Hello,
tl;dr is there an automated way to measure workpiece height without using the touch plate?
We are a cabinet shop and use our machine mostly for sheet goods. We have registration jigs for the sheets for the x and y directions. We still need to use the touch plate to get the height of the materials as that does change enough to matter.
I’m wondering is there something like a cheap laser that could be mounted to the spindle and used to measure the distance?
thanks!
Trevor
The papertools.ai software has been poking at ways to do it with a camera.
There are various galvo lasers that manually focus with a line and a dot. You might be able to use that to get X inches above the surface.
I don’t know if or how well Avid’s software supports them, but you can get a touch probe that goes in your spindle and works on contact with anything. I put a wired one in mine but they RF and IR versions as well. Best used with ATC for a production shop (not the wired one, unless you have an automatic connector too).
The one I got was: s5000LED Wired CNC Probe – DrewTronics
but I think you can get cheaper (cost and quality, of course) from Amazon.
Warning: the tips are very precise, very fragile, and very expensive. I think I’ve spent $200 on replacement tips so far, but I’m also writing my own probing routines so lots of opportunities to get it wrong.
Since installing the touch probe, I haven’t used the touch plate at all. Note: I also have a toolsetter, as does the current Avid setup, which handles the “measure the tool” requirement. My software measures the touch probe with the toolsetter to cross reference everything.
laser rangefinders are not, IMHO, accurate enough for cnc. However, a laser on one side of the spindle and a camera on the other might be, since it’s the angle that counts, not the speed of light.
This video might help https://youtu.be/-dk5WDKdWBQ?is=A6pu2aOh5LRWTkR3
Thanks this is all helpful to know about what options are out there!
This is really interesting thank you for sharing.
If you’re a cabinet shop doing sheet goods you should zero off of your table. That way you never need to zero off the top of the material. Pick a consistent thickness in CAM and never thing about Z zero again
Eric,
Thank you. The one other complexity I should have mentioned is that we have a vacuum table with a gasket. I was previously Z-zeroing from table but it led to inconsistent results due to the gasket compression. The gasket compresses different amounts depending on material.
I don’t have a vacuum table, but it was my impression that the gaskets are for sealing only - the work should be pressed against the table when under vacuum. If you’re being supported by the gaskets, either the gaskets are too big or they don’t have enough “squish” room in their grooves. Am I mistaken?
I’d try and measure how much that compression is, and see how much it actually matters.
If you’re doing production work I’d try to solve for the compression, perhaps there’s a different vacuum material you can use. Are you doing a plenum with LDF, or a grid system with insert gaskets?
I recommend this because right now you’re chasing TWO moving variables: Your material thickness AND your table height.
Eric and all thanks for your help!
Eric - a while back Leire (who is amazing!) helped me come up with the following strategy that has worked completely well. I set the work surface location to be the mdf spoilboard - NOT the surface gasket. Then I Z-zero from the work piece top. That has been working excellently for us.
Using the touch plate isn’t a big deal I just thought if someone had something simple to take that one more step away it would be nice. However it sounds like we’ll continue using the touch plate for now.
Thank you all again.
Trevor