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# Thread: 4th axis touch probing

1. ## 4th axis touch probing

Can anyone point to, or post, a how to on creating a touch probing macro for a rotary axis in mach3? I have mine set up, but I'm just manually moving to a position that looks right and setting zero. Then I touch off a known reference and subtract the 2 z positions to offset from center. That worked well enough for my test, but it would be great to be able to:
Attach a probe input from the touch plate to a dowel pin in the chuck
Attach the probes clip to a dowel in the collet
Have the macro prompt for diameter of dowel in Chuck and collet
Move spindle to a relatively close location that is mostly centered on the dowel in the chuck
Touch for z position and divide by 2 to know center. Back up and move in the y axis out of the way to then move down and probe the y position.
X could be manually moved, but the z and y would be nice to do as a routine instead of what I am doing now.

I have found some things, but no actual code yet. I'd pay for this capability of that is an option.

Any help towards this would be great. I'm sure that rotary owners will appreciate it down the road too.

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2. ## Re: 4th axis touch probing

From the Mach3 manual:
Program G31 X~ Y~ Z~ A~ B~ C~ to perform a straight probe operation. The
rotational axis words are allowed, but it is better to omit them. If rotational axis words are
used, the numbers must be the same as the current position numbers so that the rotational
axes do not move. The linear axis words are optional, except that at least one of them must
be used. The tool in the spindle must be a probe.

In other words, Mach3 can only execute a Touch Probe command on the X, Y and Z axes. It cannot handle a rotary axis.

You may need to set up a custom sensor for the rotary axis and then do the zeroing by hand.

Cheers
Roger

3. ## Re: 4th axis touch probing

Originally Posted by RCaffin
From the Mach3 manual:
Program G31 X~ Y~ Z~ A~ B~ C~ to perform a straight probe operation. The
rotational axis words are allowed, but it is better to omit them. If rotational axis words are
used, the numbers must be the same as the current position numbers so that the rotational
axes do not move. The linear axis words are optional, except that at least one of them must
be used. The tool in the spindle must be a probe.

In other words, Mach3 can only execute a Touch Probe command on the X, Y and Z axes. It cannot handle a rotary axis.

You may need to set up a custom sensor for the rotary axis and then do the zeroing by hand.

Cheers
Roger
Thanks for trying to help, but I don't need to probe anything on the rotary itself. It seems like it would be mostly like an auto tool zero setup. If I had a known diameter dowel of steel, say 1/4 inch. Then if I touch the top of it and it is the contact surface of the probe, then the z zero would be 1/8 from the touched point. Same for the y axis. I do not need any info about the a axis itself.
I'm really just trying to find the exact center of the rotary axis. I set mine up as removable for when I need to be for full sheets and still be able to turn something 4 foot long max. So if I were to surface my table and then mount it back on, the machine z zero would be different for the center.
I've seen someone in YouTube do this, but he never put the macro out, just said he would and it's been 2 years since posting. It did exactly this. I've reached out to him, if he replies, I'll add it here.

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4. ## Re: 4th axis touch probing

Ah, OK.
I do the same thing with my rotary. But I confess I do it 'by hand'.

Cheers
Roger

5. ## Re: 4th axis touch probing

Do you have a stylus type touch probe? I made one using the good old "3 pairs of bearing balls" setup, and it's changed my life.

Anyroad, I don't have the code in front of me but basically I manually position the tip near the side of the calibration dowel facing me (the 4th runs across the machine as I look at it) and with the tip eyeballed to about centre height.

The macro runs:

Incremental mode

Find the front - rough first, back off, come in again slow. Something like this:
G31 Y30 F100
G01 Y-1
G31 Y2 F30

Store the Y position (from the DRO)

Hop the Z up, rapid to the other side of the dowel and come down again to the same height we were at the front.

Repeat the two tap process to find the Y position of the back of the dowel.

Ycentre = (Yfront + Yrear)/2

Hop the Z up, move to Ycentre (absolute position, not differential for this move).

G31 the Z down to touch off the top of the dowel at the centre.

Your Z centreline is Ztop - (Yrear-Yfront)/2.

Set your work offsets accordingly and the cycle is done.

The Z part is a bit pointless if you don't have pre-loaded tools in holders with all the length offsets programmed in. I did it once, then turned up a round bar of about 40mm ali which is as long as the centre height of the 4th. Pop my tool height probe on top and I can set tool height as usual, but now to the centre height of the 4th.

Sorry, not near a computer with the macros on it and this may not be much good to you if you don't have a touch probe. But hopefully it gives you an idea.

6. ## Re: 4th axis touch probing

Originally Posted by dharmic
Do you have a stylus type touch probe? I made one using the good old "3 pairs of bearing balls" setup, and it's changed my life.

Anyroad, I don't have the code in front of me but basically I manually position the tip near the side of the calibration dowel facing me (the 4th runs across the machine as I look at it) and with the tip eyeballed to about centre height.

The macro runs:

Incremental mode

Find the front - rough first, back off, come in again slow. Something like this:
G31 Y30 F100
G01 Y-1
G31 Y2 F30

Store the Y position (from the DRO)

Hop the Z up, rapid to the other side of the dowel and come down again to the same height we were at the front.

Repeat the two tap process to find the Y position of the back of the dowel.

Ycentre = (Yfront + Yrear)/2

Hop the Z up, move to Ycentre (absolute position, not differential for this move).

G31 the Z down to touch off the top of the dowel at the centre.

Your Z centreline is Ztop - (Yrear-Yfront)/2.

Set your work offsets accordingly and the cycle is done.

The Z part is a bit pointless if you don't have pre-loaded tools in holders with all the length offsets programmed in. I did it once, then turned up a round bar of about 40mm ali which is as long as the centre height of the 4th. Pop my tool height probe on top and I can set tool height as usual, but now to the centre height of the 4th.

Sorry, not near a computer with the macros on it and this may not be much good to you if you don't have a touch probe. But hopefully it gives you an idea.
I have been thinking about ordering one. Cncrp suggested a couple, relatively inexpensive. And if that will be a better method, I'll order that tonight and see what I can do.
Thanks for the information.

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7. ## Re: 4th axis touch probing

You won't regret it. I think I've seen them around for under \$200, they make an enormous difference.

You could probably do something similar with a dowel in your spindle collet, mounting the dowel in the 4th chuck via an insulating sleeve and using that dowel as the touch probe but there's not a lot of give or spring when the spindle over-runs at the "probe" touch.

8. ## Re: 4th axis touch probing

dharmic I had a touch probe ordered and paid for, from Wild Horse Innovations I think it was. After I ordered I found out they had never shipped anything for the past two or three months. I called and they said, all that's all over we will ship yours next week. Long story short I never got it but PayPal gave me a refund.

So why do you use yours and how useful is it? If I knew of a good one I might be interested in buying one.... again.

9. ## Re: 4th axis touch probing

I use mine primarily to set up work offsets. I wrote macros for the work offsets page that let me find edges and the centre of a hole. So I can load up my workpiece then use that tool and those buttons in Mach3 to find and set my workspace zero, then run the toolpath from there.

I guess, the way I'm using it now, it's not a lot different to jogging with a wobbler or sprung offset type edge finder except that it allows me to drive from the MDI without worrying about my crappy hand controller getting mixed up between 1mm and 0.01mm jog steps - it's just a lot smoother.

But I'm in the process of writing Fusion 360 POST handlers to allow me to use fusion's tool probing too, which will simplify the process even further - and use the probe to more of its potential.

10. ## Re: 4th axis touch probing

So I found this on Ebay https://www.ebay.com/itm/Kinematic-T...LCRn:rk:2:pf:0

I am going to check CNC Router Parts also, I just want something that works.,... without paying \$1700.

Looks like CNCRP does not carry one.

11. ## Re: 4th axis touch probing

Originally Posted by wmgeorge
dharmic I had a touch probe ordered and paid for, from Wild Horse Innovations I think it was. After I ordered I found out they had never shipped anything for the past two or three months. I called and they said, all that's all over we will ship yours next week. Long story short I never got it but PayPal gave me a refund.

So why do you use yours and how useful is it? If I knew of a good one I might be interested in buying one.... again.
Seriously! I purchased from them just a couple hours ago. That is one of the places cncrp pointed to.

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12. ## Re: 4th axis touch probing

Originally Posted by ubergeekseven
Seriously! I purchased from them just a couple hours ago. That is one of the places cncrp pointed to.

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This is the link to the other one they pointed me to. https://www.sorotec.de/shop/3D-Finde...ster-6411.html

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13. ## Re: 4th axis touch probing

Originally Posted by ubergeekseven
Seriously! I purchased from them just a couple hours ago. That is one of the places cncrp pointed to.

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It looked really nice, but they never shipped, never answered emails, never responed to the PayPal dispute. I hope the one I just ordered off eBay is ok.

14. ## Re: 4th axis touch probing

Originally Posted by wmgeorge
It looked really nice, but they never shipped, never answered emails, never responed to the PayPal dispute. I hope the one I just ordered off eBay is ok.
While looking for a digitizer on eBay that was different from the one linked in this post, I find the wildhorse one listed. I will to the seller and my purchase on the actual site. Waiting for a response now. Hopefully I can actually get that one. Looks to be better quality than the linked one. Maybe not.

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15. ## Re: 4th axis touch probing

zeeflyboy had one from somewhere else, I think, that looked pretty good. If you can be bothered wading through his posts on the OmioCNC mega thread he had a link in there IIRC. I came close to just buying that one instead of doing my own.

16. ## Re: 4th axis touch probing

The guy I ordered from on eBay has 100% positive feedback and has a great website with instructions on how to use, and software he sells. I hope Wild Horse Innovations comes through for you. It looks like a really nice one.

17. ## Re: 4th axis touch probing

Originally Posted by wmgeorge
The guy I ordered from on eBay has 100% positive feedback and has a great website with instructions on how to use, and software he sells. I hope Wild Horse Innovations comes through for you. It looks like a really nice one.
I went ahead and ordered the one you linked. There is a lot of information on his site. Can't wait to test this thing out.

Going to get the other refunded.

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18. ## Re: 4th axis touch probing

These looked good, but looks like they lost their shop in the California fires..

https://drewtronics.org/

19. ## Re: 4th axis touch probing

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20. ## Re: 4th axis touch probing

The wildhorse probe person wrote back to me this morning. I specifically asked about the fact that someone in the forums said they never received the device and never had anyone contact them. This is what he wrote back with.

Hi,

We are currently able to ship orders within 2 business days of receipt of payment. We did have an interruption in production which required that we refund a small number or orders in order to deal fairly with our customers. This interruption was cased by circumstances outside of our control.

----

I now will be getting the ebay one that was suggested in this forum and I might get the wildhorse one. I'm going to wait for a while to see if it actually comes in. If not, I can always get a refund. If it does, I can compare them and post what I find on here. I might have one to sell at some point. Or I can eat the cost.

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