How to harvest free ground precision bars for a CNC touch probe
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- Опубликовано: 1 сен 2020
- Here we strip a couple of ground bars from an old bust DVD player.
The bars are part of the laser scanning mechanism and perfect for diy touch probes.
This is just a short video to show where I get some of my touch probe parts.
Keep watching for a full series on my probe coming up. 
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You call that probe you made crap! wow I would be very happy if I could make something as detailed as that. I totally agree so much precision stuff is being dumped due to our scrapping of technology. Some of the machining and optics in these devices is beyond belief, especially the older models.
Thanks for the comment its a tongue in cheek thing about the probe its not very repeatable and the probe can only move a three of four mm before hitting the end stop. Stay tuned I have plans for a new one with IR comms.
Too much stuff is considered disposable and made to not get fixed, the planet simply cannot support all this disposal. I try to use scrap wherever possible.
I gave it a like for the cat of course !
Yep the cat that wont take no for an answer, her who must be fussed. Honestly needs more looking after than my wife!!
I built one too. I think one of the root causes of problems with this idea is that with 6 points of contact, it is over-determined. You could actually take 3 of the balls out and the bars would still be able to rest. The problem with this is that they wouldn't return if perturbed. What this implies to me is that it is actually the tiny amount of flex in the frame and bars that allows all 6 points to contact and complete the circuit. This, in turn, implies that there should be no friction at the points of contact. This is difficult to achieve as you need something with good electrical conductivity, that is hard and has no tendency to gall or stick and won't corrode.
It is an interesting problem.
Hi Ian,
Yep I agree with you, I am working on a proper kinematic probe that will hopefully work well enough for a home mill. As I see it in the home shop we only need an accuracy of 0.01 mm which I am inclined to think is possible. My mill has a repeatability of 0.02mm and is typical of chinese imports I feel. I hope to make mine heavily crash proof as a long term buster of tools it makes sense for me!
I am currently working on a power drawbar but next is the probe, software is nearly complete and design is sketched out.
David
@@CazualHaze I've subscribed to your channel because I am intrigued by this. One thing I am trying is a high pressure, somewhat conductive lubricant ( tungsten disulfide) to see if it alleviates the stick/slip issue. The other thought was instead of having a complete circuit around all six points of contact, drive the rods with a pullup together and have pulldowns on each of the balls. If the first rod contacts ball 1 and 2, the second rod 3 and 4, ... contact is when !((1 || 2 ) & (3 || 4 ) & (5 || 6 )) is true (where || is a logical or and & is a logical and). This way, if the first rod only has to rest on ball 1 or ball 2, the second and ball 3 or ball 4, ... I'm thinking it would require far less spring pressure to make it reliable since only one ball for each rod would need to be contacted.
I'll check in to see what you are doing - I'll probably be fooling around with this for quite a while. It's a fascinating challenge - how to make this very sensitive and repeatable without requiring ultra-precision in any of the components. All this to avoid buying an off the shelf bed levelling probe for my 3D printer.
@@ianboard3555 Thanks for subscribing. I am still a new channel and appreciate the connections.
I see what you want with the low contact force on a 3D printer just bought one myself ( see next video) They have very small steppers high force is not a problem with any cnc cutting machine! I am intending to use gold plating solution for reliability. Just detoxing the alcohol out of my kidney before I sell it to pay for the gold solution.
Best
dslr, camera phone -doesn't matter. You had the stuff you were working on in frame and we could see it all and learn from it. I'm checking out your new build right after this.
If you can find old VCR from back in the day, will yield that plus especially the shaft used in video reading cylinder and a lot of other good stuff when things were made like tanks.
Yep over the years I have scrapped a lot of old pro tech and found many useful parts.
Thanks for the tip!
What is the advantage of using IR transmission over the radio frequency one, something around 844Mhz?
Good question. My thoughts were if you happen to be lucky enough to have more than one cnc machine then one probe could theoretically connect to either machine or both.
But IR inside a cabinet is far less likely to get out of the cabinet and into another (its easy to turn down the power so range is very short). Not sure if its flawed logic but seems a good idea to me. IR is also extremely cheap.
I like your cat,huali?
Lily, or Lily the stink as we call her!