Stuck at "Adjust Chain Lengths" - sides never the same and one or the other is way too short

I get to " Adjust Chain Lengths" and it always feeds out very different lengths. First iteration left seems fine - right is way too short. Start over. Next iteration right seems fine and left is way too short.

By “seems fine” I mean that length puts the sled pretty close to the center of the 4x8 ply if both sides were that length.

Stuck, never works. Any options? Like maybe set it up so that each side has the exact same number of links out and the sled is pretty well centered top to bottom of the spoil board?

Seems like that’s what this is trying to do. Aren’t we simply trying to center the sled between the motors? How the plywood is centered horizontally is really meaningless isn’t it?

With the “Adjust chain lengths” routine, the Maslow calibration routine is using the values it generated from the Triangulation cuts and resultant measurements you made to place the sled to what the Maslow thinks is the center of your workpiece. The two chains should play out at equal lengths. Then, when you connect the sled to the chains, you are directed to press the Center button (don’t remember if that is the correct title), and the sled will move a little bit, presumably to the center of the board. When the sled is centered on a 8’x4’ work piece (if that is the maximum size of the machine you built and specified in GC) then the machine now knows the maximum distance it can travel in any direction and still be on the workpiece. Double check your post triangulation measurements, and try a complete shut-down and restart of software and hardware.

Good luck.

As an old programmer going back to the late 70’s rebooting is in my DNA so that’s happened for sure already - several times.

But no matter what one side feeds out “enough” and the other side is always far too short. And it’s not consistent. Sometimes the left is too short and sometimes the right is too short.

Perhaps it’s significant that it’s never the case that both sides are too short.

As I’m typing there is one thing I haven’t done that I should try. I should try different USB ports. It’s on COM3 and communication has always seemed fine. I’ll try that.

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As long as you don’t get connection loss the port should not matter.
This is the first time I’ve seen and error described like this.
To dial in:

  • FW and GC version number (no, “the latest” does not tell us if you are using the developer or release version).
  • Is this the first time you uploaded the FW and did the calibration?
  • Are “top feed” and “bottom feed” clear and selected correctly during calibration?
  • Is this the setup with the ring?
  • Does “test motors and encoders” pass without fail?
  • Are you running win$ and what version?

Further things might become visible by deleting the logfile in the GC folder, starting a new calibration, closing GC after both chain are feed out and sharing the log file and the groundcontrol.ini (in your user folder).
If anything was on the arduino before, a wipe eeprom, delete groundcontrol.ini and do calibration from scratch might help.

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There’s a specific setting in ground control that stores the amount of chain to be fed out. I think it’s in maslow setting rather than advanced. Are you doing this during calibration?

Could it be a loose connector? It seems strange that it moved from one side to the other. Maybe significant electrical interference?

@madgrizzle - been thinking about you … are you back home yet?

No, I’m still in Jacksonville… my neighbor says that from what she can see, the house is intact (no trees laying on top of it). Don’t know about the shed though. there’s no power (pretty much no one has power in Tallahassee). No real reason to go back without power being on… would just be hot and miserable.

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Glad you are safe and home is in tact. So much devastation along the beaches. Hope all is OK whenever you can get home. All the best.

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Like the others, I think there is a value off somewhere.

Success! After about 15 tries. On the last couple I went back and redid the motor measure. Two decent lengths and hooked up the sled. I held my breath and proceeded. On the test cuts the two long distances were less than 2 mm different so I’m calling that success. Cut a little 15" test circle and it’s a 15" circle as close as I can measure. And that’s with the rough sled. I’ll have to pick it up Monday but I’m excited.

The process forced me to come up with some ideas for dealing with the loose chain, strategically placed screws on the spoil board. A small lag bolt temporarily placed high on the spoil board to hold the sled while attaching the chain. A cup hook instead of just a drywall screw to hold the bungee. Anything that doesn’t kill you makes you stronger.

To put it into perspective, I know guys who spent days getting their $60,000 gantry machines properly set up.