The Great Motor Mystery / Discussion

This is the discussion related to the wiki page The Great Motor Mystery.

Very inspirational Engineering work!

CidVilas 25 Oct 2010 15:28

I havent read the whole post, but this is very inspirational and also makes me realize that Makerbot is doing OpenSource right! Open firmware, hardware, QA, and even research/development! Great work guys!
This post really made you a rock solid company in my eyes!

Re: Very inspirational Engineering work!

charlespax 25 Oct 2010 16:09

Thank you. Positive comments like you are what helps keep me doing this 13 hours a day.

Very Interesting

RobHunt 30 Oct 2010 08:00

This was very interesting to read and reminds me a lot off the debugging process in software. Starting at the output and working your way back up the chain to find out where the bug is coming from. It is also quite a rewarding experience when debugging, especially if it is code you didn't write as you get a very good understanding of how it works and it is a great feeling when you track down the problem. Posting this on the wiki is a great idea if something like this is ever encountered in the future, you have a detailed documentation of it for reference, normally stuff like this is locked away in someone's head.

Imrcly 30 Oct 2010 16:34

Used the Fix for the seized motor at the bottom of the page, worked great.

Jeremy A Green 02 Jan 2011 02:35

I wonder if some of the failures are related to the gear mesh being too tight between the motor pinion and the gear box. Even if it's not seized, it could be causing abnormally high load on the motor. The brushes on my motor seemed to have a pretty small contact area with the commutator.
After my motor started to act up, I noticed that the resistance when it was working was between 30 and 40 ohms. Then it would get stuck and the resistance would be less than 1 ohm. I could get it spinning again with 12 volt battery and then it would work for a little while on the extruder controller before it got stuck again. When it was stuck, the voltage on the h-bridge would drop down to about 5 volts.

Version A Issues solved for me. :-)

Dr Black Adder 17 Feb 2011 02:34

I had all the same stuff happening to mine. Checking the resistance AT THE POINT THE MOTOR STOPS was my vital clue. It was always down around 2 ohms.
Yes 2.0
My guess was that there was some issues inside the motor. Pulled it down, (through the back, it involved opening up the rear of the motor), used a scalpel to clean the gaps between the commutator pickups, reassembled (this was the hard part, required fine wires to get the contacts back to their proper placement), and finally reassembled.
Motor goes once again, no stopping yet……
Update, motor stopped, I disassembled it again, commutator was clogged again, so I've modified the brushes to reduce the problem. Now I've just got to do some printing to see how good the fix is(update: Printing for 3 hours now, not one issue WITH NO RELAY BOARD :-) )!
If you're feeling adventurous drop in to my blog for a photographic tour of my ordeal, and guide to the solution. Thingomatic Extruder Motor Repair

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-Dr Black Adder
http://hsrc.static.net/blog/

Last edited on 19 Feb 2011 00:04 by Dr Black Adder Show more