Re: Stripping Rubber - caution, long and tedious
--- In Indoor_Construction_at_yahoogroups.com, "barrysholder"
<barry_at_...> wrote:
> I just received Harlans rubber stripper and I can't quite figure
it out...
Rubber is sold in widths of 1/8, 3/16 and 1/4 inch. Any of these
will work. I'd buy 1/8 or 1/4 if I were buying new. The supplier is
FAI Model Supply. Either Tan Sport or Tan Super Sport is more than
adequate when learning to fly indoor duration or scale models. Tru-
Weight rubber seems to be best suited to sport models.
One pound of rubber is a *lot* for indoor - often a multi-year
supply. For model classes where rubber weight is unlimited
(Ministick, EZB, Int. Stick, etc.) it is often best to just strip
rubber to a few likely widths and then tie motors to length at the
flying site once you determine appropriate loop lengths thru
testing. For classes like F1d and F1m it's best to pre-make (and
weigh) motors at home. In other words, don't strip the entire one
pound box all at one time.
I'll walk you thru a visualization of the Harlan stripper:
With the crank on the right and the cutters at the back you have two
knobs, one on the left and one on the right. The two knobs control
the two overlapping blocks or "rubber guide". Rotate the knobs to
open the width of the slot in the guide as well as to vary the
position of the entire rubber guide left/right in relation to the
cutters.
The slot should fit the rubber strip width closely but still allow
the strip to move forward and backward freely. The slot width
adjustment is critical and typically the best way to set it is to
reduce the size of the slot until the rubber can't be moved and then
back off until it is just moveable.
The width of the cut rubber is determined by turning both knobs to
position the 1/8 or 1/4 inch(or whatever size)rubber strip in
relation to the cutters. I usually adjust it so the strip that is
being cut to the desired width is on the right or crank side of the
rotary cutters and the remainder is on the left.
With scissors, cut a few 4" - 5" long pieces of your rubber strip to
use for setting up the Harlan stripper. Don't just feed in a piece
of 1/8 or 1/4 and try to adjust the cut "dynamically"...it's harder
to do and you end up with the remainder strip (the one on
the "left") of varying width.
It is almost impossible to then use the remainder because there is
no way to determine which edge is variable. Variances in strip width
cause uneven drag thru the rubber guide and the result is inaccurate
cutting. Avoid this whole problem by setting up the stripper with
short sample strips and then cutting 8-10' or more of rubber all to
the same size.
Push the sample strip into the slot until it meets the rotary
cutters and turn the handle. You will feel it catch and draw the
strip into the rotating cutters and through.
You will need a tool to measure the width of the resulting cut. A
dial thickness gauge is preferred by most flyers (Mitutoyo 7300 or
similar. Check Ebay, much cheaper. Other brands are OK too such as
Peacock, SPI, Teclock, Chinese knock-offs, etc.) The Ebay search
keys "dial thickness gage" or "dial thickness gauge" will produce a
listing of gages that are available.
An alternative is a dial caliper. Not as user-friendly but will work
fine. Insert the cut strip and measure. You want the pressure of the
caliper jaws to be enough to generate a very slight "tug" but not
significant compression of the rubber. Cut rubber edges are often
slightly concave and the slight "tug" will compress just the edges
enough to produce a true measurement of the strip width. Hold the
sample strip in the caliper jaws up to a light to better visualize
the measurement.
Adjust both dials on the Harlan stripper to reposition the "rubber
guide" left-right as needed and cut another sample. The dials are
calibrated in .001", but much depends on the pressure of the jaws,
and the strip thickness (which varies on Tan usually from .038-
.045").
Always cut and tie rubber dry, never lubed. The lube will often
cause the knot to slip. Many people, including me, wash the talc off
the rubber and blot/air dry before cutting but that isn't a
requirement. The main reason is to keep the cutter blades clean and
sharp.
On the Harlan stripper the trick is to learn to move both dials to
move the 1/4" strip left/right. That is where the paper calibration
marks come in handy. By moving them both the same you can move
the "rubber guide" in relation to the cutters without changing the
drag on the rubber (by varying the opening size).
The Harlan stripper, because of its design, is vulnerable to nicks
on the blades so be careful not to bump them.
Small or thin rubber will gain a static charge as it exits the
cutters on the back side of the stripper and will cling to the
rollers. It then tends to get pulled back into the cutters. Keep an
eye on the out-spooling of the rubber and don't allow it to get
pulled back in.
Rubber in hobby stores from Peck Polymers seems to be Tan Sport from
FAI, repackaged. Sig's rubber is probably also Tan Sport.
Received on Thu Apr 27 2006 - 09:08:56 CEST
This archive was generated by Yannick on Sat Dec 14 2019 - 19:13:44 CET