| Precision shank adapter bushings convert
bits with 1/8" shanks into 1/4" shank tools for use in routers /
spindles with 1/4" collets. Most industrial grade spindles (e.g.
Colombo, Perske, Elte, etc) use collets and tool holders based on
international standards with collets available for most popular shank
diameters. Unfortunately, the vast majority of commercial and consumer
grade routers use proprietary collet / nut designs which offer
compatibility with a very limited set of shank diameters, typically 6mm,
1/4" and 1/2".
The clever lad in the back of the class asks, "Why not offer all of
your most popular tools with 1/4" shanks?" Good question The
answer is COST. The cost of raw 1/4" submicrograin carbide blanks
(before grinding) is more than the retail price of many of our 1/8"
shank tools. Now add the additional grinding necessary to remove
all of the excess carbide, and you end up with a tool that can cost as
much as 10X the price of the equivalent 1/8" shank tool.
A number of vendors offer "collet adapters", reusable split bushings
that slip onto 1/8" shank tools. Although a very good idea, a
survey of those currently available reveals that most of them increase
the total indicated
runout (TIR), as
measured at the tip of the tool, as much as 0.004" to 0.012". Runout this high is enough to break the
tip off of cutters 1/16" (0.0625", 1.6mm) dia. and smaller. Bad news for
us, since a significant portion of our tools are smaller than 1/16" dia.
PreciseBits adapter bushings are mandrel ground to exacting
tolerances. When pressed onto any of our 1/8" shank cutters, the
measured TIR is typically less than 0.0004" (0.01mm), precise enough to
be compatible with drills and cutters as small as 1/64" (0.0156",
0.4mm). This, of course, assumes that the TIR
of your router / collet is less than 0.001" (0.025mm).
Adapter bushings can be positioned anywhere along the 1/8" shank to
accommodate applications where deep reach is needed (rear position) and
others where the bit will be choked up deep into the collet (shoulder
position).
BUSHINGS CANNOT BE REMOVED OR REUSED! |
