Newsgroups: comp.robotics,cs.robots
Path: brunix!sgiblab!sgigate.sgi.com!olivea!spool.mu.edu!news.cs.indiana.edu!sandshark.cs.indiana.edu!jla
From: jla@cs.indiana.edu (jason almeter)
Subject: Re: Drills
In-Reply-To: hrynkiwd@cuug.ab.ca's message of Sat, 5 Feb 1994 06:24:51 GMT
Message-ID: <JLA.94Feb8112535@sandshark.cs.indiana.edu>
Organization: Indiana University Computer Science
References: <2ijh8s$pq8@handler.eng.sun.com> <CKqn5G.KvM@cuug.ab.ca>
Date: 08 Feb 1994 16:25:35 GMT
Lines: 75

>>>>> On Sat, 5 Feb 1994 06:24:51 GMT, hrynkiwd@cuug.ab.ca (Dave Hrynkiw ) said:

Dave> Forget the cordless drills - go for the cordless screwdriver!
Dave> These little babies have the neatest planetary geardown system you've
Dave> ever seen.  Even have mounting holes for the gearbox & motor.  And
Dave> depending on the size of screwdriver you get, you can mount an R/C car
Dave> motor to it.  I've seen this done here in Calgary at an R/C truck pulling
Dave> contest.  Sucker had so much torque he was smoking the tires at the end
Dave> of his 80 ft run.  Also speaks volumes for the abuse the planetary gears
Dave> could take.

Dave> No real electronics in mine (Black & Decker baby model).  Just a
Dave> simple chrg circuit, 3 position switch, and two nicads.  But that geardown
Dave> is just so *easy* to take out to use.  I'm just searching for a mate to this
Dave> one.  (SCAN GARAGE SALES!!!)

Dave> Post any other info you dig up, ok?  Lots of us Sumo-roboticists would
Dave> like to hear more!

This morning I thought I would open up my cord-less screwdriver and
have a look see.

A word of advice, if you have a Black & Decker Power Driver with
Automatic Lock, don't disassemble it, the planetary gear mechanism is
loose in there.  The automatic lock mechanism is not fun to put back
together.

I case you are curious about it, here is what I did and what I
learned.  If you disassemble your screwdriver, don't blame me if you
ruin it.  8^)

- There are two screws in the handle.  I removed these and opened the
case a bit to see the batteries.  The metal gear box held the front of
the handle closed.

- The gear box is held on with a U shaped clip.  I pried it out with a
screw driver.  When I finished removing it, the planetary gear
mechanism exploded onto my work area.  If yours is in this state, here
is what I found... 6 metal pins, 1 metal ring, 1 round carriage for
planetary gears, 1 triangular carriage for gears, 3 black plastic
gears, 3 red plastic gears, and 1 smaller metal gear still on the
motor shaft.

How I put it back together (in case you need to know)...

- The metal ring is keyed and should slide all the way into the
housing.  In the base of the housing is a somewhat triangular piece
attached to the tool shaft.  I believe that this 'triangle', the keyed
ring, the 6 pins, and the round planet carriage form the auto-lock
mechanism (when I got it back together, back-driving the tool locked
up).

- I inserted the 6 pins between the triangle and the ring, two to a
side.  When you get the last pin started, you can use the round planet
to drive it home.  This was the hard part, they don't want to go in
there.  I put one pin into each side and then put the other three in.
I alternately used a pair of needle nose pliers, a pair of tweezers, a
small screw driver, and 2 wood skewers.

- When it exploded, the black gears came out last, so I put them in
first on the pins of the round planet carriage.

- The triangular carriage has a gear that fit between the black gears.

- The red gears went on.

- The metal gear came off its shaft and went between the red gears.

- The handle (with screws reinserted) went part way in.  Then, running
the motor and applying a bit of force lined up the keyed motor shaft
and the metal gear and the handle went the rest of the way in.

- The U pin went in with a few raps from a screwdriver handle.

My seems to work, good luck.
