Hi!

I'm quitting tobacco on a taper method and am so distracted I can't
mill straight slots in a 1x2 bit of poplar, so I figured I'd just
ttalk about the latest design. Drawing out the agony helps make sure I
give myself credit for every positive step, and that I'll never
relapse; the experience is unforgettable.

Two knurled 10-24x2 inch brass flat head machine screws press two
1x2x15 inch bars of wood together running in two clearance holes in
the upper bar, and two through tapped holes in the lower bar.
Sometimes I reinforce such tapped holes with CA glue and run a stud in
and out until they pass class 2. Tapered sides make the knurled heads
accessible. A groove holds a Calrod element on each mating face.
Pressure takes the minor bends our of the rod elements. The side walls
near the face are tapered 30 degrees to allow a 120 degree bend to 60
degrees included angle. A few coats of varnish over a computer printed
card makes it a lasting asset. (Decoupage)

Holes adjacent the Calrod ends accept the (bent) element wires, and
from the far side, wood screws in tapered holes make contact with the
wires and accept a ring terminals. A DPDP switch in a simple harness
made from the toaster oven's power cord alternately applies choppped
AC power from the dimmer to the elements in series, and measures their
DC resistance in series with a meter. Ther resistance changes as the
elements heat up. I hope to find a percent resistance (maybe 125%) at
which the elements reliably heat acrylic from both sides for bending,
without any bubbling or sticking. The ohmmeter serves as a thermal
monitor, uncalibrated.

I'm so disturbed by the slow decrease of tobacco use I spend my time
wondering about things like "Am I breaking symmetry with this next
operation? How should I label the parts? What operation will follow
this one?" I'm just grinding through it. I make a LOT of mistakes
right now. I can't see the finish from here; there's a good drawing in
emachineshop.com format available. A sequence of operations is not
available. That's what I am developing.

That Kapton you all mentioned would ba great. Teflon tape might, not
evaporate at these low working temperatures but it is risky. I flamed
a bit of silver wire insulated with teflon deep in a vehichle chassis
once and smelled the phosgene formed. Yikes! I do not want that here,
so perhaps a wrapper fo Kapton would be appropriate, with the splines
used for screen doors holding it in place.

Off to read Wikipedia on Kapton.

Thanks to Gerry, Jim, David, and Don!

Doug


On Nov 4, 4:21*am, wrote:
I bought a toaster oven from Goodwill for $10 and removed all four 12
inch long Calrod heating elements. I say Calrod, which is a brand
name, and mean the type of element in a metal tube with MgO
insulation, not the wire coil in a quartz tube. They were wired 2/2
series/parallel in the toaster oven and each rate 575 watts.

I chucked one in the lathe drill chuck and placed the wire end loosely
in a tailstock drill chuck, then applied abrasive paper. I noticed the
outermost ends could be sandpapered to a bare steel finish, while most
of the length would not give up its grey oxide finish, most likely
from use in the oven.

I strapped one onto the inner surface of a bend I'd made before in 1/4
inch acrylic, connected it to a 300 watt lamp dimmer, ran the power up
slowly until the dimmer made the noise characteristic of passing and
clipping AC power, and ran the power all the way down, to find that at
this setting, the element would not even boil water. I ran it up very
slowly, and eventually got a pretty clean re-bend in the acrylic. A
half-wave rectifier would have doubled the control range. Full power
to one element would fry the cheap $5 dimmer. Four elements in series
definitely would not.

I'll clean the stuck plastic off the element with lathe sanding as
before. Maybe I'll wrap it with Tefflon tape next time. There was only
a little sticking.

I have the $40 metal bending brake from Harbor Frieght and hope to
integrate one element into the brake to heat plastics at or near the
bend point so they can be accurately bent. I'll need a bend clamp or
stop while the whole setup cools. I overloaded my bender and the steel
pivot body cracked. Cheap Chinese **** and one year warranty expired.
I'll have to duplicate the bending bar clamp holes and the mating
threaded holes in the back half of the new bender. The pivot body, of
course, was made of compressed Diet Tab bottle caps.

I'm just reporting on some of the fun I've been having here at
Replikon Research, working mostly on the MOEPED for my one-credit
Seminar and Project at NVCC, PHY 298, and developing a fully expanded
specification for a self-reproducing universal machine tool. And it is
fun.

A fully expanded universal machine tool could make it's own
transparent plastic machine guards, could mill flutes in a drill, mill
or reamer bit, grind or regrind bits, etc. There are lots of loose
ends to finish off.

Doug Goncz
Replikon Research
Seven Corners, VA 22044-0394
(Why not send me a QSL? That's a valid, complete postal address, at
least the clerk said it is.)