[keen]

Hi Folks.

I am keen to get your technical feedback on a new Design Touch Probe I have been developing.

Please note I want to respect the rules of this forum and do not in this posting offer this invention for sale etc. I am interested to receive your technical thoughts and feedback only via this thread.

Cheers Keen

https://www.youtube.com/watch?v=f4ARkpeCXX4

https://www.youtube.com/watch?v=9X2EKattGyY

[soymilk]

Nice work keen. Not to be pedantic, but wouldn't this be a "crash damage resistant" design, as opposed to "crash resistant". All likeliness of crashing is still there. As seen here



How easy would it be to change out the shaft if its bent? I watched the videos again, but I didn't see if the probe could measure Z.

[brianbonedoc]

Nice - when can I buy one?

[keen]

Nice work keen. Not to be pedantic, but wouldn't this be a "crash damage resistant" design, as opposed to "crash resistant". All likeliness of crashing is still there. As seen here



How easy would it be to change out the shaft if its bent? I watched the videos again, but I didn't see if the probe could measure Z.

Thanks for your feedback. Maybe Smash Resistant would be more accurate!

Yes the Probe measures Z just the same.

It is unlikely the shaft or stem would break - but if it did, I am thinking it best to supply a replacement stylus assembly. It has a simple design and will help keep the overall cost down.

Cheers.., Keen

[keen]

Nice - when can I buy one?

Hi Brian. Thanks for the feedback.

I want to respect the forum rules and not discuss price or supply etc here, this thread is for technical matters.

You can send me a PM re other matters.

Cheers Keen

[kstrauss]

Does the probe have normally open contacts or normally closed contacts like the Tormach #32309? I ask because several times in the video you mentioned failure due to forgetting to plug in the cable.

[Zetopan]

Keen:

The "secret" to having the internal contacts working for millions of cycles without requiring any maintenance is to have electronics that detects when the contacts are about to open and drop the current to zero. This is how the older Renishaw probes operate (I have purchased multiple Renishaw probes on eBay for very low prices). Having a constant current running through the contacts (without the low voltage sensing) will result in arcing when the contacts open up. If you sense the voltage increase before the contacts open, you can reduce the current to zero before the contacts open and totally prevent arcing. This will also greatly increase the sensitivity of the probe since the stylus deflection is greatly reduced as well. A timeout has to occur before a test constant current gets reapplied, and if the contact is still open drop the current to zero again and wait the timeout again. You can often get Renishaw probe interface boxes on eBay for reasonable prices, although you may prefer making your own electronics (that's what I would do in your situation).

[kstrauss]

I haven't checked which are expired but Renishaw obtained numerous patents covering their ideas including the arc reduction technique that you mentioned, a breakaway stylus, use of strain gauges, piezo sensors, optical sensors, wireless connections, etc, etc. Something to consider if you decide to commercialize the improved touch probe.

[wildwhl]

I really like your style keen. Well done.

WW

[Dallas J]

I'd certainly be interested in this probe. I use a standard edge finder cause of dealing with expensive probes just hasn't been worth it to me.

[keen]

Does the probe have normally open contacts or normally closed contacts like the Tormach #32309? I ask because several times in the video you mentioned failure due to forgetting to plug in the cable.

Hi kstrauss.

Normally closed.

[keen]

I'd certainly be interested in this probe. I use a standard edge finder cause of dealing with expensive probes just hasn't been worth it to me.

Thanks for your feedback.

Keen

[keen]

Keen:

The "secret" to having the internal contacts working for millions of cycles without requiring any maintenance is to have electronics that detects when the contacts are about to open and drop the current to zero. This is how the older Renishaw probes operate (I have purchased multiple Renishaw probes on eBay for very low prices). Having a constant current running through the contacts (without the low voltage sensing) will result in arcing when the contacts open up. If you sense the voltage increase before the contacts open, you can reduce the current to zero before the contacts open and totally prevent arcing. This will also greatly increase the sensitivity of the probe since the stylus deflection is greatly reduced as well. A timeout has to occur before a test constant current gets reapplied, and if the contact is still open drop the current to zero again and wait the timeout again. You can often get Renishaw probe interface boxes on eBay for reasonable prices, although you may prefer making your own electronics (that's what I would do in your situation).

Thanks for that Zetopan.

The high end Renishaw type probes are very sophisticated, accurate and reliable. But that comes at a high price if purchased new with the warranty.

The Hallmark Design Probe is much simpler - think of it as an improved Tormach SPU 40 passive probe ..hopefully at about that price point.

So with that always in mind, I needed to keep the design simple.

Cheers Keen

[keen]

I haven't checked which are expired but Renishaw obtained numerous patents covering their ideas including the arc reduction technique that you mentioned, a breakaway stylus, use of strain gauges, piezo sensors, optical sensors, wireless connections, etc, etc. Something to consider if you decide to commercialize the improved touch probe.

Hi kstrauss. I think I am clear on this but some more checking would not hurt.

Cheers Keen

[keen]

I'd certainly be interested in this probe. I use a standard edge finder cause of dealing with expensive probes just hasn't been worth it to me.

Yes they were also my early thoughts - for practical workshop use you don't need a highly priced delicate instrument. That is why I bought the Tormach SPU 40 - and it was almost good enough .

Keen

[MichaelHenry]

Have you given any thought to an optional longer probe? I can see where there may be a need for something like once in a while.

[SCzEngrgGroup]

I'm surprised you're getting more love for this here.... My one and only reason for never using that type of probe is I know I would periodically break the !@#$%^&* stylus, and they are always expensive. I really like what you've done, and the improved accuracy is extra gravy. If you can keep it in the same price range as the Tormach probe, I would think you would do very well with this. I'd buy one, and no doubt unintentionally put your "break resistant" claims to the acid test! :-)

Regards,
Ray L.

[keen]

Have you given any thought to an optional longer probe? I can see where there may be a need for something like once in a while.

Hi Michael.

Yes there are different versions that could be made - but one step at a time. Cheers

- - - Updated - - -

I'm surprised you're getting more love for this here.... My one and only reason for never using that type of probe is I know I would periodically break the !@#$%^&* stylus, and they are always expensive. I really like what you've done, and the improved accuracy is extra gravy. If you can keep it in the same price range as the Tormach probe, I would think you would do very well with this. I'd buy one, and no doubt unintentionally put your "break resistant" claims to the acid test! :-)

Regards,
Ray L.

Thanks Ray - I appreciate your encouragement.

Keen

[Advil]

Yes, I am extremely interested in this.

What kind of tip is on your stylus? It looks like you are putting on a ruby or similar? It's still possible to crash and break it, even with the incredible amount of travel you have built in. You'll need to be very up front about what replacements will cost so people feel at ease with the design.

It doesn't seem completely necessary for the tip to be anything other than carbide.

Another thing I've always wondered, what about making a probe that's both conductive and mechanical? Have a mode switch on the side so that when dealing with metals you can use conductive for perfect accuracy and for non-conductive materials use the mechanical mode?

EDIT - I believe I heard in the video your stylus is ceramic?

[tbev]

I totally agree, I'd like to have one but only if I wouldn't get TOO pissed off when I broke it, I don't need to spend the kind of money most others cost but I'd love to justify the convenience with a lower price. It looks awesome, I have all the faith in the world that if you've made it, especially from the ground up, it's fantastic!

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