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Author Topic: Does this product exist?  (Read 6137 times)

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Offline Davek0974

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Does this product exist?
« on: September 21, 2016, 03:20:54 AM »
If not, the idea was mine.... ;D

Having seen the carnage caused by the failure of a Z-probing routine for tool height a couple of times now, I was thinking if there was a probe plate on the market that was spring loaded - heavy springs will be needed, had the top surface as the normal probe plate and then as the springs compressed due to a failure of some sort, the extra movement triggered an e-stop?

Having heavy springs will make it appear as a solid to the probe routine, but still be able to compress and hit the e-stop.

Just wondering  ;)

Offline Tweakie.CNC

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Re: Does this product exist?
« Reply #1 on: September 21, 2016, 04:04:19 AM »
A few years back I designed a low profile tool setter which was intended as an open source project for all. There must have been something there that I had not realized because I was approached with a request to sell the design. Well I sold it (so cannot disclose any further details than have already been posted) but, to this day, I have never seen it on sale.
The related thread is here http://www.machsupport.com/forum/index.php/topic,21525.0.html and post #54 shows the overrun ring which triggered the EStop in case of emergency.
I use the prototype many times a day and it has never overrun so I consider the G31 to be 99.9999% reliable. Just why it behaves for some and not for others is probably one of those great mysteries that may never be solved.

If I built one, then there has got to be a fail-safe probe plate available on the market somewhere.  ;D

Tweakie.
PEACE

Offline Davek0974

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Re: Does this product exist?
« Reply #2 on: September 21, 2016, 05:29:06 AM »
Hmm, seems they shelved it - i cant find it if it is out there :)

Offline Chaoticone

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Re: Does this product exist?
« Reply #3 on: September 21, 2016, 10:08:30 AM »
Some use a small cylinder with a couple of prox switches and a plate mounted to the end of the shaft. 1st switch seen as probe input, 2nd switch seen as estop. One end mounts to table/bed so that shaft is pushing in direction of spindle. Something like these. The right single acting cylinder (spring extend) may not even require air to work for this.

https://www.automationdirect.com/adc/Shopping/Catalog/Pneumatic_Components/Pneumatic_Air_Cylinders/Metric_Compact_Air_Cylinders_(H-Series)/H12M020MD-M

https://www.automationdirect.com/adc/Shopping/Catalog/Pneumatic_Components/Pneumatic_Cylinder_Position_Switches/4mm_Square_T-Slot_Cylinder_Switches
;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!

Offline Davek0974

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Re: Does this product exist?
« Reply #4 on: September 21, 2016, 10:11:32 AM »
Thats quite a neat idea, i have no idea how accurate the trigger repeatability is for the proxy though - may not be good enough. I have a load of that stuff here so might be easy to test.

Offline Chaoticone

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Re: Does this product exist?
« Reply #5 on: September 21, 2016, 12:52:04 PM »
Decent switches will have extremely accurate repeatability. The rate the probe is moving at each time the switch is being made is likely the most important variable (slower = higher accuracy).
;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!

Offline RICH

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Re: Does this product exist?
« Reply #6 on: September 21, 2016, 07:12:19 PM »
I have been doing a lot of probing on the lathe using G31. Have yet to have a problem and have tested it over and over for touching off tools, finding points etc.
BUT
In my probing for the lathe screen I manually jog to say about .1" of the surface and then probe at a SLOW federate. Repeatability is +- 0.0002" ( frankly I find it faster than the usual method of a double probe ......fast probe rate and then a slow rate ). At the slow probe rate. the amount of probe overtravel is less than most could even measure
( probe overtravel is calculable ).

To each their owne ..........

RICH

Offline Chaoticone

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Re: Does this product exist?
« Reply #7 on: September 21, 2016, 09:19:11 PM »
Solid advise Rich.  :)
;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!

Offline Davek0974

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Re: Does this product exist?
« Reply #8 on: September 22, 2016, 02:20:51 AM »
Yes a lot do use it and one of the fails i had was my fault although due to an unexpected issue - i was probing with a tool length offset applied and the routine did not like it so plunged the head into the bed at rapid rate :)

The other time was an engraving tool with a 0.2mm tip - might have been dirt or something but it drove that tool into the aluminium bed nicely :)

Both would have been prevented with a "safety" touch-plate so it does seem a good idea.

I have no idea how it works on a lathe though - do you have insulated tooling or still use a plate somehow or are you talking about an electronic probe itself???

Offline dude1

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Re: Does this product exist?
« Reply #9 on: September 22, 2016, 02:28:55 AM »
what code are you using there is one out there that does crash if the home and work is under 25mm diffrences