Is there a way to re-position a drawing within GC?

As I am testing my machine, I wanted to create a milling operation that is a square of 3 feet by 6 feet. I want the drawing to sit centered in GC on the work table. The sled within GC is shown dead center which is great but when I load the 3x6 drawing, it is mostly off the page because the bottom left corner of the drawing is lined up with the cross hairs. Which are dead center.

Is it possible to line up the drawing withing GC and still have the cross hairs in the center or is that out of the scope of what GC can do?

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Depending on your CAD you could position the drawing already at X0/Y0.
In GC you move you sled with the arrows and how far it moves is a setting you can change.
At the desired position you click ‘Define Home’.

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When you create an .nc file, all the measurements are relative to a given point, often the lower left corner of the image. In GC, the crosshairs indicate the ‘Home’ position, where GC expects all measurements to be made from. To center the 3 foot by 6 foot rectangle in the workarea, you would need to move the ‘Home’ position 1.5 feet up or down, and 3 feet to the side. That would put the crosshairs away from the center of the workarea, but the cut centered in it.
To have both the cut and the crosshairs centered, you would need to move the image in the source program to be centered on the origin there, then re-create the .nc file.

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OK…that is what I thought. I was thinking there might be another way but as you said, that would be done in the cad program.

Thank you for your input.

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Could you customize a series of settings? Could I have a laser setting, a 1/4 bit setting, a 1/2 inch etc saved somewhere as a profile for ground control. I sometimes have different profiles for 3d printing when I use different tool heads.

CNC machines costing thousands of dollars implement something like that, ‘path compensation’. It’s not trivial to implement, and to date most folks here have made the tool sizesetting in the program that generates the gcode file, along with the stock dimensions of the piece being cut this session.

I came to ask this same question, when trying a few test cuts I wanted to be able to select a specific portion of the workpiece to have them cut on, but I couldn’t figure it out.

I’m using Easel, so yes it sounds like the lower left corner of the piece I’m drawing on is what Easel is considering zero, and the Maslow/GC is considering the center/crosshairs to be zero.

It would be extremely handy to be able to move the shape to be cut to a specific place of the board while in GC, but I realize that is likely out of the scope of what GC needs to do.

Is there a way to tell the Maslow to use the lower left corner as “home”, thus syncing up what Easel thinks and what GC thinks? I thought I would try moving the sled to the lower left corner and redefining home as that lower left corner, but haven’t got that far yet.

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As the Maslow works best in the middle of the workarea, I try to do my work there if I can. Here’s how I use Easel to accomplish what I think you’re describing.

If I want to cut a specific piece of a multi-part project, I duplicate the project in Easel and delete the parts I’m not going to cut. Then I ‘select all’ and in the ‘Shape’ tab of the control panel I choose the center position button and change the X and Y values to 0. Now when the gcode is generated the part will be centered on wherever I have set ‘Home’ to be in GroundControl. While you’re there, take note of the ‘Width’ and ‘Height’ that Easel shows for the selection.

Back in GC, I pick a spot on the material to be cut that’s big enough and attach it to the workarea near the middle, oriented for the cut. Then I drive the sled to the spot that will be the center of the piece and ‘Define Home’. After checking that the sled will be supported all around the cut, I’m ready to go.

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yes, that’s exactly what you should do

I’m with you Maslonians. I also would like to be able to move the file around in GC. but it does appear to be out of the scope of what GC can do so we work around it.

I have a job I want to do that has 9 pieces to cut out and all 9 pieces just fit on half a 4 x 8 sheet of plywood. I bought Maslow for just this kind of project. Because Maslow is sooooooooooooooo slow, it takes a long time to move those cross hairs to the lower left corner to set up the home position and start the job.

Have you discovered in GC that if you point to a spot and hold the left mouse button for about 3 seconds, you get a circle around the point with x & y coordinates indicated, and an option to move the sled to this point. After the sled gets there, press the “set home” button up on the “keypad”, and BINGO, the drawing moves to this point. This makes it really easy to move the default start point of the Easel drawings the lower left corner of the workpiece in Ground Control. One feature I would like to see in GC would be a real time x & y coordinate read out of the cursor position. Also would be nice this feature could be set to either inches or mm.

Thanks!

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Thanks for the replies I will test some of them out. Dustcloud, I did not know that!

My main purpose is that knowing it cuts better toward the middle, be able to lay out in Easel exactly where I want specific parts cut on the sheet. The simulation in Easel is very handy for this and lets me see where everything will be, which is good for planning. As long as I can set Maslow home for 0,0 in the lower left corner, I think everything will be great. Even if it immediately wants to move back to the center to begin cutting as long as the shapes are all placed properly I’m happy.

Great suggestion @Dustcloud. Do we want to see a “set home” button added to that long press menu? That way you wouldn’t actually have to send the sled all the way to the corner

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that would be good, but it really should be implemented as G54 so that you have
a good way to switch back to the original coordinates.

Making it easier to move Home would be a cool feature.

If you shut down GC with the sled someplace other then home, is it possible to lose calibration? Also, if the sled goes outside the specified work area, can cal be lost? If so, care must be taken to not do these things. It might not be so difficult to do the “cursor hold” thing, reset Home, and accidentally go outside the boundaries.

I ask these questions because I sent the sled “over the top” once, and got a “unknown chain length” error, and lost home when my laptop went to sleep another time, which left we with a cal error at restart.

If you shut down GC with the sled someplace other then home, is it possible to lose calibration?

the arduino saves it’s position within a couple seconds of stopping, so it
remembers where it is unless you cut power while it’s moving.

note, having the laptop go to sleep so that communications with the arduino are
cut counts as cutting power while moving

Also, if the sled goes outside the specified work area, can cal be lost?

if the chains move on the sprockets, you loose the calibration, but as long as
the chains remain attached and you don’t cut power, you should not loose
calibration.

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Many laptops shut off the USB ports when going to sleep, that would cause the Arduino to lose power. It it was stationary at the time, it probably wouldn’t lose its place, but if in motion, it would be sure to lose it.

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If your chain jumps on the sprocket (as mine does), or if you lose power, or if your pc goes to sleep during operation, or if you use a different program besides GC and don’t return the sled to the EXACT position the GC “thinks” it should be then YES, you will have to re-calibrate chain lengths every time these things happen. I know this because I have had to do this. I can now calibrate Maslow with my eyes closed and standing on one leg!

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So long as it’s the EXACT same leg!:grin:

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touche. :wink::wink::wink: