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I promised a video showing the APM tool setter in action and how I calibrate it. I have no connection with this company but I think it is a great tool for the money and it takes out the guess work on setting zero for Z. Sorry for the video quality it is hard to keep the phone on the action and watch the bit move to the setter.
https://youtu.be/M8U3HibL270
Why do you do this way instead of using some kind of zero plate?
Accuracy no zero plate or switch I have used has been consistent my current machine used an electronic switch that you set on the table or material I went through 2 of those, the first one was replaced under warranty the second was $395 so I looked for another option. The electronic switch when they failed to work destroyed themselves. When I had my ShopBot the aluminum plate was inconsistent and I was always left wondering if I got a good height there is no guessing using this. The other thing is you can measure height anywhere on the table without re-setting your zero. This will also not damage fine tips of sharp tools.Quote:
Originally Posted by EricSchimel
Thanks for sharing the method! I've not seen this product.
Strange, the aluminum ZZero plate method we use is quite consistent nowadays (and for some time now). It is simply an open/close circuit reading taken based on the thickness of the plate. Once you get the thickness of the plate (defaulted and almost always 0.121") then you have all you need to zero consistently.
To clarify any confusion with an easy way to check the ShopBot Zero.
Zero the bit out to the table/bed (however your file is set up) with the ZZero plate/clip and the C2 routine. Once complete, move the plate out of the way, and if you want to take an extra step, move the tool over just off the side of your material, give the tool a Move->Z, 0 (MZ, 0) command. The tip of the bit should now be just touching the top of your material that you zeroed to. You can rerun the ZZero routine again and recheck to test your consistency.
You can get some deviation depending on the bit material and if there is any grime on the plate, clip, bit/collet assembly as the circuit would not be being closed as quickly/cleanly as direct metal/metal with no grime.
Otherwise for non-conductive bits, we use the pressure-sensitive ZZero plate which speeds up the zeroing operation as well.
-Tom H
I had some slight inconsistencies with my hand held zero plate so I switched to a fixed metal plate. That was better, but not perfect, especially when using things like V Bits. It'd dull the tip or get marginally different readings I think because of the difference in shape between a V bit and an end mill.
I finally built and switched so a zero plate that uses the same inductive sensors that are on our prox switches and it's super consistent now. It's fully automated too, I just run my zero routine and my machine taps the inductive button and I'm good to go.
For sure, the zero plate is all based off the trigger of input 1 which is controlled by this on/off switch that exists between the clip and the plate. For some bits, this conductive trigger does not happen instantly due to the low surface area at the tip of these bits (particularly like VBits). This, plus other factors can be additive in how fast this trigger occurs, gets to the board, card and to your computer to trigger the stop and change in direction back up. When working ideally, this delay will be nominal to where even a new VBit tip should hardly leave a dot on the zero plate. But this behavior can change in small increments similar to how deflection/play is additive across the machine.
Often times we will hear about it in support at the point that the Z Zero assembly has some failure in it now (a wire progressively got looser or degraded) where input 1 no longer triggers at all and a bit has dug into the plate or something.
I'm sure there are some changes that have to be made even with a fixed electronic switch, functionally it is the same as even a fixed metal conductive plate. Where if you are zeroing with an offset to your machine bed, for most that bed is a spoilboard that has its thickness change on a regular basis, so the offset to this bed would have to be adjusted/plugged in each time it changed.
I still like the "dumb" conductive plate!
-Tom