A while back I received some very good suggestions on RCM for turning
tapers. I put them to the test and turned some tapers with one new
wrinkle - the lathe tool was mounted upside down and fed from the compound
on the back side of the workpiece. This method suggested by Sherline
seemingly allows more control via better visibility.

Later I decided to make some WW square and hex collect blocks to use with
the small Sherline vise. Having a set of WW collets from 1/64 through 5/16
", the quick set-up collect blocks seemed like a good addition to my
Sherline collet set. So I set out to make everything on my big lathe, using
5C collets for good centering. Turning the 20 degree collect nose tapers in
the blocks was a piece of cake but then, Bam! Trouble reared its ugly head.
I had no tap to thread the WW collect opening in the drawbar for collect
closing. What to do? Careful measuring revealed the thread to be 9/32 -
40. Human, that's a strange one. None were found in my tap drawer. OK,
let's look in the catalogs and buy one - none listed in 3 or 4 catalogs,
none shown in McMaster-Carr on line.

What to do now?? Quitting wasn't an option with several hours work already
in the project, besides it would be really cool to have a pair of WW collect
blocks. So, hey!, let's make a tap to thread the WW drawbar. Raw stock
came in the form of a 5/16 drill rod turned down to 9/32. The drill rod,
held in a 5C collect, was threaded 40 pitch on the big lathe and the end
chamfered 3 threads. Then the new tap was heated to "beyond magnetic" and
quenched in oil. While still warm from the quench it was tempered for 45
minutes in a 350 degree oven. (the wife wasn't home)

So now if I ever need one again (unlikely) I have a very special 9/32 - 40
tool steel tap for threading the male ends of WW collets.

Bob Swinney

I think it is cool you made one . But MSC has them for
$18.46 ea.
Jim

"Robert Swinney" wrote in message
. ..
A while back I received some very good suggestions on RCM for turning
tapers. I put them to the test and turned some tapers with one new
wrinkle - the lathe tool was mounted upside down and fed from the compound
on the back side of the workpiece. This method suggested by Sherline
seemingly allows more control via better visibility.

Later I decided to make some WW square and hex collect blocks to use with
the small Sherline vise. Having a set of WW collets from 1/64 through
5/16 ", the quick set-up collect blocks seemed like a good addition to my
Sherline collet set. So I set out to make everything on my big lathe,
using 5C collets for good centering. Turning the 20 degree collect nose
tapers in the blocks was a piece of cake but then, Bam! Trouble reared its
ugly head. I had no tap to thread the WW collect opening in the drawbar
for collect closing. What to do? Careful measuring revealed the thread
to be 9/32 - 40. Human, that's a strange one. None were found in my tap
drawer. OK, let's look in the catalogs and buy one - none listed in 3 or
4 catalogs, none shown in McMaster-Carr on line.

What to do now?? Quitting wasn't an option with several hours work
already in the project, besides it would be really cool to have a pair of
WW collect blocks. So, hey!, let's make a tap to thread the WW drawbar.
Raw stock came in the form of a 5/16 drill rod turned down to 9/32. The
drill rod, held in a 5C collect, was threaded 40 pitch on the big lathe
and the end chamfered 3 threads. Then the new tap was heated to "beyond
magnetic" and quenched in oil. While still warm from the quench it was
tempered for 45 minutes in a 350 degree oven. (the wife wasn't home)

So now if I ever need one again (unlikely) I have a very special 9/32 - 40
tool steel tap for threading the male ends of WW collets.

Bob Swinney

Thanx for checking, Jim! After reading your reply, I went back and looked
in the MSC catalog again . . . . yep. ! there they were, in the special tap
section of the catalog. But hey! It was a good learning experience, anyway.
At $18.46, MSC's is a bargain! Figuring my time at $100 per hour *my* tap
worth about $300, not counting the Sherline threading attachment and 45
minutes of electricity to heat treat.

Bob Swinney
" Jim Sehr" wrote in message
...
I think it is cool you made one . But MSC has them for
$18.46 ea.
Jim

"Robert Swinney" wrote in message
. ..
A while back I received some very good suggestions on RCM for turning
tapers. I put them to the test and turned some tapers with one new
wrinkle - the lathe tool was mounted upside down and fed from the compound
on the back side of the workpiece. This method suggested by Sherline
seemingly allows more control via better visibility.

Later I decided to make some WW square and hex collect blocks to use with
the small Sherline vise. Having a set of WW collets from 1/64 through
5/16 ", the quick set-up collect blocks seemed like a good addition to my
Sherline collet set. So I set out to make everything on my big lathe,
using 5C collets for good centering. Turning the 20 degree collect nose
tapers in the blocks was a piece of cake but then, Bam! Trouble reared
its ugly head. I had no tap to thread the WW collect opening in the
drawbar for collect closing. What to do? Careful measuring revealed the
thread to be 9/32 - 40. Human, that's a strange one. None were found in
my tap drawer. OK, let's look in the catalogs and buy one - none listed
in 3 or 4 catalogs, none shown in McMaster-Carr on line.

What to do now?? Quitting wasn't an option with several hours work
already in the project, besides it would be really cool to have a pair of
WW collect blocks. So, hey!, let's make a tap to thread the WW drawbar.
Raw stock came in the form of a 5/16 drill rod turned down to 9/32. The
drill rod, held in a 5C collect, was threaded 40 pitch on the big lathe
and the end chamfered 3 threads. Then the new tap was heated to "beyond
magnetic" and quenched in oil. While still warm from the quench it was
tempered for 45 minutes in a 350 degree oven. (the wife wasn't home)

So now if I ever need one again (unlikely) I have a very special 9/32 -
40 tool steel tap for threading the male ends of WW collets.

Bob Swinney

According to Robert Swinney :

[ ... ]

Later I decided to make some WW square and hex collect blocks to use with
the small Sherline vise. Having a set of WW collets from 1/64 through 5/16
", the quick set-up collect blocks seemed like a good addition to my
Sherline collet set. So I set out to make everything on my big lathe, using
5C collets for good centering. Turning the 20 degree collect nose tapers in
the blocks was a piece of cake but then, Bam! Trouble reared its ugly head.
I had no tap to thread the WW collect opening in the drawbar for collect
closing. What to do? Careful measuring revealed the thread to be 9/32 -
40. Human, that's a strange one. None were found in my tap drawer. OK,
let's look in the catalogs and buy one - none listed in 3 or 4 catalogs,
none shown in McMaster-Carr on line.

To add to the fun -- that is not a normal thread form It is a
buttress thread. Look at a collet under magnification to see what it
looks like.

Here is an eBay auction selling them:

8921767285

He also sells the taps for the 10mm (D size) collet drawbars as
well. (Hmm ... he specifically says that the 10mm is a buttress thread,
but does not for the WW collets, so I may be wrong.)

Enjoy,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

Yeah, Don. Going in to this project, I would have guessed the littlle
collets were buttresss threaded but upon close examination they proved to be
ordinary 60 degree threads. I suppose in such small sizes there is not
enough loss in strength, standard over buttress, to justify the extra
complications of "square" threading. I would expect larger collet threads
to be more square; however I think 5C's are 60 deg. (not that I'm going to
try to make any).

Bob Swinney
"DoN. Nichols" wrote in message
...
According to Robert Swinney :

[ ... ]

Later I decided to make some WW square and hex collect blocks to use with
the small Sherline vise. Having a set of WW collets from 1/64 through
5/16
", the quick set-up collect blocks seemed like a good addition to my
Sherline collet set. So I set out to make everything on my big lathe,
using
5C collets for good centering. Turning the 20 degree collect nose tapers
in
the blocks was a piece of cake but then, Bam! Trouble reared its ugly
head.
I had no tap to thread the WW collect opening in the drawbar for collect
closing. What to do? Careful measuring revealed the thread to be 9/32 -
40. Human, that's a strange one. None were found in my tap drawer. OK,
let's look in the catalogs and buy one - none listed in 3 or 4 catalogs,
none shown in McMaster-Carr on line.

To add to the fun -- that is not a normal thread form It is a
buttress thread. Look at a collet under magnification to see what it
looks like.

Here is an eBay auction selling them:

8921767285

He also sells the taps for the 10mm (D size) collet drawbars as
well. (Hmm ... he specifically says that the 10mm is a buttress thread,
but does not for the WW collets, so I may be wrong.)

Enjoy,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---