Status: Work In Progress
Last updated: May 20th 2018
The Rascal CNC is a hobby grade CNC machine designed BY the Community FOR the Community with the simple goal of being able to cut foam board airplanes, for more details: CLICK HERE
Make sure you've got all your parts and Rascal Kit ordered before you get started.
The Rascal mounts to a flat sheet of MDF or plywood. This baseboard should be 3/4"x42x42” minimum, but the thicker the better. Pick up a sheet from your local lumber store and then you'll need to seal your baseboard with one of the following:
It's critical that the baseboard is sealed to prevent it from warping over time. Lastly, frame the underside of your baseboard with 2x4s and mount it somewhere solid and permanent.
Rascal kits come off the mill with a few rough edges. You'll need to hit each piece with sandpaper (200 grit) and then seal all wood pieces with one of the following:
Just like with your baseboard, it's critical that the wood pieces are sealed to prevent them from warping over time.
Note: I was able to get a really nice finish with a few coats of rattle can + sanding in between. Then I finished them off with satin spray polycrylic.
The Open Builds aluminum rails are cut to length at the factory but NOT at a perfect 90 degree angle. You need to sand your (3) 1000mm rails until square before building the Rascal. You don't need to square your 250mm rail.
1. Check square
Use a drywall square (best) or speed square to get a baseline for how square all (3) 1000mm rails are. This process will identify which side of the rail needs to be sanded.
Note: Make sure you are checking square against the height of the rails as seen here.
2. Choose X beam
Choose the most square of the (3) rails to be your X beam. Then sand rails till square with 80 grit emery cloth or standard sandpaper. You can do this by hand or with a disk sander.
3. Once X beam is square
Install vertical plates on your X beam and check for square again. Additional sanding may be needed.
These (2) plates mount to the X beam and glide on the Y rails with v groove bearings. In this section I will show you how to install the guide v groove bearings onto the vertical plates.
1. Prep your guide bearings
You need (2) regular bolts and (2) Sidewalk bolts per plate in the following configuration:
bolt > v bearing > spacer nut > washer > wood > washer > lock nut
2. Install guide bearings
The top (2) are regular bolts and the bottom (2) are Sidewalk bolts. The Sidewalk bolts are needed because of the clearance limitations in the aluminum rail channels. Securely tighten down the Sidewalk bolts while leaving the top guide bearings loose. The top bearings have an adjustable slot for precision mounting.
Using the 250mm rail, place the vertical plate into position. The bottom bearings should ride on the underside of the top rail, and the top bearings should ride on the top of the rail.
Hang the plate upside down and move the adjustable bearings toward the center of the plate. This will snug the bearings down onto the rail. The plate should feel solid on the rail while still gliding freely.
4. Test alignment
Once the bearings are adjusted, test their alignment by firmly grabbing the top of the plate and moving it in all directions. There should be no wiggle or play in the bearings. The only movement the plate should experience is back and forth down the rail.
5. Tighten bolts down
Tighten down your adjustable guide bearings while still mounted on the rail. As a final test, remove the vertical plate from the rail and then slide it back on. It should rejoin the rail easily.
Perform these steps on both vertical plates.
6. OPTIONAL - Add drag chain attachment to vertical plate
This attachment allows you to install a drag chain on your Y axis.
One of your vertical plates will have two holes near the bottom.
Use a drill bit to add some holes to the attachment piece.
Then add your wood (2) screws.