|Forum topic by Kelly||posted 01-04-2015 04:40 AM||1063 views||1 time favorited||1 reply|
01-04-2015 04:40 AM
After watching the pains a couple people went to, making a simple circle using a band saw, I just wanted to post a photo of my band saw circle cutting jig.
Of course, “my” idea is stolen from others who went this route before me. Still, the simple modifications I added: 1) improve reliability; 2) improve ease of use; 3) if you are capturing saw dust, it redirects dust through the table; and 4) you can produce larger circles more comfortably.
Unlike others, my table extends all the way over to the band saw throat arm. Because of this, the blade will move about half way into the jig during operation. This provides counter balance for larger circles, and is what causes sawdust from the cut to be pulled down through the jig and table, rather than bounce off the table, just left of the cut.
Adding a stop means I can always be sure the cut of the actual circle will start only when the blade is straight across from the pivot point, avoiding binding of the blade (if you switch guides, such as going from a Carter Stabilizer to a stock guide, you will have to compensate for the guide you are using).
With this jig design, you do not have to pre-size the wood. As long as the wood will clear in the throat, when spun, you merely need to push the wood into the blade and, when the stop hits the band saw table, spin the wood to make a circle of whatever predetermined size you chose.
The stop can be permanently adhered to the underside of the table. It should stop the table when the pivot pin is directly to the right of the teeth of the blade. Anything before or after will cause the blade to twist and bind. Even if it didn’t break, it would wader off track.
As can be seen in the photo, I used a track bar. This allowed me to use a moving pin holder, which is nothing more than a T shaped piece of aluminum with a set screw to lock it, and a hole just big enough to accept rivets I use for the pivot pin.
The cut outs are just to reduce weight on the right side.
Size your blade according to the diameter of the circle you are going to cut. As with all band saw blades, you can grind the back sides of the blades to round them over, reducing friction and allowing slightly tighter cuts.