MadCow Bomarc

[troj]

Whats the reason for using microballons in epoxy?Don't mean to steal the thread.Sorry.

No need to apologize. If you've got a question, ask!

That's where build threads are great -- it's an opportunity to see how folks do things, ask questions, understand why, and learn.

-Kevin

 

[sodmeister]

Not sure what type of "micro ballons are used" as it is a generic term me thinks (correct me please)as some "fillers " act and do different things when added to epoxy.
I myself add West 406 Colloidel silica adhesive filler to my 30 min. epoxy and of course West slow cure epoxy.The 406 added ,applied then smoothed with alcohol does a great job on fillets and filling gaps to add structure.
I built an SKS rifle from the ground up using anodized aluminum,wood, the rifle action and some careful re-designing (Canada`s version of the BATF) and have fired over 2000 rounds through it.
Strong ? I need a new firing pin LOL

Paul

 

[troj]

Not sure what type of "micro ballons are used" as it is a generic term me thinks (correct me please)as some "fillers " act and do different things when added to epoxy.
I myself add West 406 Colloidel silica adhesive filler to my 30 min. epoxy and of course West slow cure epoxy.The 406 added ,applied then smoothed with alcohol does a great job on fillets and filling gaps to add structure.

Microballoons is a specific type of filler -- glass microspheres.

There are lots of other fillers, including colloidal silica, fumed silica, phenolic microspheres, chopped fiberglass, milled fiberglass, etc. All have different properties, and some (faring compounds) are easier to sand, while others add structure and make it harder to sand.

-Kevin

 

[sodmeister]

That`s what I like about the colloidal silica (although that `s pretty much the only one I have experience with) it spreads easily and fairs nicely when mixed to the proper thickness,and sands easily.

BB

 

[troj]

Finally, visible progress!

On and off, for the last couple weeks, I've been working on sanding and shaping. An arduous process that I tend to work on, set down, work on, set down, etc. Well, it's finally done, which means assembly resumes!

Today, the wing assembly went onto the rear tube. The forward tube is not glued in place, and the wing assembly is not glued to that tube.

The tube, however, is in place so that I can use tape around it to help hold the wing assembly in place, while the glue dries.

-Kevin

 

[troj]

With the initial glue partially dried, I've started on the reinforcing step for the wing assembly. Rather than just rely on an external glue joint, the instructions have you insert 3 dowels, each 1" long and 1/4" diameter through the main wing, down through the body tube.

The dowels get glued in place, then the entire assembly flipped over and an epoxy fillet applied to the inside of the tube, around the dowel.

Thus far, I have the dowels in, and am allowing the glue to dry a bit. I'll get the fillets done in the next few days.

This is a really cool way to reinforce the joint, I think.

-Kevin

 

[sodmeister]

I never noticed the dowels in my kit (It`s in the "to build pile) neat idea.Glad I have this build in my favorites for when I get around to building mine.

Keep up the fine work !

Paul

 

[troj]

The Bomarc is still progressing. Today, I mixed epoxy with microballoons, thinned it and painted that over all the wood.

That's curing now; I'll start the joys of sanding tomorrow.

-Kevin

 

[sodmeister]

Kevin, what do you thin the epoxy with ,alcohol ? I`ve wanted to do the same thing so as to really "wet" the wood as a first coat ,then apply a second thicker coat.I use Finish Cure epoxy on balsa nose cones and paper transitions ,but would like to apply a primary thinner coat.

Paul

 

[troj]

Kevin, what do you thin the epoxy with ,alcohol ? I`ve wanted to do the same thing so as to really "wet" the wood as a first coat ,then apply a second thicker coat.I use Finish Cure epoxy on balsa nose cones and paper transitions ,but would like to apply a primary thinner coat.

I used acetone.

It weakens the epoxy, but for my purposes, that's not an issue.

Many moons ago, my dad and I built an R/C boat, which is mostly plywood. One of the things the instructions have you do is coat the finished hull with an epoxy/acetone/microballoons mixture, not only to fill the grain but also to waterproof it. That's where I got the idea from.

-Kevin

 

[bsexton]

Do you have any rough guidelines for the ratio of epoxy, filler and acetone for sealing the wood?

 

[troj]

Do you have any rough guidelines for the ratio of epoxy, filler and acetone for sealing the wood?

I mixed laminating epoxy, added enough microballoons to get it about to the consistency of molasses, then thinned it down so it was thin enough I could paint it on.

We'll see if I remembered the right ratio. I suspect I may have to touch up some spots.

-Kevin

 

[Pat_B]

Nice job. Does your body tube seem to be of high quality? I bought 3 of the DX3 kits and all three have a very prominent raised seem area that really can't be filled. It's almost as if though about 1/4" of the seem is raised just slightly. I'm wondering if they were wound properly to begin with.

 

[troj]

Nice job. Does your body tube seem to be of high quality? I bought 3 of the DX3 kits and all three have a very prominent raised seem area that really can't be filled. It's almost as if though about 1/4" of the seem is raised just slightly. I'm wondering if they were wound properly to begin with.

I've not seen anything similar with any of the tubes with this kit.

I have seen tubes like you describe from various sources over the years, though. Almost makes me wonder if it's not due to humidity differences.

-Kevin

 

[duggyhow]

Hello, can someone give me detailed instructions on how to make the conduit assembly. I can't make heads or tails out of these instructions of Madcow. Thanks alot.