Variac Replacement Knob (Omaha Maker Group)

Eric said I had commented one too many times about the block of 2x4 that had served to replace the old knob that was missing on our Hackerspace Variac. So he walked to the marker board and sketched out a design for a knob, one with STYLE and Pizazz. I thought, okay I know how to make that design a reality....

(This is to fulfill our Bare Paint instructable session from May 21st, 2013 in the Omaha Maker Group)

Step 1, Lasercut the Parts Out of Acrylic and (optionally) ABS Plastic

First, lasercut out the image onto a clear piece of Acrylic. Carefully remove the part and the tape. I then attempted to use a recycled piece of ABS plastic for the base of the Arrow. This took too many passes and was very scorched by the time it was done. No matter, I washed the part and painted it afterward with blue acrylic paint.

Step 2, Superglue Pieces Together

Print out a large Red gear with a 3D pritner. This will be your replacement handle grip. The file for this was drawn from a textbook example by Kory Mikos. Add to the gear a wooden circle with screw holes to match those of the gear.

Now that the blue paint has dried, we will add the 1st lasercut plexiglass piece to the blue part with superglue. Use drill press to make a hole through the center, the diameter needed for the Variac stem. Make sure before you drill that the parts align with the 3D printed Gear.

Step 3, Lasercut Another Arrow

Lasercut another Arrow, this time using frosted Acrylic. This will be for the visible layer of the knob. Line up the Arrow with the red gear, and use a sharpie to mark where the holes should go. Use top piece as template for remaining 2 pieces that have been glued together, so that they all have the same drill holes. Using polypropyline washers, mount the parts together and use the 1/2 inch drill rod to bore through the center of the knob and act to align the parts.

Step 4, Cut Screws and Mount

Using either a hacksaw, or a bolt cutter, remove the length of the screws, after the nut has been securely tightened by hand. Mount the Knob onto the stem of the Variac by pusing the hole onto the stem. You may be able to do this easier, if you turn the knob while easing it into place. Now the Variac has a 3D printed and Lasercut knob!