Replies

1. 
   WillGeorge | Jul 08, 2005 10:57pm | #1

   What should I be looking for?

   Just me... A nice straight cut! Rip and a miter...

2. 
   Steinmetz | Jul 08, 2005 11:14pm | #2

   Mark, Woodwork is not rocket science: even if every measurement was 'dead on' to specs, the material (wood/fiber etc) will flex/ bow/swell/shrink/twist/and deform enough to 'belie' all those efforts to be absolutely perfect

   With wood, the emphasis should be on close (but not zero,) tolerance and repeatability. Use jigs to accomplish the two. I rely on known dimensions, when setting up any operations to check settings.
   Don't assume the degree marks on your miter gauge are accurate or the height adjustment dial and angle selector is consistent.

   I keep and use various sections of aluminum/steel or brass bar or flat stock to quickly set and check the fence to blade parallelism ie: 1/4" 1/2 3/4 7/8, 1' etc together with some smaller shim stock can be selected and stacked to arrive at just about any required setting.

   I also make up aluminum square and angled references to quickly
   double check settings that must be reused over and over .
   Steinmetz.

1. 
   WillGeorge | Jul 08, 2005 11:21pm | #3

   DAMN.. Better reply than mine!

3. 
   KeithNewton | Jul 08, 2005 11:41pm | #4

   Mark, That sounds good to me. I have found that sometimes if it is not so good, that I can improve the runout by putting a reference mark on the inside flange, and on the inside of the blade and then testing the blade in various positions.

   I would start by locating the point of maximum runout at the top of rotation. Mark both the blade and the flange at this point. If the runout stays at the same point on the blade as you loosen and rotate the blade to another position, all of the runout would be in the blade. If it stays at the same point relative to the high point on the arbor, then obviously the blade is good, and that .001 gets doubled each time you double the distance out from the center of rotation.

   Having said all of this though, I would suggest that each time that you try repositioning the blade, that you start and stop the motor, and as the motor winds down, while sighting down the plane of the blade, watch for there to be a little bit of wobble in the blade as the blade slows down through the descending RPMs. . You may be more able to find the sweet spot easier by eye than trying to measure for runout when the blade is not spinning.

   After you align the blade to the slot, the fence to slot, the final check is to inspect both sides of the kerf for signs of the back side of the blade cutting on its way up. There should not be any scratches from the backside up-cut.

1. 
   MarkRD | Jul 08, 2005 11:54pm | #5

   Keith,
   Thanks.
   I'm wondering how the blade "wobble" changes as the blade gets up to speed. I suspect that some of that .008 is going to "go away" (especially since I'm using a thin kerf blade).Also, I find it pretty hard to SEE a change of .005 (I can feel it but naturally wouldn't touch a moving blade :-)Mark
   

   Measure it with a micrometer, mark it with chalk, cut it with an ax.

1. 
   KeithNewton | Jul 09, 2005 12:56am | #6

   I could not swear that the wobble is not induced by belt memory vibration or something, but when I am mounting a blade that I need the best possible cut that I can get, this is something that I do watch for along with making a cut and inspecting both sides of the kerf for any unwanted scratches due to run-out, vibration, or line of feed. I do think that I can see it if there is more than I think there should be.
   The amount of static run-out will be greater as the RPMs are descending, like a tire that is out of balance will be greater at a certain speed, and may diminish at a higher speed.As far as touching the blade, you can feel of the blade with the tip of a pencil just behind the teeth, and the marks will give you feedback for where the high point is.
   You can use your chalk if you prefer.