Trouble with older Grizzly 16" bandsaw and how to avoid blade wander?

[David Tolsky]

I own an 10 yr. old Grizzly 16" bandsaw. I've recently taken it out of storage and have it up and running again. I've got this bad side to side swivel of the whole table assembly that shouldn't be happening to my knowledge. If the table moves so does the fence and that can wreak havoc on standard cuts and resawing. I've recently begun resawing common red oak with horrendous results. Blade wander with a brand new 1" resaw blade. Have any of you experienced this side to side swivel and what can be done about it? The saw has a heavy cast iron table.

[Erik Loza]

David, no personal experience with your machine, especially whatever is going on with the cast iron table but in regards to "blade wander" (assuming we are talking about the same thing...), that is almost always a symptom of indadequate blade tension. You may or may not be aware of this but it takes a lot of tension to get the average 1.0" blade into cutting range. 1.0" blades really tend to magnify any issues with setup or with the machine itself. Have you tried something like a 0.50" blade, just to get the machine dialed in?

Erik

[John TenEyck]

The table shouldn't move; are you sure everything is tight and nothing's broken? As Eric said, are you sure your saw can tension a 1" blade. Many times the manufacturer is rather optimistic (read Marketing overstating it's capabilities) in what they say the saw can tension. My Delta 14" has tension marks for a 3/4" blade, but can't even adequately tension a 1/2" blade. It still cuts OK with a 1/2" blade, but it's definitely not optimum.

John

[Myk Rian]

Was the blade under tension during storage? Might have to replace the tires.
The table won't move if it's set in the trunions correctly.

[Tom M King]

I have the tension cranked WAY up on a 24" Centauro to do a great job of resawing with a 1" blade. I'm no expert, but it would surprise me greatly if a 16" bandsaw will tension a 1" blade good enough for a clean resaw cut.

[Susumu Mori]

My experience echoes what Eric and Tom said.
If you think about it. You push the wood into a 1-inch band. The band buckles easily unless tension is quite high. If it buckles, the blade angle becomes oblique to the wood and the tail (the opposite side the blade) swings to the right or left. If the band is as wide as 1 inch, the tail most likely starts to rub against the woods. These are all bad. I initially tried to keep the blade straight with the blade guides but nothing works better than just cranking up the tension. With my FB510, I had to crank it up beyond the 1-inch mark. Once it gets tensioned well, things start to work well. As many experienced guys here say, it starts to cut without blade guides. As Tom said, I can't imagine that my 14-inch BS can tension a blade with such a force.

My impression with 1/2 inch blades is quite different because I'm not sure if we can tension such a narrow blade as high as 1-inch blades. So, I rely on blade guides. Maybe other more experienced guys can give you more guidance but I would go with 1/2 inch with smaller saws.

[John TenEyck]

The recommended tension is the same for blades of the same type regardless of width. Said another way, you can apply just as much tension on a 1/2" blade as a 1" one. For example, Lennox says all their blades are designed to handle 30K psi.

John

[Tom M King]

Yes recommended tension may be the same for any width blade, but it takes a LOT more force to put that tension in a wider blade. The ability for a bandsaw to apply this force is the limiting factor.

[glenn bradley]

Tension aside, you have to fix that table issue. Did someone pick it up by the table while moving it and crack a trunnion perhaps? That would be my first point of inspection. For me, the main reason to remove a table when moving a bandsaw is to keep my helpers from using it as a handle ;-)

[John TenEyck]

Yes recommended tension may be the same for any width blade, but it takes a LOT more force to put that tension in a wider blade. The ability for a bandsaw to apply this force is the limiting factor.


Of course, and that may be the heart of the issue for the OP, but the conversation took a different turn there relative to whether or not you can tension a 1/2" blade as high as a 1" one.

John

[Erik Loza]

...it would surprise me greatly if a 16" bandsaw will tension a 1" blade good enough for a clean resaw cut.

Most of the Italian 16" machines will tension a 1.0" blade just fine. Not sure about any others.

Erik

[David Tolsky]

Glen my fear is that you may be right about the broken piece. I've already had a friend weld a broken cast iron piece beneath the table. By removing the table again I hope to get at the meat of the problem. I've got to stop that table from moving. Anyone in So Cal want to come over for lunch and check it out? 😉

[David Tolsky]

My resaw blade is actually 3/4" and I'm wondering about the tension issue. It seems I've got it almost as tight as it can be. How much tension is too much when using a resaw blade? I think I saw some loose bolts as far as the table goes, so I'll remove the table to check it out.

[Erik Loza]

Regarding the question about tensioning, my rule of thumb for any blade is, "As much you need to get a straight cut", without the guides being involved. And that amount of tension could vary. The tension you need to put into your 3/4" blade to get a straight cut on a piece of, say, 4/4 wood could be not enough to rip a piece of 12/4 wood of the same species. So, rather than get hung up on PSI figures, I just keep cranking until the blade does what I want. If the straight cut never happens, you have your answer as to whether or not your machine will handle that blade or not.

Erik

[John TenEyck]

Let's say you have a 3/4" wide blade with 3/16" deep gullets. That leaves you with 0.56" of width. If the blade is 0.025" thick you have a cross sectional area of 0.0141 sq. in. To get to a band tension of 25K psi you need to apply 353 lbs of force on it. You have two options to actually measure if your BS can apply that much force. One is take the spring out and measure the force vs. deflection of it. You can do that with a bathroom scale and a small hydraulic jack if you build a little cage to hold it all. An easier way to get there is to measure the strain in the blade as you increase spring tension. All you need are two small C-clamps and a vernier caliper. You clamp the vernier jaws onto the blade with a 5" gap between the jaws. At 25 K psi tension in the blade it will stretch about 0.0008"/inch. So for a 6" gage length you need to see a change in length of 0.004" on the verniers. If you crank up the tension but can't get that much stretch in the blade then either the spring isn't strong enough or the frame of the BS is bending too much. On my 14" Delta cast iron BS, I can't comfortably apply more than about 12K psi on a 1/2" x 0.025" blade. It still cuts straight as long as the blade is sharp and the set is equal on both sides, but manufacturers recommend 25 K psi or higher for best performance.

John