Front-Back Bandsaw Blade Wobble - Woodworking Talk - Woodworkers Forum
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post #1 of 12 Old 01-18-2020, 06:43 PM Thread Starter
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Front-Back Bandsaw Blade Wobble

Hi Everybody,

I'm trying to find some help figuring out what's wrong with my bandsaw/blades. I have a Wen 3966T bandsaw, and with the original blade, it tracks perfectly. It's hard to find a 100.75" blade to fit it, so I've tried 100.5" and 101" blades. Grizzly had a closeout for some 1"x101" blades, and I'm trying to get those working - the other blade I've been using is a 100.5" wood slicer.

With either the Wood Slicer or the Grizzly blade, I cannot get rid of the front to back motion. If I clamp a piece of wood behind the blade with the table and rotate the blade, I'll get up to a 1mm gap between the blade and the wood that varies as I rotate (i.e. no gap to ~1mm). I get a similar but reduced effect with the wood slicer, and again, no front to back motion with the original blade.

I've watched a few videos on aligning bandsaws, including both of the Snodgrass videos (which are very helpful, except for this issue). I tensioned the blade and made sure the wheels were coplanar (they weren't due to varying tension), and then started to adjust them to try to minimize the issue. I tried to look for warp in the wheels and didn't notice any. I did notice the blade shifting on the wheels with this motion, particularly on the bottom wheel.

Is there something wrong about using a blade slightly off length, is this bandsaw a piece of junk, or is there something else I'm missing? Both the Grizzly and Wood Slicer cut well when new (the original blade did not...), but my concern is that the front to back motion will result in one part of the blade wearing out too fast (the Wood Slicer didn't last long at all).

Thanks!
-Andrew

-Andrew
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post #2 of 12 Old 01-19-2020, 12:13 AM
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Welcome to the forum, Andrew! Add your location to your profile so it shows in the side panel.

My gut feeling is that if you can get a 100" to 101" blade properly tensioned then it should work just fine. You can always have blades made to length but the bigger issue is that your blade(s) aren't properly welded. There should be virtually no front to back movement as the blade runs its course. If you have a large enough known flat surface upon which you can lay the blade then the entire blade should touch that surface (on its back). Even name brand blades are improperly welded on occasion, maybe not as often as lesser blades, but it does happen.

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post #3 of 12 Old 01-19-2020, 10:49 AM Thread Starter
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I put the first three blades I tried on my table saw, and sure enough, the last two had gaps under the welds. The Grizzly didn't have much of a gap, less of a gap than wobble. Since the new Grizzly blade is cutting well enough, do you think there will be any other adverse effects besides the blade wearing faster close to the weld?

I bought a set of those Grizzly blades and tried another one, and it is better but still has some of that wobble. I got 7 new blades from Grizzly (six on closeout). What are the odds of getting three blades with bad welds in a row? I guess I can keep sticking other blades on, but hopefully the current one is good enough. It's got to be less than 1/32" front to back...

Thanks for your reply!

Front-Back Bandsaw Blade Wobble-bandsaw-blade-table-saw.jpg
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-Andrew

Last edited by difalkner; 01-26-2020 at 11:23 PM. Reason: rotate photo
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post #4 of 12 Old 01-19-2020, 12:37 PM
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Iíve ordered from PSwood.com , they will make blades in any length. Mid priced timber wolf blades.

http://www.pswood.com/timber-wolf-bandsaw-blades/
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post #5 of 12 Old 01-19-2020, 01:18 PM
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I agree with David.

Since you have a blade that tracks perfectly, it is probably the other blades that are the issue, not the bandsaw. Those other blades all came from the same source and were purchased at the same time, so I suspect there was some manufacturing flaw that day, and they are not well made. I would contact Grizzly and see if they will replace or refund the defective blades, certainly the unused ones.

As long as you can tension the blade properly, small differences in length shouldn't matter. Because the blade drapes on both sides of the wheels, a difference of 1/4 inch in blade length translates to 1/8 inch of movement at the tensioner. Most bandsaws should accommodate that easily.

I buy my blades from a local shop that takes them off large spools and welds them to order. Last Tuesday, I walked in and ordered two 3/8 inch 6 TPI blades at 105 inches for $15 each. They made them for me on the spot and I walked out with the blades five minutes later. If you want 100.75 inch blades, they can make them for you. I asked about it a long time ago, and they told me that they ship orders all over the country:
http://www.industrialblade.net

Disclaimers: No relation, other than as a satisfied customer. There are similar custom bandsaw blade shops elsewhere, but Industrial Blade always gets it right for me and prices are reasonable.
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post #6 of 12 Old 01-20-2020, 01:35 PM
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I guess what I would ask is this. Is this front to back motion happening on both sides of the blade, the pic you posted shows a gap on the backside of the blade. Is it consistent on the front or is the gap showing up there as well? If there is no gap on the front side of the blade does it really matter what's happening on the back? I suppose the only issue is what could be happening with thrust bearing if the guides were set on the low spot on the blade. Does this issue have any significant effect on cutting material?
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post #7 of 12 Old 01-20-2020, 04:04 PM
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Quote:
Originally Posted by BNB187 View Post
I guess what I would ask is this. Is this front to back motion happening on both sides of the blade, the pic you posted shows a gap on the backside of the blade. Is it consistent on the front or is the gap showing up there as well? If there is no gap on the front side of the blade does it really matter what's happening on the back? I suppose the only issue is what could be happening with thrust bearing if the guides were set on the low spot on the blade. Does this issue have any significant effect on cutting material?
Good point, but it does matter what is happening on the back. Even if the front of the blade does not move when the bandsaw is running, it may move once you start cutting. The thrust bearings support the back of the blade as you make the cut. If the back of the blade isn't straight, then the teeth may move forwards and backwards in conjunction with the non-straight back of the blade pushing against the thrust bearings while cutting.

I think it matters, especially for curve cuts.
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post #8 of 12 Old 01-20-2020, 04:46 PM
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Quote:
Originally Posted by BNB187 View Post
I guess what I would ask is this. Is this front to back motion happening on both sides of the blade, the pic you posted shows a gap on the backside of the blade. Is it consistent on the front or is the gap showing up there as well? If there is no gap on the front side of the blade does it really matter what's happening on the back? I suppose the only issue is what could be happening with thrust bearing if the guides were set on the low spot on the blade. Does this issue have any significant effect on cutting material?
The blade material is parallel along the length of the stock, it is cut and welded so any variation on the back will show up opposite to that on the front.

The blade will only track properly when the weld is square so the performance of the saw will be effected by a defective blade.

Like everything else the quality of the finished product will depend on the care of the operator and the precision of the machine, often it depends on who welded the blade. When I was purchasing a lot of blades I insisted that one particular employee weld the bands because I knew he cared enough to put out a quality product.
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post #9 of 12 Old 01-26-2020, 05:25 PM Thread Starter
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Thanks for the replies guys! You guys are right, the blade is parallel away from the weld, so the front and back are wobbling together. I did check previously just to see if the weld was less thick.
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post #10 of 12 Old 01-26-2020, 09:16 PM
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Some minor front to back wobble won't hurt anything. As for you bandsaw setup, go back & watch the Snodgrass videos. Pay close attention to his comments on "coplaner!" You can buy or make a jig for silver soldering bandsaw blades. Sometimes a blade will brake prematurely and you can salvage it by grinding a bevel and silver soldering it back together.
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post #11 of 12 Old 01-30-2020, 07:20 PM Thread Starter
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Yeah, I remembered that he pointed out that it should be a little off co-planar. With this blade (1" thickness) it actually needed a bit of adjustment at the bottom to get it to line up so it was centered on the wheels, and not hitting the front or back of the guard (it tended to ride a bit forward on the bottom wheel and back on the top wheel without adjustment).

-Andrew
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post #12 of 12 Old 01-31-2020, 01:31 PM
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Save yourself a LOT of grief and watch "Band Saw Clinic with Alex Snodgrass" at
I order all my bandsaw blads from Carter Products.
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