New Convert

[tomausmichigan]

Brent


Thank you for all your work, your clear explanations, the great
drawings, everything! I have made 8 jigs of varying heights and
sharpened several plane irons with great success. I put a 3* back
bevel on my LA block plane and was working a convex curve, when I
realized I was planing against the grain and getting a decent surface.
THAT never happened before! I can't believe how fast and fine the 3M
paper cuts.

I did notice that the extension calculator gives strangely non-linear
extensions for minor changes in jig height, specifically from 1.687 to
1.75. I ended up making a 29* plywood jig rather like the LV original
angle setting jig but much larger, setting the blade extension from
that and marking that number down. I suspect consistency is more
important than absolute accuracy in degrees.

Keep up the good work! I have banned 'chipbreaker' from my
vocabulary.

Tom

[tomausmichigan]

Brent

Thanks for all your work,the clear explanations, the great drawings,
the photos, everything! I have made several jigs in several heights
and honed some plane irons with great success. I put a 3* back bevel
on a LA plane iron and was working a convex curve ,when I realized
that I was planing against the grain and getting a decent surface.
THAT never happened before!

I wonder about the extension calculator. It seems to give strangely
non-linear extension values for minor changes in jig height,
specifically from 1.687-in. to 1.75-in. I ended up making a plywood
gauge at 29* rather like the original LV angle setting jig, only much
larger. I suspect that consistency is more important than absolute
accuracy in degrees.

Keep up the good work! I have banished the word 'chipbreaker' from my
vocabulary.

Tom

[Brent Beach]

Hi Tom

Glad you found the pages helpful.

On the extension calculator, could you give my the full set of inputs
you used so I can see what is happening.

In general, an increase of 0.01" in jig height should require an
increase of about 0.02" in extension with a sharpening angle of 29
degrees. Since 1/32 is about .03" you should expect an increase of 1/32
every couple of 0.01" change in height. Because it rounds to 32, the
jumps can be irregular.

The calculator shows the actual angle to 0.1 degrees.

As you say, an angle around 29 is usually fine. A small error in setting
the extension does not matter a lot - you should hone to a good edge
anyway. Small variation from one honing to the next will not matter
much. You might have to hone a few seconds longer.

In looking again at the extension calculator and at the analysis I did
to get the formulae, there appears to be an error in the calculator. It
may be that when I changed the calculator to handle slanted jigs I made
a mistake.

I will spend some time on it tomorrow and make sure it is correct.

On the abrasives, aside from cutting quickly and having PSA backing, the
3M are readily available from a couple of online merchants. I have
tried to get other abrasives of equal quality and have had a lot of
trouble finding a source that will sell the quantities that sharpeners
need - no, 50 sheet packs will not be ok. I continue to look for other
good abrasives.

Brent

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Victoria, B.C., Canada