Hi all;
I was wondering what the strategies are for setting a 1 or 2 flute cutter to zero using a touch plate.
If you look at a 2 bladed cutter (say like a trim bit) the cutter protrude from the tool body quite a bit probably 0.200" or more - that and the cutter body is usually has some kind of non conductive paint on it. I had to turn one of my V bits 90^ to get a cutting edge to contact the touch plate in the X-Y axis
Looking at a spiral flute tool like an end mill, the only part of the tool that is the advertised dimension are the actual lips of the flute (and quite frequently only the tips of the lips) - if you try to X/Y zero it you will not be able to make contact with one of the lips in one of the two (X/Y) axis
In both scenarios one of your X/Y coordinates is going to be out ~ in some cases possibly up to 0.200"
So what are the strategies for dealing with these situations?
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Zero your X and Y using something with more reliable dimensions, then switch tools and zero your Z with whatever you’re going to cut with. X and Y don’t change with tool changes as they are based off the center of the tool. Shoot, you could use 1/4" metal bar stock for zeroing X and Y as long it’s straight and you make sure your controller has the right diameter.
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That is exactly what I would up doing - just cut off a little 0.250" stainless rod and used that on the X/Y
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If the spiraling of the flutes is at a large enough angle and the tool touches the probe with enough contact length then you should be able to get an accurate read of the outside tool dimensions on both sides. In the case of a non-spiraled tool, then a steel rod or other alternative would certainly provide good accuracy 
I liked the steel rod method - no changing settings for different tools, just as easy to set up.
The one issue I did have was I think that the gantry had moved during the tool change as zero was out at the end of the job by maybe 0.100" … not sure if I inadvertently moved it or I lost steps somewhere.
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