Building my own retracting ATC magazine - More than a year long development

I have been working on an enclosed retracting ATC magazine since about July of 2023. I completed it in August of last year and I have done somewhere around 10,000 tool changes with it. I think it’s cool so I figured other people might want to see it.

For some background, I have been running some version of an ATC on my machine since I first bought it in January of 2020. It first used an exposed rack on the left side of the machine to hold tools. It worked but I constantly had to worry about dust getting on the tool tapers an causing ejection failures. I had one failure nearly cost me a spindle so I decided to make something better after only a couple months. My second iteration was a disk of tools in a small enclosure with a door:

It worked reasonably well but it was expensive and bulky. It cost me about $4,000.00 in parts to make. There was a bunch of electronics, a couple servos, an expensive gearbox, fancy bearings and a few sensors. It needed 4 outputs and 3 inputs to work which meant I needed to expand my controller and I eventually switched to LinuxCNC (you can see the topic I made about it here: Adventures with LinuxCNC). We used this for a couple years with few issues. I didn’t love it though and I wanted to reduce the complexity and size. I also thought I had an idea that could be sold if I could make it simple enough. I didn’t end up deciding to sell this because CNCDepot stopped offering the plug and play kit for Avid machines (probably because they are the OEM for Avid’s new ATC spindle) and I happened to still be in the beta group and browsing the forum when Avid published a post on here about their upcoming EX controller. I figured that they were going for ATC and I am just one guy and can’t compete with Avid. Oh well, I still got what I think is a great piece of equipment that is my most reliable iteration yet.

On my machine, the center-line of the spindle can reach a little bit more than an inch over the front edge of the machine. I had an idea one day that I could put a retracting magazine on the front that only required 1 output to work. I added another output and input to increase the reliability but they aren’t necessary. Here are some pictures:





The whole thing is built from laser cut and bent parts, 80/20, a couple rails, 2 pneumatic cylinders, one inductive sensor and a couple solenoids. On my 5’ wide machine it can have up to 20 pockets (I am only using 18 right now). I use a pneumatically actuated z-axis independent dust shoe but this whole thing would work with a spindle nose mounted dust shoe if you reduced the number of tool pockets. The cover is mechanically linked to the magazine and the joints use dry bushings to make it last longer in a dusty environment. One solenoid actuates the magazine and the other is used to blow off the tool taper before picking one up. There is an inductive sensor mounted to the spindle nose to verify that a tool is present or not present when it should or shouldn’t be. The tools are held in a custom designed pocket that does not require perfect placement or motion control to pickup or put down. They can handle any reasonable length of tool less than 7/8" diameter or tools up to 1-1/2" diameter at a length of 2-1/2" or less. The pockets are mostly 3D printed and have held up extremely well to use. I put several of them through a stress test of 20,000 cycles and never saw any appreciable wear before we started using them. These 2 are still in the machine and working great. There is also a mount for a tool probe that holds it below the surface of my table to protect it. I think I went through about 15 design iterations in CAD and 2 hardware prototypes before landing on this final iteration. Not counting my time (at least 1000 hours for both the hardware and software design) I am into this development about $6,000. The final BOM cost is about $2,300 at a quantity of one. I imagine if I had pursued selling that I could have gotten it down further through bulk and a little more optimization.

My machine is running a customized version of the Probe Basic UI for LinuxCNC. Each tool pocket is numbered and can have any tool number assigned to it. This allows me to have tools setup in holders but not in the machine. The tool change macro is smart enough to know when a requested tool is not in the magazine and automatically move to the MTC location and ask you to insert the right tool.

Overall, I am quite happy and proud of this ATC design. It is definitely my best yet and has proven itself to be quite reliable over the last few months of use. It actually is about 20-30% faster tool change time than my last one which is a bonus.

I am interested to see how Avid does their own retracting magazine they have talked about.

4 Likes

that’s awesome! Are you sharing the design for the pocket? I’ve been thinking about doing a pocket style tool holder like that. Something that I can easily 3d print and move around on my table to add more tools when I don’t need my full 4x8 (maybe attached with magnets).

I like it! :+1: Awesome! I didn’t notice at first but you used a exstended gantry an shifted over to one side. Clever!!

Great job. Can you say a little bit about the tool height setter pictured in your post? Is it a purchased item or self made?

I’m thinking about it. I really would like to recoup some of my cost on the development. I currently sell my V1 of these on Tindie for only a couple dollars more than it costs to make them. I am about to change that over to V2 (which is what is on my machine) that has better mounting and can handle the larger diameter. Maybe when I do that I will post my V1 design.

That is a DrewTronics TS1000. I don’t think it’s amazing but it is the best one I have used so far. I like how the touch plate connects to the side of the sensor with a built in weak point in case you run a tool through it. Don’t ask me why I like that…

That is pretty pricy. How does it compare with the $100 variety available on Amazon or the one that Avid offers in their Ex Controller upgrade.

Never looked at the one in the EX upgrade. As for the Amazon ones, I have used a few types and they have all either failed after a few months, had unreliable trigger points or too small to be useful for me. I consider them to be only good for occasional hobby use. I have a small one from Amazon on my little machine at home. You get what you pay for.

Thanks. I like the way you mounted yours.

1 Like

I’ll take two of the enclosed tool holders if you can adapt them to the ex controller.

Sorry, there is no realistic way for me to do that for you. The whole system is not ready for sale. I never developed assembly instructions and I don’t have an EX controller to test on. Most importantly, I do not have the time to help anyone figure it out in a reasonable time. You might get more information from Avid on their upcoming system if you ask them. If you still want to talk, send me a pm.

I understand, let me show you what I have done, I took some of the 4040 extrusion and some linear rails and mounted on the far end of my machines hoping to use an air cylinder to retract the tool bar out of the way way not in use. But not having enough inputs nor the programing skill to pull it off all I got was the mechanical part done, then came EX system and I have one machine on mach4 and one on centroid acorn, and the amount of chips that can land and stay on the tapers is unbelievable. So I really like your vertical way of thinking and the giant shoe box it all slams shut in. lol If you steer me to any design info on your enclosure and inner working I’d be grateful.



Your hardware should work fine. You could add something as simple as a fixed cover with a long bristle strip on the front edge of it that the tools push through when they move forward:

Not sure how well it would work but it would be better than being in the open. Use some double acting pneumatic cylinders to move the rack in and out. Be sure to keep the tubing lengths equal to each cylinder to prevent binding. You will also want some flow limiters to keep it from slamming open and closed. As for software and I/O, not sure about that. There are 3rd port expansion boards for the ESS but I don’t recommend sticking with it or Mach 4. It isn’t good software. Especially when you start trying to customize it. I know almost nothing about Centroid stuff but I do know they have decent documentation and expansion options. Try taking a look at their site and see what you can find.

1 Like