Bandsawing problem

Is the blade tension high enough? It sounds like the thickness of metal currently being cut is the key. The blade want's to wander, and only the blade tension keeps this in check.

Joe Gwinn

I've seen it a few times. The chip load and friction is quite a bit higher in the middle of a big round cut. I've found it's alway been blade tension in my case. A squirt of kerosene now and then seems to help a little.

My opinion only.

I've seen this too, even with proper blade tension. As Yooper says it's the chip load filling up the gullets on a wide piece. A blade with bigger gullets (fewer TPI) or reduced feed rate/pressure usually fixes the problem. Art

A good point on the teeth per inch. I hadn't considered that.

It sounds as if the blade gets hot , expands , and loses tension. I wonder if a belleville washer could keep the tension more constant. Coolant might help.

Have you tried stopping the cut and rotating the part so the saw is not cutting a full 5 inches?

Dan

What it sounds to me like is that the blade tension is not high enough. I know that on the 4x6 saws, the tension needs to be as high as you can manage with the little knob provided -- a bit of pain is needed to get it close to where it should be.

But those saws will not handle a 3/4 blade, so you must have something larger.

Another possibility is that the teeth are losing their set on one side of the blade, causing it to bow towards that side. On the 4x6, there is a step turned in the wheels so the blade teeth are not contacted at all. If you try to use a smaller blade in there, it will iron the set out of the teeth towards the wheel. Saws made to handle a range of blade sizes use a rubber tire on each wheel for drive -- and to protect the teeth from contact with the cast iron of the wheel. If yours has the tires -- make sure that they are still in good shape.

Good Luck, DoN.

Chip load calculation and recommended chip load for various materials on page 18:

tension related. I thought I had the blade tight enough but maybe I've gotten weak. And thanks Dennis for the above link. Eric

You can get blades with varying TPI that are just for rounds and oddball shapes where a fixed TPI blade doesn't work that well. I think Starrett was one of the first with them, but most of the other makers have them now. That's if you're going to be doing a lot of that kind of cutting. Otherwise, get some Castrol stick lube and carry on.

Stan

You can get blades with varying TPI that are just for rounds and oddball shapes where a fixed TPI blade doesn't work that well. ... Stan

I've had acceptable results with a 10/14 TPI, 1/2" blade on a 4x6 bandsaw cutting 6" wide CRS plate the hard (but straight) way. A 6 TPI blade does work better.

jsw

I do use variable pitch blades. And flood coolant. What has me flummoxed is that this problem is new, occurs with different, new blades, and with blades of different pitches. So I think the problem is not related to the blades themselves. I'm thinking it may well be blade tension. The next saw job I'll try more tension and if that doesn't work I'll investigate the pivot points. Eric