new substitute for vacuum bagging?

[rocketsonly]

Hey, I was thinking, has anyone tried heat shrinking a specific mold or madrel, as opposed to vacuum bagging it? It seems pretty logical because the heat shrink will adhere very tightly, and you could do multiple layers if desired.

Any comments?!

 

[DynaSoar]

Originally posted by rocketsonly
Hey, I was thinking, has anyone tried heat shrinking a specific mold or madrel, as opposed to vacuum bagging it? It seems pretty logical because the heat shrink will adhere very tightly, and you could do multiple layers if desired.

Any comments?!

It's an empirical question. We can get some scraps and try it.

OTOH, how much heat shrink tubing costing how much? There's a vacuum system for sale for $195 in the Yard Sale section.

How big does heat shrink tube come?

 

[Stymye]

you can buy heat shrink tape in 4" wide rolls and heat shrink plastic in large rolls

I have used it to seal machinery prior to crating it up for overseas shipping, it's not cheap, but would work very well.

 

[rocketsonly]

Originally posted by DynaSoar
It's an empirical question. We can get some scraps and try it.

OTOH, how much heat shrink tubing costing how much? There's a vacuum system for sale for $195 in the Yard Sale section.

How big does heat shrink tube come?

I'm not sure how expensive it is, but Marvin's parents have HUMONGOUS rolls at about 13" wide and unlimited length (maybe not unlimited, but it sure will take a while to deplete it).

I've heard some people having success with a one of those food vacuums. I have one that my parents have never touched, so we'll try that out as well.

 

[DynaSoar]

Originally posted by stymye
you can buy heat shrink tape in 4" wide rolls and heat shrink plastic in large rolls

I have used it to seal machinery prior to crating it up for overseas shipping, it's not cheap, but would work very well.

100 feet of 1.5" ID heat shrink tube, $119.50
4 feet, $4.95
https://www.crowbarelectricalparts.com/Tape.htm

60 yards of 6" heat shrink tape, $33.14
https://www.boatfix.com/bymfg.ASP?make=SHRINK+FILM+ACCESSORIES

For what I think it's for, I think tubing would give better results. Tape wouldn't give as even a squeeze. Hard to say which would cost less in the long run.

 

[DynaSoar]

Originally posted by rocketsonly
I'm not sure how expensive it is, but Marvin's parents have HUMONGOUS rolls at about 13" wide and unlimited length (maybe not unlimited, but it sure will take a while to deplete it).

I've heard some people having success with a one of those food vacuums. I have one that my parents have never touched, so we'll try that out as well.

Well geez Lousie, empirical question indeed.

What's it take to shrink it, a hair dryer type thing?

 

[DynaSoar]

Originally posted by DynaSoar
Well geez Lousie, empirical question indeed.

What's it take to shrink it, a hair dryer type thing?

OMG! d00d! It may be a self-controlling process. You could be onto something here.

Lay out the shrink tape and wax it.

Epoxy the mandrel.

Slide the sleeve over it.

Epoxy the outside (won't take as much due to epoxying the mandrel first).

Wrap it with the waxed tape.

The heat of curing should do the shrinking! Or at least get the process started.

Ask [email protected] what he thinks.

The mortgage is due in today. Moving is days away! I NEED to get myself down there.

 

[rstaff3]

For all its worth, I have the Shadow composite techniques tape set and one thing he covers is heat shrink tape. IIRC he says it will work for tubes 4" and under but won't work well for larger items. It will only work for tubes, not fins or other items.

Shadow and Aerocon sell the tape also.

 

[wwattles]

My wife had some leftover heat-shrink sheets from doing some Christmas presents last year that she let me play with (the wrap, not the presents). I tried it on a hand-carved foam nosecone with a hairdryer as the heat source.

First problem was the heat from the dryer softening the foam.
Second problem was the uneven shrinking crushing the foam.

I was still somewhat new to the hobby at the time, and just went with a balsa nose instead, but you may have more success.

WW

 

[aksarben10]

Heat tape only worked on tubes. I have all the stuff and plan on trying it this winter, aerosleeve on a 4 inch tube with heat tape.

If you are looking to glass fins, I use a pressure technique instead. I sandwitch the fins in between thin 1/4 pink foam and MDF boards. I use clamps for pressure but I know that some people use a press, like a hydraulic arbor press.

It works out very well the fins come out very stong and smooth. All that is left is trimming off the root edges.

Scott

 

[rocketsonly]

Originally posted by DynaSoar
Well geez Lousie, empirical question indeed.

What's it take to shrink it, a hair dryer type thing?

Yea, it looks like a hair dryer thing, but the air blown out of it is ridiculously hot! You can get burned just from the air being blown out!

 

[shockwaveriderz]

I have used both heat shrink tape that has a mylar release layer on the inside so that it will not stick to the mandrel assuming you are using epoxy resin..I have also done some experiments with heat shrink tubing using a .002 teflon wrap on the inside to prevent the heat shrink tubing from sticking to the epoxied mandrel.... both seem to work pretty well as far as being CHAD (cheap and dirty) vacuum forming...

 

[DynaSoar]

Originally posted by shockwaveriderz
I have used both heat shrink tape that has a mylar release layer on the inside so that it will not stick to the mandrel assuming you are using epoxy resin..I have also done some experiments with heat shrink tubing using a .002 teflon wrap on the inside to prevent the heat shrink tubing from sticking to the epoxied mandrel.... both seem to work pretty well as far as being CHAD (cheap and dirty) vacuum forming...

Well, we've got the mylar, but I'm wondering if the wax will work on the heat tape itself. I haven't found any tubing bigger than 1.5" and that's not quite big enough for 38mm ID tubes. Mostly I'm trying to save steps and make them faster. That's why I'm hoping the epoxy/heat/tape can be combined.

 

[shockwaveriderz]

heres where you can get 3-4-7" diamter heat shrink tubing at reasonable prices:

https://www.nyblimp.com/cs.htm

 

[rabidsheeep]

dunno if these help but:

https://xoxide.com/heshtu.html

computer mod stores can have heatshrink for cheap (for neatening wires)

xoxide is alittle pricy

i dunno how big of peices your talking of

 

[shockwaveriderz]

dyna: I don't bother to wax the mylar....this heat shrink tape available here will release automagically from the epoxy

https://www.shrinktape.com/

https://www.shrinktape.com/hishrink/release/

 

[Rubr_Duky]

I've used perforated shrink tape from airtech (google it) that worked well, either without any release between the part and the tape (just make sure you remove it right away) and with peel-ply, and with peel-ply and breather. IMHO, the peel-ply & tape worked really well. I got some non-uniform, spiral ripples just using it alone, but I over wrapped, and then sanded it down to O.D. anyways.

Oven cure is best, but make sure you use a LOOONG cure epoxy, because the tape takes a certain amount of time to shrink. I figure if you plan it right, you can pre-heat your oven (if your piece will fit) to the tape's shink heat, and then kick it up to epoxy cure temp when you put the part in. Should give you plenty of wet-out, and the perforations expel epoxy nicely. The tape does stick to the epoxy pretty good if you don't use peel ply unless you take it off while the part is still warm, the tape is still semi-flexible. I did it on a lathe, and just pulled the loose end, and it would all come off!

Of course, I was working on some pretty short tubing, so you may not be able to fit it all in your oven.


RD

 

[shockwaveriderz]

I was using thin C grade balsa with jap tissue and finishing resin .....I was using the shrink tape to form a helicopter blade on a wood dowel that was wrapped with .002 teflon film and doube sided tape....

I wrapped at an angle of attack and I also got the thin ridges of epoxy between the spiral wraps if they did not overlap....This bleed thru was sanded off....each end of the spiral wrap of the heat shrink tape was taped in place with masking tape to allow the resin to bleed out each end.....I preheated my home oven to 200-250 F and baked for 4-6 hrs .....the thin balsa sheet,jap tissue finsihing resin(water thin) wetted out beautifully.....