# Problem with Calibration

Almost finished calibrating my machine(8ft top 4x6 work area )and I came to a problem where when I hit “center machine” I find that I’m off by 2 1/8 inch to the right and 1 1/8 inch high from center of work area, I didn’t want to go to the next step and run the test pattern, I was afraid that sled would go off on the right side of the work area. What can I do to get the Sled centered before I run the test pattern?
I don’t know if this is because my frame is a little smaller than the normal frame.

Gary

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Are both chains the same length? That defines the vertical centerline, and the workarea height and the motor height above the workarea are used to calculate where along that line the 0,0 point is.
If the chains aren’t he same length, it’s possible that the left chain has jumped a couple teeth based on the fact that that chain must be longer to put the sled to the right of the centerline. I would do the chain calibration again to see if that changes things.

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you mean to the to the sled? if so I’ll recalibrate and check. just so you know the machine measurement
between motors was 2438.4 mm and by hand was 2400 mm.

That is short, is that a smaller frame?

yes, instead of 10ft top beam its 8ft, the work area is around 4x6

This is where I would start looking. It could be that a bad connection on one of the wires is making us loose some encoder pulses. I would check that all the connectors are properly seated and run the Test Motors/Encoders function to make sure all is well if you see different lengths. That inaccuracy in the top beam measurement is indicative of something being off.

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you mean both chains the same length to the sled correct?

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Yes. After running the set chain lengths function both chains should be the same length from where they attach to the motor to the end

that’s a lot of error (~0.004 per link, compared to the 0.001 that we would
expect), can you stretch out your chains and see how long they measure (and if
they have the same number of links)

also, it should be just shy of 378 links between motors. I know it’s a pain to
count them, but if you could validate that it would help.

ok still trying to recal will be back

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since the calib was 3/4 done and I didn’t want to take the chains off and count the whole chains, so right before “connect the sled” I tried to count the links (big fingers hard to do, kept getting 1 or 2 links ether missed or over) but this is what I counted, left chain from top sprocket 261 links, right chain 260 links.( could be a missed count) I hooked up the sled anyway and clicked " moved to center button), now I’m only about 3/4in right of center mark and dead on in the work area height, much better then before but I still like to get it in center.

I went ahead and clicked the test cut button anyway, the sleds bit moved all the way to the upper left and went off the work area by 3-4in, so I stoped it and let it move back to center. Now what do I do?

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What do you see when you run the Actions -> Test Motors/Encoders function?

Would you be willing to share a copy of your settings file (groundcontrol.ini) file? It will be located in your home folder (C:/users/yourname)

not good with computers, but Ill try, haven’t test encoders yet, was afraid I’d screw something up while calib
I have a 4x6 work area, could it be the machine thinks its larger(4x7 ?)

all motors seem to pass

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If you haven’t told it that it’s smaller, it will think that it’s 4x8

This is a great point. The calibration cut pattern is based on the work area dimensions in GroundControl. These default to 4x8. If you didn’t change it to 4x6 then it would run your sled off the side of the work area.

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I thought that’s what the calib did, okay I changed the work area to 6ft then reran the test again and this time
it cut 1,2,3,and 4 about 10in in from the side edges and 5 about 9.5in down from top edge that’s like a 2.5x4.5 work area unless it should be that way, don’t know

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That’s exactly what we’re looking for. The calibration process will attempt to place the cuts about 10 inches in from each border. This is to avoid your sled getting unstable near the edges of the work area, as well as giving breathing room in the event that the uncalibrated machine gets a bit closer to the edges than expected. Fear not, you still have the full 4x6 foot work area available!

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The calibration routine makes the cuts based on what it thinks the workpiece
size is.

so if you go in and change the workpiece height/width before you do the
calibration, everything should be good.

If you don’t, you run the risk that the cuts will be too close to the edge.

David Lang

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Thanks Guys…YESSS! so your saying my machine is cailb and nothing more to do?
now what do I do to get it centered or is that 3/4in to the right okay

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