Mold release wax/stuff question

General Discussion
1

I’ve got an idea that I want to run by some of the folks here with a little more composites experience than I do. I want to make a close-fit sleeve for a carbon-fiber rod, and none of the CF tubes I can find are anywhere close to a real close fit.

I was thinking of just coating the rod with mold-release wax and wrapping it with a couple layers of CF and FG cloth, then just sliding it out after the resin sets.

Would this work, or is the mold release stuff not that slippery? Any better ideas on making this workable? Maybe just some axle grease, lithium grease, WD-40?

2

Check with these people.

http://www.mann-release.com/products.htm

3

I don’t believe that the rod would just slide out. When I pull the skin off my table it seems like it is pretty stuck. You might be able to create a foam rod the size you want then grind/knock/cut out out when your finished.

4

I’ve read about people using what they call a ‘bladder’. It is an inflatable inner core, basically like an bike tube.

5

I’ll tell u what I used to do when making the UAV’s main wing spars-

  1. use a meatal rod ( aluminum) at the diameter u need ( this is your plug/master), beter use a hollow one ( pipe) .

it has to be perfect! no scratches etc.

  1. apply mold release agent , let it dry and wipe in fast strokes to get a good sleek shiny finish.

repeat this step at least 5 times untill u feel it’s enough.

  1. make sure the rod is longer than the desired pipe your making. this is crusial for the “releasing step”.

grind one end of the rod ( about 1/2 inch) and make two “flats”.

explanaition- when you get to the “release step” you need to hold the rod tight so it does not roll or move.

if you leave it round you wouldn’t have any way to hold it good.

by grinding you you can clamp it or hold it with a plier.

  1. wrap the rod tight in spiral motion with microglass, then with the CF scedule you want.

better do a wet layup ( wet the fabrics on a wetting table).

  1. then wrap the whole thing with PeelPly - tight!

this will assure you get a good finish in the inside…

  1. after resin is fully cured, you are ready to release it…

you need to freeze the plug (this will shrink the metal rod more than the CF therefore releasing them from one another)

a good way to freeze the rod is to spill water into it ( remember I avised to use a hollow plug!)

and blowing air into it from a compressor with an airgun, pistolet or whatever u call it.

  1. now while one side (the grinded one) of the rod is clamped, hold the CF shell at the other side ( far end) with

a pipe wrench ( yeah the red ones are great and you also feel like super mario when using them)

and twist the shell back and forth untill you hear that craking sound that indicates the realse has been done.

now try to do some more maneouvers ( improvise) untill you get the full release done.

  1. DON’T EXPECT AN EASY FIGHT!!! somtimes it goes in just a brief and somtimes it will take the breath out of ya’…

somtimes a short pray is essential.

GOOD LUCK

lee

6

Shwuz,

I’m going to assume that the CF rod has a slight taper, or none at all. I would use some Poly Vinyl Alcohol, ( PVA ) in a pump sprayer, as the release agent.

Spray the rod with two light coats, with a dry time between coats, and use, of at least an hour at room temp. What is the application you intend?

7

edit to step #4:

it might be easier to use a dry microglass and wet it only after it’s wrapped on the plug.

microglass is so delicate it might be to hard to deal with when it’s wet.

regarding the CF layers, u can do either wet or dry layup…your choise.

8

The application is for a stiffening rod on a two-peice surfboard. And the rod I have order is actually a carbon tube, .5" outer diameter. I’d like to mold it directly to the rod so I can get as close a fit as possible. I’m afraid if I try to find an aluminum pipe or the like it might not be as close a fit as I want. The good thing is I only need about 6" of depth on the tubes I’m molding, so I’m hoping that would make it easier to break loose from my “mold”.

10

Thanks for that, Pierre! I don’t know about ordering from there, but it inspired me to do “one last search” (after about 50 other searches) for .500" ID carbon tubing, and I found it! So, forget about the mold release issue for now…

But since you’re here, Pierre, how is your travel board holding up? I was just planning on PMing you about that today.

11

Hello Shwuz,

I had just deleted my post because I found out the telescopic tubes were apparently of only very small diameters. You’re talking about 0.5" tubes, isn’t that too small ? Otherwise, it’s safe to order from these guys (I’ve bought some H-glass recently from them).

Meanwhile, I came upon this : http://www.vernk.com/Construction/ColdfireMotorTube.htm

With respect to my 3 parts travel boards, I wanted to strengthen it for my next annual november trip and instead of strengthening the bolts/nuts I was thinking about adding some carbon tubes as well. But I’ll work on that sometimes during the summer.

12

Hey Shwuz.

Try and find the right diameter carbon fiber sock cloth, called “braided carbon fiber”

It’s a manufactured, woven sock of carbon fiber that you can stretch out somewhat to adjust the diameter.

The place I shop sells it ; Composites Canada.

Guys sometimes use it to make carbon kite bars, although 90% of the kite bars sold are now carbon…

Google “Braided carbon fiber” , there’s a forum a third of the page down that gives lots of supplier info…

Cheers Kiterider…:slight_smile:

13

Yeah, I wouldn’t trust a single .5" rod, but I’m planning on using three, so I figure that should do the trick.

14

I’ve had good luck with bees wax based water proofing paste - but you gotta work hard to get is super smooth with out rubbing it off.