Hi Andy, You are going to trigger a number of people with this one :) Guy with harmonic drive CNC 4th axis does milling on home made drill press! Next up is an SK 30 housing with centering I guess. I started making a one with balls last year, but got distracted half way through by the Schaublin. You design is much more elegant, especially how the 6 pins form the retention. Have you tried soft soldering carbide? Does it need any special technique?
This is a beautiful build, and as others have noted, it's cool seeing you do careful handwork on a manual machine rather than using your fancy cnc equipment.
A really good design. Renishaw's TP2 is in fact very similar to this, using 6 rods in similar confuration in an anadized aluminum tube. The anodizing provides insulation for the rods from the holder. All in a .5" or so diameter device. I suspect they had a jig that held the probe tip holder inline witht he housing while the glue holding the pins dried. Adding an op amp to the output would perhaps also help with trigger accuracy. Renishaw has an excellent paper somewhere on the change in resistance before the contact actually opens. The TP2 that I have has some concentricity issues, but I don't know its history so who knows. It was free so can't complain.
Andy, If you were to tap the shank so a screw could lock the the probe holder in the Vees then tap the center as an assembly for the probe tip you might get near zero run out. just have to mark body and probe holder so they always get assembled the same way.
Sorry, I only just understood this comment, and and realised that is exactly the idea that I came up with in the follow-on video. So, please don't feel that I failed to acknowledge the idea, I just came up with the same thing independently and hadn't noticed that you got there first.
the more common probe cycle is to rotate the spindel so the same "point" of the stylus always touches regardless of direction... so not only centering you take out the "error" of not center by just making sure you use the same side of the ball.. :)
If this design was patented, half the world would be in jail already:) Unless it's patented by Renishaw, their prices are so high that they could care less what DIY crowd is doing. But the original author must have been a real genius to come up with something so precise, yet so undemanding, as long as it's calibrated with reasonable care, and parts are not exactly bent, twisted or otherwise deformed. This version looks interesting, but I'm pretty sure that three calibration bolts which would align the shaft with the axis of the machine would play much more important role than the shape of contacts/supports...
The original 6-balls, 3-rods design was definitely patented by the founder of Renishaw when working at Rolls Royce: patents.google.com/patent/US4153998A whether the version using rods instead of balls is also patented is not something that I looked into. In the case of the Renishaw patent, it will have expired after 20 years. I think that the 9-rods modification is nearly as clever as the original concept, but very much builds on that original design.
Looking at the model (Thank you!) if the 3 horizontal pins were lower, and the shaft stub was adjustable in the housing (the housing becomes 2 parts) then it might be possible to adjust concentricity?
One simple mod would be to slice the hub between the stylus and the three rods, put in a dimple with a small ball bearing in it, and then have 4 tiny screws bolting it back together. Then you couls adjust the screws to centre the ball. This is largely what the "real" spindle-mount probes do. (CMMs might not bother, as you only care about relative motions there). Making it better would be a good start, but then I am seriously considering writing a calibration routine. Probe a hole, rotate the spindle, probe the same hole, calculate offsets correlated to the spindle position (using the spindle encoder) and then you can calculate the offset in X and Y for any spindle angle.
I think this could be 3d-printed (I would use nylonx) .. with the holes undersized - ream them out to size. The other bit would be 6 (or 8) grub screws holding a threaded insert for the probe itself - these could then be tweaked to true it up (You want a both concentric and straight probe)
Bonus model: Something similar but fitting directly to an ER20 spindle, for routers with limited Z height. a360.co/3HHQlHs ER16 version: a360.co/3n15pIk
Hi Andy, You are going to trigger a number of people with this one :)
Guy with harmonic drive CNC 4th axis does milling on home made drill press!
Next up is an SK 30 housing with centering I guess.
I started making a one with balls last year, but got distracted half way through by the Schaublin. You design is much more elegant, especially how the 6 pins form the retention.
Have you tried soft soldering carbide? Does it need any special technique?
I think I'm going to try 3d printing one. Thank you for sharing this!
This is a beautiful build, and as others have noted, it's cool seeing you do careful handwork on a manual machine rather than using your fancy cnc equipment.
A really good design. Renishaw's TP2 is in fact very similar to this, using 6 rods in similar confuration in an anadized aluminum tube. The anodizing provides insulation for the rods from the holder. All in a .5" or so diameter device. I suspect they had a jig that held the probe tip holder inline witht he housing while the glue holding the pins dried. Adding an op amp to the output would perhaps also help with trigger accuracy. Renishaw has an excellent paper somewhere on the change in resistance before the contact actually opens. The TP2 that I have has some concentricity issues, but I don't know its history so who knows. It was free so can't complain.
Centered awesome! Great build Andy! Thank you, Phil
Just found this channel. Good place to be. Now to binge watch the other videos.
Nice job 😀
Very nice, thank you.
Regards from tommylight.
Andy, If you were to tap the shank so a screw could lock the the probe holder in the Vees then tap the center as an assembly for the probe tip you might get near zero run out. just have to mark body and probe holder so they always get assembled the same way.
Sorry, I only just understood this comment, and and realised that is exactly the idea that I came up with in the follow-on video. So, please don't feel that I failed to acknowledge the idea, I just came up with the same thing independently and hadn't noticed that you got there first.
This touch probe is awesome thank you for sharing
Cheers Andy, cracking little design...I think I've just found my next project!....
Thank You !
Cheers Andy. Nice film
the more common probe cycle is to rotate the spindel so the same "point" of the stylus always touches regardless of direction... so not only centering you take out the "error" of not center by just making sure you use the same side of the ball.. :)
If this design was patented, half the world would be in jail already:) Unless it's patented by Renishaw, their prices are so high that they could care less what DIY crowd is doing. But the original author must have been a real genius to come up with something so precise, yet so undemanding, as long as it's calibrated with reasonable care, and parts are not exactly bent, twisted or otherwise deformed. This version looks interesting, but I'm pretty sure that three calibration bolts which would align the shaft with the axis of the machine would play much more important role than the shape of contacts/supports...
The original 6-balls, 3-rods design was definitely patented by the founder of Renishaw when working at Rolls Royce: patents.google.com/patent/US4153998A
whether the version using rods instead of balls is also patented is not something that I looked into. In the case of the Renishaw patent, it will have expired after 20 years.
I think that the 9-rods modification is nearly as clever as the original concept, but very much builds on that original design.
Looking at the model (Thank you!) if the 3 horizontal pins were lower, and the shaft stub was adjustable in the housing (the housing becomes 2 parts) then it might be possible to adjust concentricity?
One simple mod would be to slice the hub between the stylus and the three rods, put in a dimple with a small ball bearing in it, and then have 4 tiny screws bolting it back together. Then you couls adjust the screws to centre the ball.
This is largely what the "real" spindle-mount probes do. (CMMs might not bother, as you only care about relative motions there).
Making it better would be a good start, but then I am seriously considering writing a calibration routine. Probe a hole, rotate the spindle, probe the same hole, calculate offsets correlated to the spindle position (using the spindle encoder) and then you can calculate the offset in X and Y for any spindle angle.
I think this could be 3d-printed (I would use nylonx) .. with the holes undersized - ream them out to size.
The other bit would be 6 (or 8) grub screws holding a threaded insert for the probe itself - these could then be tweaked to true it up (You want a both concentric and straight probe)
A Simple Nail Clipper made with basic tools.
It's not a touch pro, it's a touch bro.
Man, I really hope this isn't patented.
Not likely. Since it is now published in the public domain.
Bonus model: Something similar but fitting directly to an ER20 spindle, for routers with limited Z height.
a360.co/3HHQlHs
ER16 version:
a360.co/3n15pIk