Calibration issue with small frame

Due to space issues in the shed, I decided to build a small frame for my new toy.
I built the default frame, scaled to have a 2400mm top beam - work area is approx 1600 x 800
I realise that I should cut the chains to a suitable length, but being a compete beginner and a long way from anywhere, when I connect the sled I just run the extra chain through and let it ‘dangle’.

Calibration gives an extended chain length of about 1320m, which means that when I hang the sled it sits just below center. However, at this point I keep getting the ‘Unable to find valid machine position for chain length’ message in Ground Control .

Is there anything else I should change in the settings to account for a smaller than normal frame? Should I just bite the bullet and cut the chains to length?

Firmware and Ground Control 1.26


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Longer than needed chains do not matter to any size frame, in terms of how the software calculates position, it just becomes an issue of managing the slack. It’s good to have some tension on the unused chain as it comes off the sprocket. Search the forums for “chain slack tension” and you will find lots of great ideas.

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Have you changed anything or just left everything default? Upload your “groundcontrol.ini” file and I can review your settings and let you know.

Edit: I recommend going to the wiki section of the site and following the “How To: Get Calibrated!” wiki.


Managed to get it working - not sure what helped, but:

  I kept the full chain length but followed some of the advice on

adjusting chain tension


  I wiped everything and installed firmware and Ground Control

v1.25 rather than 1.26: for some reason, Norton on my PC really
didn’t want to run GC1.26!

Anyway, can now cut things!



Hm, I wouldn’t think antivirus would prevent GC from running. Did you get any errors? I’m starting to become more skeptical of v1.26.

Norton told me that because only a few people had downloaded it,
then I couldn’t trust it. Even when I set it on my trusted list,
Norton refused to run it.

Hate it when a computer tells me what to do.


Make an exception for it:

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