Making perforated U-channel flashing - success!

I’m in the midst of a building project, and needed some (120’) u-shaped flashing with ventilation holes. After calling around to the local metal fabricators, and metal supply companies, I couldn’t find the material - or “flashing” at a reasonable cost. So, why not make it myself? I was going to get a CNC router eventually… so I ordered a Shapeoko XXL, waited patiently, and it arrived. I was still hesitant because I had not really run a CNC router before, except in college and a few times at my friend’s house recently. I was taking a big risk - if this didn’t work out, I’d have to spend money on the metal stock (and freight).

I decided to use a v-groove chamfer bit (single flute, straight cut, 60 degree included angle, solid carbide) and only go partially into the material. My goal was 3/16" or so sized holes, .25" apart. Ultimately, the spacing can vary as can the size so long as they don’t connect. Coils stock is 24 gauge Alunimum.

I created my design in Fusion 360, and used their CAM post-processor to generate the G-code.

Then by hand, painstakingly cut a 42" x 28" 3/4" MDF board. Drilled and sunk 4 holes, in the same location as 4 of the base screws, again by hand. Could I have CNC’d these? Probably, but this is all “new” to me in a way, and I knew I could accurately drill the holes. I then removed those 4 screws, and used longer screws (45mm or 55mm) to connect the two boards.

Started out by routing a channel on the left side of my new spoilboard - this was so I had a reference to line the coil stock against. Then I ran the holes just in the MDF - sanity check and I wanted to cut into the aluminum with nothing below:

(PLEASE NOTE: at this point I was manually tending to the power cable):

A “beauty shot” of it in action (PLEASE NOTE: at this point I was manually tending to the power cable):


Clamp setup (NOTE - power cord properly tied into cable chain):

I’ve been using bCNC to send the job, only because its preview was better than the other programs I tried, but I’m probably going to set up Chilipeppr ( on a Raspberry Pi. My internet at the barn (workshop under construction) is not, shall we say, the greatest, so I’m not sure it will be a good setup (until I run a cable and set up an access point).

I’m halfway done - and just thought I’d post and share since I was successful :smiley:. Not too sure I’d post if I had failed :stuck_out_tongue:.


Some other things to mention:

  1. It’s dangerous to run it with the power cable loose. I ran two jobs - the initial job and the first flashing job. I was considering mounting the power cable for the router above the router (hanging), but decided against it and attached it to the cable chain. If the machine had freaked out, my reaction time would have been slow.

  2. Though the v-groove works, I probably would use a bit sized to the exact hole size I need, if I could find one. While the holes have been nearly identical, there is some variation because it relies on the Z-height being constant - over the course of three jobs the bit slowly worked its way up, and since I didn’t surface my spoilboard, there is some slight unevenness. That being said, when the Z-height is correct the holes are frighteningly identical, and any board unevenness doesn’t show. Since this is going to be effectively hidden, there is no harm in some variation.

  3. Is it appropriate to want to cackle like a mad scientist when running the machine for the very first time?

  4. I’m very impressed with the machine - running it, a vacuum, and my laptop all off the same power cord and at the same time and no disconnections. Oh and a floor fan. I’m guessing the disconnection issue was resolved with the latest board revision (large cap!), but I was still just a bit nervous since I have 16+ hours of job to run.

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Nice creative use of the Shapoko. I just love seeing all the unique things people are doing with their CNC’s.

Total machine time: 22 jobs at 45 min/ea, and the final job took 30 minutes. Thought I’d post pictures of the finished product.

(one of many pieces :smiley:)