I'm making a set of lockpin spindles, or pinchucks as the woodturning
catalogs call them.
I'm wondering if there's an optimum diameter for the pin in relation to
the diameter of the spindle, which has a flat milled equal in depth to
the diameter of the pin. I'm guessing "educatingly" that the smallest
pin practical would give the best wedging action.
Probably not critical with wood, where I'll be using the spindles the
most, but they might have use in metalworking where a lot of accuracy
isn't needed--to hold a pulley for machining the OD of the hub, for example.
I can't find anything in my limited reference library, anyone have some
info on this?
TIA,

Ken Grunke
SW Wisconsin
http://www.token.crwoodturner.com/
Member, Coulee Region Woodturners AAW chapter
http://www.crwoodturner.com/



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I'm making a set of lockpin spindles, or pinchucks as the woodturning
catalogs call them.
I'm wondering if there's an optimum diameter for the pin in relation to
the diameter of the spindle, which has a flat milled equal in depth to
the diameter of the pin. I'm guessing "educatingly" that the smallest
pin practical would give the best wedging action.
Probably not critical with wood, where I'll be using the spindles the
most, but they might have use in metalworking where a lot of accuracy
isn't needed--to hold a pulley for machining the OD of the hub, for example.
I can't find anything in my limited reference library, anyone have some
info on this?
TIA,

Ken Grunke
SW Wisconsin

I've made up a number of those, too. For wood, I'd think it would depend on
the type of wood. Hardwoods would be OK with a small pin, but softwoods might
allow the pin to dig in and spin. Also the tolerance of the hole.

Might consider two opposing flats and two pins. Could make the pins shorter
and still get grip, yet keep pressures balanced.

John Martin

JMartin957 wrote:


I've made up a number of those, too. For wood, I'd think it would depend on
the type of wood. Hardwoods would be OK with a small pin, but softwoods might
allow the pin to dig in and spin. Also the tolerance of the hole.

Might consider two opposing flats and two pins. Could make the pins shorter
and still get grip, yet keep pressures balanced.

John Martin

The problem with two pins is having twice the chance of losing one in
the pile of shavings under the lathe, I'm sure you are no stranger to
that experience, John ;-) Otherwise it's a great idea, I may try it on
the bigger spindles. Maybe grooves in both the pin and spindle to allow
a thin O-ring to hold the pins on?

The set I had mad previously, which were too short, all used 1/8" pins
and it worked OK--they were from 3/8" to 1" spindle size. On the 3/8"
one almost half the diameter was milled away--not very good for accuracy
and the workpiece came loose more often.

I just finished the first one, a 5/8" with a 1/8" pin. My unscientific
conclusion is that a pin should ideally be no larger then 20% of the
spindle diameter, and 10% would give the best holding power for hard
materials but would be impractical below a 1/2" spindle size (1/16" pin,
5/8" spindle).

--
Ken Grunke
SW Wisconsin
http://www.token.crwoodturner.com/shop/
Member, Coulee Region Woodturners AAW chapter
http://www.crwoodturner.com/



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