Hi Dave,

Just watched the video. Sorry to hear about the arm motor burning up. I myself know that so well, and yeah its so disappointing when it happens. I myself am in the process of replacing servo motor gears from an old Actobotics Gear box motor that servocity use to sell and currently redesigning my latest creation yet again. Good luck with the motor (buy a spare or two) Ive learned that now

Dave, Your problem-solving and creativity continue to inspire! This is amazing work. I can't wait to see how the replacement elbow motor works out.

Hello Dave, that could have been a fire starter. It is always better to use a fast blowing fuse as used in cars. It is cheap and easy to install!

Thanks you guys for the kind words and support.

@RobotHappy, I feel your pain. When Servocity switched from the old Actobotics platform to the new GoBilda platform it really making upgrades or repairs on the old system hard. I love the new Gobilda stuff but the old Actobotics was imperial layout and Gobilda is metric. Even though most parts look the same the hole patterns just don't line up a lot of the time. Then ya gotta pull out the drill or rebuild the whole thing. Ugh. Most of my robot was built with the old Actobotics platform and I'm challenged each time I need to update or repair. Well, I guess such is life and it goes on and changed. We must adapt.

@walunit , Wow, what a nice thing to say. I appreacheate your kind words. Ya, I'm looking forward to seeing what I do to untie this knot also. LOL. Stay tuned.

@Dark Harvest , I fully agree and think your advice is a great suggestion. In fact I'm a firm believer is fusing circuits. Most of my robot's devices, lights and servos are indeed fused. However these DC Motors are controlled and (are supposed) to be protected by the Sabertooth motor controllers and their Kangaroo position and speed daughterboards. They recommend that you do not fuse the board and let the controller be the watchdog for stalls and runaway conditions. The Kangaroo has a setting that when turned on and set properly will stop the motor if it senses a runaway. I did have this feature turned on. Oddly it has worked for me in the past when I encountered issues like this when I was tuning these motors the first time. Not this time obviously. Ugh. This is why I think either the Kangaroo failed or there was an issue with the wiring or Electrical Magnetic interference (EMF) on the signal wires. I was messing around with the wiring and doing some rerouting just before this runaway and lock up happened. So, getting back to the fuse. Dimension Engineering does say that if I want to fuse the motor controller circuit I should do it after the Sabertooth controller and not before it. The controller has overvoltage protection and this way it will stay alive and active even after the motor is disabled when a fuse blows. I may follow your suggestion and fuse these motors like I mentioned above. However I need to respectfully disagree on one point. I've found that slow blow fuses are better to use when protecting motors. Here's a good description I found that stats this better then I can:

Quote:

A slow blow fuse is used instead of a fast blow fuse when a circuit experiences brief, high current surges during startup or operation, like with motors or large appliances, as the slow blow fuse can withstand these temporary spikes without blowing, while a fast blow fuse would immediately trip.

I'll post back when I make some more progress on all this.

Holy, I moved your post into a new thread because your robot thread kept crashing my phone. It's so long with so many posts, hahagood for you . We'll have to figure out a way to solve that for large posts since there's no "paging" anymore.

Dave, it's a good thing you caught it in time before anything else went up. It looks like the motor brushes might have saved the electrical because they melted pretty good!

Have you looked into putting new brushes in there? A while ago, I ordered a pack of different brush sizes from Amazon to fix the motor on my miter chop saw. I did have to file one of the brushes down to get it to fit, but she got back up and running.

I guess the only thing you'd have to check is the armature to ensure it didn't melt any wires. If not, you might be able to get new brushes in there.

@DJ. thanks for the maintenance help with my thread. Ya, I've been working on that old robot thread for over a decade now. LOL. It's gotten pertty long.

New brushes? Ha, no, I hadn't thought about that. I was getting ready to throw this old motor in the bin but now you have me thinking. At over $250usd per motor it may be worth it to see if I can't salvage this one. At the very least it would be a good project to tinker with. I'm pertty certain everything else is OK other then these little brushes. Maybe that blue cap needs changing also. Thanks for the tip and idea.

You can file the brush down if you get a bigger one. I put the file down and slide the brush back and forth on the sides to shape it. It files quickly

check the armature if it doesn’t look burnt. And check the armature contacts. Seeing how the brushes look I imagine they took most of the damage. Hopefully they burnt and saved the armature.

usually it’s the copper contacts of the armature that melt. But if the brush sacrificed fast enough it’ll save it

Outstanding. Thanks for the tips. Sounds like it shouldn't be a hard.

Hey dave,  I still have a good amount of Actobotics U-channel and some other parts I could send you if you need. Hopefully I will have the right ones

@RoboHappy, wow, thanks for the offer. I really appreciate it. Actually I have a ton of stuff myself and dig into it more than I would have thought. I'm glad I stocked up years ago. I can usually rebuild or adapt but it's a pain sometimes. If I come across something critical that I'm in need of I'll reach out to see if you have it.  If you do and are willing to part with we can work a deal. Thanks again!