Communications and belt retraction issues on a cold day

Troubleshooting
1

I’ve used the Maslow successfully for a few simple projects now, and I was really getting confident. Then today, I had so many issues I about kicked it. The job is finished successfully now, so I’ve calmed down (LOL!). But here’s what I experienced:

  1. Belts not retracting fully. This happened with all of them, but the bottom left I think? (1st motor counterclockwise from the power chord) seemed the worst. I power cycled a bunch of times, extended, retracted, multiple times, increased retraction force, and eventually just mashed “retract all” till it came up. A couple times that worked, a couple times it didn’t.

  2. Lost comms mid-job. I’m using my wifi network to connect because the maslow network never worked for me. That WAS pretty reliable, but it still seems to fail from time to time.

Some troubleshooting that seemed to work:
It’s a sub-zero day in CO, but my garage is still probably ~20F. I thought maybe the cold was screwing things up, so I put a space heater next to the disconnected maslow for a little bit until the parts felt warm. Then, I kept the heater on, and out of the way throughout the successful run. Maybe increased the ambient temp by ~5 degrees.

Mashing “Retract All,” power-cycling, and using naughty language

I noticed just before lost comms once, I got a few error messages that one of the motors had missed a signal (Sorry, didn’t save the serial output). Seems like other folks associated that with ESD from the shop vac, and dust in the connections. So, I disconnected all the motors, blew out the serial ports, and reconnected. Then, I left the shop vac off for most of the run, except to vacuum up dust in short bursts and as far away from the Maslow as I could get.

The piece needed 4 passes to complete. These “fixes” took the thing from failing less than 50% through the first pass maybe 3 minutes in) to completing all four passes successfully (>30min).

On the successful run, I also got the message: “MSG:WARN: Motor current on Bottom Left axis exceeded threshold of 4000” four times in the first couple minutes, then no messages of any kind for the remainder of the ~30 minute cut. I think that was the motor that was having trouble retracting…?

Anyway, it was (finally) a successful cut, but I’m just wondering if 1) I identified the correct issues or just got lucky, and 2) if there’s any way to anticipate and prevent some of these things in the future - improvements to my setup (like the vacuum), regular maintenance (cleaning connections?) strategies while running (let it get dusty, or vacuum persistently?)

2

If you suspect the vacuum, you might try extending the hose so that you can locate it further away from the Maslow. For extra credit, plug the vacuum into a different circuit, to minimize power issues.

3

The most common cause for this I’ve found is something sticking in the arms. Either the idler gear on its shaft (this is fixed in the 4.1 upgrade), or the belt spool itself sticking.

Here’s a technique I’ve been trying to diagnose which arm may be problematic.

Do the usual to unmount the M4

  1. Extend all the belts
  2. Go into config, and drop the retraction force down to 600 and “Save” it.
  3. Now try retracting.
  4. If any belt fully retracts (not just partially), write the retraction force on a post-it note and stick the note to that arm’s motor. i.e. keep a record of the retraction force on the arm itself.
  5. For any belts that have not fully retracted, go back to step 2 and up the retraction force by 100. Keep repeating this process until all arms have fully retracted.

Any arm that needs a retraction force of over 2000 needs to be disassembled and cleaned, paying special attention to the idler gear and the belt spool.

When putting the arms back into the stack, try to have them in order from lowest retraction force to highest (here’s where those post-it notes come in), with the lowest being closest to the sled.

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4

My belts stopped retracting. Took everything apart, added grease to the gears, spools etc, haven’t had a problem since.

At the time I was worried the grease would get dirty and make things worse. Has not been a problem yet.

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