[scott216]

I have a new passive probe and it doesn't seem to be very accurate. I used the set screws to calibrate it. I put an indicator on the probe tip and hand rotated the spindle (grabbing it up by the motor). Runout was 0.0001", so that's as good as it's gonna get. In the offsets table I entered 0.1181" for the probe diameter. I double checked the ruby diameter by measuring with a micrometer. I secured a high quality (Hermann Schmidt) 123 block to the table and measured X-axis across the 1" side. To do this I zeroed on the left side of the block, then jogged to the right side (not changing Y and setting z height the same on both sides of the block) and used the Find X- button and got a reading of 0.9908. Repeatability is very good, withing a tenth, but accuracy it terrible, over 9 thou off. I did the same on the y-axis using the 3 inch side and it read 2.9922" Again, repeatability is great, but accuracy isn't. Do I have a bad probe?

[Doubleoh9]

Change the diameter you have in the tool table for the tip. Back when I had Mach3 I used a wizard that would calculate the effective diameter of the probe tip by probing different sides of a bore. The "effective" diameter was never the same as the measured. Flex in the shaft and other factors most likely contribute tho this error.

Jim

[keen]

Hi - Have you seen my series of videos on this

eg.

keen

https://www.youtube.com/watch?v=M6kL62v_ecc

[MFchief]

Jim, do you happen to have the name of that M3 wizard? I'd like to check it out.

Terry

[Doubleoh9]

Probe-It! Mach3 Wizard | Crafty CNC

Pretty cool set of functions - all probe related.

[scott216]

Hi - Have you seen my series of videos on this

Nice video, thanks. So I have to figure out the effective diameter. Is it trial and error or are there some formulas? My probe seem to be about 0.008" off, so would I just increase the ball diameter by 0.004"? I do have a ring gauge I could use for testing if that would be better. It's too bad that the deflection varies between x and y axis. I think I'll look into getting some shorter tips to minimize that.

[scott216]

I think I have my probe setup as good as it's gonna get with my the stock probe tip. I changed the tool diameter for the probe from 0.1181" to 0.1095". I took a ring gauge 1.20009" centered the probe in it, then and probed x and y. I got:
X+: 0.6001
X-: 0.6002
Y+: 0.5998
y-: 0.5998

So I'm +/-- 2 tenths, which is pretty good for anything I'm gonna do. I do want to get s shorter probe tip and see how much that helps..

[pickled]

That's actually REALLY good for that passive probe scott216. Did you run different feed rates too? I found that my probing speed was a critical reliability factor for both precision and accuracy. Changing to a stiffer stylus and running multiple iterations of a master ring gauge was the only way that I was able to qualify it and get results that met my needs. The passive probe should be sold with a disclaimer of, "results may vary".

I find myself using the Haimer a lot more than the passive probe these days. The passive probe is awesome for quick jobs where you can be a few thou off, or if you just want to probe a surface. For the price it's hard to beat the convenience and speed. All my old wigglers are pretty much shelved thanks to the Haimer and the probe, and that is a good thing! Oh yeah and I ran that ProbeIt set and found it to be really cool! I run the Tormach CNC Scanner a lot for 2D stuff as well and it is pretty slick for reverse engineering.

[scott216]

I think my feedrate was 20 IPM.

[MFchief]

Thanks for the link Jim, I'm getting ready to check it out.
Terry

[pickled]

I think my feedrate was 20 IPM.

It was interesting when I was doing my study a couple years back I found the optimum was 19 IPM on my 1100 series II. I'll have to see if I still have the data file laying around because I was looking at 2 different lengths of styli versus the feed rates using a factorial design. I blocked it by radius probing versus straight edge features. It was a neat test to knock out over a weekend. The variance of the results was definitely impacted by the travel speed...which surprised me. If I can't find the graphs I might re-do the study when I have some down-time because it was pretty quick. I should probably look into swapping prings as well. The evolution of Keen's work on the stiffening of the probe was fun to watch.

[squirrel_41]

Have a look at my routines it callibrates the probe for you
http://www.cnczone.com/forums/vertic...-routines.html

Just remember this is for Metric only at the moment

Also when I do my probes I fix the Probe to Z axis backplate and use it as a "offset probe" this eliminate any run out.

[scott216]

Here's some pictures I took. I show the probe results before and after changing the ball diameter from actual to effective.

Attachment 298338
Ring Gauge setup


Attachment 298340
Results with actual ball diameter


Attachment 298342
Results after adjusting to an effective diameter

[pickled]

That's a nice looking fixture plate on your machine! Do you cut metal or just serve food and drinks on the table of your Tormach LOL? Seriously though I am jealous of how well your probe dialed in and the cleanliness.

[squirrel_41]

My probe routine calibrates the probe diameter every 10 Degrees.

[scott216]

That's a nice looking fixture plate on your machine! Do you cut metal or just serve food and drinks on the table of your Tormach LOL? Seriously though I am jealous of how well your probe dialed in and the cleanliness.

Thanks, I just made the fixture plate the other day.