Turbinedoctor,
Congratulations...Good catch!
I've used these many times with much success. Dont you love it when a plan comes together!!!
The most frequent application I've run across for tapered reamers, is to ream tapered holes for
tapered pins and dowels.
Tapered pins are my personal favorite when I have to dowel most things together. IIRC, they are
1/4" taper per foot.
Westinghouse, General Electric, & Allis Chalmers steam turbines are full of them...so are boiler
feed pumps, centrifugal multi-stage pumps, etc. ad nauseum.
They are primarily used to locate mated housings or joints that do not have gasketing. These joints
will usually have permatex, tite seal, or some other joint dressing.
Pros:
-- When assembling housing halves, you can set the pins with a couple of light taps from a small
hammer, and the pins actually locate the housing as you set it.
-- If a tapered hole gets buggered up, you can ream it slightly larger (deeper) and get a new
surface. You may have to drill a tad deeper before final reaming so that the reamer will feed in.
-- You can blue check the pin to confirm contact.
-- It is fairly (within .001") repeatable when done with care.
-- They are versatile...they can be driven with an air ratchet if done with moderation and a sensitive
hand. Just press a nut on the square drive end (carefully) and use a regular socket and air ratchet.
Use BOTH hands and keep the reamer axis in line with the hole axis...usually the reamer will follow
the hole pretty good. When you get close to the final depth, you can always go back to using the old
T-handle...
Cons:
-- A pin removal method is usually needed...a thread in the big end for pulling, or jack bolts in the
joint of the housings. The small ones can be punches out if they are in a drilled through hole.
-- Gasket thickness is critical sometimes, if exacting precision is desired. Go with the original
gasket thickness and blue check pin for fit quality.
-- If you ream a hole and the reamer bottoms out, the hole will NOT BE TRUE. You must drill the hole
deep enough that the ream never touches bottom...ask me how I know this one.
-- You really dont want to do this, but on occasion, I've had to actually cut off a reamer to match
the size of the pin diameter at the small end. This was recommended by a factory rep when there was
no other way. They replaced the reamer.
-- Care must be taken when installing pins...use a small hammer and dont beat the $h_t out of it. The
hole will dialate, destroying the intended accuracy.
I've never made any, but seems to me they would be ideal for locating mold halves, when making bullet
molds.
You will enjoy using these new reamers. Precision work with hand tools.
Nivlek