pop bottle cowls

[rcaddict]

just tried to make a cowl using the shrink method but wasnt very succesful as the bottle was quite thick plastic, am i right to think cheaper thinner bottles will work best

[John Duncker]

I have had success with both thick and thin.

Generally used 2 litre Pepsi [ burp] bottles.

Used on my 12 scale combat models.

[nigel newby]

Just made a new windscreen for my plane. Used a Tesco diet lemonade bottle. The plastic is quite a nice thickness for it. Worth a try at about 49p a two litre bottle.

[PatMc]

I've used any type of bottle that's made of heat shrinkable clear plastic that happens to be handy.
Also shrunk the bottle over a glass fibre layup for more substantial hatches & simple cowls - saves a lot of sanding etc.

[Richard Harris]

I have found that the trick is to make your mould over size so that it is a tight squeeze into your chosen bottle, this way you dont have to shrink it to its extreme.

 

Painted on the inside it doesnt look to bad.

Here is a video I made many years ago on making a canopy from a pop bottle for a free plan I designed over on the other forum.

 

 

Rich

Edited By Richard Harris on 16/12/2018 15:46:22

[SONNY MONKS]

excellent job rich.

[rcaddict]

thanks richard i will try again - you make it look easy

[rcaddict]

so ive made the balsa mould and everything goes ok until i try to remove the mould from the shrunk plastic, any tips

[Stearman65]

Great demo.

[Denis Watkins]

Posted by oldgit on 06/01/2019 14:32:07:

so ive made the balsa mould and everything goes ok until i try to remove the mould from the shrunk plastic, any tips

You need the plastic hot yes, but too hot and there is more shrinkage that tightens the form

Also, a very smooth mould, varnish, dry, rub down, and again

Harder timber is better than balsa, as balsa does compress more easily, and allows that tight grip

But harden the balsa with the varnish as a minimum

Hardwood formers are waxed and polished

Edited By Denis Watkins on 06/01/2019 16:08:51

[rcaddict]

denis - I will varnish the mould as you suggeand try again

[Richard Harris]

If you watch the video I explain how I cut mine, I add strips of wood each side when making the former larger than needed before finishing it. This creates a gap to cut through and can be added to the rear and bottom, it can get quite thick around the neck of the bottle but a hacksaw blade goes through this with ease.

I've only ever had to varnish a former when I had some pulled on a vacuum former, balsa has always been fine for one offs.

Rich