CNC: Quick way to origin off a squared board on big machine?

Space Teams CNC
1

Is there a quick way to lay down an already squared board on the CNC and set the origin properly?

Z-axis is easy. I home to the surface of the spoilboard and I’m done.

The X and Y axes are a PITA. I have to set the board down with the bit at the edge, then I have to move it away, and then I have to move along the board and then I have to bump the board again–repeat until you get it right. Finally, touch the other axis. Then lift Z, and subtract half the diameter of the bit.

This taks a LOT of button pushing. The lack of a jog dial really hurts.

Is there a much easier method that I’m missing? At the very least, is there a way to lay a square board that automatically matches and transfers the squareness of the machine axes? At least then I can leave a bit of oversize and just sorta set the origin off the corner of the board visually.

Thanks.

2

have you tried using the benchdogs?

The marker lines are also made with the machine itself and those are a good indicator

What’s all this math you’re talking about? I don’t use any of that when setting up the cncs

3

I use the dogs for this. Run this to move to the bottom left corner that the dogs create:

G0 X59 Y81

4

If you use a bottom right datum and square to the front right* of the machine, using F as your vacuum zone this is the gcode:

G0 X1538 Y81

You will want to subtract or add 1/2 of your bit’s diameter in mm if you want to stay inside the material. Typically I remove the dogs and run knowing that 1/2 of my bit will go off the material.

Also note that these simple gcode lines will run the spindle during their move.

5

ALSO:

This assumes you home the machine and zero the XY at the home position before running the G0 command or using the pendant to jog to those locations.

I don’t remember how to jog to an exact location using the pendant but it is possible

6

Don’t precut your part perfectly square. Leave it oversized and use the CNC to cut your perimeter. Use the spoil board dogs, vacuum zone lines, or existing through cut marks. Eyeballing it is sufficient 99% of the time.

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7

I generally let the CNC cut the outside as Charles recommends, though that precludes some hold down methods, and it isn’t always possible.

There are two issues: getting the piece square and locating a corner accurately. The bench dogs should help with both.

On the old CNC, I used an edge finder a few times. I haven’t tried that yet on the new machines; I’m not sure we have them set up to do this. You need to turn the spindle on at low speed, somewhere around 1000 rpm, while having movement control via the pendant. Does anyone know if that is possible?

8

If i remember correctly the gcode controls the speed which is translated via the controller. I don’t think we can manually control it like that but I could be wrong

9

I do 2 sided stuff pretty much exclusively lately - so squaring is pretty much essential. I use posterboard as the base on the vacuum table - and mount the piece to the posterboard via the super glue method. Once that is done, I have a very low profile, adjustable piece which i square to the machine via a t-square against the piece and the edge of the machine… i can get it perfectly square. once it’s perfect - i turn on the vacuum and it’s stuck in place.

10

I made a standing offer to add LinuxCNC to these machines. That would bring back a monitor, jogwheel, wireless toolsetter, a very strong capability to recover jobs, g-code control of the spindle rpm, and with one additional sensor we can correct the racking error in the gantry. It can also be made to move faster if we want to do that. And it’s running on a standard well-defined and supported flavor of g-code.

And I can make this work as a dual-boot system, and if somehow the whole interface board stopped working, it would take all of 2 minutes to move the plugs back to the original configuration.

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We’ve explained multiple times why Linux will not be used on the machines at this time.

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