Runout: arbor to blade impact?

[orren countin]

I checked the runout on my saw using a quality gauge. On the face of the arbor I saw perhaps saw a .0005" change, really just noise as I rotated the arbor.
I put in a brand new unused 10" blade and saw a .009" runout measured below the gulleys near the teeth.
Another 2 used blade measured about the same runout or .009".
What is the multiplier to from the arbor measurement to the near edge of a 10" blade?
These blades are 10" 80tooth carbide, $20 on sale variety, Kensington and Concord Blades PN WCB1000T080HP.
what are you thoughts?
Thanks

[johnny means]

I wonder why you are measuring this stuff? Does the saw give you problems?

[Dan Friedrichs]

No blade will be perfectly flat, so it could be error from that - not necessarily the arbor.

When people measure alignment of miter slot to blade, it's recommended to mark a particular spot on the blade and rotate the blade by hand such that you're measuring against the same spot on the blade on both the "front" and "back" end of the miter slot, exactly for this reason.

[John TenEyck]

I drew that out in SketchUp using your 0.0005" runout on the arbor at 1" from the center of the arbor. At 4.5" from the center of the arbor, about the bottom of a tooth gullet, the runout would be 0.0.0028". Seems like something is amiss with your measurements or those blades. I've never measured anything more than about 0.003" at the gullets on 10" blades I've tested.

John

[orren countin]

Im seeing swirls in the cut and thought I could reduce them so not needing to joint

[orren countin]

I ripping so no miter involved.

[Lee Schierer]

With blades you generally get what you pay for. A $20 blade isn't going to give you the performance of a better quality blade. I looked at some of those blades online and I don't see any indications of prestensioning like you see in better blades. Note:Tensioning Ring (Carbide tipped circular saw)The area in the blade where it is pretensioned for maximum flatness over a broad temperature range and operational speed. Can be seen on most blades as a faint ring approximately 3/4 the diameter the blade.

Your measured run out of the flange would give you about .0025" at 10 inches, or roughly 4-5 times what you measured at the flange.

[orren countin]

I drew that out in SketchUp using your 0.0005" runout on the arbor at 1" from the center of the arbor. At 4.5" from the center of the arbor, about the bottom of a tooth gullet, the runout would be 0.0.0028". Seems like something is amiss with your measurements or those blades. I've never measured anything more than about 0.003" at the gullets on 10" blades I've tested.

John
your awesome. You read my question and provided a great response. I must have blades that have runout on them. Ill myself a good blade and test again. The Forrest blades state a runout of <.001 and they say other blades its common to see .010 on other blades. I try again with one of those.

[Lee Schierer]

Im seeing swirls in the cut and thought I could reduce them so not needing to joint

Swirls are generally caused by poor blade alignment to the miter slots. Thin kerf blades will also give you more blade marks than full kerf blades. Also an 80 tooth blade (Concord Blades PN WCB1000T080HP) is the wrong blade to be ripping with.

[orren countin]

Nice. Thank you. Im gonna get a good blade and try it again.