Wow man, this is looking super nice. I'm going to have to start peaking at Flebay more often to see if I can score a cylinder like that!
How do you have it wired/plumbed? I was thinking the best way to control it would be though the Acorn, as in a button to the Acorn then the Acorn output actually releases the tool. Then the Acorn could decided if it should actually release to tool or not, as in if it's choochin' at 5k RPM not a good time to release the tool. I'm kinda assuming the Acorn is capable of this.
PZ
It has been a bit of a long winding road to get it to work. I hope to outline the entire project when I'm sure it works as it should, consistently, and then I'll provide the details. I think I made enough errors and experienced most of the possible pitfalls that it should help others from making the same mistakes. In just the last day or two I am to the point where it works ok, I think ! lol. One of the main things that hindered me over the last couple weeks was the solenoid that directs air to the cylinder ( for retraction and extension ) was faulty. I bought a "Fastek" from ebay that somewhere stated it was made in the good ole USA. Well, although that may be true, I find it unlikely because it so closely resembles all the clones from China ( and I mean it really looks like a rolex copy... from 5 feet you would say they are the same ). Perhaps a company in the USA just assembled the parts here ? I don't know, but the one I have is not a good product and I will be looking for a refund. Ultimately, I ended up "re-purchasing" another brand ( for the same cost $29 ) which is the same ( Airtac- made in Tawian supposedly ) as Sam / CNC4XR7 used (the youtube which I referenced above.) I believe he used another thread size / pitch, however. This is what I have : Airtac brand Air Pneumatic Solenoid Valve 2 position 5 way 1/4" 4V310-08-B-DC24V
I have it wired with a switch to manually actuate it. The switch is NO so it won't release the tool until its manually powered by me to do so. Personally, I would only have Acorn actuate it if I had a tool changer. That is a future project that I hope to get to, but I kind of doubt the Acorn has the capability of that anyway. One of Centroids other , more expensive, DIY controller cards does have this capability since it is a closed loop controller capable of reading absolute servo position. There may be ways around having absolute position for a tool changer but it seems like it would be more of a headache to implement. That being said, I haven't really looked into it much.
So basically the solenoid , in its normal un-powered state allows air flow to the cylinders retract piston which makes sure the piston won't push out at all due to gravity. Even if it did protrude on its own, it cannot provide enough force to compress the "belleville" spring washers to release the TTS tool holder. When the solenoid is actuated by the switch, the solenoid redirects the air flow to the ( 3 stage cylinder ) ( instead of to only one of the cylinders to retract ) to compress the belleville washers. Some multi stage cylinders have an air port for each stage but this one has internal "ducting" so added external hoses daisy chaining them isn't needed. I suppose this is only negative in that one could , if they wanted to, reduce the number of active pistons to reduce the power of the cylinder.
I mean to give all the details and part numbers for the entire project but I want to know its working 100%. So I will, in more detail, outline the pitfalls I experienced so others won't have to experience them. If you watch the video I posted I kind of edited out a flaw. So if you look closely, there is a delay from the time I actuate the switch to the time the cylinder actually pushes the piston out. This is caused by the faulty solenoid ! The solenoid would sometimes have a short short delay, but other times it would get very very long... as long as 8 seconds after powering it via the switch. As well, it appears it somehow was restricting air flow. At this time I don't know how much, but it seems as though it was not giving the full 100psi to the cylinder. As soon as I changed the solenoid to the Airtac brand, the cylinder seemed to produce the needed force to release the tool with only 50 psi and would be instant when flipping the switch.
I need to remake two items that I had to make on my little crappy 9x30 ? harbor freight lathe I got years back for $500 new. ( I really need a better lathe ! ) Why, because currently the drawbar nut and belleville washers show signs of a wobble so I need to re-do the nut and clamping "top cap" to fit a bit tighter on the spindle shaft. Its tricky to make it loose enough so it won't bind, but tight enough that it won't be unbalanced / wobble. The lathe has cross slides that are so sloppy the cutting bits chatter and grab making perfect cuts inconsistent and rough too. Any suggestions on lathe's are appreciated. I've considered another Precision Mathews lathe but with the current tariff war the PM 1340's are over $5k. I missed out on a south bend lathe locally for under $1k recently, which likely would have been a good option... but that's another story altogether.....
On another note, I have another spindle encoder option coming in the next month or two to test. If it works well, it is ideal for the PM940 with belt drive if one wants to do rigid tapping. Should be under $200 in total but very reliable and consistent.
Best,
Jake
. The servo motor as a spindle seems to be a really elegant solution too. You are sure to be happy with these mods, I know the noise drove me nuts so just that alone was worth doing. 
