Servos that only last a few hours

[tristanfrn]

Hello,

I have big problems with the servos on the Axidraw V3, which make some Axidraw almost unusable. I really have a hard time identifying the problem.

I’ve got 18 Axidraw V3, running 3-6h per day. On some Axidraw the servos will last several days, but on others they will only last a few hours. For example, on one of my Axidraw, I have to change the servos every 3-4 hours, which seems to me to be extremely low in terms of lifespan. I specify that everything works perfectly well except for this problem of servos.

I checked that there was no friction, weight or particular shock. I also checked the voltage, which seems correct (230V in France).

I tried many types of servos: plastic, metal, expensive, waterproof… But none seems to solve the problem of lifespan.

The strange thing is that the lifespan seems to depend on the machine used, and especially that some servos only seem to “hang”. For some servos, if I then plug them into an arduino and apply a gradual rotation from 0 to 180 degrees, it seems to “wake them up” and they can be used again for a few hours or days.

My hypothesis is that there is probably a problem related to the power supply (I am based in France so 230V) which would damage the servos, but I am not sure of anything.

Have you ever had this type of problem? Do you have any ideas for diagnostics we could perform to identify the source of the problem?

Thank you for your answers

[Windell Oskay]

I’m sorry to hear about the trouble. (It looks like you emailed the exact same thing to us as well.)

My first question is whether you are using the original power supplies, and whether you are using any kind of voltage adapter. Second, which software are you using to drive the machines? And, would you also please check which firmware version the different machines are on, perhaps the one that is failing the most, versus one other? (You can query it with the Config tab of AxiDraw Control, for example.) Finally, do all of these machines have USB Micro B connectors, rather than USB Mini-B connectors?

The quality of servo motors seems to vary a lot, often even from the same manufacturers, and we’ve seen servo motors that last for both days (under strenuous use) and years (under light use), but hours definitely indicates that something is wrong.

The usual things that can increase servo life are those that reduce the load on the servo: Ensuring that there’s no added stress (via weight or rubber bands for example), ensuring that the slide moves completely freely, and minimizing the pen-up to pen-down travel distance.

It is possible that there’s a problem with that particular EBB driver board, such it should be replaced. It’s also possible that adjusting the servo timeout value (if you’re using the regular AxiDraw software) can make a significant difference, or potentially moving to a different servo driver pin could make a difference. There may be some interaction between the power switching on the control board and certain servo motors as well.

[yadicu]

Hi there

Allow me to add my two cents..
I own an AxiDraw SE/A3.

The servo is indeed the machine’s weakest component.
Mine lasted less than 100 working hours. :-|

The worst, however, is that if you are unlucky enough to live outside the US

( ಠ‸ಠ )ﾉ
you will likely wait for
! more than 1/2 a year !

to get replacement. (robotshop order started Oct’21, delivered May ’22)
( ಠ‸ಠ )ﾉ

To add insult to injury, evilmadscientist support let me know they would send me free replacement if I were a US resident.
(I still got the mail, folks..)

No luck there being a EU resident.
So I exercised Buddha-like patience and finally got 2 replacement servos – AFTER MORE THAN 200 DAYS.

I would thank evilmadscientist.com for their effort but I do not think that thanks are appropriate here.

¯\(°_o)/¯

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