Major problem with Z axis on Thingomatic

Summary:

Z axis on Makerbot Thingomatic slides down while printing resulting in the print head travelling through the already printed material. I have tried reverting the firmware version to 3.0, tried each possible configuration for "Hold Z axis", tried increasing the steps per mm for the z axis, nothing seems to help.

Major problem with Z axis on Thingomatic

PiWarrior 04 Aug 2012 17:26

I acquired the Makerbot Thingomatic in a roundabout way. My old high school comp eng teacher had purchased the unassembled kit over a year ago including the MK6 extruder with what I am pretty sure is Gen 3 electronics. He assembled it but never got around to putting in the time into making it work. Recently I had been talking to him and he offered to let me take it for the summer to get it to work and use it then return it in the fall. Sounded good to me.

Unfortunately, after taking it apart and setting it up properly, I got everything to work except for one problem. When I tried to print the calibration cube the print head ended up pushing through the already printed layers until a point where it would put so much force on the part that it lifted it from the print bed and carried it around while printing.

I have looked around for help online but it seems like the solutions for other people who had the a similar problem dont work for me. Like I said in the summary, I tried to revert the firmware back to 3.0, tried adjusting the hold Z axis problem, and tried adjusting the steps per mm of the Z axis and nothing has worked. It is unfortunate that it has been so long since it was purchased as I do not think that I can get any support or warranty on it. If anyone has any experience with this kind of problem I would really appreciate the help, I would really hate to give my teacher his printer back non functioning even after an entire summer.

Re: Major problem with Z axis on Thingomatic

Jetguy 04 Aug 2012 19:06

First off, you definitely can get some support.

Did you follow the calibration for the RF voltage on the stepper drivers?
http://wiki.makerbot.com/thingomatic-doc:calibration

How hot is the motor getting (warm to the touch is OK, so hot it burns is bad)?

If you reverted back to firmware 3.0, the only answer is you are skipping steps. This occurs because of mechanical bind (typically over-tightening the screws holding the z motor to the wood frame) or the stepper driver not being adjusted.

Again, if you reverted to 3.0 and have the problem, it can only be a mechanical problem or adjustment. There is no known failure mode from a firmware or software perspective if you are on 3.0 (and I've seen then all) to work sometimes (like homing) but not during a build.

Last edited on 04 Aug 2012 19:08 by Jetguy Show more

Re: Major problem with Z axis on Thingomatic

PiWarrior 04 Aug 2012 19:43

I did follow the steps for calibration for the RF voltages, but I'll take a look at them to see if I screwed that up. The Z motor gets pretty hot, just below being too hot to touch. Do you think that temperature could indicate a problem? Also, I have tried adjusting the screws holding the motor into the frame and haven't had any luck. I've also made sure to lubricate the lead screw and slide rods.

Re: Major problem with Z axis on Thingomatic

Bluemetal 06 Aug 2012 15:54

It should not be that hot. Check the voltages.

Re: Major problem with Z axis on Thingomatic

nhand42 18 Aug 2012 01:14

Agreed on the z-motor. Mine is only slightly warm. It's not even as hot as a shower. It's definitely not hot like a cup of tea.

PiWarrior, this probably means the Ref voltages are not set correctly. There are multiple motors used by Makerbot and it's easy enough to use the wrong table of Ref voltages. Lubrication will help when it's moving, but the z-motor doesn't move very much, so the heat is produced by the very nature of stepper motors; they are constantly working even when not moving. Too much heat indicates too much voltage. When you get the voltage correct it will be luke-warm to touch, make no noise when idle, and still be impossible to turn by hand when the motors are enabled and z-hold is working.

With regards to the "head pushing through the cube". I had a similar problem recently, it might be your problem as well. I recently upgraded from skeinforge 37 to skeinforge 50 and it was laying down too much plastic per layer. Skeinforge generates an M108 g-code that controls the extruder flow rate (actually the extruder motor RPM). Makerbot has moved to 5D printing and they're commenting out the M108 g-codes, replacing them with an additional fifth vector on every head movement, and relying on the firmware to interpret that fifth vector to control the extruder flow rate. This is the "Dimension" plugin. But my firmware is still expecting the M108 g-codes.

Look for ";M108" lines in your G-CODE output, there will be many of them. If any of them are commented out with the semi-colon then you've got 5D printing enabled, and I bet that's your problem. They should all be "M108" without the semicolon. If you look for a file "replace.csv" in skeinforge (under ~/.replicatorg of all places) it is inserting the semicolon. Remove the semicolon and it will stop commenting out the lines. You still need replace.csv to convert "M108 S" into "M108 R", so don't remove the line entirely. You should also disable the Dimension plugin in your Skeinforge settings.

The other possibility is in the Speed plugin the flow-rate is set incorrectly. The Makerbot website recommends setting the Flow Rate equal to the Feed Rate (e.g. 40 mm/s). This is correct advice for 5D printing, but it doesn't work on my firmware, so I've set the Flow Rate to 4.57 which works well for my prints.