Originally shared by Frank Herrmann
Hello Friends, here you see my Weekend Project. I’ll automate all processes in XDisPlace. This means also to make a cheap ATC (Automatic Tool Changer). Video session about this topic next weekend. Hope you like it and i’m curios about your Comments 
Thinking out of the box. Nice.
How does it manage tool depth in the database?
@Joseph_Fitzgerald you see the microswitch in the background? I’ll use this for tool length sensor … i don’t have a database. The system get the endmill and will make a touch probe.
Nice job Frank, I’m fond of it!
What kind of spidle do you have. I suspect it’s AC+freq. converter.
How do you control the torque? Is known that the unwinding torque should be at list 10-15% greater… What I am trying to say is if one wind a nut with all the available torque, it is supposed he won’t be able to unwind that nut with the same motor. It’s very clear it’s not your nut’s case!
@Alex_Paverman You can call me Frank This is a DC Spindle with 48V/400W for a CNC3040. I use a DC Motor driver, so i have full control over this spindle, but sadly only up to 24V … but another driver will come next weeks. So, i can measure also the current of this spindle. In this case i can control the current and also the torque and of course the direction of this spindle Arduino + https://www.pololu.com/product/1451
Thanks Frank.
Maybe I should be ashamed but I will, still, put another question. I cannot figure which is the exact role of that white plastic collar hitting the vertical rod… 
It is some sort of electrical switch? Or is it for a pre-orientation of the nut?
No problem, yes thats a pre-orientation. The Collet has a key with 17mm. I choose a bigger Nut (18mm) to let the collet slide in the nut and i have some more space
Is nut tighten enough?What happen when spindle warms up?Does endmill get loose?
Not tighten enough to mill aluminum or steel but good enough for other materials. But, i have to test this
I had flying endmills during milling plywood because of not tighten enough nut. It is serious stuff.
@Frank_Herrmann Drilling pcb is not a problem. I did a lot of custom pcb on my cnc mill and always I had problems with contours etc. FR laminate is trickier than wood.
Hi Frank
It is a quite interesting idea for ATC which is not involving a $5,000 spindle – just if you allow me to add a quick thought to the tightness issue above – can’t it be another added small step motor with air impact wrench alike from under the machine table to tighten the collet ? Also the key and the collet can be turned in a way to correct its pre-orientation whatever it could be when it is fully stopped – Your idea might be a very successful new ATC method
@Naguib_Habashy sorry for my late answer. I love simple solutions But if you use an air impact wrench the you have to hold the spindle and this make the process to complicate.