Help with RAMBo

Hello,

I just upgraded my Prusa Mendle with a RAMBo board so I can do some experimenting with dual extrusion. The board I had previously was a printrboard which was great for starting out on, but limited in capabilities.

Anyways, the problem is I can't get it operating right. I recently worked out the logic for the endstops but now the problem seems to be the number of steps per unit for the x, y, and z. Does anyone know how to calculate this or know the general numbers for a prusa? I am using the Marlin firmware and can't quite make heads or tails of how this version calculates steps per unit. It seems like the firmware has ultimachine default settings. Should I stick with Marlin and try to calibrate everything or try another firmware? RAMBo is compatible with all RAMPS firmware correct?

Also, the only way I could figure out how to get these endstops (mechanical) to work is to connect them to the ground and signal pin. I'm not sure if this is typically how it is to be set up or not but it seems to be working.

Thanks in advance! Hope I can get printing for the holidays, like I'm sure most of you are!

Matt

Mv, tell us a bit more about your setup. How many teeth are on your x and y pulleys, and what pitch are your z screws. RAMBo uses Marlin, as well as repetier firmware. The only thing specific to the RAMBo noard that the firmware handles differently is that in your configuration files, you need to specify motor current with a value of 0-255 ( start with 185 ) and define microsteps. By default i believe that both firmwares are set to 1/8, the max on the RAMBo (for now!)

Calculate your steps per mm, and under configuration.h plug those numbers into STEPS_PER_MM like any other firmware.

I.E., if you have GT2 belts which have a .2mm pitch, and have 15 tooth pulleys, and are 1/8 stepping and have 200 step/rev motors, you take

200*8=1600(steps per rotation)

15*2=30(teeth on pulley times pitch)

1600/30=53.333 steps per mm

Many thanks, John. Your advice worked great and I think I got it all worked out (as far as steps/mm go).

Problem now is that when it goes to home on the end stops, the x-axis works great but as for the y and z... not so much. They seem to be going through the end stop but eventually recognize that the end stop has been triggered (after a few seconds of the agonizing grinding and skipping of the steppers) and then it stops as it should. I can't for the life of me figure out what would be causing this, especially when the x axis is working just fine. Any ideas on what might be the reason for this?

Also, this may sound like a dumb question but I would rather be safe than sorry. I just put T2.5 belts and pulleys on my printer. I am assuming that they would have a pitch of 2.5mm, correct?

Thanks again!

Matt

EDIT

Now the described effect of the y and z axis is occurring with the x-axis as well. What could this possibly be?!?!