Bandsaw circle cutting question

[Jeff Horton]

I finally got some bandsaw blades and started cutting some round blanks for the lathe. Made a simple circle jig and cut out a few 8"-11" dia blanks with my 3/8" blade no problem.

I went to cut out some 3 or 4" dia wheels for a reproduction cannon carriage and the saw just wouldn't cut that small without binding. So I switched to a 3/16" blade I bought by mistake.

While it would cut the small radius I had fits with the thing wanting to walk. I could never get it to cut a true circle. I would just cut tighter radius and made a mess. I ended up free handing them and truing them up on the lathe.

I am guessing that I didn't have the blade set up correctly but just wondering if someone else had seen this and might have a clue what was happening? I doubt I will use that blade again for a long time but I would like to know what I did wrong.

[Mark Pruitt]

Hmmm....for starters, did you re-adjust your guide blocks and thrust bearings when you switched blades?

[Jim Becker]

If you're cutting turning blanks...just free-hand them all. Quicker, easier and it's not necessary to have a "perfectly round" blank...since it's unlikely you'll be able to mount it perfectly centered anyway!

[Ken Garlock]

What Mark said.:)

Also, don't be afraid to put some tension on the blade. Some people/companies would have you believe that a sloppy, under-tensioned, blade is a good blade. Would you want a loose steering system on your car? Why would you want a loose blade in your saw.

[Jim King]

I have the same problem with small sizes, I made a plywood disc that fits on my table saw and glued sandpaper to it . Very easy to get the little ones rounded perfectly with it.

[Jeff Horton]

First off, I wanted the round wheels finished off the saw. This was not (to be) a lathe blank. I wanted rough saws round wheels. It should have been able to cut this size circle with that blade. It works perfect on the larger dia's and thicker wood. So something was obviously wrong with the blade/setup.

As for blade tension, that might be part of the problem. I have to back way off on the tension on this small blade or it just runs off the wheels. With a lot of tension you get it to track in the center of the wheel and then all of sudden it just runs off one side of the wheel or the other. I finally discovered if I lowered the tension the problem went away. Maybe I backed off to much.

And yes, I set the guides, tracking etc. before I started.

Thanks Jim, maybe it has something to do with the small size? The larger ones worked perfect first try.

[Ken Garlock]

Something that just occurred to me, is the leading edge of the blade exactly at 90 degrees with the center line of the wheel point of rotation? IF you are changing blade sizes, you may have shifted that cutting point and as a result you have created a situation where the blade is cutting into the blank prior to being perpendicular to a radius to the pivot point. It took me many tries and much frustration before I discovered the solution. In short, your blade should be a tangent to the circumference of the wheel you are cutting.

[Frank Fusco]

Cannon? You got my attention. I collect cannons. And, I recenlty went through just what you are trying right now with similar results/frustration. Before getting smart, I ended up freehanding with a jig saw. Results were less than satisfactory. When I finally got smart, I realized there is a reason why cannon/wagon wheels were made in sections then fastened together with an iron band around them. If I ever get over the lazies, I'm going to remake the wheels in the proper way.

[Robert E Lee]

Sometimes the blade will try to fallow the straight grain of the wood if the saw is not set just right.
Bob