Try a different blade. If it goes away it is the blade. If it continues it is the saw.
Try a different blade. If it goes away it is the blade. If it continues it is the saw.
How high is your blade raised when it makes the noise? Is the arbor flange hitting the underside of your insert?
My suggestion is to change your blade and maintain your ZCP. If noise persists, probably it is your plate. If noise disappears, probably there is something wrong with your blade.
All the best.
Osvaldo.
OK let's dig into the acoustics. 30 teeth x 60 revolutions per second + 1800 hertz. Can someone with musical talent say what note that is? On what instrument can it be played? Since we are considering air being pinched by the side of the teeth a wind instrument might be close, maybe a kazoo? Since it is happening on both sides of the tooth,,,two kazoo. (kazwoo?)
Anyway, opening the gap by a few thousandths should lower the volume.
I had the same problem when I changed to a phenolic insert. I never truly figured out the issue but I concluded that it was the teeth raking against the slot sides in the ZCI. I also use thin kerf blades. I cut the ZCI with Forrest WWII combo blade although I now use Freud Industrial blades almost exclusively. I figured the combo might have a bit larger set on the teeth than a rip blade. However, it still made the high pitch raking sound when I put the rip blade on.
I finally got fed up enough to spend almost an hour with coarse sand paper to open up the slot just a tiny fraction. Problem solved. That phenolic insert is hard and it will take a while.
Edit: I just realized it would have been a LOT easier to set the blade angle +/- 0.1* and "trim" the slot that way.
Last edited by Brian Tymchak; 09-20-2020 at 11:32 AM.
Brian
"Any intelligent fool can make things bigger or more complicated...it takes a touch of genius and a lot of courage to move in the opposite direction." - E.F. Schumacher
Yes, try a different blade. Make sure the blade is tracking properly and is tensioned correctly. You can turn the blade by hand with a dial indicator against the side at the table and at the wheels to look for oddities. If you don't have a dial indicator you can find one for cheap on Amazon. Very useful in the shop.
JKJ
Did you find the cause of the noise? I was going to suggest that since the insert is phenolic to take a black marker and coat the inside edge all the way around the insert and then see if you see a contact point. It will rub it off. The opening the slot up would do it also. This would tell you where to enlarge it.
Did some more investigation. First started by turning the belt by hand. Noticed that at a certain spot the tooth would rub (just barely) and make the scraping noise. Noticed it happened on both the right and left side, but more pronounced on the right side. Continued when I rose the blade. Turned the saw on and slowing opened the zsi It opened more on the left side (thats the way it tilts), the right side I opened up very slightly to as the stop doesn't stop at exactly 90 like it's supposed to. Long of the short I still hear the scraping but it's not as pronounced. If I took of the 90 stop, I could open it to the right slightly more and that should probably fix it. Interestingly enough I believe the blade has some wobble per se. When I watched it running I noticed right at the front of the inert that the blade almost had a slight wobble to it. Before I started all this I removed the ZCI and noticed the scraping like others suggested. Another thing I noted is the blade doesn't stay perfectly 90 at all heights. When I went to lock it at 90 I had the blade raised approx 1.5", I then raised the blade and noticed the top half of the blade moves slightly right, taking it out of square.
There is an adjustment on many bandsaws to align the guide post so it moves in a straight path from top to bottom. On mine I adjusted the post to center the blade in the guides with them cranked all the way up and all the way down. If you have bearing guides be sure none of the bearings are pressing on and deflecting the blade at any point, while adjusting and when running. Also, I adjust the saw until the blade is centered on the crowns of both the upper and lower wheel.
If there is wobble and the tires are worn they may need to be replaced. A warped or slightly bent blade can make the blade wobble, as can buildup on the blade or tires from cutting sappy wood.
I vote for wind noise.
"A hen is only an egg's way of making another egg".
– Samuel Butler