Wild horse Econo probe

[nutzilla]

So, I purchased an econo probe from wild horse innovations. I aligned and compensated the probe tip. But when i probe an edge it is constantly off by .025 when compared to and edge finder. Is there a setting I am missing?

Nhut

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[109jb]

You say off by 0.025, but don't tell if that is inches or mm.

If talking about inches - What is the diameter of the probe tip and of the edge finder? For example, if the edge finder is 0.200" diameter and the probe tip is 0.150" diameter then they would be detect the edge at 0.025" difference because of the difference in tip radius. (0.200-0.150)/2=0.025

If talking about mm - 0.025mm is less than 0.001" and I would say that is a good result for a cheapy probe.

it also depends on how fast the probe tip is moving toward the piece. A typical probing routine would have the probe approach the piece being probed at a faster rate first, back off and then approach much slower to improve the probing results. If you are just using a G38.x move then set a low feed rate to test your probe results.

[nutzilla]

You say off by 0.025, but don't tell if that is inches or mm.

If talking about inches - What is the diameter of the probe tip and of the edge finder? For example, if the edge finder is 0.200" diameter and the probe tip is 0.150" diameter then they would be detect the edge at 0.025" difference because of the difference in tip radius. (0.200-0.150)/2=0.025

If talking about mm - 0.025mm is less than 0.001" and I would say that is a good result for a cheapy probe.

it also depends on how fast the probe tip is moving toward the piece. A typical probing routine would have the probe approach the piece being probed at a faster rate first, back off and then approach much slower to improve the probing results. If you are just using a G38.x move then set a low feed rate to test your probe results.

It's off by .025 inches. Probe tip is .125 and edge finder is .200. I don't understand why there would be a difference. It's finding the edge so that edge should be a constant zero point.

[Jim Dawson]

It probably takes 0.025 overtravel to change the switch state. If it's consistent, then just add (subtract?) the 0.025 to the probe tip radius and the zero should be correct

[IMT]

You said you "compensated for the probe tip", how? By simply taking half the probe diameter? The probe stylus will deflect some before the switch opens, thus the effective probe diameter will be less than the measured diameter. .025 seems like a lot but I haven't used the wildhorse probe. With the Tormach passive probe and the original stylus my effective diameter is .111 where measured is .118.
With a 5mm renishaw stylus with a 4mm shank the effective diameter is .194 where measured is .197.
Once you find the effective diameter, rotate the probe in the spindle 90, 180 and 270 degrees and check it. The force to actuate the probe will change with direction, changing the effective dia. The more flexible the stylus the more it will change.

[109jb]

It's off by .025 inches. Probe tip is .125 and edge finder is .200. I don't understand why there would be a difference. It's finding the edge so that edge should be a constant zero point.

Using an edge finder you have to know the tip diameter, whether it is a standard edge finder or a probbe tip. If the edge finder is used and has a diameter of 0.2" then when the edge finder moves off-center the spindle centerline is 0.1" from the edge (0.2/2=0.1") With the 0.125" probe tip, the spindle centerline is 0.125/2=0.0625" from the edge when the probe triggers. The diameter of the tip has to be compensated for.

[nutzilla]

Using an edge finder you have to know the tip diameter, whether it is a standard edge finder or a probbe tip. If the edge finder is used and has a diameter of 0.2" then when the edge finder moves off-center the spindle centerline is 0.1" from the edge (0.2/2=0.1") With the 0.125" probe tip, the spindle centerline is 0.125/2=0.0625" from the edge when the probe triggers. The diameter of the tip has to be compensated for.

I did compensate for the tip diameter. The tip is .125 and I compensated .0625. But it shows being off by .025. I can understand a few thousand but .025 is way to much for any probe.

[brianbonedoc]

Nut - what speed are you probing at? I always use 20ipm.

Also to calibrate the probe I would probe the center of a hole, say .25 and increase the probe tip diameter in the tool library until it probed the correct size.

having said that, I hated my wild horse probe. I got sick of it constantly losing alignment and bought a used renishaw MP3 and have been loving it.

[IMT]

I did compensate for the tip diameter. The tip is .125 and I compensated .0625. But it shows being off by .025. I can understand a few thousand but .025 is way to much for any probe.

The .025 difference is the flex in the stylus. How long is it and what diameter is the stem?

[nutzilla]

Tip is .125 and stem is 2" long. Wild horse said I need to measure effective tip diameter. Anyone know how to do that?

I'm all measuring at the default speeds tormach has it set at.

[SCzEngrgGroup]

Tip is .125 and stem is 2" long. Wild horse said I need to measure effective tip diameter. Anyone know how to do that?

I'm all measuring at the default speeds tormach has it set at.

Measure in both directions on a feature of precisely known dimension. For example, probe both sides of the 1" dimensions of a 1-2-3 block. Your measurement, if you assume a 0125 tip diameter, will come out LESS than 1", due to the over-travel required for the probe to switch. For maximum accuracy, you need to measure in a number of different proboe orientations (by measuring, rotating the spindle, measuring, etc.), as the over-travel, which is what causes the effective tip diameter to be less than the actual tip diameter, will be different in different orientations, due to the 3-lobe design of the probe "switch".

Regards,
Ray L.

[IMT]

Tip is .125 and stem is 2" long. Wild horse said I need to measure effective tip diameter. Anyone know how to do that?

I'm all measuring at the default speeds tormach has it set at.

The 1-2-3 block method works well but adds additional variation because of backlash in the machine axis and a different amount of stylus flex in each direction (due to differing actuating forces in opposite directions inherent to the probe switch design).
I prefer to take a skim cut with a known diameter endmill and probe the cut surface.
The method is as follows:
* Get a new good quality high speed steel .250 endmill. Use HSS because they tend to be closer to nominal size than carbide.
* Mount a piece of stock in the vise and clean up the left side with a skim cut. Make sure you approach in the +X direction.
* Set work offset to G55 and zero the x-axis.
* Set work offset to G54 and probe the surface just cut, using the probe feature (I still use Mach3, I assume PP still has the probing setup features)
* Raise the probe and move to X0.000
* Set work offset back to G55 and look at the x position on the DRO. It should be 0.125 if not, adjust the probe diameter by twice the difference and repeat the probing step.

Rotate the probe 90 degrees and check again. You will see the variation due to actuating force. You can eliminate some of this by rotating the probe so it always deflects in the same direction.

[Advil]

...Rotate the probe 90 degrees and check again. You will see the variation due to actuating force. You can eliminate some of this by rotating the probe so it always deflects in the same direction.

Exactly. Keep it simple. Mark the spindle and mark the probe. Always line up the two lines facing the operator when using the probe. Do all calibration and testing with the probe and spindle in that same orientation. When you are tweaking the screws, always turn the probe/spindle lines back toward you before every probe test.

You'll get it down to within a few tenths pretty rapidly.

I use the same mark on the spindle to identify the high spot for indexing my end mills for minimum runout when that's necessary, but in this case since the probe tip is adjustable all that matters is that the tip is always in the same clocked orientation and the 3 leg axis in the probe is always in the same orientation so actuation force for each axis always applies the same to the probe.

Even if you hate indexing tools, you might as well do it for the probe since you can't use a tool changer with it anyway. It's worth the 5 seconds to line it up when putting it in if your probe results will be .0005 or better if you do.

[IMT]

Indexing the probe in the spindle the same way every time is important to eliminate the error due to runout of the spindle/bearing/collet, but that is not what I'm talking about here. If you always use the probe in the same position the effective diameter will be different when probing in +X than it will be in -Y. It depends on the stiffness of the stylus and the variation in the actuating force of the probe, with the 3 lobe design there is inherently a difference in actuating force depending on the direction the stylus is deflected relative to the lobes. Probing will be more consistent if you rotate the spindle so the stylus is always deflected in the same direction relative to the probe body. I put a scribe mark on the spindle and the probe body, with the scribe marks facing the operator the cable going into the probe body is on the right (+X), I probe in +X this way and when I probe in -Y I rotate the spindle so the probe cable points in -Y etc... This was important using the passive probe and the supplied 3mm stylus with a 2mm ceramic shank because it flexes enough that the effective diameter changes by .002 depending on direction. When I switched to a 5mm stylus with 4mm shank the eff. dia. change dropped to around .0003

[jeffrey001]

Try programming a S100 M3 and measure with a dial indicator for run out oif the tip.

Jeff

[IMT]

Try programming a S100 M3 and measure with a dial indicator for run out oif the tip.

Jeff

LOL! Then follow up with a G0 Z-100 and you won't have to worry about probe accuracy anymore.

The title of this thread is "Wild horse Econo probe" which is a corded probe. When the spindle turns on with the probe installed the results are not pretty.

[SCzEngrgGroup]

And runout at the tip tells you absolutely nothing of value about the accuracy when probing...

Regards,
Ray L.

[Jim Dawson]

LOL! Then follow up with a G0 Z-100 and you won't have to worry about probe accuracy anymore.

The title of this thread is "Wild horse Econo probe" which is a corded probe. When the spindle turns on with the probe installed the results are not pretty.

I love it !

[jeffrey001]

LOL! Then follow up with a G0 Z-100 and you won't have to worry about probe accuracy anymore.

The title of this thread is "Wild horse Econo probe" which is a corded probe. When the spindle turns on with the probe installed the results are not pretty.

OOOPPSSS, Forgot it was a wired probe, never worked with a wired probe, I must admit, should have never replied

Jeff

[Dallas J]

I need to go back and double check the deflection for actuation on my probe but I most definitely don't see 0.025". I see a 2-3 thou at most when comparing probing one side, flipping the part, and probing the same corner (now on the other side). My estimate is based on faces lining up. Even though I do finish passes on full length walls from one side, the chamfers would be hugely mismatched from left/right side cutting.

I'll try checking a 1-2-3 block and report back what I see.