daven

My Feedback: (1)

It will work with a top hinge

combatpigg

My Feedback: (3)

Dave, I chickened out and went center.
Actually my fridge motor burned out while doing the wing and I wasn't going to try the kevlar top hinge on the elevator without a vacuum.
Too bad, because I can see how skin hinging it would be a time saver.

I ended up running almost a continuous strip of EZ hinges per side. I wonder if some lightweight cloth and resin can be worked down into the hinge gap on both sides to seal it?

vicman

My Feedback: (10)

CP, do you have the switch on your pump or are you just letting it run?

combatpigg

My Feedback: (3)

I've got the 5-15 inch pneumatic switch that I set to 10. The vac bag only needed a quick shot every minute or so. It could have boiled off all the fluid, but I run it with a 1 gallon jug for a puke can that drains back into the system. It could also be the starting cap, but the unit sounds like it is trying to start...it just wont though.

iron eagel

Sounds like the Cap may be bad...
Although it never is that simple for me, usualy I get the shorted motor.

smoknrv4

My Feedback: (11)

Is there any websights that have info on building a vacuum sytem for wing bagging, I need one baaaadddd, but I know nothing about it.
Thanks

combatpigg

My Feedback: (3)

There are quite a few pretty good ones. If you do a google search you'll hit pay dirt. I got the vacuum switch off of ebay. You will want to use a relay rated for 120 volts, also. A vacuum gauge, some rubber tubing and a check valve is also required and these are at your auto parts store.
I made a storage tank out of an empty 5 gallon propane tank..you will need to get pipe fittings at your hardware store to fit the tank with. I think the copper line coming off the vac pump is 1/4". Robbing a pump out of an old frig isn't too difficult. On my frig, the whole bottom mechanical chassis unbolted and rolled out from under the fridge.
Here's some more progress, umpteen Bondo sessions later. It would be interesting to see how fast a pro bodyman could whip this stuff out.
I got a 1200 watt forced air heater at Walmart for $10. It's just perfect to cure parts in a cold garage. I have some random blocks of foam that I loosely arrange to direct the heated air with.
The heater doesn't get hot, just 80-90 degrees or so.

MJD

My Feedback: (1)

Try searching "vacuum bagging wing" on Youtube.

Here's our local supplier: http://www.compositescanada.com/form.php?functionID=426

You can buy decent structural epoxy there too.

I bought an HVAC vacuum pump new on fleabay for something like $150. Got an adjustable vacuum switch in a hefty NEMA 4 enclosure new there for $25.

MJD

daven

My Feedback: (1)

If you keep your eyes out at E Bay, you can find some very nice used pumps cheap.

I prefer pumps that are rated to run continously, instead of using a relay, but thats just me. You can adjust the pressure with an air bleed (cheap and effective).

In two minutes found this one. New it would be several hundred dollars.

http://cgi.ebay.com/Gast-Vacuum-Pump...item1c180f99a1

racer639

I used a belt driven vacum pump off of a Ford disel pickup runs continuous no problems, ford expects them to 100,000 miles with no problems so bagging model parts shouldn't be aproblem forever

vicman

My Feedback: (10)

Thats an awsome deal Dave!

I did mine with the switch. If you look back I did a thread on what happens to a Viper wing if the switch stops working properly[&:]

smoknrv4

My Feedback: (11)

I remember seeing that Vic, that was cool, well not for you of course.[:@]

combatpigg

My Feedback: (3)

I'm gonna run a vacuum line off my Jeep over to the garage.

Now comes the time to ask advice. I think in the past I used polyester resin to finish the plug....
I've also got some oil based polyurethane on hand, but IIRC I used polyester resin to get a tough, glossy finish after wet sanding and buffing.
Any thoughts?

Also, it's time to glass the 1/4" medium balsa stab. What's the usual layup? There isn't any spar in there [yet].

Filling the weave of 3/4 oz cloth. I've read too many differing ways to do it. I'm leaning towards Klasskote primer with talcum powder. I've heard others swear by water based fillers.
I'm willing to spend a little bit here. I plan on using Klasskote for the top coat over the whole plane.

gltruett

My Feedback: (23)

I have had excellent results with Duratec Surfacing Primer: http://www.duratec1.com/dp04.html It is a polyester based product so shipping can be high if you can't find it locally. I spray it on with a cheap gun and compound it from 400 paper all the way to polishing compound. It will give you a mirror finish and in my opinion works much better than automotive primers.

daven

My Feedback: (1)

I wouldn't use anything thicker than 2oz on the stab, and thats probably overkill.

I keep a roll of 1.4oz on hand, thats what I would use, although to be honest, I think 3/4oz would be plenty.

3/4 oz weave is pretty easy to fill with High Build up primer alone, shouldn't need talcum power, just do a few real light coats, wet sand, and then a few more light coats.

vicman

My Feedback: (10)

I use .75 and 1K primer.

combatpigg

My Feedback: (3)

I'll use the 1.4 oz then. The elevators are pretty thin. You would never guess the stab is 1/4" thick at the high point.
sahartman's Proud Birds got a slurry of watered down spackle smeered over them. I like the idea of that, but wonder how well it held up over time?
I've got some high build lacquer primer left over from painting my truck last summer.
I loved the old K&B primer. It sanded off like chalk and left a perfect surface with very little effort.
I bought some 2 part primer from a automotive paint store, [but I ran out]. I shudder to think about going back to buy more because everytime I walk into that damn store I'm out $100 bucks with just a little bag of goodies to show for it.

iron eagel

I like using epoxy and Microballoons for filler, talc works well also. When doing glass over a very thin surface I often use a couple of layers of light cloth (1/2 oz) with the weave turned in an alternating manner to add strength. You would be surprised how strong it gets without adding a lot of weight. Another material I have used is carbon fiber veil a few layers of .02 oz/ft works very well and I have used it on a couple of planes thus far using lacquer to bond it onto the balsa. Only one of them has been airborne but it has taken a fair bit of abuse and held up well.

daven

My Feedback: (1)

I bought some of that Carbon Veil and hope to use it for an experiment this winter, looking forward to it. Have you had any issues with it blocking RF? My antennas will all be internal.

iron eagel

Dave,
I have only used it with an external antenna 72 Mhz thus far. Apparently internal antennas with 72 Mhz is not possible but I have heard of people using it with 2.4 Ghz without issue. Your best source of information on radio issues are the Soaring guys, they have dealt with carbon fiber for some time now. A guy who built up a B1-b using carbon fiber for the entire structure claimed no problem with 2.4 Ghz with his ship in the composites Forum...
Thus far other than high performance gliders not many have used the stuff all that much. I have a sport plane that is entirely covered in this way but have not completed it yet, it been sitting for the better part of two years waiting for wingtips I plan to finish up soon.
MatttK AKA MTK has done a lot of work with carbon he may have some more info on the subject.
Sorry I could not be more helpful.

combatpigg

My Feedback: (3)

Thanks to all for the finishing suggestions. I ended up going to Napa and got a quart of 2 part "2K" acrylic high build primer. It comes out of a Badger gun in a fine mist with no thinning.

For priming the wing I might go with a full size spray gun.

A lesson learned the hard way. DO NOT let kevlar cloth meet up with a sharp trailing edge. It doesn't not get fully saturated with resin during the layup and it resists attempts to sand it flush with any surface. I've had to "over sand" it below the surrounding area, then encapsulate it with FG, resin, Bondo. I'm also wondering if I got what I ordered. I ordered 1.7 oz kevlar and this stuff is much thicker than the same weight of FG cloth.

The fuselage plugs will be ready for molding soon. I need to see if some old gelcoat is good any more, or if I should dump it and buy fresh. Same goes for old PVA, I don't know how long it lasts.

Throwing stuff out before you get any use out of it is a hidden cost of this hobby.

vicman

My Feedback: (10)

Yeah, the Kevlar needs to be encapsulated. It pops thru paint too.

smoknrv4

My Feedback: (11)

Comin along nicely CP. "Encapsulated"....Whew![sm=bananahead.gif][sm=confused.gif][sm=spinnyeyes.gif] What does that mean, you'll have to forgive my question, sounds like a very intellectual word.

vicman

My Feedback: (10)

Forgot there might be toolmakers reading this thread.

combatpigg

My Feedback: (3)

Vic, it takes one to know one...

SRV, it means buried, entombed, mummified.... this fuzzy kevlar crap keeps boiling to the surface like a monster you think got killed in those horror movies. I've soaked the fuzz repeatedly with thin CA, then sanded it down below the surrounding surface, then glassed over it. It just created a ton of extra work. Every time I try to go for the finished product, a few stubborn bits of that crap resurface. If the Kevlar was about half as thick as the stuff that got delivered, it wouldn't be such a job to "feather it in".