I'm going off of the usual clock "repair" subject this month and
dealing with a clock "making" tidbit.
I'm now in the process of creating a center wheel and arbor
assembly for the Fromanteel Reproduction Clock (a rather long
winded side project) and I'm including this particular portion
because I have yet to see - anywhere - a step-by-step procedure
for making a tapered center arbor with a solid pinion. What basic
knowledge and experience I may possess both come from many
compiled hours of failed attempts....trial & error...trial & error......
STEP 1: Use drill rod - or silver steel as some call it - for stock
(mild steel is no friend here). The diameter should be at least - and
better yet, practically the same as the finished pinion diameter.
Face off one end of the stock and drill a center hole.
STEP 2: Fit the center-drilled portion into the tailstock dead
center and turn down the thin 'carrier' portion of the arbor (which
extends through the plates and carries the most of the motion work
and minute hand).
It pays to take your time making this cut; such a long, thin section
(this one is 3/32" diam and almost 2" long) is really quite weak
toward the middle - even with the support. Too aggressive a cut
can ruin the piece - and possibly other things!!!
STEP 3: Next, turn down the next small step which will
eventually be your pivot surface in the front plate. Make sure to
keep your faces square here.
It is ok to remove the end support piece (now embracing the dead
center) after you complete this step. I use a jewelers saw to gently
remove it, then round off the end in the lathe.
STEP 4: This is the point where I switch the piece around in the
collet (the collet size will remain the same). Grip the piece so there
is a little over 1/2" protruding. First turn down the back plate pivot,
then the small 'intermediate' portion (make sure you chamfer the
edge of the pivot shoulder afterward). Finally turn down the
seating for the center wheel. It must be a nice push fit to seat the
center wheel (and remember to leave enough extra length to allow
for riveting the center wheel later).
STEP 5: Now it's time to form the pinion blank. Give yourself a
little more room to work (maybe an inch or more) and turn down
the opposite side of the pinion blank - a parting tool is probably
appropriate here (as seen in the photo). Doing this now will avoid
possible damage to the pinion after the leaves are formed.
STEP 6: Transfer the piece into the indexing head in whatever
gear cutting setup you have at hand. In this case I am using the
milling machine. You are now ready to form the leaves on the
I sometimes pre-cut the pinion with a circular slotting saw (not
shown here as I'd rather show the pinion cutter ready to engage).
The slotting saw will remove most of the waste, and to make an
easier job for the pinion cutters to come in late in the game as the
clutch reliever. Like a good relief pitcher in baseball --as tough and
well made as they are: they are wicked expensive, and should be
treated like the highly paid specialists that they are....
JIG: Here is where the jig comes into play. I have a steady rest
that came with the Schaublin lathe, but I'm beginning to believe that
it was not designed for it as I'm not able to work any piece with
the crosslide less than 8 inches long without interference. So I
made up this tapered brass tailstock female center drilled to-
perfectly (and I mean perfectly) - hold the front end pivot to lend
support to this section. The hole is drilled through the entire piece
to accept the thin "carrier" portion of the arbor. You can see it in
use in the next step.
As much as it seems a lot of work to make up a "one-off" type jig.
the carrying hole is perfectly reamed 1/8" and will be of use in
future projects. Also, it really didn't take all that much time to
make up as I knew the taper (2 degrees) of the tailstock. All in all
it took about 20 minutes to fabricate.
STEP 7: Finally, transfer the piece - with pinion formed - back to
the lathe in its original alignment (with brass tailstock center
employed). It would be best to hold the 'seating' section in the
collet because it is solid (you don't want to hold a pinion in a
collet......ever!!!) and any collet marks left on the seating will not
be seen once the wheel is riveted on. Now you can form the taper
(which, of course, will be of your own design) best cut from right
to left...very lightly.
A final note: it is easiest and most practical to do as much final
polishing as possible on each portion as it is completed. The
tapered arbor is very difficult to safely chuck in the lathe once
|This Month: 7 Fun Steps (and a jig) to making a Tapered
Center Arbor With A Solid Pinion
The center wheel and tapered arbor. The center wheel has been crossed out and
is ready for polishing. The arbor must be hardened first, then polished.
|1/8" drilled hole to accept
arbor front pivot.