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Machine probe options

GiroDyno

Cast Iron
Joined
Apr 19, 2021
Location
PNW
I'm trying to add spindle and tool probes to a Brother S2Dn. I was going to go the Blum route but there must have been a huge price bump, quoted $9700 for the hardware plus $2600 installation...

A quick Google search yielded a video of someone installing a Renishaw system (
) That led me to eBay where I found Renishaw spindle probe/receiver combo (with warranty) for about $3300.

Out of curiosity I looked for other options and found EMG (https://emgprecision.com/cnc-digitizing-touch-probe-series/) who has a complete kit (Both probes and receiver) for $2600.
Has anybody ever heard of or used one of these?

The technology in probes seems pretty well established, is it to the point where todays knock-offs are as good as the originals from 5 years ago? I'm not doing anything crazy; probing WCS, basic inspection or bearing bores and would like to do in process tool checks.
 
I can't comment on other brands of probes, but I installed a renishaw OMP-40-2 on my robodrill and purchased renishaw inspection plus macros. It already had a table probe so added a relay to route the skip signal from the spindle probe receiver when that is active. It was fairly straightforward and Renishaw tech support is stellar.

If you want to save some money, search for new old stock receivers and omp40-2 probes. There are a few models/revisions out there that function the same but are priced differently. Renishaw will verify if a serial number is genuine too. I don't know what macros Renishaw offers for a brother control, maybe Brotherfrank can chime in on that.

Renishaw also offers a crash replacement program which I unfortunately had to use. You can call them for the current pricing, but a crash is a real possibility so factor that in versus an off brand that may be unsupported in a few years.

Good Luck,
Mike
 
That price seems very high? I'm in europe, but a random search of online shops gives me a baseline price of:
- https://www.damencnc.com/en/tc52-workpiece-touch-probe-toolholder-for-example-hsk-f63/a2834

As I wrote this, that's the equiv of about $5,300 USD (perhaps you need an extra few 10s of dollars for shipping?).

I believe others have used the Renishaw hardware with the Blum macros. Renishaw charge for their macros, I'm totally unclear what Blums policy is? I've asked people at Blum before if I can hack on their macros, improve them, and share the results, and they've said "yes" a couple of times... I don't know if they just don't understand the question though?

Anyway, the Blum macros are very desirable as they simply calculate a trigger delay at your desired probing speed and this lets you probe at full speed on a single hit, maintaining micron repeatability.

So this video is probing at 1,000mm/min touch speeds (Blum claim the probe is accurate up to 2,000).
- https://www.instagram.com/p/CxybkFqI4pv/

There are various options for integration with the machine, but mine is just 2 inputs and one output. Seems to work well
 
Out of curiosity I looked for other options and found EMG (https://emgprecision.com/cnc-digitizing-touch-probe-series/) who has a complete kit (Both probes and receiver) for $2600.
Has anybody ever heard of or used one of these?

Those are Chinese probes that they've had made with their own branding. The exact same ones with different branding are available for half that price on AliExpress.

I have no idea if they're a viable alternative to a Renishaw or Blum. Personally, I don't think I'd risk it.
 
The hardware behind probes is pretty well established. I would expect any sort of reasonably executed knock off to be on-par with the Renishaw.
The software side is maybe less obvious... do they go through batteries faster, do they communicate as fast? TBD.
What actually makes me nervous is longevity of the seller. If I blow up a probe in a week, month, year will they still be around to offer a replacement?

EG needs to chime in, I'm sure he has experience with these!

I am more curious about the plunger style tool probes, those seem straightforward enough there has to be some proven options in the <$500 category.
 
From what I can see, probes will trigger fairly accurately in the tens of microns range without an issue. However, triggering in the microns range needs some fettling of the design. Also the majority of spindle probes seems to use the three armed design to sense movement, and this creates some lobing accuracy differences depending on direction. Blum claims to have some technology to smooth this (but I don't know what, or if Renishaw do the same)

So then the engineering issues seem to come into things. For my woodworking router I have a really nice $200 spindle probe which has proved great! If it breaks I'll buy whatever else is on the market around that price. However, this product also uses an oil flood to stop the contacts oxidising, and apparently this is an issue for this type of design. I presume the high end stuff either gold plates the contacts or uses immersion in fluid?

Also if you stick the spindle probe in something like a Speedio, then it's going to take a bashing... Just whirling around it's living a hard life and that's before you bash it down into the spindle at a zillion miles an hour. I would imagine this will add some strain to the life of many spindle probes and some might fail to keep their calibration under the Brother tool change?

However, tool setters seem like a different game... If you go on ebay, there is a very common design for $40 or so. I have one for my woodwork router, but never measured it's accuracy. I see them for sale under another name for use with the Brother and by all accounts they get into the micron range of repeatability? They aren't going to have anything like the same hard life. I doubt the tops will survive tool break checks in the same way the pricey ones will (what are the tops made of? Certainly not replaceable on my $40 one?). However, I guess consider them disposable? Cable lengths seem like an issue with these ebay specials as well. Plus I wonder how coolant resistant they are, people who dismantled them say they are just kind of potted, so I guess buy a couple and keep swapping out until you get to the best built one? Still seems like a cheap sport!

I think this is a difficult game to comment on. Seems like the high end tools definitely have polish and accuracy tweaks that the rest of the market lack. However, if the discount is enough, then I would be all over the generic. In this case though the alternative is still quite a bundle? Do please post here if you do pickup one?
 
From what I can see, probes will trigger fairly accurately in the tens of microns range without an issue. However, triggering in the microns range needs some fettling of the design. Also the majority of spindle probes seems to use the three armed design to sense movement, and this creates some lobing accuracy differences depending on direction. Blum claims to have some technology to smooth this (but I don't know what, or if Renishaw do the same)

So then the engineering issues seem to come into things. For my woodworking router I have a really nice $200 spindle probe which has proved great! If it breaks I'll buy whatever else is on the market around that price. However, this product also uses an oil flood to stop the contacts oxidising, and apparently this is an issue for this type of design. I presume the high end stuff either gold plates the contacts or uses immersion in fluid?

Also if you stick the spindle probe in something like a Speedio, then it's going to take a bashing... Just whirling around it's living a hard life and that's before you bash it down into the spindle at a zillion miles an hour. I would imagine this will add some strain to the life of many spindle probes and some might fail to keep their calibration under the Brother tool change?

However, tool setters seem like a different game... If you go on ebay, there is a very common design for $40 or so. I have one for my woodwork router, but never measured it's accuracy. I see them for sale under another name for use with the Brother and by all accounts they get into the micron range of repeatability? They aren't going to have anything like the same hard life. I doubt the tops will survive tool break checks in the same way the pricey ones will (what are the tops made of? Certainly not replaceable on my $40 one?). However, I guess consider them disposable? Cable lengths seem like an issue with these ebay specials as well. Plus I wonder how coolant resistant they are, people who dismantled them say they are just kind of potted, so I guess buy a couple and keep swapping out until you get to the best built one? Still seems like a cheap sport!

I think this is a difficult game to comment on. Seems like the high end tools definitely have polish and accuracy tweaks that the rest of the market lack. However, if the discount is enough, then I would be all over the generic. In this case though the alternative is still quite a bundle? Do please post here if you do pickup one?

Kinematic (three arm) probes are old old tech, pioneered by Renishaw sometime in the 1970's. It's very simple and about as close to a perfect design as anything gets - reliable, easy to manufacture, utterly repeatable regardless of manufacturing precision...

I'm sure Chinese kinematic probes work fine and are comparable to known quantities, purely by the nature of the mechanism. It's hard to get wrong.

The lobing accuracy is the only downside, and it's primarily from the flex in the stylus vs. the non-uniform force required to trigger the mechanism depending on direction.

The only way I can imagine this could be "smoothed" is by compensating the results based on known deflection variations. Some machine controls already do this anyway.
 
Kinematic (three arm) probes are old old tech, pioneered by Renishaw sometime in the 1970's. It's very simple and about as close to a perfect design as anything gets - reliable, easy to manufacture, utterly repeatable regardless of manufacturing precision...

I'm sure Chinese kinematic probes work fine and are comparable to known quantities, purely by the nature of the mechanism. It's hard to get wrong.

The lobing accuracy is the only downside, and it's primarily from the flex in the stylus vs. the non-uniform force required to trigger the mechanism depending on direction.

The only way I can imagine this could be "smoothed" is by compensating the results based on known deflection variations. Some machine controls already do this anyway.
Two probe inherent terms have been used in this thread: accuracy and repeatability. In fact, accuracy is not a term which can be addressed to probe. Probe is a device which, once it's stylus is deflected, generates electric trigger signal. The aim of "Renishaw type" probes is to generate this signal always at same deflection. This is repeatability. In both types of Renishaw probes (three arm and strain gage), the repeatability is based on ability of mechanical kinematic system to return the deflected stylus to its starting (seated) position. The lobbing phenomena is simply treated by appropriate calibration technique.
The kinematic mechanism is in fact so simple to build, that no matter who the builder is the new instrument assures decent repeatability. The problem is how to assure it for 100000 and more touches. Not everybody knows how to do it.
I've been supporting several forum members with installation of "alien" probes from EMG and Drewtronics, and seems that they are happy with their equipment.

Stefan
Cogito Ergo Sum
 
Two probe inherent terms have been used in this thread: accuracy and repeatability. In fact, accuracy is not a term which can be addressed to probe. Probe is a device which, once it's stylus is deflected, generates electric trigger signal. The aim of "Renishaw type" probes is to generate this signal always at same deflection. This is repeatability. In both types of Renishaw probes (three arm and strain gage), the repeatability is based on ability of mechanical kinematic system to return the deflected stylus to its starting (seated) position. The lobbing phenomena is simply treated by appropriate calibration technique.
The kinematic mechanism is in fact so simple to build, that no matter who the builder is the new instrument assures decent repeatability. The problem is how to assure it for 100000 and more touches. Not everybody knows how to do it.
I've been supporting several forum members with installation of "alien" probes from EMG and Drewtronics, and seems that they are happy with their equipment.

Stefan
Cogito Ergo Sum
What I've noticed is that after many cycles CMM kinematic probes like the TP2 or TP20 modules eventually stop reseating properly. They appear to mechanically reseat, but remain electrically open circuit until you give them a tap. I've not encountered this with machine probes, but it's possible that I've just never put enough cycles on the ones I've had.

I assume this is due to some kind of breakdown of the surface of the pins/balls - it has been explained to me before, correctly or not I don't know, that the oil in the probes serves two purposes - to prevent oxidisation of the contact surfaces, but also to ensure that the mechanism goes open circuit "cleanly" (no arcing), so that the geometric position that it all goes open circuit is maximally repeatable.
 
What I've noticed is that after many cycles CMM kinematic probes like the TP2 or TP20 modules eventually stop reseating properly. They appear to mechanically reseat, but remain electrically open circuit until you give them a tap. I've not encountered this with machine probes, but it's possible that I've just never put enough cycles on the ones I've had.

I assume this is due to some kind of breakdown of the surface of the pins/balls - it has been explained to me before, correctly or not I don't know, that the oil in the probes serves two purposes - to prevent oxidisation of the contact surfaces, but also to ensure that the mechanism goes open circuit "cleanly" (no arcing), so that the geometric position that it all goes open circuit is maximally repeatable.
The aim of the oil inside the probe is to lubricate. The trick is - in order to lubricate, at least thin film of the oil should be present on surfaces of kinematic stage members, but this film can not isolate the electrical contact. From other side it can not be conductive, as the whole electric circuit will be shorten.
I believe that the reason of the TP2/TP20 malfunction is a material fatigue of the spring which is pushing the moving element against the base.

Stefan
Cogito Ergo Sum
 

Those are the same probes I mentioned above. Do you have any experience with them?

I have given Renishaw enough money in my life that I wouldn't feel guilty about buying one of those, provided that they work OK.
 
Do you have any experience with them?
Well, now I can give some feedback about the WENTAO probe.
I fully connected it and tried it out, everything is fine. Signal reception is stable, operation is stable even in heavy fog due to coolant. This is what it looks like on our machine, hehe, a new probe on the machine, which was released a few months after I started first grade)))) The receiver is in the upper right corner.
IMG_20231206_155106.jpg
 








 
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