Colibri, Wiru are better quality sets. Make sure the name & Origin
are on the sets as now there are some look alike Wiru type sets
made in India sold for a lot more than they are worth.
I agree with Kenneth, and would also add Bergeon to the list of
quality tap and die manufacturers. Watchmaker sets use a finer pitch
than that used by jewelers. If you are making threads on fine metals
(softer than brass or stainless steel), stick to the jeweler’s pitch.
If you have an Otto Frei catalog, there is a great description of
this on pg. 528.
I use screws a lot in my work. Often, I purchase tiny machine
screws of brass or stainless. You can find these at hobby shops, as
they are often used for model railroading. The REALLY tiny ones
(OOO-120) I get from Small Parts in Miami. www.smallparts.com.
They also sell individual taps and dies for these tiny screws. High
quality=not cheap, but cheap tools are not always the best value. If
you decide to use pre-machined screws, you can usually just thread
the screw into the soft metal for a perfect fit. I drill my hole at
80% of the diameter of the screw. Use lubricant, and just screw in a
few turns, back it out, and do it again. Again, this will only work
if you are screwing into a soft metal, like silver or 18k gold. If
you try this with brass, steel, titanuim, or even white gold, it may
not work, and you will have the added problem of extracting the
broken screw from the hole.
Please remember to use a lubricant when cutting threads with either
the tap or die. It is also important to be absolutely straight when
you are tapping a hole, and be very careful not to break the tap.
Yes, they do break if you start to bend them while tapping, and it is
very easy to do this. They are a real PAIN to remove, since they are
of a hardened steel (and you are crying since you just broke an
expensive tap!). Take a 1/4 turn in , then back out, then advance by
a quarter turn. If you are tapping into a “blind hole” (one that is
not drilled all the way through) be sure to remove the tap and blow
out the chips at the bottom, or you may break your tap. Also remember
that most taps are fairly pointed, to guide you into the hole, and
the point will hit the bottom often before the threads are fully cut
(breaking the tap). Most taps are in the $4.00 range, but the tiny
000-120 tap will cost you around $40.00! 00-90 screws/bolts are the
smallest size you will normally find in a hobby shop.
Having said all this, I must also tell you that most jewelers get
by with nothing more than a screw plate and small set of taps. A
screw plate is a small rectangular plate with a series of tapped
holes in it, in progressive sizes. The wire is filed to a point,
inserted into the hole in the screw plate, and the plate is twisted
around the wire. I have seen these used, but rarely are they in good
shape. The threads are usually worn out on the most popular sizes.
They are also usually in the watchmaker’s pitch.
If you are new to this technique and wish to try it, or will only use
it occasionally, I’d recommend the screw plate. Get a good one. If
you get the “bug” and want to screw or bolt a lot of things together,
just buy a matched tap and die in the size or sizes that you are
using. I doubt you will use all the taps and dies in a full set.
Doug
Douglas Zaruba
33 N. Market St.
Frederick, MD
@Douglas_Zaruba