Last night I wandered out to my garage to print some brackets for a homemade ham radio SDR ( software defined radio ). My printer had been sitting powered up for a long time.
It’s an ancient “Makerfront” large format bed-slinger. I had upgraded it to an MKS SKIPR card - 32-bit, with embedded RPI-like host processor. And a BL-Touch. And Klipper.
ANYWAY, now it doesn’t work. The X axis motor makes a terrible grinding sound and doesn’t seem to know which direction it’s going. Then the printer stops with an error. Something about no trigger after full motion. With the motor off, I can move the extruder back & forth by hand and it’s perfectly smooth.
My first suspicion is that the SD card which is running the Linux side has failed. SD cards are known to be unreliable when running operating systems. The SKIPR card has a socket for an emmc card, which is supposed to be more reliable. When I put this together, Makerbase emmc cards were not available. Now they are, and I’ve ordered one, along with an adaptor so I can stick it in my PC to load it up.
In the meantime, I’ll load up another SD card with a fresh MKS image, and copy my printer.cfg into it. Swap the driver module with another axis, and see if the problem goes with it…
I guess it’s possible. But it worked the last time I tried it. And there’s really
not that much wear or use on that stepper motor. But it’s an idea. I have
another stepper motor in a box for another project; I’ll temporarily patch that
one on just to see if it can turn.
The fact that the problem stayed on the X axis with driver swap is telling. You also mentioned that the axis moves freely so a mechanical issue is most likely out of the question.
You were right. It’s the motor. Weird how it failed just sitting on the shelf
for a year. Whatever, the new motor in the box runs fine. Of course it still
gives the error, because it’s not mechanically installed. Out to install it now.
Thank goodness these things are fairly standardized!
I’ll probably take the old motor apart just to find out what went wrong.
A thought occurs… depending on how you have tested this; it might be the cable or a connectors rather than the motor that has a broken connection. Bad wiring (especially if creased or corroded) can produce very similar symptoms to a bad motor. Just bear this in mind if you still have issues after swapping out the motor in situ.
Came here to say the same thing — in fact much more likely to be cable than motor. This sounds a lot like bad wiring to me, and I learned about this the hard way before I bought proper crimping tools.
Indeed. The new motor was smooth as silk out of the printer. Now I installed it and it’s doing similar weird things. Time to start wiggling some wires.
OK, it’s fixed. It was the connection at the control board. The wires are terminated in Dupont headers, and I would describe the connection quality as
“casual”.
Smooth as silk now.
I wonder if there are better connectors out there? Connectors that will positively click into the box headers on the board?
JST XH 2.54mm 4-pin connectors should be what you are looking for, at least for most boards.
Here is an example crimp tool and variety set of housings to show what’s out there. I have no experience with this particular set, which is one of a great many virtually identical units; this is just to show the kind of thing that is available.
(I bought a few different crimp tools and lots of different sets of crimp connectors separately, which you probably don’t care to do?)
Good Duponts are much better than bad ones… but that doesnt mean I hate them any less. (I’ve lost too much of my life to dodgy dupont connectors, so you are in good company )
My Duet board uses Molex KK254 connectors; same pin size and spacing as the Duponts, but polarised, and with a beefier socket design with more ‘spring’ pushing contacts together. molex KK254 at DuckDuckGo
Is that a heated garage or is it as cold, and moist, as outside?
In a damp environment every connector will fail eventually. I guess you don’t want to use gold plated connectors everywhere.
Would there be any spray available to apply a layer of grease on the metal contact strips inside?
It’s the garage. Not heated, but waterproof and insulated. Part of the house.
It wasn’t corrosion - just the connector had backed off. Sometime this week,
I will upgrade all those connectors to JST, which will lock positively onto the
board.
In general, for dirty connector problems, I use DeOxit. I call it “radio repair in a can”. Although these days, I mostly use a little bottle with a needle tip.
)