Paddleducks
Old Yahoo Group => Yahoo Messages => Topic started by: Derek Warner on June 14, 2005, 06:51:36 AM
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Morning paddleducks
With PS Decoy I have to build one conventional type ventilator - dimensions of 1 1/2" diameter mouth x 1 1/2" depth (38 x 38 mm) on say a 6" (150mm) height
Was going to use brass shim, but am interested in styrene - can it be pressed (deformed 38 mm) with a male & female former?
Any comments on moulding styrene sheet greatly appreciated
regards Derek
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I often use styrene sheet to make parts for my models.... I've made
all sorts, from gun turrets, ventilators, lifeboats, and even full
hulls.
To make small parts such as you want is relatively easy - though some
practice is needed to get it just right. A female mould is not
normally required, just a male mould....
Lets assume you wanted to make a small lifeboat as it's an easy one
to explain...
1. Make a MALE mould in the shape of the hull
2. Then take 2 1/8" pieces of plywood and cut a hole in each the same
shape as the top of the boat (ie the deck level)
3. Using small nails or pins fasten the two pieces of ply together so
the two cutouts align EXACTLY. These don't need to clamp the pieces
together, just simply allow you to quickly and easily align them at a
later stage of the process...
4. Get a sheet of tin that fits neatly into your oven - Don't try
this while your wife is around, she'll kill you!
5. Turn the oven on LOW - I find around 90 Celcius in an electric fan
oven is about right, and place your styrene sheet onto the tin plate
and pop it into the oven.
6. Watch the styrene VERY CAREFULLY - you'll see it just start to go
soft and buckle when it reaches the right temperature - This is a
critical stage... Too hot and it'll melt or tear when placed over the
mould, too cold and it wont take the shape you want. Experiment with
simple shapes to get the correct temperature.
7. Put the styrene into the plywood plates to make a sandwich (ply,
styrene, ply). It's best if the aligning pins go through the styrene
to hold it firmly - They should push through easily if the styrene is
at the correct temperature.
8. Take the ply/styrene sandwich and quickly press it firmly over the
make mould... Hold for a few seconds to allow the styrene to cool and
voilla!
A few points to remember... The temerature is critical, and you MUST
work quickly once the styrene is ready to mould... A little practice
will soon get you into the swing of things.
Getting back to your vents, I've made smaller versions by maing them
in two parts.... An upright tube (easily obtainable) and then
moulding the cowl by using a marble as a mould and 2 pieces of ply
with holes drilled into them so they slip easily over the marble.
Once moulded and trimmed a little, just glue the cowl onto the tube
and there you have it... Instant ventilators - Well almost :-)
I hope that helps.
Regards
Eddy
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Hi Derek,
I should have said that I have made lifboats up to 10" long using the
technique I described, a vac forming machine is only really needed
for items larger than that, so your vents should be pretty easy.
Good luck
Eddy
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Hi Derek,
One thing I forgot.... If once youve moulded the top of the vent, you
glue a length of 1/16" square styrene around the cowl, it gives an
easy mark to trim the cowl to final size, and also makes it look like
the metal has a turned flange on it... Just finishes it off nicely.
Okay, enough for this evening....
Regards
Eddy
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I'm grateful to Eddy and Derek for raising this issue. This entire
discussion on styrene is very interesting..not to mention, IMPORTANT
to paddler building. Although you are both referring to the use
of styrene for fittings, I would like to offer my own comments about
its use on superstructures.
Owing to the critical weight considerations of paddlers (particularly
side paddlers under 48") light styrene can be considered an essential
material in building everything from paddlewheels to entire
superstructures. As we have seen many times, the lighter you can make
the superstructure and the lower down you can move the Centre of
Gravity, the more stable the boat will become and easier to control.
I have recently witnessed the use of much 1/8" ply being used on the
superstructures of both kit and scratch built R/C model ships. At 1:48
this represents a huge scale thickness of 6". Not only does this add
far more weight to a superstructure than necessary, but it is also
unrealistic and FAR MORE difficult to cut accurately than styrene. I
find it hard to believe that the superstructure of a paddlewheeler
would be 6" thick!
When I first acquired my own 1:64 RMAS "Director" sidewheel Tug, the
superstructure was made from 5/16 ply! This meant the superstructure
walls were a scale 9" thick or more. This created a lot of
unwanted weight and, combined with ALL the other C of G issues it had,
it was virtually impossible to operate without capsizing. This was
probably why the owner was anxious to dispose of her for a mere $20.00
!
1/16th aircraft ply is also used extensively in model ships and
although far more suitable than 1/8" ply, it still represents a scale
thickness of 3" at 1:48.
In my opinion the MAXIMUM thickness of ANY material we should be using
for 1:48 superstructures should be 1/32 or a scale 1.5". For those who
like to work in wood, 1/32 Aircraft Ply is available and a typical
cost in Canada is approximately Can$7.00 per sq. ft.
In styrene a very good equivalent is .020 (just under 1/32") and is
available here in Canada at just under Can$1.00 per sq. ft. The beauty
of this material is that it's so easy to work with. Cutting it is
literally a SNAP or it can be shaped with paper scissors. Gluing it
is instant as it joins even with lowly lacquer thinner and even has a
slight working time berfore it sets. I would NOT recomment the use of
CA (instant) glues with styrene but rather solvent adhesives which
"weld" the work together. By using formers, ribs, backing plates and
gussets, a very strong superstructure can be fabricated from this
material which is extremely LIGHT and has an appropriate and realistic
wall thickness.
An added advantage is that it can be "pounced" to simulate rivet
lines, bent conveniently with gentle heat and even, as Eddy
demonstrated, press formed into shapes. I have seen some lovely little
tugboat hulls vacuformed in the home! It's a material par excellence
for R/C model ship superstructures that does not rot, warp or split.
For almost "paper thin styrene", I go to our local "dollar store"
which sells a 16" x 12" "FOR SALE" sign for Can 0.98 cents. Using
a frame type construction, this is the material I'm planning to use
for the superstructure of my 1:64 "Director" Tug.
Where a wood superstructure is to be simulated, I have had success
with laminating wood veneers to the styrene either in panels and/or
strips to simulate planks. Self adhesive veneer edging can be
purchased in rolls from your local lumber store in a variety of
different woods including pine, oak and mahogany. So long as the
styrene is "keyed" first, a good spray contact cement will bond the
two materials well. CA can be used, except I don't trust it over the
long term.
So, if you have not considered using styrene sheet for your paddler
superstructures, do think about it seriously...it's a joy to work with
and it will save weight from creeping too high into your model and
creating those C of G problems which, as we've seen, can be so
devastating to a model paddler.
Thanks to Eddy and Derek for bringing up this fascinating thread, and
we look forward to hearing from ANYONE who has can share their
experience with this styrene.
PJ
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Styrene sheet.
After the write up that PJ has just given, what else is there to say except
to confirm everything he says?? However I would like to add a couple more
points on the plus side, just to try and convince anyone who is thinking
about it.
There is no priming and rubbing down required, to stop the grain showing
through, as is required for wood.
Cut it to shape with sharp knife and a ruler.
It never warps, rots or splits.
If you leave things slightly oversize it is very easy to rub it down with
400 or finer sandpaper to give invisible joints on the corners. Gussets are
easy and very effective indeed to give strength.
If you have a Dremel, don't try to drill holes with it. It is way too fast,
even on the slowest speed, and melts a bigger hole than you expected!!! I
use a pin vice to hold small drills and then hold the pin vice in a cordless
drill/screwdriver, on its lowest gear. Works very well. You can however use
a Dremel to mill away bits with the appropriate cutter. Go gently or it will
melt it and ball up on the cutter!!!
All I can say is" Give it a go" It really is great stuff to work with.
Glad to see you back on-line PJ.
David