right. And you can use the E2 stepper driver for Z2 if you want to.
Self-built Prusa i3 MK2 clone
My things: https://www.thingiverse.com/slippyr4/designs
My Prusa firmware port for ramps & MKS : https://github.com/slippyr4/Prusa-Firmware

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