Calibration and Thermal Runaway (New Build) / New Bearings  

Calibration and Thermal Runaway (New Build) / New Bearings

Just wanted to share a couple Thoughts on my first time build of the MK2 platform...
Disclosure: The MK2 is being used for the low production of parts in our company.

*All the steps for assembly were very concise.....
*A couple of the pictures of the Frame / Power supply / Control case we a little dark and hard to see details.
*As mentioned in the instructions the Frame assembly is extremely important. Take X / Y measurements , side to side, front to back.
even use a carpenter L square to view the finished product for 'SQUARE'

I had two issues with the final build and testing.
*FIRST
- when performing the XYZ calibration, it would fail consistently. what I did not realize was I had left the X Axis Stepper motor Pulley screws loose
so I could adjust the belts after mounting the X axis on to the Z rods.
This caused the calibration to fail over and over...until I realized this point.
- BUT.... the unfortunate part was the system message reporting ONLY that I should re-examine the entire platform build.
Even in the documentation there was no mention of specifics. A small blurb talking about possible items to check would have savde me
a lot of time. Especially since the simple tightening of a pulley screw would fix the issue, instead of having to possible suspect the entire
frame structure assembly.
SO : I recommend that the easy suspects be mentioned before the drastic last resort of dis-assembling and maybe needing to square the frame.

After discovering this issue of the loose X Pulley, the calibration was accomplished and it finished the 4/4 and 9/9 point calibration
with no problem.

*SECOND
- As a first build, I decided on the supplied Whistle on the SD card as a first print to test the printer build.
- All was going fine until I noticed the Cooling fan did not turn on and the corners of the build, of course, were curling....
- I found I had plugged the Fan Cable in backwards and fixed this problem and the whistle print completed in a perfect print.
- I asked CHAT help and found out that the FAN only turns on after the second layer.....this was not mentioned anywhere....
- I next imported one of my designs and started to print this 45 minute build and after 2 - 3 minutes the print failed with Thermal Runaway error.
- I read on the forum that the Power Supply may have been Adjusted too low to handle the Heater Element current needs.
- I removed the power supply, opened the case and found the TRIM POT next to the Screws.
- Using a meter ( and being careful ) I plugged in the AC cord and powered up the supply.
- I measured 12.2V on the output of the supply. I am an electrical design engineer and I know that most all designs that use a typical 12VDC
input are generally accustomed to handle an input voltage range from 10 - 13.6V easily.
- I adjusted the output voltage using the TRIM POT to 12.7V and reassembled the power supply unit to the MK2 Frame.
- I also checked to be sure the HEAT Element and Thermister were both secured and tight.... They were ok !
- I started the build of my part once again and the print finished without any issues.
- I have built at least 5 other large parts with no issues in Thermal Runaway so this seems to be a working solution.

* Final Thoughts
The kit comes with the standard LU8 type bearings, I do not like these so I always replace them with the PBCLinear FJC08 product.
These are a bit expensive but very worth the cost of $11 each for the LONG run. I recommend checking them out for a production use.
There is an impressive YOUTUBE of their product everyone should watch. Check their web site.

I think the overall design is solid and the final print quality is extremely Impressive. I have a Makerbot Rep 2X that I have retrofit with may
custom parts and while the print quality is also Extremely good, for the cost of the MK2 I would not hesitate to buy this for any production needs
a company may need.

I hope my thoughts on this product and my Build experience helps others choosing to 'build' the MK2.

Thanks
Chuck