Bandsaw jumping blade guides

[Joe O'Leary]

I am cutting bowl blanks on my Mini Max 16 inch saw, and the blades keep wanting to twist and jump the guides.
I am using a shop built jig which seems to be aligned well with the blade. Any ideas what might be causing this?

[John K Jordan]

I am cutting bowl blanks on my Mini Max 16 inch saw, and the blades keep wanting to twist and jump the guides.
I am using a shop built jig which seems to be aligned well with the blade. Any ideas what might be causing this?

It would be best to see your bandsaw, your jig, and watch how you are working. Many possibilities. Some things:
Size of blade? Cutting too small radius/twisting blade? Improper tension? Guides/thrust bearing not adjusted properly? Too much force pushing? Dull blades can twist.

JKJ

[Robert Hayward]

Are you cutting green wood? If so you might have a swarf build up on the tires, guides or blade. Your blade might be dull.

[Richard Coers]

How wide of blade and what cutting radius are you doing? My guess is you're cutting to small of radius with the blade.

[Mel Fulks]

See if the “loop “ has a twist in it . Or a crooked weld.

[Joe O'Leary]

Thanks, John.

Size of blade? Tried 1/2", 3/8", even 1/4". all had problems
Cutting too small radius/twisting blade? Radii were 5 to 6", but the blade was twisting.
Improper tension? I don't think so, but possibly. I have a little gage, then I add some judgment. Never had a tension issue before.
Guides/thrust bearing not adjusted properly? Possible. The guides on this machine are unusual, but beefy. I do know how to set them.
Too much force pushing? My most likely culprit. The blades are not skip tooth and I may have been too aggressive.
Dull blades can twist. All new blades.

I tried cutting off the corners first and that helped a great deal.

I'll try to record my next blank

[Mike Goetzke]

Is the blank flat on the bottom or can it rock?

[Joe O'Leary]

Is the blank flat on the bottom or can it rock?

I cut them all flat.

[Bernie Kopfer]

Had this problem a couple of times and both were the pivot point not being tightened enough. Tiny bit of slippage sure made for problems.

[Joe O'Leary]

Had this problem a couple of times and both were the pivot point not being tightened enough. Tiny bit of slippage sure made for problems.

Good point, Bernie. I'm using a ¼ X 20 cutoff bolt as a pivot. Maybe that's too small? I made sure to align the front of the saw teeth to the center of the pivot point.

[Reed Gray]

Well, if blade is properly tensioned, and sharp, you should have no problem cutting a 6 inch diameter with a 1/2 inch blade. I would guess that your pivot point is not correct, or off a bit. You would encounter the same problem if your rip fence is not in line with the bandsaw blade. I never used a jig for cutting circles. I cut into slabs which lay flat, using a 1 1/4 inch blade on my Laguna 16HD, and then scribe circles on the slabs, then cut the slab sections round. I do prefer to keep the corners on the blanks because that keeps my fingers farther away from the blade, and if I do slip, my fingers are not pointed into the blade. I do have a big lazy Susan for spinning the blanks on, which is easier than cranking the dividers/compass all the way around. I do spin it a couple of times around the circle, and have a detail light to see the circle line. A magic marker could also be used. Try a blank with a scribed circle and see if you still have a problem.

Never figured out a jig for cutting circles. I am one who uses the wood in a manner that lets me get the most blanks from a log. I would think that a jig should be on a sled with a bar on the bottom to fit into the slot in the table like on the table saw. You would slide it into the cutting blade to a certain point, and then spin the blank to cut the circle. If that stop point is a bit off, that would cause the blade to drift in the cut. I would expect that the exact point placement for the pivot pin to be in line with the teeth of the blade, and not the middle of the blade.

I never found it to be efficient to try and cut a perfect circle. When I did, the blank was always off +/- up to 1/8 inch or so. Mounting method, face plate, drilled recess, or between centers, all got the same result, no matter how careful I was.

robo hippy

[Joe O'Leary]

Well, if blade is properly tensioned, and sharp, you should have no problem cutting a 6 inch diameter with a 1/2 inch blade. I would guess that your pivot point is not correct, or off a bit. You would encounter the same problem if your rip fence is not in line with the bandsaw blade. I never used a jig for cutting circles. I cut into slabs which lay flat, using a 1 1/4 inch blade on my Laguna 16HD, and then scribe circles on the slabs, then cut the slab sections round. I do prefer to keep the corners on the blanks because that keeps my fingers farther away from the blade, and if I do slip, my fingers are not pointed into the blade. I do have a big lazy Susan for spinning the blanks on, which is easier than cranking the dividers/compass all the way around. I do spin it a couple of times around the circle, and have a detail light to see the circle line. A magic marker could also be used. Try a blank with a scribed circle and see if you still have a problem.

Never figured out a jig for cutting circles. I am one who uses the wood in a manner that lets me get the most blanks from a log. I would think that a jig should be on a sled with a bar on the bottom to fit into the slot in the table like on the table saw. You would slide it into the cutting blade to a certain point, and then spin the blank to cut the circle. If that stop point is a bit off, that would cause the blade to drift in the cut. I would expect that the exact point placement for the pivot pin to be in line with the teeth of the blade, and not the middle of the blade.

I never found it to be efficient to try and cut a perfect circle. When I did, the blank was always off +/- up to 1/8 inch or so. Mounting method, face plate, drilled recess, or between centers, all got the same result, no matter how careful I was.

robo hippy

Reed, I hear you. You pretty much described how my jig works. as I said, I

align the front of the saw teeth to the center of the pivot point. That should be right.

I'll try the jig a little more carefully. If that doesn't work, its back to circle templates and freehand.

[John K Jordan]

…
I never found it to be efficient to try and cut a perfect circle. When I did, the blank was always off +/- up to 1/8 inch or so. Mounting method, face plate, drilled recess, or between centers, all got the same result, no matter how careful I was.
robo hippy

Same here. Made the typical jig and quit using it shortly. I prefer to mark precisely and cut by hand, just barely outside the marked line. I do find it easier to stand at the side of the bandsaw and turn the blank; lets me rotate more accurately (and keeps the fingers well out of the way.) Then I either use a 10” disk sander to the line or if I want more precision jam mount and turn it on the lathe.

[Bernie Kopfer]

Also I’ve encountered difficulty if I did not solidly lock the slider so it couldn’t move when I reached the correct alignment point. Movement there actually broke a blade once. Only once!

[Neil Strong]

I never found it to be efficient to try and cut a perfect circle.

I stopped pre-cutting circles altogether about a thousand blanks ago...

With smaller <10" green wood I put the the half billet cut to length with the chainsaw straight on the lathe.

For <10" seasoned wood I quickly nip off four corners on the bandsaw with jig and quick straight push cuts and approximate angles.

For >10" green or seasoned I cut to hex on the bandsaw with jig and quick straight cuts and approximate angles

On larger blanks above 15" I often roughly nip off a few more corners, particularly near the end grain.

Straight cuts with a 1-¹/₄" blade with 1 or 1.3tpi gets the job done quickly.

Whether it is quicker to pre-cut the >10" blanks first on the bandsaw with straight cuts or just turn down to round on the lathe is a toss up... until trued the lathe speed is restricted and you do get up to speed quicker with the larger pre-cut blanks. I found no time benefit from pre-cutting to round after I got my larger bandsaw that allowed for the quicker straight cuts with the 1-¹/₄" blades. My blanks are sourced from local logs so your options, methods, priorities and preferences might be quite different from mine.

One side benefit of the offcuts is that I can use them in my wood fire and they are of more value than a greater volume of wood shavings that I have bag and distribute.

I was recently given a couple of dozen neat round blanks from a turner that has now passed on (to wherever turners go) that were prepared waiting to be turned at least thirty years ago. Happy to receive them as they included some nice woods and all very seasoned, but they did remind me of how much extra work the round blanks used to be on my small bandsaw.