I used the 1" Whiteside 6210 spoilboard cutter and cut 0.02" in two passes for both sides in order to get the piece as flat as possible, but, I always have problems trying to get the thickness of the material even after doing this.
For example here are the results I get:
1.123" and 1.152" doesn’t seems like a lot (You could just use something in between as the thickness of the material right?) But, I would like a more precise number so I don’t scratch the spoilboard.
I tried to change the method and use a table with glass on it like this:
Now I got 1.114" 1.116" & 1.112" That seems a lot more precise to me, What do you guys use to get the thickness of your boards using the calipers? Am I doing something wrong? Thanks.
Let’s assume your spoilboard / table is perfectly flat (been surfaced recently).
When you measure with the jaws of the calipers they need to be perfectly flat. It looks like you are using a good technique, squeezing the jaws with your fingers. I wiggle the caliper back & forth a bit, both sideways & up & down, while doing that until it settles into the smallest reading.
Are you zeroing or checking zero before measuring? It’s a little troubling that you would have that much difference between the jaws & the tail. Also zeroing the tail on the table before measuring that way?
A difference of 0.004" sounds reasonable. A 0.019" difference does not.
Also check the surface of your wood for loose pieces of grain, fuzzies, etc… a very light dusting with some 220 sandpaper on a block might get those numbers even closer.
If you’re doing a through cut, I would use bottom of stock as your zero (origin) in CAD then zero off of the spoil board. If your entered stock thickness value is larger than what your stock actually is then you cut a little bit of air when you zero off the bottom; but if you zero off the top, you cut the difference into the spoilboard.
If you havent fed your piece of stock through a jointer and planer or some other power tools to make it flat and the sides parallel, then the thickness of the board can vary wildly. You can’t assume wood right from the hardware store to be uniform in any dimension.
If all you’re worried about is not machining through into the spoil board, then what matters is how high your stock is at the point where you are setting the Z zero. Thats easy if you are zeroing on a corner. Clamp the board down and measure from the top to your spoil board. If you’re zeroing out in the center. Then you are at the mercy of your stock being flat. If the board is cupped or bowed or anything, you can’t easily measure how far it it sticking up above the spoil board.
I have the same caliper. Have you changed the battery? If the battery is getting low my caliper reads inconsistently. I would change the battery before you go crazy with a lot of adjustments.
The way calipers like this work is there is a little grid under that label. When you close the calipers and set zero and then move the head the grid is read by the number of pulses a receiver in the board receives. If the battery is low not all the pulses are read consistently and it makes the readings inconsistent.
