ShopBot Acorn ATC retrofit
Posted: Thu Jan 14, 2021 5:57 pm
Hey everyone, I've been running Acorn on my ShopBot for a couple of years now. I blew up another HSD spindle earlier this year and finally decided to go the ATC route. I got a CNC Depot S30C spindle and retrofitted it:
https://photos.app.goo.gl/AFtf83bhhoeiDpb87
I have a pretty beefy control system and steppers (thanks Gary Campbell) however it is open looped. I wanted to set this up in such a way that there were plenty of fail safes so I didn't drop tools on the floor or do any other damage.
I have a Hitachi Wj200 VFD and I was able to set it up so that a relay closes when the spindle is completely stopped, That is wired into an air pressure switch. I have both of those sensors on a circuit connected to an input on Acorn. If that sensor, and the VFD relay aren't closed there's no circuit. Once there is a circuit my code will allow the tool change to start. This is to ensure that I have plenty of air, and that the spindle is truly stopped before releasing the draw bar.
From there I have the M6 script setup to drive over to each prox switch and check it's location. It's pretty simple, basically I built a quick and dirty test script to drive to each prox switch and noted it's location. When M6 starts, the machine goes to where those switches should be. If I'm within a few thousands the M6 script continues, if I'm off an error gets put up and I can choose to re-home. That way I never try to pick up or drop off a tool if location isn't spot on.
From there it's a pretty standard tool change. The only surprise mod I had to do was the dust dock you see in the video.
I'm sure there are more complex ATC systems out there with more fail safes, but I feel like this is pretty solid for what I'm working with. If I do anything more with it I might get an Acorn breakout board and add some sensors for tool in/tool out in the forks and also for the dust shoe...
https://photos.app.goo.gl/AFtf83bhhoeiDpb87
I have a pretty beefy control system and steppers (thanks Gary Campbell) however it is open looped. I wanted to set this up in such a way that there were plenty of fail safes so I didn't drop tools on the floor or do any other damage.
I have a Hitachi Wj200 VFD and I was able to set it up so that a relay closes when the spindle is completely stopped, That is wired into an air pressure switch. I have both of those sensors on a circuit connected to an input on Acorn. If that sensor, and the VFD relay aren't closed there's no circuit. Once there is a circuit my code will allow the tool change to start. This is to ensure that I have plenty of air, and that the spindle is truly stopped before releasing the draw bar.
From there I have the M6 script setup to drive over to each prox switch and check it's location. It's pretty simple, basically I built a quick and dirty test script to drive to each prox switch and noted it's location. When M6 starts, the machine goes to where those switches should be. If I'm within a few thousands the M6 script continues, if I'm off an error gets put up and I can choose to re-home. That way I never try to pick up or drop off a tool if location isn't spot on.
From there it's a pretty standard tool change. The only surprise mod I had to do was the dust dock you see in the video.
I'm sure there are more complex ATC systems out there with more fail safes, but I feel like this is pretty solid for what I'm working with. If I do anything more with it I might get an Acorn breakout board and add some sensors for tool in/tool out in the forks and also for the dust shoe...