New toy… economical 3D probe

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New toy… economical 3D probe

This topic has 27 replies, 10 voices, and was last updated 2 December 2022 at 22:29 by John Haine.

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21 November 2022 at 12:21 #622025
John Haine
Participant
@johnhaine32865
This little gadget arrived in he post this morning – a 3D probe from China. Neat little design that takes up minimal daylight, has 6mm shank. Works on the original Renishaw principle, available from several sellers on eBay and AliBaba. Prices range from ~£50 upwards, this one cost me ~£59. A few people have used them over on the mycncuk forum and found them very good.

Though I have home-made conductive edge and height finders which I use with probing routines of course they don't work on non conductive materials and the height one is really limited to tool setting.

I'll report back!
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21 November 2022 at 12:21 #15401
John Haine
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@johnhaine32865
21 November 2022 at 12:55 #622034
KWIL
Participant
@kwil
I have a similar one used on a Bridgeport mill. It is my go to device for edge finding and for centering.
21 November 2022 at 15:07 #622048
Nealeb
Participant
@nealeb
How easy is it to centre the probe? I have a similar device but a bit chunkier that came with my second-hand CNC mill. Works OK but recentring after changing the probe is a pain. The three adjusters are difficult to see and their thread pitch is a bit coarse. OK, maybe I shouldn't need to change probes that often but I do have a habit of occasionally driving them into the work, to the extent that I now make my own.
21 November 2022 at 15:44 #622060
Ian Johnson 1
Participant
@ianjohnson1
That's neat and compact John will it work with Mach 3? Might be just what I need for my KX1

IanJ
21 November 2022 at 15:55 #622062
Baz
Participant
@baz89810
If it will plug in to Mach 3 I will be adding one to my Xmas present list!
21 November 2022 at 16:03 #622064
John Haine
Participant
@johnhaine32865
Haven't tried it yet but I'm assured that it is Mach3 compatible. Just has a NO NPN compatible output.
22 November 2022 at 12:45 #622176
Martin Connelly
Participant
@martinconnelly55370
I have had some issues with Mach3 probing macros. Does it come with any software or a link to where they are available? The issues are powering past the point of contact and damaging probes. I see from looking at the blurb for these they only have a 4mm over run limit in XY and less in Z. I have considered putting a magnetic break point in a probe to avoid damage.

Martin C
22 November 2022 at 13:18 #622183
John Haine
Participant
@johnhaine32865
I've written my own macros and not had overrun issues.
22 November 2022 at 14:15 #622189
Martin Connelly
Participant
@martinconnelly55370
The problems are not consistent, usually the macros I have work but occasionally they go gaga.

Martin C
22 November 2022 at 14:17 #622190
John Haine
Participant
@johnhaine32865
Ok, just lashed up for a quick trial, and it works beautifully with Mach3. Mine was set up for NO npn, i.e. expects the probe to assert a low level as if the probe was grounded. Exactly what the new probe does, so no change required. I just needed to provide a 5v supply for which I use an old phone charger.
22 November 2022 at 19:23 #622235
Pete Rimmer
Participant
@peterimmer30576
What interface does the probe plug into normally John, i.e. when not used with a CNC device?
22 November 2022 at 20:23 #622244
John Haine
Participant
@johnhaine32865
Just needs a 5v supply. It has some cool built in green LEDs that light when powered and turn red when triggered.
22 November 2022 at 20:32 #622245
JasonB
Moderator
@jasonb
But how does Mach3 or whatever you are using know when to touch the surface if the wires only go to a power supply?

Or is it more of an electronic edge finder that simply flashes red on contact with the edge
22 November 2022 at 21:38 #622253
John Haine
Participant
@johnhaine32865
I was replying to Pete. There is a signal wire too for the probe input to Mach.
23 November 2022 at 04:40 #622268
Bruce Edney
Participant
@bruceedney59949
I have one. Seems to work great on LinuxCNC using the Probe Basic Subroutines. I have added a resistor to the supply wiring so I can use another input to indicate that the probe is plugged in. I need to modify the routines to check that input before running the rest of the g-code.
23 November 2022 at 19:20 #622379
Pete Rimmer
Participant
@peterimmer30576
Posted by John Haine on 22/11/2022 21:38:21:

I was replying to Pete. There is a signal wire too for the probe input to Mach.

Thanks John. I will have to look at getting one of those.
24 November 2022 at 16:04 #622489
Martin Connelly
Participant
@martinconnelly55370
I've looked at my Mach3 macros again and there was a lack of a G91 relative movement code at a couple of places. Now that I have put them in the macros seem to be working as expected. I think in some cases G91 was already set first by another macro running which did not set it back to G90 absolute motion and in other cases the direction of travel was the same for both G90 and G91.

Martin C
24 November 2022 at 16:53 #622497
John Haine
Participant
@johnhaine32865
After being alerted by someone over on mycncuk I've downloaded a wizard called ProbeIt, the demo version, from Craftycnc. Looks like a good substitute for the macros, though not tried it yet.
25 November 2022 at 10:18 #622606
Les Riley
Participant
@lesriley75593
I have been using ProbeIt for a couple of years now and it works well. Worth the cheap price.

I use it with my home-made CNC probe.

Finding a hole centre:- **LINK**

Les
26 November 2022 at 16:43 #622755
Martin Connelly
Participant
@martinconnelly55370
Tried ProbIt this afternoon and I have a warning for anyone with a rigid or near rigid probe, don't use it in its current release. I put a piece of aluminium tube in the vice only held loosely as I did not want to make it oval. I decided to try the internal hole probing routine. After the probe has made fast X axis contact with the right hand inner surface it backs off then makes a slow approach for a more accurate contact. Then it does what it should not, it moves towards the material before pulling back again. In the case of my lightly held tube it actually moved the tube in the vice. I also observed it doing the same thing when probing in the Y axis. This is not good and needs to be corrected. I stopped at that point because I didn't need to find it was doing similar things with other probing options and running the risk of damaging my probe.

Martin C
26 November 2022 at 19:36 #622781
John Haine
Participant
@johnhaine32865
Martin, you should raise that issue with the supplier.
27 November 2022 at 16:26 #622856
Martin Connelly
Participant
@martinconnelly55370
Have done. He wants me to do a few tests at different settings.

Martin C
27 November 2022 at 16:35 #622857
John Haine
Participant
@johnhaine32865
Would be great if you could share the results please Martin. I have downloaded and installed the wizard and had a play, including the tip calibration where it didn't seem to do anything alarming, and probing an external edge. Haven't tried a hole yet, or paid anything!
29 November 2022 at 12:04 #623031
Martin Connelly
Participant
@martinconnelly55370
I had another play with ProbeIt, this time before doing anything else such as probing with my usual macros or running any code. The issue seems to be that ProbeIt does not respond as quickly as my macros triggered by clicking a button. This may be due to the simplicity/complexity of the different probing options or macros. I put a spring over the tip of my rigid probe to try ProbeIt and it is clearly over-running after contact. With my macros I can do a fast approach at 330mm/min and get what looks like an instant stop on contact however ProbeIt bends the spring at both a 330mm/min and a 33mm/min approach. This will not be an issue with a probe such as the probe being discussed in this thread which has a 4mm leeway in the X and Y axes.

I could buy one of these probes but the simplicity and low cost of a home made rigid probe seems hard to beat as long as you have a system that responds rapidly on contact and you don't want to use it on non-conductive materials (I pull out the edge finder for such times).

Martin C
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