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Prusa Mendel 16x16x12 Rebuild Assistance

Posted by dwm.cadman 
Prusa Mendel 16x16x12 Rebuild Assistance
February 08, 2015 06:59PM
A Prusa Mendel with a build envelope of 16"x16"x12" was given to me from a guy I know at a company clearing out their warehouse to make room for new equipment. I've used ZCorp and MakerBot 3D printers and have a lot of computer and networking experience but never really dealt with anything like this from the ground up. I've decided to rebuild it for the experience before going to the expense of building a new one. It's easier to swallow ruining parts on this than ones I pay for.

I will need some guidance from the veterans to get it printing good parts.

Progress so far:

1. Cleaned the machine and lubricated the all-thread lead screws and guide rods.
2. Identified the controller as an Arduino Mega 2560 controller.
3. Installed the Arduino Software and configured it for COM6. Windows successful recognized the driver.
4. Installed Repetier Host 3D Printer Software
5. Established communication and moved X, Y, and Z axis using Repetier in manual mode.
6. The motors are Minebea-Matsushita stepper motors: X and Y axis use Part Number 4K1-1106 Type 17PM-K901-G2VS; Z axis uses 2 motors, Part Number FH5-1034 Type 17PM-J801-P1VS.
7. Dual extruders have the same motors as the Z axis. I think the hot ends are J-Heads.

Issues to address:

1. Firmware: I have no idea what firmware was installed on the Arduino. I think I will overwrite it with the Repetier Firmware so that all Repetier Host features are supported. Is there anything other than Repetier that I should be aware of and/or use instead? What information do I need to set up the firmware properly?

2. The Z axis all-thread lead screws are jamming in both directions. I'm not sure if the problem is in the threaded rod/nuts, motor, alignment, drivers, or all the above. There are 2 motors so they could be out of sync or turning at different rates but I don't know how to check this. There is a support bracket missing on the left Z axis guide rod which is probably contributing to it.

3. Calibration: X, Y, and Z axis are not homing properly and are pretty far from where I think 0,0,0 should be. I'm not sure how to calibrate this and need some help figuring it out.

4. Build plate is belt driven and wobbly. When it stops it wobbles. I'm not sure if it's the belt or mounting hardware. I can tell that the bearings are probably part of the issue. They do not all touch the guide rods.
Re: Prusa Mendel 16x16x12 Rebuild Assistance
February 11, 2015 06:44AM
1. You need to install firmware such as Marlin. There are heaps of sites like this [airtripper.com] that will help you. You will need to install the Ardunio software first for your board to be able to install the firmware. Repetier is the software you use to create and run your prints!!

2. Again, start with the firmware and ensure that it is correctly configured for z axis. Post a pic of your machine and photos to make it easier to identify your problems. What type of thread are you using? Are the motors wired correctly. Again there is a heap of info on this on this forum and others. The z axis support rod will need to be fixed otherwise you will not get accurate builds.

3. The machine if built correctly, will have limit switches, one for each axis. These can be adjusted by moving them in a direction till you are happy with where they should stop when homing. Again firmware will need to identify these limit switches.

4. Bearing are probably worn...which will happen but they should last quite a while. They will wear out faster if the rods are not parallel and aligned probably. You should be able to move the bed (without belts) with no effort at all and with the pressure of your finger, you will feel if there is any bouncing in the bearings as you move it (bad bearings or mis aligned rods) It could also be that the pots need adjusting on the z axis, not enough power going to the motor and can cause shuttering as well.

First thing. Head to ardunio site and download the software for your board. Then download (I suggest Marlin but there are others) the firmare and follow instructions to upload to your board. If it was me I would disconnect your belts and screws, connect with Repetier or prontrface etc, and move your motors manually. If you are running a Ramps Board you may have to adjust the pots for your motors (easy to do) to ensure they are getting the correct power. Once that is done you can then start looking at entering the correct speeds for your motors to suit your typ of belt and leadscrew which we can sort out later once you have done the above.

Edited 1 time(s). Last edit at 02/11/2015 06:53AM by Chaser30.
Re: Prusa Mendel 16x16x12 Rebuild Assistance
February 11, 2015 02:32PM
Thanks for your suggestions. I'll get started with them tonight!
Re: Prusa Mendel 16x16x12 Rebuild Assistance
February 12, 2015 04:53AM
I should also mention about the jumper settings under each stepstick. The guy before you may have not set up the board properly. Heres a guide, most people i believe use all three jumpers under each stepstick for the motors using 1/16 step.

jumper Yes/No step size
1 2 3
no no no full step
yes no no half step
no yes no 1/4 step
yes yes no 1/8 step
yes yes yes 1/16 step

Lift each stepstick and see if there are the correct amount of jumpers on each drive!!!!!
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