If you need to quickly and accurate find and set the angles of sin tables, jigs and so forth, a digital protractor is worth its weight in gold and then some. I’ve had this Fowler Mini-Mag Eelectronic Protractor (PN# 54-422-450-1) since about 2008 and use it every day for setting the angle of drilling jigs for grips. It’s small, a breeze to use and the plain 9 volt battery lasts a very long time. I may change it once every year or two — it’s sure not often. Fowler says you should get about 250 hours of use from one battery and given how short of a time it runs when I do a set up, it’s no wonder it lasts a long time.
Basically, you zero the protractor, set it one your work piece or jig and record the angle. The grey circles on the sides of the protractor are magnets that I rarely use. The photo of it stuck to the side of my drill press’ column is just to show that the magnets can hold it in place. By the way, I true my table to my drill press’ column so zero for me is the table.
Now this is a precision gauge so I protect it and have never dropped it (knock on wood). As far as standing up to daily use, it has done great and my shop goes from hot and humid in the summer to below freezing in the winter. I literally just took the above photos for this blog post and am pretty sure the unit is nine years old or real close to it. It sits in its box on my shelf except when I need to use it.
I selected this originally because of the Fowler brand name and its specs. It can measure 90% on each side so 360 degree total with +/- 0.2 degree accuracy. Yes, that is two tenths of a degree and repeatability is .05 degrees.
Another consideration for me was size. In the photos, the Mini-Mag is sitting one one if my drilling jigs. I needed the unit to be relatively small and it certainly is. It’s 2-3/8″ tall x 2-3/8″ wide x 1-3/8″ thick and its all of my jigs just fine.
Once I got this, I was able to set up faster and the number of times I made a mistake due to the wrong angle plummeted. Like I said earlier, for me, it’s been worth its weight in gold and then some.
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