Masso G3 ATC build update - new larger ATC ISO20 tool rack design

I have been busy over the last months with a few big projects.

This update provides details of my newly designed 24 position aluminum linear tool rack for my ISO20 spindle tool holders. Below I have included images of the CAD/CAM, components, machining, and a link to a video of the machining of the various tool paths. I had already done most of these toolpaths in aluminum before, so had a fairly good idea of the F360 parameters that were successful, but what was new to me was using multiple (tiling?) setups for this 36" long x 6.5" wide aluminum stock.

NOTE: I recently decided to make my YouTube channel and Instagram page public, but depending on time, may still continue to post updates here, as I can add more content for those who feel they benefit or are interested in the extra information and detail. Please jump to end for links of the journey does not interest you :grinning:


I have been very pleased with the functionality of my Masso Jianken ATC build. Over time I have added more tools that could not be held on my 13 position linear tool rack. It was not a problem, as Masso allowed me to add a dedicated tool change location(as many as I wanted actually) that I used for these tool changes - I just needed to be ready with the tool in hand for drop in/drop off. To get full functionality from my investment I knew it was time to make a larger tool rack.

As an aside, the number of tools/holders one uses can grow quickly. Things that add to tool number:

  1. I prefer to work in metric, but also use imperial tools.
  2. I machine aluminum, plastics, and wood, and prefer to have some end mills dedicated to a particular material
  3. I use single, double and triple flute end mills
  4. Some of the same endmills I have with various coatings
  5. I have diameter ranges for many common end mills - 3mm > 8mm and 1/16">3/8"
  6. I have several special use end mills - facing wood or aluminum, thread milling, diamond drag engraving,…
    The point is that 24 holders fill up surprisingly quickly :grinning:

When designing this new rack I had the following criteria:

  1. I really liked the spring action of my original tool holder design, so knew I would use springs again for this one
  2. I wanted to fit as many tools as possible on the rack
  3. Like my current design, I wanted my tool setter to be mounted on the rack
  4. I wanted to keep the strength of aluminum, as well as the mounting to the current 8020 aluminum extrusion

With the new rack I went from 13 to 24 tool positions, and lost only about 5cm more Y travel (which for the work I do is not an issue).

Here are a few before and after photos (the photo of the 4 new holders was a test mock-up on acrylic):

Here are a few photos of the parts:

Here is the assembled rack before mounting:

Here are some F360 screenshots:

Workholding and setup challenges/solutions:

  1. I wanted to make sure my design/measurements would work, so I milled a small - 4 holder - acrylic test piece, and along with the 3D printed holder and components, used that as a proof of concept. With that confirmed, I used the acrylic piece as a template to mark the locations of all the holes on the aluminum - I like to do this to check my toolpaths and X/Y zeros.
  2. My machine setup does not allow for passthrough, and has less Y axis distance than a regular Woodworker. I knew I needed to machine the part in sections. I used a variety of precision measurements to scribe an accurate centre line for the length (36") of the part, as well as to find the cenre point that would later become the CAM model centre for all operations. I then used my 90 degree chamfer end mill’s point to line up the part using the centre line reference. NOTE: if I needed it to be within a few 100ths of a mm I would have used my 3D probe, but it was not needed, and, the stock aluminum edge was most likely not that straight anyway :smile: .
  3. I wanted a very firm hold on the stock, but did not want to risk milling into my aluminum fixture plate, so I mounted my stock on top of a 6 mm piece of acrylic. This gave plenty of room for drills/end mills to pass through the aluminum stock.
  4. I did not want to risk an accident by having any loose stock when cutting out the 42 mm OD tool holder holes, so I took the time to drill and tap the aluminum and acrylic sheets. From my earlier template marks, I knew exactly where the centre of each of the 24 holes would be, so used that as my guide. It was a lot of extra work, but in the end the workholding was rock solid. NOTE: to save some time, I used the locations of the tapped acrylic holes as a guide for when I turned my stock to mill the 2nd half - it meant I only needed to drill holes in the aluminum stock, not redo the tapped holes.
  5. I got lucky when I needed to clamp the stock to my M6 threaded fixture plate. The roughly 6.5" width of the stock allowed me to use a minimum of eight M6 screws with washers along the edge to clamp it down - this worked very well.
  6. For the F360 CAM. I needed to learn how to create 4 different setups to machine the entire part. Two setups were for one half, then two more on the 180 degree rotated stock. It worked very well because 1) I had my centre line/chamfer bit method to locate the stock, and 2) I was very careful to double check my X/Y zero for each of the 4 setups - having learned the importance of that the hard way :face_with_hand_over_mouth:.

Here are some photos related to the aforementioned points:


Outside of forums I am establishing myself as TMDesign

YT video link summarizing tool rack machining:

My Instagram page(with link to my YT channel):

Thank you for your interest