Communications and belt retraction issues on a cold day

Troubleshooting
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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?)

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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.

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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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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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I have been operating the maslow in the cold alot in the last couple of weeks. I reported in a separate post about breaking belts.

I was also having a similar issue as you apparently: one of my belts was a pain to retract. I would click retract 4 or 5 times to get it fully retracted. I didn’t stress about it too much and had some successful cuts.

After I snapped my belts, I started to bring the maslow inside the house. I would run it out to the shop and start the cut while it was still warm from the house. The belts retracted effortlessly. I am pretty sure the cold was affecting the belt retraction somehow.

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Could you elaborate on why when putting the arms back into the stack, you put the best functioning arm lowest, the worst one top? have you noticed different behaviour?

Thanks for all your input btw, I got a spindle as well, and made the angle of my bed >22 degrees.

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According to Wikipedia:

The term “whac-a-mole” (or “whack-a-mole”) is often used colloquially to refer to a situation characterized by a series of futile, Sisyphean tasks, where the successful completion of one just yields another popping up elsewhere.

In this case, at least one part of the M4 seems to be reacting poorly to extreme cold. This could have to do with moisture freezing up the gearboxes or some other reasons, but the Real Solution ™ may be to keep the critical components a bit warmer. So, here’s a partly-baked idea. That is, I think it should work, but I haven’t tried it or anything. Anyway, it’s cheap and fairly simple, so here goes…

Enclose the sled with a lightweight insulating shroud. This could be cylindrical, with the same diameter as the sled and a height that can handle the sled, router, etc. Close off the top, but leave the bottom open and fashion a (conveniently removable!) way to attach it to the sled’s outer edge.

Add openings for the belts and umbilical and don’t worry too much about sealing anything. (FWIW, I’d use something like aluminum-covered bubble wrap for the surface and stiff steel wire for the frame’s hoops and posts. Foil tape should work well for the seams…)

Once the M4’s motors and router are running, I suspect that they will help to keep things warm, but you’ll need a way to get things started. Here are a couple of possibilities:

  • Somewhere nearby, set up a source of medium volume, low pressure, warm air. (The output port of the shop vac might work nicely for this.) Feed the air into the shroud using a lightweight, flexible hose such as this, bound to the umbilical.

  • Bind a heating pad into the inner surface of the shroud, well out of the way of the mechanism and belts. Set its temperature to the lowest setting, at least initially.

Although you could control the heat source with a thermostat, a simple thermometer might work just as well. Make sure that it is measuring the temperature of the sled, not just the surrounding (enclosed) air. Wait until the temperature gets up to the desired operating range before trying to run the M4.

Good luck!

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This is because when I pull apart the stack of arms, the one at the top is the first one that I can access. So if it is the worst performing, then it is also the one that I’ll most likely be doing some work on in the future.

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