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trophy
03-12-2010, 02:17 AM
I am trying to vac form Lexan .007" and .020" thick with limited success.
I keep hearing about wave length, what does this have to do with the type of plastic one forms?
I am using 22ga nichrome coiled wire, not sure what effect if any the ga has has on Lexan.
How far above the lexan should the elements be?
At present it takes 20 seconds to heat the .007" Lexan to a droop.
All help appreciated

spektr
03-12-2010, 02:40 PM
wave length.... It is usually referring to the IR part of the spectrum that the emitter transmits heat with. Usually has very little to do with forming, the plastic sees heat, the wavelength of the heat just changes the rate at which things heat up. There is some optimization available, but when cal-rod, nichrome wire and quarts lamps all have about the same effectiveness on plastic, with heating times within seconds of each other, I tend to not worry a lot about it.....

How did you like the Aussie Supercars in Bahrain?

Scott.

trophy
03-12-2010, 03:05 PM
Hi Scott,
thanks for the speedy reply.
Yes loved the V8's at Bahrain.
My current project (1/24th slot car body's) is making the latest Holden and Ford cars as raced at Bahrain.
Any ideas how I can get rid of the big bubbles that form on the bonnet and roof, I have sanded with 240 grit but has not helped.
Tried .020" holes but they show up in the finished parts.
Gill A

spektr
03-13-2010, 09:25 AM
VETTEL IS ON THE POLE IN BAHRAIN!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Get some 100 grit drywall screens and LIGHTLY sand the roofs.
The issue is usually the fact that large smooth areas seal off
before getting sucked down. My headlight lenses do the same
thing in mold tryout. Also strategically located xacto knife scoring
works well turning corners. Take a #11, my favorite, and with
the handle perfectly vertical, put the point of the blade on the
roof of the car. Rotate the blade 90 degrees and pull it towards you.
This makes a small v shaped notch. Keep the handle perpendicular-ish
to the mold surface and make mini-grooves around the corners.
.005 inch / 5 thou should do it without transferring to the surface
of the part. Try the screens first and remember to wrap around
the roof contour down the body sides just a bit to give the trapped
air a place to go ..

When are you sending me a couple bodies? I bet they ship better than
a good southern beer.......

Scott.

trophy
03-14-2010, 12:46 AM
Scott what are drywall screens.
and where does one buy them.
I have worked out what they are in fact I have some 10" disks but not called by that name.
I am sure the sheets are not available her in NZ.
Who knows what the mailman will bring.
Go the Holden to you guys there GM.

MyCattMaxx
03-14-2010, 01:56 AM
Drywall screens are sheets that look like a screen, has holes all over it.

spektr
03-14-2010, 07:19 PM
Imagine window screens coated with 100 grit media. Its for sanding down drywall mud after you tape the wall. Drywall in the states is the gypsum boards with hard paper facing we use for interior walls. I'm sure you guys have a similar product. Where they sell taping tools they should have it.. If not, GENTLY use 100 grit sand paper. just light surface scratches, not material removal. The scratches promote evacuation of flat surfaces.....

CRAAAAAAAP Vettel broke a header and settled for 4th.

COOOOOOOOL Schumacher was a non factor..

2 weeks to the AUSSIE GP........

Whats Nascar?

Scott.

MyCattMaxx
03-14-2010, 07:25 PM
Nascar is a race with 2 rules. Drive fast. Turn left...lol