Hello again people! I am going to be building a speargun as you have seen in my other posts. My question is. Using prepreg can I get away with using a shrink wrap to pressure it or do I need vacum bagging?
Thanks guys!
vacuum bag
Shrink wrap tape will apply far more pressure than a vac bag. It’s all you need.
It would be a sleeve or a tube that would fit over the parts.
Shrink tape works best on round mandrels, any shaping and vacuum bag is best. Shrink tape will also leave a slight spiral pattern as well.
Vac bag will apply far more pressure than any shrink tape on this world. But shrink tape works also.
I was under the impression that shrink tape applies approx. 10psi?
I thought I had read somewhere that shrink tape can make 90 psi and that’s the same as an autoclave.
This data sheet says just 7lbs ! http://www.acpsales.com/pds/Shrink-Tape-PDS.pdf
Still I do it often enough and it works great, no need for vacuum bagging as the tape is easier to do for me. It also will not pinch the laminate up as a vac bag might.
Plenty to choose from for your application, the tape is more versatile, especially with joints and changes in diameter etc.
Good supply from these people - http://www.shrinktape.com/
HI-SHRINK TAPE SELECTOR GUIDE
115R 210R 220R
Film Polyester Polyester Polyester
Shrink Percentage 15% 10% 20%
Shrink Force (lbs) 4.5 5.5 7.0
Shrink Initiation 150°F 65°C 150°F 65°C 150°F 65°C
Temp @ Max Shrink Force 302°F 150°C 302°F 150°C 302°F 150°C
Max Recommended Usage Temp 356°F 180°C 356°F 180°C 356°F 180°C
Melt Point 484°F 251°C 484°F 251°C 484°F 251°C
320R 520R 208X
Film Polyester Polyester Polyimide
Shrink Percentage 20% 20% 8%
Shrink Force (lbs) 11.5 22.5 7.0
Shrink Initiation 150°F 65°C 150°F 65°C 158°F 70°C
Temp @ Max Shrink Force 302°F 150°C 302°F 150°C 410°F 210°C
Max Recommended Usage Temp 356°F 180°C 356°F 180°C 752°F 400°C
Melt Point 484°F 251°C 484°F 251°C N/A N/A
If you need you can go to home depot and buy the film used to cover the floors while painting. I’ve used it before in a pinch.