Hello
Ive been making carbon tubes by rolling them over a mandrel, wraping mylar around them , wrapping them in heat tape and putting them in an oven.They come out pretty nice except I get a few air bubbles that I miss when squeezing them out.
I was wondering if I did the layup with a peel ply on top , and then heat tape, would the heat tape wrinkle up the peel ply or would the peel ply stay in place?
Thanks in advance
peel ply or release film?
Maybe and Yes.
I’ve had bad luck with tubes. If you don’t wrap the fabric/prepreg around the mandrel REAL tight, when you shrink tape it, obviously, any slack will wrinkle the fabric.
Peel ply will prob’ stick well to the fabric if using pre-preg, or spray adhesive onto dry fabric…if the fabric will wrinkle, the peelply will as well. You will of course, have the peelply textured surface finish. WHICH might be good if you want to coat them in a clear coat/urethane.
Release film will never work for a good finish. It won’t shrink like the shrink-tape, and just wrinkle no matter what, unless stretched around the fabric as tight as the shrink tape.
Very likely it will wrinkle. I’ve had similar problems myself.
BUT…
Try it for yourself!!
As for the air bubbles, are you using the oven to shrink the tubing?
I’ve had a lot of success starting in the center with a heat gun, and shrinking outward. This pushes the excess resin along the length of the tube, filling any potential dry spots and helping to displace any trapped air.
Good luck!
Im doing wet layups with my tubes. I am using .014 mylar over the top and then wrapping it in heat tape. You have to pull the heat tape real tight to work out the air bubbles. But this works. You end up with a compressed clear finish. The only problem is if you miss any air bubbles when squeezing them out with the tape, you have covered covered them up with the mylar and tape , so you dont no there there to fix them .So its kind of a crap shoot.
I have also done layups where I do a wet layup around a mandrel and just put peel ply on it, let it kick and then pull the peel ply off and bruish on a couple coats of clear while in the oven, wand a torch over it to get ant little air bubbles out and these always look great but not a compact wrap.
Im pretty sure the heat tape will wrinkle, but Ill try an experiment
[QUOTE=Fan O’ Zakk;24799]Very likely it will wrinkle. I’ve had similar problems myself.
BUT…
Try it for yourself!!
As for the air bubbles, are you using the oven to shrink the tubing?
I’ve had a lot of success starting in the center with a heat gun, and shrinking outward. This pushes the excess resin along the length of the tube, filling any potential dry spots and helping to displace any trapped air.
A heat gun. This might work ! I do use the oven to shrink the tape. Ill do a layup the way I normally do. Put the .014 mylar on it, wrap it in tape, and then put a heat gun to it and see what happens. If this works it will make my day.
I am using a heat tape that shrinks at 170 degrees, is that what you use?
I use the shrink tubing from Soller Composites.
Im not using shrink tubing. I never never tried it. How well does it work compaired to shrink tape ?
Tonight or tomorrow I am going to try a layup with a heat gun on the tape to see if it helps remove the bubbles, Ill post how it works
Thanks again,Terry
Dunstone has perforated shrink tape. Maybe that will solve your problems?
I did a little test today and think I may have it worked out. Ill try the real deal tomorrow.
Dunstone tape is the product I am using. I have used the preforated tape before but the flat tape seems to work better for what Im trying to achieve.
Tonight I layed up a one foot section of 4" tube. Then brushed on a heavy coat of epoxy over the top. Put a sheet of waxed .014 mylar over the whole mess. Put tape on it to hold it in place,sqeegeed all the air out, then wrapped it in dustone tape. Through it in the oven , cranked the oven up to 170 degrees
for just a couple minutes. Then turned it down to 90 degrees.
When it cured I had a straight, shiny, compressed tube with no air bubbles or pin holes.
Now I just have to get it to work on a long piece.
Thanks guys for the help so far.
The way Im doing these tubes is just too messy.
I have a question.
One way I roll tubes is to roll 3 wraps and put peel ply on and thats it. This gives me the wall thickness I am looking for.
The other way is the way I described above with heat tape to compress the layup. It takes 5 wraps for the same wall thickness
with this aproach.
Is the 1st way 1/2 as strong due to being resin rich and less wraps?
exact strength #s are not known…but yeah, resin rich laminates are not as strong as correct ratio ones. If you need an exact wall thickness, think abt post machining or adding extra layers in certain areas.
Good comments, Thank you.
I am mainly working with 8.3oz carbon right now. Once I get down a closer to prefered process for me. I can see what a consistent tube wall size I am making, then I could make adjustments by using thinner product.
As far as post machining, is there a good backyard way of doing this ? I have an old lathe I rigged into a tube sander. Sandpaper is some hard cutting on carbon if your trying to machine the OD down
What are you trying to do? Insert one tube into another, just to connect, or fully telescopic system? Lathe would be good, you can achieve exactly what you want, depending on your setup.
Also, depending on what you are doing, you can test your setup for the right thickness and strength, and work from that.
Im in a hobby, High power rockets. Ive been scratch building carbon rockets in the winter fot a couple years.
In the past making parts just for myself, so I could make an airframe grind it down redo it , whatever, Time and lack of experience wasnt a problem. But now I have a few freinds that would like me to make some parts for them so I have been experimenting trying to come up with the best way I can to make these parts in a backyard enviroment.A little faster and a little better. So as I experiment ask what sometime even seems to myself like silly questions but its great to get the feedback
The easiest way to make a real good looking tube so far for me is to do the layup, put peel ply on it, put it on a rotisserie, when it sets up I pull off the peel ply , brush on some clear with the oven ramp up to 120degrees to flow out the epoxy.
This way looks real nice and is easy but I dont have any real compression so its resin rich and not the strongest tube.
The mylar and heat tape deal we have been discussing in this thread works pretty well but its real hard to get the bubbles out at the seem of the mylar and is a very messy deal in general.
Doing a layup and just wrapping in heat tape only seems to make a good strong tube but leaves spirals
Im starting to think the way to go for me is to just use the heat wrap tape process and if someone wants it finished with a glossy carbon finish I will sand it down and add a wrap of directoinal and clear that.
I want to be able to offer a tube that when someone builds a project out of it they can just wet sand it and clear for there final finish
Thanks , Terry
preeettttty.
Well, final product begins ans ends with a consistent process and part. Do 3 layers, with one method, and that is your wall thickness. if you keep changing methods, your part changes and can not sell it as a consistent part.
As for the finish, you can sand and wetcoat it. If you really want to start mass producing parts that are always the same, WITH minimal amount of work…I think a mandrel (or bladder mold) and then 2 part outside mold is the way to go. you won’t have to finish the tube to be smooth (except maybe the flashing). You also will have control over thickness.
This is what Im working on now, trying to find one process that works for me and my backyard tooling. Ill post pics of my Tools, you might get a kick out of the setup.
Wow , never thought of that. So you would roll your layup around the mandrel and then set the whole thing in a in a two part mold. I doubt I would ever go that far but sounds like a great idea.
I owned a collision shop for 13 years, always learnng in that field.But this stuff is more of a craft , talent, I apreciate the pros after playing with this stuff.
When you guys yse apray adhesive to hold doen a fabric,When the epoxy wets it out, does this release the adhesive?So if I was wrapping a tube around a release material it would also release where I put the adhesive?
Thanks , Terry
Ive looked into the 77 adhesive and it looks like it leaves a residue. Cant have that. the inside of the tube has to be a nice finished also.
What would really help me is a way to tack just the first edge when laying up these tubes, maybe a quick dry epoxy, when it gets sticky I could stick the fabric on. This should hold it down and allow me to get a tight wrap without the fabric slipping around the tube?
Can you use prepreg? That solves your sticky problem.
Looks like you made a box with heat lamps. Maybe you could modify it to get up to prepreg temp?
I’ve watched tubes being made with prepreg being wrapped around mandrels. Pretty nice.
Tbone: I think after the epoxy has eaten away the adhesive, it might not leave a glossy inside, but it won’t be sticky. If it does, thread a rag of acetone though, it’ll clean up. But generally, spray adhesive isn’t always the best.
dy123: yeah, prepreg would be the way to do for tubes. MUCH easier. If you want to invest in a roll, that is always problematic due to storage needs. (freezer) But, there ARE some prepregs with VERY long outlife (Newport I think has one)…