Bandsawing

Ed in Tampa · Post by **Ed in Tampa** » Fri Feb 22, 2008 10:02 am

I had two interesting things happen in the last couple of days. I will tell of the first here and open another thread for the other one.

I was making some shelves for a project and I need to notch a corner out on each on to get around a support. I got my bandsaw down and set up a fence and began my cuts. I needed to remove a block two inches long and about an inch wide. As I was making these cuts I noticed the band saw was making a strange noise and at the end of the cut the blade seemed to be slowing down. The cut however was near perfect, the best I had ever accomplished with the bandsaw.

I had four shelves that needed this cut and on the second or third one it dawned on me what was wrong. I had forgotten to tension the blade. I stopped immediately tensioned the blade and proceeded. However the cuts were no where as good as the cut quality I was getting before.

The cut showed the normal bandsaw waver but when I looked at the cuts made with a untensioned blade the cut was dead straight. For the life of me I can't figure this one out. I would have thought it to be the exact opposite where a loose blade could wander all over the place and tensioned blade would be straight.

You should set the cut with the untensioned blade it looked like it was either hand sawn or done on the table saw the sides were smooth and perfectly straight.

Any idea why the untensioned blade actually cut better than the tensioned blade?
Ed

Ed in Tampa · Post by **Ed in Tampa** » Sun Feb 24, 2008 9:38 pm

Any Ideas why the cut would actually be better with a loose band saw blade over a properly tightened one?
The only thing I can think is the blade is damaged some how messing up the set of the teeth.
Ed

beeg · Post by **beeg** » Sun Feb 24, 2008 10:33 pm

I can only think of two things that might do that.
1. no set to the teeth.
2. the lack of tension allowed the blade to turn slower, but your feed rate was faster than it should have been??

Did the blade get bent or broken?

Ed in Tampa · Post by **Ed in Tampa** » Sun Feb 24, 2008 10:43 pm

beeg wrote:I can only think of two things that might do that.
1. no set to the teeth.
2. the lack of tension allowed the blade to turn slower, but your feed rate was faster than it should have been??

Did the blade get bent or broken?

No the blade didn't get bent or broken. I had just forgotten to tighten it. When I realized my mistake I set the tension to the correct setting and noticed immediately the cut quality actually went down. I was totally surprized.
Ed

charlese · Post by **charlese** » Sun Feb 24, 2008 11:28 pm

Ed in Tampa wrote:...
Any idea why the untensioned blade actually cut better than the tensioned blade?
Ed

No I don't, but since you aren't getting a lot of suggestions - thought I'd write something.

I'm thinking of a hand saw cutting a thru dovetail. You got that kind of cut with the un-tensioned blade. Obviously the speed of the blade together with the feed rate were perfect.

I think the question is really about the tensioned blade. What made the tensioned blade give an un-smooth cut. - - Are the blade guide blocks square? Was the speed too fast? I think (and that's just a hunch) that a fast moving blade may tend to set up a harmonic type vibration that might have caused the difference.

I've found that most of my short, straight cuts with the band saw are pretty darned smooth. Wavy cuts only happen with extended lines and curves, on 3/4" boards. There are saw blade marks on re-saws however. I usually run on speed A + , or almost B.

reible · Post by **reible** » Sun Feb 24, 2008 11:32 pm

Hi,

I don't have the shopsmith bandsaw and I don't have the instructions they have with the blades. In general this sort of bandsaw has a lever that indicates a position relative to some fixed measurement scale built in to the saw.

Several things can come into play, like the blades are not always the length they indicate... ie a 72" blade if measured could be 71-1/8 or some other number within some tolerance. The wheels have some sort of tire on them and the thickness of this can be different between materials and how much wear they have been exposed to. The material the blade is made of can be different... The indicator is a reference point but is not a positive point.

Some have gone to the lengths of purchasing a gauge that measures the tension of the blade, other look for a musical note range, still others use an amount of off set if you push the blade with your thumb.

Some blades will tell you the method they want you to use, what they say is for their blades no matter what type saw you have. One example of this might be Timber wolf blades and you can read about that adjustment at:
http://www.woodcraft.com/articles.aspx?articleid=391

Other examples of methods I'm sure can be found at other sites that sell other brands of blades as well as sites that deal with bandsaw cutting. Combine with type of blade and what you are cutting and how thick or thin the cut all make up for a lot of options. Perhaps some additional searching and reading will help better expain what you are seeing and even give you some more ideas of things to try.

I've picked a Wood Slicer this winter and can't wait to check it out when the weather warms, they are sold by Highland Hardware. They have a few pages on resawing that I'm going to put to some use... and hope for some very good results.

Ed

curiousgeorge · Post by **curiousgeorge** » Mon Feb 25, 2008 12:22 am

I've picked a Wood Slicer this winter and can't wait to check it out when the weather warms, they are sold by Highland Hardware. They have a few pages on resawing that I'm going to put to some use... and hope for some very good results.

Ed, what is a Wood Slicer?

a1gutterman · Post by **a1gutterman** » Mon Feb 25, 2008 12:24 am

It is a brand of bandsaw blade. Gotcha back George

. http://www.highlandwoodworking.com/index.asp?PageAction=VIEWCATS&Category=295

reible · Post by **reible** » Mon Feb 25, 2008 12:35 am

Hi,

You need to read the description at:
http://www.highlandwoodworking.com/index.asp?PageAction=VIEWPROD&ProdID=1293

I also picked up this blade for cutting green wood:
http://www.highlandwoodworking.com/index.asp?PageAction=VIEWPROD&ProdID=6944

I know some people who think the wood slicer is the best thing since sliced bread... which by the way I understand you can do with them.... These are the same people that turned me on to carter guides, also a great but expensive update. I think I might have to have a red light come on when it's running because is so quiet....

Ed

Also here is the like to the library there:
http://www.highlandwoodworking.com/inde ... ustom&ID=3

a1gutterman · Post by **a1gutterman** » Mon Feb 25, 2008 12:43 am

Say Ed,
What do you think about carbide band saw blades? Please see posts 4 and 5 of this thread https://forum.shopsmith.com/viewtopic.php?t=1232 .