Introduction: Magnetic ShopBot Dust Skirt
I work at The Mill, a makerspace in Minneapolis, MN. We've got a shopbot and it's a fantastic machine.
The original dust skirt on our ShopBot took one too many hits and frankly I wasn't a big fan of the design. This one is built using some scrap 3/8" polycarbonate, a 2" #8 bolt and nuts, and 16 3/8" x 1/4" cylindrical rare earth magnets.
There are 2 pieces to the design.
The first is the main shoe that clamps onto our spindle.
The second piece is used as the spacers as well as the dust skirt. You can create as many spacers as you need for the length of bits you use. I made 2 to start.
This system makes it extremely easy to remove the skirt for bit changes, z-zeroing, or operating without the hood altogether. It stays out of the way of the Y gantry when the z axis needs to be raised. It also eliminates the need for that silly thumbscrew that held on the factory dust hood. You could rarely get to it when you needed to and it was located in a potential pinch point.
I've included the DXF files so you can take this to any cad/cam combo you like.
Step 1: Create a Jig to Hold Your Polycarbonate Blanks
I created this using some scrap 5"x12" polycarbonate pieces so I used a jig vacuumed to the table and generous amounts of double stick tape to hold the polycarbonate down in the pocket. I cut the pocket 1/4" deep out of 3/4" MDF. The pocket is "dog-boned" at the corners so the square blank fits.
I cut rounded corners at the ends of the main shoe and skirt pieces but left the long edges at the full 5" width.
Step 2: Cut the Pieces
I used a 1/4" single flute / "O" flute bit. The cuts were clean. You can use many different types of bits to cut polycarbonate but "O"flute and straight bits are recommended.
I've included 3 files. One contains all of the vectors combined. If you are cutting this from a larger sheet of material, you will need to do a few edits to weld the long straight edges into the skirt and main shoe pieces.
Step 3: Fit the Magnets Into the Holes
Be sure they are inserted with the correct polarity. I redrilled the holes with a 1/4" drill bit after they came off the shopbot to enlarge the holes slightly. The fit was just tight enough that I didn't need to use any adhesive. If you need adhesive, loctite brand plastic epoxy is said to work well.
I got the magnets from K&G.
1/4" dia. x 3/8" thick
Grade N52 - Nickel Plated
Step 4: Drill a Hole for the #8 Bolt
I used a 5/32 bit for the bolt to slip through. The things to be conscious of are getting the hole at a perfect 45 degree angle, leaving enough material above and below, and drilling the hole so the bolt slides freely. I'd recommend a drill press and a vise if you have it. A steady hand and a drill will work as well.
Insert the bolt with a washer and lock washer at each end. Thread on the nut and finger tighten.
Step 5: Attach the Skirt Material to One of Your Skirt Pieces.
I re-used the vinyl skirt material from the original shopbot dust hood. I drilled holes slightly smaller than the original mounting screws found on that and simply let the screws tap themselves as I screwed them in. Test the fit on a piece of scrap so you get it just right for the screws you are using.
Step 6: Attach the Main Shoe to the Spindle
The spindle should fit snug inside the hole without tightening. Tighten the bolt but DO NOT OVER TIGHTEN. Adjust the shoe so the dust collector hole is in front of the spindle so that it will not be in the way when you raise the z axis. You will need to reroute your dust collection hose.
Step 7: Attach the Rest of the Pieces.
The magnets do a great job of aligning all of the layers without the need for any other indexing mechanism.
I didn't bother gluing the dust collector fitting into the shoe but you may want to seal that with some silicone adhesive.