I’m building some tooling and need to make some simple cutouts (squares/circles). I’m running into issues where the pockets are slightly off than the desired size. For example, when cutting a 3" diameter circle the actual measurement of the cut out circle is 2.97ish". I would consider this close enough but I need to fit a 3" object into the circle. What is the easiest way to get the desired outcome? Is there a better way than the iterative process of test cuts and adjusting the size?
This is the method I used to get my machine within 0.001"
http://docs.carbide3d.com/article/42-how-to-calibrate-the-machine-for-belt-stretch
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Perfect! This is exactly what I’m looking for.
Calibrations are getting closer but I’m still out ~0.01" (short). Since ive already adjusted $100/$101 can I re-run the test with my current settings or do i need to set it back to 40 first?
You can use your new values. Just make sure in the formula to use the actual values, not 40, when doing the calculation again. I did it twice on my machine, and the number didn’t really move the second time so I stopped. As long as everything is measured accurately the first time, you should not need to repeat.
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Did you put pins in the holes to get an accurate measurement or did you just eyeball the edge?
You should be able to get closer than that.
Using the hole method, you would measure directly with a pair of calipers in the holes (inside edge to inside edge) at least until you get it close enough to get a good solid fit with some metal pins. Again, need to do it in something solid enough that some pressure on the calipers to get a good reading isn’t going to deform the material. Until you’re close, using pins here can lead you a little astray if you’re far enough off that the holes and pins aren’t a good tight fit. That said, @RichCournoyer knows what he’s talking about. If that’s the way he suggests doing it, it must work.
I used measurements across a square with a pair of calipers. I used HDPE, but anything hard enough not to deform readily when measured with calipers is really fine (ie. soft wood or plywood not a good choice).
Here’s my file for the circle/square/diamond object. I think it’s easier when the machine is potentially way off. YMMV: 6in_circle_diamond_square.c2d (3.5 KB)
The process is basically the same, but I think the objects are easier to measure accurately.
Common mistake:
If you are measuring the error in a circle, square, etc, something that has two opposing sides, the error for the calculation is 1/2 (the error) since it the result was a -X and a +X (or +t and -Y).
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If i change my $100/$101 settings will the new values show in my settings? when i run ctrl1 $100/$101 still show 40.
i also lose homing when i run ctrl1
ctrl1 resets back to the original defaults as noted at: http://docs.carbide3d.com/article/38-shapeoko-3-default-grbl-settings
You will need to manually set $100 and $101 to your calculated values, and reconfigure homing per: http://docs.carbide3d.com/article/67-shapeoko-3-limit-switch-installation
Presumably the new defaults with CM4 will include homing being enabled.
That clarifies things. how do i go about verifying $100/$101 values?
Use the link which Rich provided:
Sorry, I’m asking the wrong question Once I’ve changed the settings in MDI how do I verify what MDI has for the values? I’m trying to confirm the changes have been made
Looks like the new settings took. Calibrated to .003", that should be good for what i’m doing. For anyone doing this I did find making a 150mm box much easier to measure than the triangle holes.
Thanks for everyone’s help and patience as I get up to speed on the equipment.
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You probably found this already, but for posterity’s sake, send
$$
to Grbl using the MDI.
I did not. Thank you!
Also, don’t forget to measure your tools… sometimes they’re not the size they say they are, especially with cheaper tools. If your tool is larger/smaller than the CAM package accounted for, then surprise, your pockets/profiled object is the wrong size.
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