You’re correct, though. I should have been a bit more specific and try to keep it simple.
As far as I understand it, the BitZero does what it should do, but at any time the bit (or dowel) is changed, the Z height needs to be re-zeroed. The X and Y should remain the same unless you move or change the workpiece, unless you’ve got a guide in place for repetitive work, for example.
I think CM does know. If there is a requirement to change the cutting bit during a project, you’d need a separate toolpath for each bit, and re-adjust the Z height before each new cut. With a BitSetter installed, CM understands the bit change, prompts for it, then pings it over to the BitSetter to re-zero the Z height before continuing with the next toolpath.
Again (me being pedantic, this time!) I don’t think it will matter. If the BitZero is doing it’s job properly (and only the designer of the BitZero can confirm this, really) it should find the corner of the workpiece, irrespective of how big the dowel is (as long as it fits inside the hole!) The cutting bit can be larger or smaller than the probe, because it’s the toolpath that determines where the cuts are made, based on the tools geometry. To extrapolate on @CrookedWoodTex comment, using a dowel will provide a more accurate corner of the workpiece than an endmill.
It’s possible the two sizes are provided for different collets rather than for any accuracy.
The measurement inside the circle should be sufficient for the machine to figure out the size of the dowel and therefore compensate for that to estimate the XY centre.
I agree that the calculation is harder with a bigger dowel since it can touch the edges of the circle in a complex way.
I think the thing that is currently a circular hole in BitZero 2 should in fact be a square hole. Maybe in BitZero 3?
Well, I commented, but it was not discussed further.
Your discussion here seems more like a critique of the design of the BitZero-2. @Gerry is correct; the different dowel sizes are a convenience so you can do your zeroing without changing collets.
One thing to be sure you do is wipe down the contact surfaces occasionally. Sawdust is an insulator, the zero “hole” will catch dust, and you will get into a re-initialization situation quickly.
The only thing further I have is that you should get the BitSetter without hesitation. You can use CM without it (by zeroing traditionally), but CM will still have a few innocuous prompts about zeroing and changing bits, etc. Just don’t activate BitSetter in the Settings.
It probably is, with the ‘moving about’ issue, but I suppose I was trying to get my head around the accuracy thing - and wether I was being a bit dim understanding it. Happily not, though
Oh yes, without a doubt! It makes life much easier - and more automated
Referring to the situation where one did not have a BitSetter.
Actually, I disable my BitSetter (and clear all offsets) when I use a 1" diameter surfacing bit. It won’t physically fit my BitSetter in its standard configuration. (There is a thread here about adding a large diameter disc to the plunger for that situation.)
There are still funny issues with the force applied to the circle when you don’t happen to have the dowel right in the centre. It is nearly always going to try to move the BitZero unit.
The old BitZero plus a “how thick is your dowel” (not a euphemism) setting in CM is surely the most accurate approach?
Yes, and that’s where we came in. @jepho holds his in place during the process, and it’s likely that will be the norm for most of us. I’m thinking of putting something less slippery (sticky shim?) between the BitZero and the stock. This would obviously affect the initial Z zero setting and I don’t think the BitSetter process will overcome that, so there might be a need to do the Z zero separately.
I think the v1 BitZero is better for folks using larger endmills which are supported by its probing operations.
The v2 is better for folks using a variety of endmills, esp. in diameters not supported by the v1, and who have a BitSetter to facilitate tool changes.
