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Author Topic: Stupid Questions re: Touch Probe Alignment  (Read 5968 times)

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Stupid Questions re: Touch Probe Alignment
« on: November 15, 2009, 12:49:41 PM »
I'm thinking about building a touch probe - the kind with the three little arms, and ball-bearing contacts.  I've been using a rigid probe, but Mach keeps randomly screwing up, and about every 3 months breaks it off.

So, the question is, how does one go about aligning the probe tip to the spindle centerline?  I want to use this for machine setup, so it needs to be very accurate.  Seems to me it must be a huge PITA to get it precisely aligned and centered, I assume by using three screws to tilt the PCB, or similar arrangement.

Regards,
Ray L.
Regards,
Ray L.

Offline Hood

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Re: Stupid Questions re: Touch Probe Alignment
« Reply #1 on: November 15, 2009, 01:04:19 PM »
The way I did mine was to have 4 screws push the part that held the stylus in place, which itself was in the main body. It is quite tricky to adjust as it moves when you tighten the screws. If I was making it again I would have the whole body moving on the arbour by the 4 adjustment screws. BTW 4 points to me are much easier to adjust than three.

Below is a pic of the one I made.
Hood
Re: Stupid Questions re: Touch Probe Alignment
« Reply #2 on: November 15, 2009, 01:05:04 PM »
Hood,

Thought I'd confuse things by posting to the correct thread....   :D

Do you have drawings of your probe?  I have no desire to re-invent the wheel....

Regards,
Ray L.
Regards,
Ray L.

Offline Hood

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Re: Stupid Questions re: Touch Probe Alignment
« Reply #3 on: November 15, 2009, 01:09:22 PM »
Heres a few more pics for you to see how I did it. The battery is there for the LED, I use that all the time and have never wired it into Mach but I do have a small jack plug socket there if I ever decide that I need to. ;D

Hood
Re: Stupid Questions re: Touch Probe Alignment
« Reply #4 on: November 15, 2009, 01:15:43 PM »
And here is one that's similar, although he doesn't show the spring that keeps the probe tensioned.  http://www.indoor.flyer.co.uk/probe.htm

If your spindle is locked, why would it matter if the probe isn't centered with the centerline of the spindle?  Once you set the axis's to zero, as long as the spindle doesn't rotate, all should be good.
Re: Stupid Questions re: Touch Probe Alignment
« Reply #5 on: November 15, 2009, 01:29:20 PM »
Hood,

Thought I'd confuse things by posting to the correct thread....   :D

Do you have drawings of your probe?  I have no desire to re-invent the wheel....

Regards,
Ray L.

Have you seen Arnies probe?  At $100+, it makes buy vs make a difficult decision.

http://www.machsupport.com/forum/index.php/topic,5004.0.html

Mike
Re: Stupid Questions re: Touch Probe Alignment
« Reply #6 on: November 15, 2009, 01:35:01 PM »
But half the fun is making it yourself!!

Offline Hood

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Re: Stupid Questions re: Touch Probe Alignment
« Reply #7 on: November 15, 2009, 01:36:04 PM »

If your spindle is locked, why would it matter if the probe isn't centered with the centerline of the spindle?  Once you set the axis's to zero, as long as the spindle doesn't rotate, all should be good.

Because if you are using it for edge finding or centre of a bore finding then you would need to rotate it 180 degrees and subtract the difference at each point you touched off. For probing it makes no difference.
Hood

Actually centre bore finding you would only need to rotate at the opposite points.
« Last Edit: November 15, 2009, 01:37:48 PM by Hood »
Re: Stupid Questions re: Touch Probe Alignment
« Reply #8 on: November 15, 2009, 01:46:48 PM »
And here is one that's similar, although he doesn't show the spring that keeps the probe tensioned.  http://www.indoor.flyer.co.uk/probe.htm

If your spindle is locked, why would it matter if the probe isn't centered with the centerline of the spindle?  Once you set the axis's to zero, as long as the spindle doesn't rotate, all should be good.

If you're using it for probing a surface to collect a point-cloud file, it doesn't matter.  If you're using it to set the work offsets, as I need to do, you need to know *exactly* what the offset of the probe trigger point is relative to the exact centerline of the spindle.

Regards,
Ray L.
Regards,
Ray L.
Re: Stupid Questions re: Touch Probe Alignment
« Reply #9 on: November 15, 2009, 01:50:03 PM »
Hood,

Thought I'd confuse things by posting to the correct thread....   :D

Do you have drawings of your probe?  I have no desire to re-invent the wheel....

Regards,
Ray L.

Have you seen Arnies probe?  At $100+, it makes buy vs make a difficult decision.

http://www.machsupport.com/forum/index.php/topic,5004.0.html

Mike


Mike,

That could be just the ticket!  Thanks!  I've long since passed the point where I'd rather buy than make, if the cost isn't too high.  $100 is more than reasonable.

Regards,
Ray L.
Regards,
Ray L.