M-Probe ("Marko" Probe) 3D Touch Probe for CNC
If you have no idea about 3D touch proble, check the internet for it.
This video shows for example finding a center of a circle: https://www.youtube.com/watch?v=_ZDlyLI_jbc
I own a self made CNC machine and a 3D probe is a great helper to align or
measure your parts on the CNC table.
Professional probes runs in the K$ range, good semi stuff in a range of a few hundret.
The designs are basicly all the same (old patent), but precision and endurance are the keys.
Most precise 3D CNC probles do need a thread machine for making.
Only by this all is "centered" and gives precision by itself.
If you mill or print it... you get problems... until now!
Have fund while making your own M-Probe!
About my project
My idea behind this project has been:
"Create a proble with a "rubbish" printer but have still maximum precision."
Precision means for this probe: "fully adjustable" in all axis to comensate "bad making".
On the printing side, all parts must be "easy" flat printable. No overhangs.
All this lead to my "M-Probe" design (Marko - Probe).
The center component is fully "floating" on rubber and can be adjusted in all axis.
I build only ONE, with out any change. I got after 1 hour adjustment a precision +/- 50um.
I did not write extensive documentation, but did a lot of photos while making mine.
If you have a basic idea about how probles are working you will get it done.
The attached fotos (37 in the zip package) should explain all.
The Zip file does contain ALL design files (Design Spark Mechanical = FREE), STL for printing and 37 (!) photos of my making.
The ready to print parts are in the subfolder "parts":
If you what more details or modify it, download Design Spark Mechanical
and open the to file: "3D Probe.rsdoc"
Hints for making and adjustment
Some notes for makers:
SCREWS, HOLES, THREADS
All screws are 3mm. All mounts do have 3mm.
Drill 3mm after printing to get easy fit.
On the thread side the drill is 2.5. I recomend to re-drill with 2.5 (cool while drilling!)
Use a thread cutter to create the M3 threads.
I cool all with alcohol while drill / treading.
All 6 Balls must be wired together to one loop with a "open" connector.
One picture you will see the thin white wires.
Important: Solder the balls BEFORE glueing to the holder, or your holder will melt it ;-)
My used balls came from a old ball bearing. I found that sanding the balls on one side
will make soldering easy. Estimate the cable length solder it, glue it to the holder.
This part is the most difficult part.
Since the connector and cables are fully custom, I did not add a slot or hole for that.
The shell of the body is strong enough for a manual slot or dill acording your demands.
The rods are make our of massive brass ind 6mm and 4mm.
The "home depot" quality made the job.
To simplify your adjustment, its recommended to try to work "clean" on the
ball glueing (leveled) and try that the proble center part ist (almost) symetical.
Try to allign it a bit with a pliers. At the end its easier to allign later.
You find instuction in the web how to align a probe.
I milled a large round hole with ONE tool (I have e.g.a 16mm cutter).
Keep your machine on X and Y unchanged after cutting it.
Now attach your probe and softare like Mach3 with a "Probe It" Extenion.
There is a tool to make probe calibration in 36 angeles... great!
Basis steps are:
- CENTER ALIGNMENT
You must center the upper part of the probe that it is centered with your spindle.
This is done by manual rotating it while watching it (or use a gauge).
It must be centered on all directions. For the center process use the outer
3 screws. Be aware that they WILL BLOCK each other, meany you must loose
the opposing on demand.
TAKE TIME FOR THAT
- Up right alignment
When the center is done you align the probe upright with the 3 screws on the top.
This is simplier, since they will not block to each other.
Again rotate the spindel with you hand and watch (or mearsure) from all angels.
Repeat 1 and 2 unitl you done.
- Check and improve your settings with http://www.craftycnc.com/probe-it-wizard-mach3
All alignemnt can be done in the range of ~2-4mm.
Its recommended to create a minimum "presure" on the silicon hose.
If they are to loose all became to "fussy". Make sure some "default" presure is on each screw.