screaming RAS shroud, any ideas?

[Mike Olson]

My Radial Arm saw has always made a high pitched banshee scream and after quite a bit of experimentation it turns out it has something to do with the Shroud over the blade. If I remove the shroud all I hear is wind coming off the blade. If I put in a smaller blade there is no scream. I have tried several 10" blades and they all seem to make the RAS scream.

I drilled 8 small holes along the back and inside face of the shroud hoping to kill the resonance but it did not seem to help at all. Was wondering if any of you might be able to give me any other ideas on what to try. I also removed the rubber dust shoot and the safety claw and nothing seems to help.

If you want to hear it you can see/hear it below
The RAS cutting starts at 0:30. My shotgun mic cuts out some of the higher pitch so it's not AS bad on video.
4:02 is using a smaller dado blade and there is no scream.


https://youtu.be/5_Riz99agvs

[Roy Turbett]

A similar question was posed in the March/April 1987 issue of Fine Woodworking (No. 63). David Snook, a saw service shop operator, responded that a whistling sound can be caused by the guard and is sometimes corrected by drilling holes in the guard. However, this is a hit and miss proposition and can sometimes make the problem worse. A screaming blade has a much more shrill and penetrating sound than a whistling blade. It is caused by an out of balance blade which causes it to oscillate or vibrate in the same way a ringing bell does. This problem requires a professional saw service with personnel skilled in hammering blades to tension or stress relieve the metal.

[Mike Olson]

maybe i'll try upping the size of the holes I already drilled to 1/4" and see if that helps. I'm hoping to not have to drill any on the outside face but perhaps i'll have to.

[Lee Schierer]

Does it make the screaming noise with all blades or just that one? I have a Craftsman Carbide tooth blade that is obnoxious on my RAS. When I switched to a Freud Blade..... no more whistling.

[John McClanahan]

I have a 50 tooth carbide tipped blade that screams just like that when mounted on my table saw.


John

[Mike Schuch]

My 16" blade screams in my 16" RAS. My 15" blades are dead quiet in the same saw. I always thought it was something to do with the tooth design of the blade. It sounds like it has to do with the proximity of the blade to the guard? Interesting!

[Mike Olson]

Does it make the screaming noise with all blades or just that one? I have a Craftsman Carbide tooth blade that is obnoxious on my RAS. When I switched to a Freud Blade..... no more whistling.
I have tried 3 different 10" blades in it and all of them scream. I might try a 7 1/4" blade from my circular saw to see how that reacts. but the 6" dado stack was quiet.

[peter gagliardi]

Take it off, and line the inside of it with something like the rubber self stick flashing tape, or the tape used to seal zip wall sheathing.

[Rick Potter]

Following up on Peter's idea....perhaps a can of that spray rubber that seals gutters and such (as seen on tv) would work even better.

[Mike Schuch]

I am thinking it has something to do with the air moving around the blade teeth being compressed when the teeth are near the guard. When there is more space between the guard and teeth the air doesn't compress in the same way and the sound isn't generated. I would guess that rubber or rubber compound would not change air compression and hence would not significantly muffle the sound.

But I am really just guessing... I would be real interested in someone proving me wrong by significantly reducing the sound by adding something to the inside of the guard!

[Mike Olson]

I don't like the idea of putting anything inside the guard that might separate and fall on the blade in a year or two. Tonight i'm going to try and add some spacers between the shroud and the motor to raise the shroud up a little at a time to see if that helps at all. If that doesn't work, then i'll increase the size and amount of holes. Thanks for the thoughts everyone.

[peter gagliardi]

I don't like the idea of putting anything inside the guard that might separate and fall on the blade in a year or two. Tonight i'm going to try and add some spacers between the shroud and the motor to raise the shroud up a little at a time to see if that helps at all. If that doesn't work, then i'll increase the size and amount of holes. Thanks for the thoughts everyone.
That is understandable, but the next time you are in a quality lumberyard, ask to see this product, you might be surprised at the tenacity of the glue!

[Roy Turbett]

You could also try adding a blade stiffener. I use a 5" Forrest stiffener on my RAS that gives me 2 1/2" of cutting depth. I also have a 3" version that I use on my table saw when I use a thin kerf blade.