Mold release

[GL-P]

I'm very good at fibreglass reinforcing tubes but I want to got the next step and make pure fibreglass tubes. What do you use as mold release??? I know you buy stuff for this specifically but I'm interested in other techniques that I can easily buy in bulk. Good waxpaper is hard to find.

 

[Stymye]

waxpaper(wholesale stores) and petroleum jelly

 

[jetra2]

Keep in mind that if you use a normal body tube as your mandrel, no standard parts will fit it. People doing mold release have used motor casings as mandrels before.

Jason

 

[GL-P]

Yep, i got a long metal tube which is perfect for this. It's a hybrid casing a friend made.

 

[rstaff3]

If the motor is a standard size you can always use a full length coupler as a mandrel and soak it out.

 

[GL-P]

But that adds the cost of full length couplers into the mix. The hybrid casing is a little too small but that allows mold release and some newspaper I can soak out. Does Pam (you know, the cooking grease) work? Just an idea.

 

[DPatell]

A full length coupler is relatively cheap. It's also reusable if you treat it correctly.

Refer to this article by Tom Cloud.

https://www.aeroconsystems.com/tips/cloud_FG_tubes.htm

 

[GL-P]

I should've said earlier this earlier. The tube will be for a 24mm rocket to handle Gs.

I have found some coupler stock from Balsa Machining Service for a resonable price. I might as well use what I have though. I'll try that trick from Tom Cloud though. Thanks for the link!

 

[DynaSoar]

Originally posted by stymye
waxpaper(wholesale stores) and petroleum jelly

That's probably adequate, and I'm a big fan of What Works. Nick from Aerosleeves recommeded mylar sheet and carnuba wax. That's probably What's Best.

For glass, I'd use What Works. For carbon, I'm going to start with What's Best. It's too expensive to take chances with.

 

[nichanderson]

Regarding wax paper, yes it works, but be sure to use a separate layer of “paste” wax when using it. Also be careful of heating the item be cured/molded when using wax paper, as I had bad problems when heating wax paper based mandrels..

$35 at Tap Plastic will get you a 100' long roll of Mylar.
https://www.tapplastics.com/shop/product.php?pid=255&

Well WORTH the investment IMO..

Regarding waxes, its pretty much anything goes. The absolute key rule when using was is to use many layers. The more the better. Let it dry and buff in-between. Seriously, you be amazed at how easily it will come off the tube or mold when properly prepared with just wax.

Even Mylar can get a little stuck to epoxy when not waxed. So wax your mylar too! I prefer to use the Mylar however as the real release mechanism. Don't tape it to the tube, just adhere it to itself some how. Tape the ends so it doesn't slide around. Then lay up your tube, let cure and the whole tube + Mylar assembly should slide right off. Then pull the Mylar off the inside of the tube and thats it.

Another option, more commonly used when doing a molded part, rather than a tube is PVA. Poly Vinyl Alcohol. It's either sprayed or careful brushed on, and is a superb release agent, that also dissolves in warm soapy water if your wax base underneath it isn't up to par and your having trouble releasing the item.

We have a nice set of instructions with pictures showing how to lay up full composite tubes.
https://www.aerosleeves.com/tut.php

Have any more composite tubing questions ? I’d be glad to answer them.


Nick Anderson
The Aerosleeves Staff
https://www.aerosleeves.com

 

[GL-P]

Thanks for the link! Yeah, I'll test a few techniques on cheap glass cloth before I take the jump on carbon fibre.

Let's see, can Poly Vinyl Alcohol be used overtop waxpaper??? Is that good enough???

I don't want to waste any of the carbon fibre I one over ebay, do I?




Oh yeah, try ebay for carbon fibre. You can get small pieces of cloth for reasonable prices. That's how I just got my stuff.

 

[nichanderson]

Nah, I'd just use wax + the wax paper itself. PVA is nice but it is more work than just waxing it up. You can even just use wax from the auto store, don't get the polisihing or rubbing compounds, cause those are filled with all kinds of small particulates.

Ebay is defintely a hit and miss for carbon fiber. Sometimes you will find a good deal, but most of the time people are selling of 3 feet of "CARBON FIBER - Like fiberglass" for $45.

Carbon fiber is certainly not spendy these days.. Aircraft Spruce has plain weave 5.7 oz carbon for $17.80 a yard.
https://www.aircraftspruce.com/catalog/cmpages/bigraphite.php

Right now there is a lot of demand for carbon fiber, and very little supply so prices are already jumping. Aircraft Spruce used to be selling that fabric for $16.50 a yard. And from what I hear, the great carbon fiber shortage of 2004 is only going to get worse.

Nick

 

[GL-P]

I got lucky. I got a 42 inch wide by 4 ft length of plain weave 5.7oz carbon cloth for $35 total (shipping included to Canada, I think taxes too). Having a temporary problem with shipping right now. Here's the main site

https://www.sollerpaddles.com/composites/carbon fiber fabric.html

I got the HP59 cloth.

 

[nichanderson]

Look like exactly what Aircraft Spruce is retailing.. 75 cents cheaper per yard at current prices.

 

[GL-P]

Look like exactly what Aircraft Spruce is retailing.. 75 cents cheaper per yard at current prices.

All carbon fibre looks the same.

1 yard= 3 feet
First Site $5.75/ft=$17.25/yard (where I got my stuff)
Second Site is $17.80/yard

I think where I got my stuff from was cheaper anyhow.

 

[nichanderson]

Yea, I messed that up. It was supposed to infer stoller composites was 75 cents cheaper, not aircraft spruce..

Carbon prices are rising more across the board.. Looking at some newer carbon products, and in the last 10 days, the price has risen 15%.

All carbon is not the same, even if it may look similar. The most basic difference is how its created, either Pan or Pitch carbon.. There are thousands of different fibers on the market these days, and are broken down by specific modulus.

By far the most common, and probably only fiber ever sold in the hobby industry is the Toray T700. I have yet to see anyone retailing anything different. For what its worth, its a low modulus fiber, so its not very stiff but a lot stronger than a higher modulus fiber. Some of the high or ultra high modulus fibers run hundreds of dollars a pound, compared to $30-40 for low or medium fibers. A 1000 yard roll of high modulus fiber on the open market could easily fetch $30,000 to $40,000

Nick

 

[GL-P]

Yea, I agree they is different grades of cloth but without getting up close and personal they look the same.

I'll get a roll of the high modulous stuff when I win the lottery, and after I get an M motor and after I start my own company and.....

It's been shipped now. It was a problem with the fact that we are a P.O. box mailing address. Oh well. Thanks guys for your help. I will probably start a thread about my adventures with carbon cloth. I will practice on the cheap fibreglass first before I try my first tube. Must not waste any!!!