3D scanning a $2 coin with 3D printer and DIY touch probe

[CVMichael]

Just wanted to show my printer scanning one face of a coin.

I uploaded the scan on Thingiverse: https://www.thingiverse.com/thing:3366129

Here's a video with it in action: https://www.youtube.com/watch?v=9lPobTaEvIE

It scanned at 0.15 mm grid, about 42,000 points, and it took about 8 hours to scan.
I made a program in C++ that controls the 3D printer through Telnet over WiFi (using Duet WiFi). The program exports 2 files, one point cloud XYZ file, and the STL file.

[Phaedrux]

That's really cool. How does the touch probe work?

[mrehorstdmd]

That's pretty impressive!

[CVMichael]

@phaedrux said in 3D scanning a $2 coin with 3D printer and DIY touch probe:

That's really cool. How does the touch probe work?

It's actually quite simple. 3 sets of switches that are wired in series. A spring pushes the contacts so that the current goes through when the probe does not touch anything. When the probe touches something, the current is interrupted.
Here's a touch probe I found on thingiverse: https://www.thingiverse.com/thing:721620 I am sure you can find many others.

Here's how I made mine:

Everything is from stuff I found around... washers for contacts (no clue what size, probably washers for M4 screws i think), PCB prototyping board (4 cm by 6 cm), 2mm and 3mm copper pipes (from local hobby shop), M2 screws, spring comes from BL-Touch kit, and finally a small sewing needle. I tried to find a small, but thick needle, because the longer it is (or thinner), the more will bend when it's touching. If you need to scan deep things, then make the pipe longer.
The sewing needle goes in the 2mm copper pipe, and with pliers I squished the pipe as hard as I could to grip the head of the needle.

[gtj0]

Very nice!

[crynool]

Holy Sh*t

[deckingman]

@cvmichael Very clever! I'm assuming that your program moves the head to a probe point, raises the bed until the probe triggers, them measures the Z height at that point before moving on to the next probe point. Is that correct?

[CVMichael]

@deckingman said in 3D scanning a $2 coin with 3D printer and DIY touch probe:

@cvmichael Very clever! I'm assuming that your program moves the head to a probe point, raises the bed until the probe triggers, them measures the Z height at that point before moving on to the next probe point. Is that correct?

Yes, that's exactly what it does
I remapped the Z motors as U axis, and the probe is connected to "E0 Stop". The program runs in 2 for loops, for X and Y, and it basically homes on U axis, reads the value, then moves back to zero. Then moves to a new point, and so on...

Here I did a test scanning sideways, on X axis: https://www.youtube.com/watch?v=mgG614AWU4s Here I remapped the motor driver of X axis as U axis, and did the same thing, homed on U axis, read value, etc...
This was my first test, I had a screw as the probe, LOL

[Nikola]

Man, this is amazing!! I created profile here just to ask if you would mind sharing some tutorial or details on this?

[ander]

@CVMichael i can´t see the video

[CVMichael]

@ander , I made all my videos private, but I forgot I had those 2 videos shared here, I made them public again