Construction of the base, hopper, and housing is actually quite simple due to a few simplifying factors. First, the plywood and the mill sides are 1/2″ thick. Second, I only angle out one pair of sides on the hopper to ensure I don’t have any compound angles to deal with. Finally, all the measurements are fairly easy numbers (no fiddly 64ths, etc.)
This article assumes you’ve got the Crankandstein 3D mill. The mill measures 6″ wide x 3″ tall x 3 1/4″ deep on the outside. I’ll generally describe the construction without specific measurements so you should be able to adapt this to other mills if needed.
Also note that I built my one in a slightly different order than I describe below. As a result some of the pictures below may appear to be out of order. I’ll note it when it happens.
The following techniques should make building easier and provide higher quality results.
- When cutting the plywood use a marking knife to score the outer ply of the plywood along your cutline. Keep your blade on the waste side of your scored line and you’ll end up with nice clean cuts without splintered faces.
- Pre-drill and counter-sink all screw holes so that the plywood doesn’t split and the screw heads are flush.
- Sand all cut edges. Hit all edges and corners with the sandpaper as well to knock down sharp edges.
- Take direct measurements wherever possible. That means holding the wood in the position it needs to be and then marking your cut lines directly rather than using a tape measure to determine measurements. This reduces the chance for errors and saves time.
Position the bucket upside down and use your pencil to trace the size of the bucket opening. Use your jigsaw to then cut out the circle but cut about 1/4″ outside the pencil line you drew to ensure there is an overhang when the base is on the bucket.
Next place the assembled mill on the base and center it. Take a few measurements to be sure you’re as close to centered on the base as possible. Then trace the mill sides onto the base. You’ll use this as a guide for cutting a rectangular hole through the base. Drill holes at the four corners of the space between the base sides that you traced. Use your jig saw to cut out the rectangle as such:
(Note that this picture still shows the base as a square sheet but by the time you do get to this step it will be a round base.)
Finish up squaring off the hole with a few more passes with the jig saw.
Next attach three of the bumper stops around the base so they’ll fit snuggly to the bucket opening. Do this by spacing them evenly around the circle about 1/4″ in from the line you traced.
Finally drill 5/16″ holes in the base so you can mount the mill later on. Use the mill as a guide for locating the holes.
Building the hopper is quite easy. Start by cutting the two trapezoidal sides. Start with a rectangle of plywood that’s 8 1/2″ x 10″. Mark two points on the bottom of the plywood face at 3 1/4″ and 5 1/4″. This is the bottom edge of the trapezoid. Connect these points to the respective top corners of the board and then out the side.
Now for the rectangular sides. Cut a strip across your sheet of plywood 5″ wide. The trick with these sides is that the ends are cut at an angle. That angle needs to match the angle of the corners of the trapezoid pieces. Here’s a great trick to get the angle right. Use the trapezoidal side piece as an angle gauge.
Now cut the rectangular side pieces to length by taking direct measurements against the trapezoidal pieces for length. Once you’ve done that go ahead and screw the hopper together:
The housing comprises two rectangular sides and a top that has a hole to match the hopper. All three can be made from a strip of 6″ wide plywood cut across your sheet. For the Crankandstein 3D this means two 3″ x 6″ sides and one 4 1/2″ x 6″ top. Place the hopper on the top trace the hopper’s bottom opening onto the top. As you did with the base hole drill holes at the corners and use your jigsaw to cut out the rectangular hole.
Drill holes one of the side pieces so that you can put the set screws in to hold the adjustment mechanism in place. You’ll see that the added width of the 1/2″ plywood means that the original set screws will no longer reach. There’ll be a solution for that later.
Clamp all the pieces around the mill and screw them together. This ensures that the housing will fit tightly to the mill.