Re: [tracker2] Jackscrew tool (and some grinding hints)
You can get small wrenches from automotive tool sources in sets called
"ignition wrenches." Or at least I suppose you still can, although I think
most cars don't have points and distributors anymore. I bought some
Craftsman brand wrenches from Sears about 40+ years ago, and I'd bet they
still sell them for working on lawnmower type engines and such. 3/16" is
just about in the small-to-middle half of the range. They come as
combination wrenches, open-end on one end and box-end on the other. The
box-end will likely still be too thick to fit the nut on the male D
connector, but the open end should fit. I've had occasion where I had to
grind the box-end thinner on one or two of the wrenches and that was easy
with an ordinary shop grinder, although they might someday break from being
A better solution is to buy the cheapest set of power screwdriver bits you
can find that has a 3/16" nutdriver bit. Or buy the individual nutdriver
bit if you can. You don't need super high strength steel because the body
of the connector you're screwing the screw into is soft and easy to strip.
Assuming the wall of the bit is too thick, chuck it in the chuck of a
power drill or drill press (the three equidistant chuck jaws fit fine on
the hex-shaped shaft) and while running the drill, place it against a
spinning grinding wheel. Remember you only have to turn down the wall for
a little more than a 1/4" from the end, just enough to clear the shell of
the connector. If you got bits made of cheap steel it'll be all the easier
to grind down. You might even be able to use a high-quality file pressed
against the bit.
Another good way of evenly turning down a round object is to drill a
matching hole in a piece of wood or metal and clamp the piece with the hole
to the grinder's tool rest so that the round object is held at an
appropriate spacing from the grinding wheel (wet the wood if necessary to
keep it from burning). Then just push the round object through the hole
and turn as it is ground away. Keep a container of water handy to cool the
By the way, I've found that many of the Dremel grinding bits are very soft
and the small bits wear away quickly when trying to remove a significant
amount of steel. Using a larger grinder (like an angle grinder) usually
works better, even if you are removing only a small amount of material in a
precise way. The secret is finding a way to hold the material in a precise
way. Sometimes you can do that with something as simple as a small C-clamp
tightened onto the tool rest so as to provide a backstop for the material
to be ground.
I've sometimes needed to shape metal in ways that ordinarily require
precision machine tools, but I've never had sufficient need to justify
buying the tools. You can buy small machine tools fairly resonably priced,
but then you'll go broke buying all the accessories you need to make them
useful for anything! I just haven't had that great a need, so I've usually
been able to find some workaround to do it with tools of lesser precision.
Just getting a decent quality drill press is a good compromise. Or even
a hand drill adapter will do in a pinch for just $30. Although I don't
have one, there's a little drill press adapter made by Wolfcraft that looks
pretty good to me that'll take any hand drill. It has its own chuck and
spindle bearing so you get accurate support and alignment for the hand
drill. I saw them at Home Depot recently.
Scott Miller wrote:
> This is a little bit off-topic, but it does actually relate to the Tracker2.
> Does anyone know where I can find a good tool for installing and
> removing the 3/16" hex jackscrews on the d-sub connectors? A 3/16" nut
> driver works, but it's hard to find one that fits well in the narrow
> clearance on the male connectors.
> A bit for an adjustable torque power screwdriver would be best, but I'll
> take what I can get.
> I used to work with a guy who had a tiny little 3/16" wrench on his
> keychain - I think he said it was an Apple part, but I'm not sure. If I
> can find a cheap source of those I'll buy a bunch and put them on the
- Hi Group,
Since there continues to be interest in this I'll fill the group in on what I
found and what I hooked Scott up.
Wiha makes a 3/16" nut driver that is small enough to do the DB9 males. It's
about $5. Details at:
To help Scott with doing production I decided to get him something he can put
in a torque limited electric screwdriver. I bought a 1/4" drive 3/16" socket
and a 1/4" drive to hex (screwdriver) adapter. Cost on these was about $2
each. I then turned down the outer diameter of the socket on my lathe. The
turning down took about 2 minutes, it was just the 30 minute trip to the
store that dominated the project.