I had an idea this weekend that I’m not sure would even work so I’m looking for input. Has anyone embedded a probe into the spoilboard? My thought is to put a piece of aluminum in the upper left corner then surface the entire board so the probe is level with the board. Now you can probe bed zero and save the spoilboard.
-Ryan J.
(not THE Ryan)
Sounds like an idea, but as long as it is not a switch you will need to connect the crocodile clamp to the endmill, do you? Then you always have to jog the machine there. I thought about this as well but distanced myself from that idea. 
In this case you will have Z zero above the spoil edge and not on the piece to be machined. I believe that the advantage of having it on the piece also favors correct leveling after the tool change
You don’t need to use a mounted, thin sheet of foil, or an embedded, machined aluminum block. All you need is to use your touch plate on the top of your spoil board rather than the top of the stock, and use the appropriate adjustment for the thickness of the plate. Having the plate mounted will make automation easier, and you can wire your fixed touch plate and a “mobile” touch plate in parallel, so you can use the same pin on your control board for both.
You could also take it a step further and use a switch rather than a plate, so an allegator clip is not required (or ground the router bit as you suggest in your next post). I have this switch wired in parallel with my touch plate:
Early on, I was switching between the top of the stock and the top of the spoil board in CAM, but I found that I often mess up and ruined stock. To “fix” this problem, I made a management decision. In CAM, I always use the top of the stock as a reference for the job, and every job expect the Z=0 point to be set before the job starts. If I want to use the top of the spoilboard as a cutting reference, I:
…and yes, this means I have to write down the stock thickness on a piece of paper to set up the job, but this process has worked well for me.
Not if you ground the router. A simple cable and magnet that connect to a non-moving metal part when you insert the router would work. Or clamping is fine. I use a macro to probe so moving to the probe point isn’t an issue. It’s no different than using a tool changer and tool length sensor.
EstlCAM provides for using the board as zero then prompts for material thickness. Someone else on here talked about how they started using the board for zero and the spoilboard is immaculate with complete cut throughs of the material. I think other CAM programs do the same.
My main question is whether I can surface both the aluminum and wood with the same bit. The aluminum wouldn’t be huge so I wouldn’t think that would hurt the bit that much.
Do you have a link for that switch? Tool length sensors do the same thing but they are really expensive for some reason.
That should be done automatically in a program like EstlCAM.
Another reason I was looking to imbed is I don’t want to lose any bed space which is what would happen with a tool length sensor. With an embedded sensor I could probe then add my workpiece.
I used this switch from Amazon. The top was slightly convex, so I used a diamond stone and honed it flat.
That should be done automatically in a program like EstlCAM.
Setting this up in Fusion 360 is also trivial, but I found, personally, that, because I was switching stock points as the origin of my job. I was messing up with setting up the stock and ruining my stock and jobs. This is a “Rob” issue. I’m not good with details, so I have to put processes/rules in place that standardize things. I stopped making mistakes when I standardized on always using the top of the stock in CAM, but I still want to use the spoilboard as reference for contour cutting, hence my process above.
Another reason I was looking to imbed is I don’t want to lose any bed space which is what would happen with a tool length sensor. With an embedded sensor I could probe then add my workpiece.
You could embed the metal slightly below the top of the spoilboard and not have to mill the aluminum.
It sounds like an elegant solution, but therein lies it’s seductive ruin… When you zero out Z, you’re not really zero’ing it out, you’re telling it “Here is Z value N”, and the default is N=0. It’s just as easy to tell the machine “Here is Z value 6mm” (or whatever thickness your touchplate is). This becomes much more important when you want/need to surface your spoil board a second or third time. If you’re just looking for the convenience of having the touch plate in the same location, then sure, glue, screw, or just plain leave it in the corner of your workspace. But I think the effort of trying to counter-sink it into your spoil board may be wasted effort, unless you don’t do (m)any through-cuts and have a well-controlled shop environment, and therefore don’t have to resurface your spoil board often, or ever.
You could just add the z offset to the probe macro. Would take a little extra work after surfacing. Zero to the probe, then find the surface, now hitting the probe sends a Z-1 or whatever.
Actually, the point of using the board as your Z means you are less likely to hit the spoilboard while cutting due to the fact that the machines knows exactly where the board is. Should be almost no need to surface the board after the initial flattening.
You will still mar the spoilboard on thru cuts. Unless you leave onion skin but that adds extra clean up and possibility of tear/chip out when cleaning up. Not to say one is right or wrong. It’s a tit for tat thing.
Most the time people need to surface is due to the 0.5mm they cut through the material has accumulated to many patterns on the surface and you can get something flat on top of it. Most deep gouges are usually gcode/user mistakes when starting.
I think many of us would be interested to see how this turns out if you end up doing it, I just have my concerns. Again tit for tat I feel like.
Someone else here on the forum has done it and stated he hasn’t had to surface in a while.
Most of the time I use a surfacing bit is to remove the bumps the screws make in the spoil board.
This was my solution. Not as clean but just requires that magnet on the router. Tape is easy to replace and Im sure design can be improved.
I did basically the same thing as Robert with a switch. You can use G53 to send your router to the switch regardless of the WCS zero. So if you’re milling a sign from its center in the middle of your spoilboard and he’s to change the bit and rezero, it’s something like G53 X1 Y1, then run your probe routine. G53 is machine coordinates so it will always be consistent from your home endstops (assuming you use them because…2023) and you don’t need to math or disturb your G54 (or G55 or G56 or whatever you’re in).
My printer is a toolchanger, so I do need a quick way to set the tool offsets for each printhead. I use the solution one of the guys on the forum came up with:
https://www.printables.com/model/120147-knobprobe-z-offset-probe-between-z-probe-and-nozzl
But now I’m wondering if a similar solution could be used to set Z on my LR3. I use an elevator bolt at the top of the printer version, to give a bigger flat surface. But the same principle applies. The nice part is that it triggers very reliably, and my z-offsets (on the printer) are very consistent (as long as the nozzle is clean.)
I’m trying to figure out if it’s worth it. It would mean a big change in how I think about the depth and workpiece. I suppose I could borrow the one from the printer and experiment a bit. I’m just wondering if this is a case of “If it ain’t broke, fix it until it is.”
