A Compass That is Not Cheap Plastic Junk!
For a long time I have been frustrated by the disappearance of the all metal compasses that you could by at any craft store. They have been replaced with cheap plastic garbage. What’s more is most, if not all, are only able to hold small number 2 pencils. If you want a compass that will hold a sharpie or a fat piece of chalk, you are out of luck. Well, I found this amazing Youtube video below and I was immediately inspired.
Body of the Compass
The main components are two 3 inch circles of 1/8″ steel sheet and two 15 inch steel round bars 3/8″ thick. This project is completely scalable. I used a hole saw to cut out the disc since I would already have a 1/4″ hole drilled in the middle. Of coarse if you do not have this available to you, you could cut them out with a jig saw or grinder. Jig trace the lid of a Gatorade bottle or bottom of a drinking glass. On the far right is a piece of plastic
shim stock shaped like the metal disc. This acts as a bushing between the plates to reduce friction for the pivot point. Before welding this all together, I will need to take one of the rods and put a point on it. I used a cheesy bargain bench grinder and just kept spinning the rod to get a centered and even point. It took about 15 minutes.
Next I needed a holder for the marker, pencil, or chalk I would be using. I chose this scrap 1 inch tubing I had around. The plan is to get the writing took in one corner and a bolt comes in from other corner and applies pressure to keep it set. To accomplish this I had to grind one corner of the tube while it was in a vise. This flattened surface allowed me to use a drill with a 5/16″ bit and drill a hole into the tube. Once that was completed, I rest a 1/4-20 nut over the hole and inserted a screw to protect the threads. I used my wire feed welder to weld the nut in place. It was a pain in the butt but still easier than bring out tap and threading new wholes in the corner of a tube.
Thumb Screw Marker Holder
This is a large piece of tubing for this job and that thumb screw is industrial quality. This holder set up will hold a lot of writing tools. Once the holder was welded on. It was time to weld the rods to the pivot discs. Then a 1 inch 1/4-20 bolt was inserted in the pivot center and a lock nut was fastened on until the correct tightness was achieved.
Setup for Use
Once everything was assembled it was time to try it out. First a sharpie was inserted in holder and tightened in place so the tip was roughly even with the point. Then the pointed end was aligned to zero on a large square and the pivot was adjusted until the marker tip reached the 6 inch mark on the square. Then a pair of locking pliers was locked onto the pivot to keep measurement. A scrap piece of painted aluminum sheet was laid out and a 12 inch diameter arc was drawn perfectly.