Make Perfect Star Knobs With A Jig Homemade Machines & Jigs
If you make jigs and fixtures for your shop, you will probably need knobs to tighten or make adjustments for various things. And if you are anything like me, you almost never have the right one on hand when you need it. So it wouldn’t be a bad idea to stock up by making a bunch when you have some free time.
This is essentially a scrap wood project, since you can make the jig itself and the knobs from any kind of scrap wood or leftover plywood you have in your shop. For the base of my jig I have a piece of 1/2″ and 3/4″ plywood about 5″ wide and 8″ long. I marked the centre in the the 1/2″ plywood for the 1/4″ clamping bolt:
I screwed the two pieces together with 1″ screws and drilled a 1/4″ hole through both parts on that mark:
Then I flipped it over and used a 2-3/8″ hole saw to drill through the 3/4″ layer only.
I’m using that size hole saw because I happen to have one, but I do think this is the ideal size for this medium size star knob. I figure this size is suitable for 1/4″ to 3/8″ bolt sizes.
Next I cut out the smaller part of the knob using a 1-1/2″ hole saw and used that to line up the larger hole saw for the cut that will shape the knob:
The hole saw should just miss the smaller part as it cuts in.
The centre of that second 2-3/8″ hole needs to be screwed in place, and I did that before completing the cut using two 1″ screws:
To lock the clamping bolt in place, I ground down the sides to make it rectangular:
Then drove it in with a hammer. To help keep it there for good, I pushed it out again and put some epoxy on the head of the bolt before pushing it back in:
I used this kind of bolt, but a regular hex head or a carriage bolt would work as well. The important thing is that it is flush with the bottom so that the jig sits flat on the drill press.
To make it so that it will cut the classic star knob shape, I laid out lines on the jig that are 120 degrees apart. To do this, I made a simple gauge from scrap plywood and cut it on the miter saw with that set to 30 degrees (90 + 30 = 120):
I can use these layout lines to position the knob for each of the scallop cuts:
The video at the bottom of this page goes into more detail on how to make the knobs themselves, and it’s pretty basic:
As mentioned in the video, it’s a good idea to make the stud knobs longer, then you can always cut it shorter as needed.
I used plywood for these, but any kind of solid wood will work as well, or better. I also used fast set epoxy to glue mine, since it will stick to the metal parts as well:
The other type has no stud, but has a t-nut inside. I used a bolt and wing nut to clamp it together until the epoxy set:
There you have it, a simple jig that can help you make perfect star knobs for your next jig build:
So, take a few hours one afternoon and crank out a few to have on hand. Not a bad idea to make some that have different size studs, like 5/16″ or 3/8″, if you find that you need these sizes occasionally. Use up some scrap and save a few bucks in the process.
I made a video showing it in action making both types of knob: