By Brock | Created September 20th, 2018 | Published September 20th, 2018
An easy way to create a knob with a threaded stud. You can cut the files as supplied if using a 1/4-20 threaded bolt, or resize the files for a different bolt size and even swap out for your own custom knob design.
Files included (2)
KNOB, ROUNDED TRIANGLE, .250-20.svg
KNOB, STANDOFF, .250-20.svg
Wood of desired thickness
Hex head bolt
1/8" upcut bit (recommended) or 1/4" upcut bit
There are 2 files that need to be cut. The linked files are for a standard 1/4-20 bolt with a .250" shaft and .438" across the flats. The resulting knob is roughly 1.5" across and .75" thick when using 1/2" material as shown.
The svg geometry is exactly centered within a blue guide square for both files. This is so that if you are using a different size of fastener, or if you want the knob itself to be bigger or smaller, you can simply scale the files on-tool and snap the svg centerpoints to your grid. You could even swap out for another knob design if you wanted.
These parts are small and may want to break free when finishing the perimeter cuts. I didn't bother securing them, I just left a thin amount of material before cutting the final perimeter pass so that when they broke free it would be somewhat controlled.
For the standoff pocket I recommend .2" deep to minimize the height of the knob and get the most support for the standoff. A standard 1/4-20 hex head is .172" thick, so add that much to your cut depth after cutting the standoff pocket.
For the hex, if you are not able to force the bolt head into the pocket you will need to relieve (dogbone) the corners. If using a 1/8" bit this should not be an issue for most woods. If you need to dogbone the corners, an easy trick is to set a negative offset equal to 1/16th of your bit diameter (.008" if using a 1/8" bit or .016" if using a 1/4" bit) and just plunge and retract the bit at each of the corners without moving Origin.
Assemble, glue and finish as desired.