Probe Interface Board Design (resistance switching)

Unpublished however I'm more than happy to get in touch and send it over, no commercial affection whatsoever attached, just a dumb (but essential) tool. Mind you there isn't any space-tech to it, easy to replicate on a cloudy sunday afternoon (see visuals). 

I'm all-in for trying your circuit when you feel it's ready though (oscope to share for sure). ps. screw renishaw and their secret magic... diy +/-0.01mm is enough!

edit; added a few visuals, you'll get the idea. Fun weekend cad...

That's a very clean design! Not sure how DMs work here but my email is on the github page.
The frustrating thing about the Renishaw (and other OEM) probe interfaces is they are still £££ second hand (and ££££ new) but based on last century tech!

I've STEP the entire assembly for you (proprietary LinuxCNC confidential IP and all lol). You should be able to unpack that lot using any half-decent CAD. If that doesn't work, let me know and I'll find another way.

Good luck with your project in a meantime, looking forward. Github bookmarked - Thanks for the link up, Philip (subscribed)

Well, totally unrelated, but I got a Blum TC50 3-axis probe on eBay a couple years ago. This is a battery-powered probe that uses bidirectional IR to communicate.
IR pulses from the CNC control turn the probe on and off, and the probe sends low-battery, probe deflected and first time the probe has been deflected. It sends immediately when the probe changes state and then at 50 Hz when there is no change. I built a controller to communicate with the probe using an FPGA and some IR interface chips. It works great, I have made up a bunch of G-code routines to find all corners and edges of parts, and also the center of holes. I created the hal code to show probe status, and also put the machine in feed hold if the IR communication fails (like obstruction in the IR path).
Jon

Hi Jon
Not unrelated at all! That Blum looks like a nice probe. My initial design (and ebay order) included IR LEDs and receivers but then I realised I'd have to build the resistance switching into the probe body... baby steps required. I also almost went down the FPGA route (the video  How FPGAs Will Change Your Life is on my 'Watch Later' YouTube list) but the draw of an ATTiny85 was too strong for the moment.

Are the details of your controller published anywhere? I would love to learn from it. If (when?) I crash my Renishaw I have the seeds of a load cell based probe in my brain and that would use IR for communication.
Philip

Mecanix wrote:

edit; added a few visuals, you'll get the idea. Fun weekend cad...
 

I just noticed you've added more - thank you. That is probably the neatest home made probe I've seen (and I've seen a few online!). Good motivation to up my standards and get my interface board published... What is the little chip on board?
Philip