roughing blanks on bandsaw

[Prashun Patel]

Just thought I'd share how I rough out green wood blanks on the band saw.

Often I'll just chuck up an octagon straight off the chainsaw. But refining an out of round blank can be a little jarring and I need to pay extra attention. It is also messy. All in all, just not fun.

For years, I would trace a template on the top of a squared off blank and then band saw roughly to shape. I have lately been using a better method: a circle cutting jig.

I started with the blank in the upper left of the first picture.

A screw on a sliding bar serves as the pivot point. I drill an over-sized hole in the bottom of the blank to catch the screw.
With the table perpendicular, to the blade I make the first circular cut. This cuts it into the traditional disk.
Next I raise the table about 10 degrees. I loosen the pivot arm and move the blank closer to the blade. Then I make the second cut.
I make a series of cuts raising the table ultimately to 45 degrees (or as far as I am comfortable), each time cutting a beveled circle off the bottom of the blank.

You end up with a cone, and the tail stock center already marked.

My blade is 3tpi x 3/8".

Now there's a big caveat here to those uninitiated with cutting thick, green wood on the bandsaw: You MUST be aware of the force of the blade. If there is any gap between where the blade exists the piece and the table, there is a chance that it can be slammed forward, crushing your fingers and ruining the blade (and the blank ;)). The trick is to use a proper wedge support under the leading edge. The risk of this rolling increases as you progressively slice the bevel disks and the base becomes even smaller. So, CAVEAT SERRATUS [sic]

[Don Frank]

Prashun,
That is a nice solution to a problem we all struggle with. It's not that you can't rough out a bowl blank from stock that is not perfectly round but it does take time to do it on the lathe and sometimes you get a little beat up in the process. Your solution of getting rid of the excess wood on the bandsaw is a good one. I like the idea of ending up with a cone instead of a simply a disc with straight sides. Even if it's just 20-30 degrees removed you could do it much quicker on the bandsaw than the lathe.
How do you secure the sliding board in the center so that it doesn't move?

[David M Peters]

I also use a circle jig for bowl blanks but have never considered making cones! I'll give it a shot next time.

[daryl moses]

How do you secure the sliding board in the center so that it doesn't move?
I would like to know that as well Prashun. I also use a circle jig but mine is not adjustable, I use a series of holes spaced 1/2" apart that I drop the pin into. It works ok but I wouldn't mind having a little more adjustment options.
I also have a bunch of wooden discs 10"-18" that have a center hole in them. I screw the disc to the top of the bowl blank and put the whole shabang on the circle jig, works great for those blanks that arent cut flat.

[Prashun Patel]

"How do you secure the sliding board in the center so that it doesn't move?"

With my knee. Just kidding.

There is a cleat that you cannot see. I use an F clamp to secure this to the bottom rail of the saw's table.

This is about the cheapest, easiest jig you can make. Two sheets of plywood. The sliding arm is dovetailed into the two flaking pieces that make the deck. A thumb screw through a t-nut is the clamp. A drywall screw through the arm is the pivot.

One bit of advice: use a non-threaded pin for the pivot point. There's nothing worse than the piece getting stuck mid cut because you have screwed it to the deck by rotating it. Now I drill the holes oversized.

[daryl moses]

Sweeeeet!! Thanks!

[Don Frank]

Perfect! Thanks!

[Michael Mills]

Looks good I like it.
Here is what I do with mine (the Runway) to help drop the blank on the pin. Helps with my poor eyesight and the darkness between the table and the wood.
Not as fancy and nice as yours but it works for me. One piece of scrap as the tabletop and two runners underneath.
I do have a place for two pins but have never used but one. Automatic sizing (in 1/64" increments) with no disc, dovetails, or anything else.
Doesn't work with the round bark side down.

[richard shelby]

I have a series of scrap plywood circles in 1" intervals. These I screw to the rough side of the blank with the flat (chainsawed usually) side down on the saw table. The upside can be extremely rough, like burl, but I follow the contour of the ply circle, and I have a lathe-ready rough blank. I've used these for several years. YOu just need to be sure the flat side is FLAT, or you'll get a stuck blade. It helps to cut lateral inlets so that the "chunks" fall off easily.

[Prashun Patel]

Yes I did the same for years. But this way, while slower, removes more wood around the base.

[Ron Rutter]

You shouldn't use a drywall screw as they are very brittle & break easily.

[Prashun Patel]

The drywall screw is a pivot only. It bears no weight or stress. It won’t break.

[Don Frank]

Prashun,
I made one of these, put a fresh three tooth blade on the bandsaw and tried it out. When I started cutting the angles off the bottom my blade drifted and did not maintain the same depth of cut. By the time I got back around to the starting point there the blade had drifted 3/4-1". (I cut a notch into the corner of the bowl blank with my electric chainsaw as a starting place for the blade.) Granted I was trying to take off a pretty good wedge at one time but I wasn't expecting an new blade to flex out that much.
I centered the pin that the blank spins on in line with the front edge of the bandsaw blade. I'm wondering now if it needs to be centered with the center of the 1/2 blade. That possibly that 1/4" difference is what is causing the blade drift.

[John K Jordan]

I'm not clear on what you mean by "drift." Do you mean the blade flexed and bowed leaving a cut that wasn't straight up and down? In my experience blade flexing is caused by insufficient tension perhaps coupled with a dull blade and a feed rate a little too high. But mostly blade tension. I use a tension gauge to check mine and was surprised at how much all my blades were under-tensioned when going by the tension indicator on the saw.

The size of the wedge removed shouldn't make any difference. I use 1/2" blades with 3 teeth/inch. I've read that some people grind off every other tooth for big wood but I've never tried that.

JKJ

[Prashun Patel]

I center the pin with the leading edge of the blade but it doesn’t seem to make a huge difference.

The same thing sometimes happens to me when trying start on a round blank. The blade flexes when the saw is off, and then cannot engage. It gradually drifts into the right position and then out when it reaches the starting point. This is bad for several reasons, including shortening the life of your blade and grinding your bearings.

If you see this happening, the solution is to cut a relief off the saw or Move the jig toward the infers before starting the saw, then sliding the jig into position with the saw on, clamp, then rotate.

I will say that if the blank is heavy, this can be tricky and dangerous. So know your skill level.

It happens when the blade is dull.

[Don Frank]

Drifted was not the right work. The blade flexed causing it to bow so that by the time I made a full circle the cut was not taking off the same depth of wedge (of wood). In thinking back it may be because of the blade not being tight enough. I had just replaced it before that cut. I'll try again and see if I have similar results. It was a big heavy wet oak blank I was trying to do about 16-17" across.
I had just talked myself into the alignment of the pin being too far left or right of where it needed to be.

[John K Jordan]

Drifted was not the right work. The blade flexed causing it to bow so that by the time I made a full circle the cut was not taking off the same depth of wedge (of wood). In thinking back it may be because of the blade not being tight enough. I had just replaced it before that cut. I'll try again and see if I have similar results. It was a big heavy wet oak blank I was trying to do about 16-17" across.
I had just talked myself into the alignment of the pin being too far left or right of where it needed to be.

I've had under-tensioned blades bow so much the teeth came out of the side of a board I was trying to resaw! Imagine that if you think fingers are safe on the side of the board!

My thick wood and resawing problems went away when I used a gauge to check the actual tension instead of guessing. I often cut wood 12" thick now.

JKJ