RUMBA vs Melzi?

I built my Mendel90 "stock" using a Melzi controller. The Melzi works fine, but if I want to use multiple extruders (an upgrade I am planning on some time in the future), I will need to change my electronics. I can get a RUMBA on EBay for about $60, which seems like a reasonable price. Anybody used the RUMBA? How much of a PITA was it to set up? And will I still be able to use my modded 600 watt ATX power supply with it, or will I need a new PSU to run a RUMBA?

Nobody? ANybody

Melzi, RUMBA, RAMBO, RAMPS...they're all pretty similar and run off the same ATMEGA family of microprocessors. Individual components may be slightly different or different combinations of configurations but they are all well supported. Wire them up correctly with whatever header pins or screw terminals or whatever connectors they have and they should operate the same.

Yes, you should be able to use your modded ATX power supply the same although you may need to split or jumper the line to power both the heated bed and everything else (separate inputs).

Thanks! Looks like I will have to buy separate stepper drivers to plug into the board I bought. Stepsticks will work, but are there others that are as good, or better, with the same pinout (8 pins per side)?

There's 3 main boards in 2 categories of stepper drivers that often get used. While Pololu is a brand name, often it also get used to refer to Pololu's A4988 steppers. A pin compatible alternative developed named StepStick. They both use the same product family for the main chip, compatible with Allegro’s A4988 chip. It can handle up to 2A of current but to reach that you need to have heat sinks installed and active cooling otherwise they'll shut down. Normal operation of 1-1.5 amps isn't a problem. Both drivers can do up to 1/16th microstepping. With either board, be sure to see what the sense resistor value is before computing what your reference voltage is.

The other common driver uses Texas Instrument's DRV8825 which can handle 2.5A (with proper heat sinking and cooling) and 1/32 microstepping. Pololu makes a driver with the DRV8825 but there are other manufacturers as well.

You can find slightly more expensive, quality boards from Pololu or other reputable retailers, as well as cheaper Chinese clones. But you get what you pay for sometimes...

There is a comparison between the two chips in the wiki here: [reprap.org]

Thanks for the info!

Got my RUMBA yesterday. Just ordered 6 of the 8825 stepper drivers by the same manufacturer for $12 - I decided I liked the 1/32 microstepping feature.

What version of Marlin should I use? For that matter, is there better firmware I can use? I may well install this on my Mendel90 now and just use it on just a single extruder until I have a chance to upgrade to an E3D Chimaera or Geeetech Mk 8 dual extruder (leaning towards the Geeetech, as they offer a 3mm direct drive dual extruder; the Chimaera is only available in 1.75mm and I already keep 3mm around the house).

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Rich K.
Got my RUMBA yesterday. Just ordered 6 of the 8825 stepper drivers by the same manufacturer for $12 - I decided I liked the 1/32 microstepping feature.

What version of Marlin should I use? For that matter, is there better firmware I can use? I may well install this on my Mendel90 now and just use it on just a single extruder until I have a chance to upgrade to an E3D Chimaera or Geeetech Mk 8 dual extruder (leaning towards the Geeetech, as they offer a 3mm direct drive dual extruder; the Chimaera is only available in 1.75mm and I already keep 3mm around the house).

Have a look at Repetier Firmware especially as he has an online configurator that asks a series of Questions then lets you download a fully configured set of files to Flash the arduino with (much easier than hand balling a config.h file) takes about 5 mins to get a fully configured firmware set.

Doug