Maslow Home Maslow Community Garden

Steps to recover after a fault?


#1

I’m trying to understand what’s required when trying to recover from a problem. Lets say things went poorly and I hit the big red button, shutting off the arduino, motors and the router… The computer will be on a battery, so ground control stayed up, but it loses its connection. Maybe things went really poorly and a chain came off. Is it necessary to disconnect the chains and reset the chain lengths?

Here’s one idea on how to do it without disconnecting the chains from the sled:

  • when setting the chain length the first time, mark 12 o’clock on the sprocket in red. When done setting the chain length, at center/home, mark a link and a matching point on the sprocket in black.

Now, when there’s an issue:

  • unhook the chains from the sprockets (maybe wrap them around a screw/nail next to the motors)
  • Set the chain length (extend both chains). Use the red mark to set the 12 o’clock position of both sprockets first.
  • Hook the chains back on the sprocket, lining up the black marks on the chain and sprocket.

This still seems like a lot of work, though I’m not sure there’s any way around it. I’m assuming that the motors don’t have an absolute position, they only know relative positions. Or maybe they know absolute position of the motor, but not the sprocket due to the gearing.

Any insight on making recovery less painful?

Related question: How can I shut things down such that setting the chain lengths isn’t necessary the next time I want to use the machine?


#2
  • when setting the chain length the first time, mark 12 o’clock on the
    sprocket in red. When done setting the chain length, at center/home, mark a
    link and a matching point on the sprocket in black.

mark the link, but not the tooth, it doesn’t matter which tooth is at 12
o’clock, only that one is.

Now, when there’s an issue:

  • unhook the chains from the sprockets (maybe wrap them around a screw/nail next to the motors)
  • Set the chain length (extend both chains). Use the red mark to set the 12 o’clock position of both sprockets first.
  • Hook the chains back on the sprocket, lining up the black marks on the chain and sprocket.

there is an option where all you need to do is set the sprockets to have any
tooth up at 12 o’clock, hook the chains with the marked links on them and press
a button

This still seems like a lot of work, though I’m not sure there’s any way
around it. I’m assuming that the motors don’t have an absolute position, they
only know relative positions. Or maybe they know absolute position of the
motor, but not the sprocket due to the gearing.

no, they are relative encoders

Related question: How can I shut things down such that setting the chain lengths isn’t necessary the next time I want to use the machine?

let the machine sit idle for a few seconds after it finishes cutting and it
saves the current position in eeprom, so that you don’t have to do anything the
next time you start it up.

David Lang