Like they say there's more than Oneway to etc. cat etc. (pun
Over the years I have developed a simple way of measuring the bottom
thickness left or the depth to which to drill, that fits the way I
If I don't forget I will lay my blank face down, straightedge on the
top and measure between the straightedge and the table surface.
If I forget or forget the just measured measure,(does never happen)
than I will, with the blank in the chuck take the straightedge and
hold it to the back of the blank and measure from the straightedge to
the top of the blank.
Than to drill for instance the center of a bowl blank I detract the
tenon or recess measurement from the total and the wanted bottom
thickness to get the depth to drill to.
Now when I get close to the final inside depth and form I will use my
calipers, (mine are similar to yours, I got them at Lee Valley, I will
measure the wall thickness going down to the bottom,
Then (this works with my Stronghold chuck almost always) I slip the
straight leg down between the chuck jaws and measure the center part of
the bowl bottom, with a recess I get the true thickness and with a
tenon I have to detract its thickness to arrive to the thickness left
for the bottom.
Doing it this way I now NEVER make any funnels like that anymore, ya
right, now I only do it when I rework the foot or the recess, just
happened to me again yesterday DARN DARN DARN.
Have fun and take care Leo Van Der Loo
> I have usually estimated bowl bottom thickness using a rod touching the
> bottom and sighting across the rims, then holding the mark move it to
> the outside and sight. I found I often missed the true thickness by 3/4
> inch. If I took the bowl off the dovetail chuck and did a caliper
> measurement from the base of the dovetail recess to the inside bottom of
> the bowl, it often would not run true on rechucking.
> On ABPW is a rough drawing of how I made a dedicated caliper. It
> measures from the shoulder of the dovetail jaws but indicates the true
> thickness of the bowl bottom to the dovetail recess, while leaving the
> bowl on the chuck.
> I should modify the instructions to cut off the nib and tip of the
> straight leg first and check the measurement on the empty chuck. It may
> be possible to trim both the bowl side and the back side of the straight
> leg of the caliper to adjust for zero. I wound up taking too much off
> the curved tip and had to epoxy a dowel tip on, but it works great for
> me. It is easy to measure and tell how much more wood to take out
> without making a flower pot with a hole in the bottom.
> Gerald Ross
> Cochran, GA
> A millennium is like a centennial,
> only it has more legs.