F-22 / Doubler clarification

[aviator_edb]

I'm getting ready to glass F-22 and the doubler tonight and have a quick question. The plans state 'While F-22 is still wet, press the doubler in place, micro the aft face of the double and glass with 2 plies...''

 

First question, should I leave the area where the doubler goes slightly 'wet' with epoxy or remove excess as normal before pressing the doubler into place?

 

Second, how much weight shoudl I be using here? I figure the weight does two things; one, it keeps the part flat and two, it ensures the foam from the double and glass/exposy on f-22 bond well. (I know, there is NO micro between F-22 and doubler)

 

thanks

[Marc Zeitlin]

First question, should I leave the area where the doubler goes slightly 'wet' with epoxy or remove excess as normal before pressing the doubler into place?

Wet, in this context, means prior to cure or green stage. Not the quantity of epoxy in the layup.

 

Second, how much weight shoudl I be using here? I figure the weight does two things; one, it keeps the part flat and two, it ensures the foam from the double and glass/exposy on f-22 bond well.

Enough to keep it flat and bonded well. A few shot bags distributed across the surface should work well - 5 lb. each or so.

 

(I know, there is NO micro between F-22 and doubler)

If there is a foam surface touching glass/epoxy, it should be micro'ed. The doubler foam should most certainly have micro squeegeed on it prior to attachment.

[aviator_edb]

I'm glad I made mentioned of the micro and doubler. Yes, Micro the doubler before pressing into the glass.

 

 

Thanks Marc.

[Phil Kriley]

Marc mentioned shot bags, and they have been very handy in my project. I bought two 25-lb sacks of lead shot at the local gun shop, and made 10 five pound sacks of shot. I used old drapery material for the bags, and put the shot into heavy plastic bags inside the cloth bags - don't want to have any lead dust to deal with.

 

I've used them throughout the build. They don't damage the foam with dings like you can get if you use iron weights. I figure they'll come in handy as ballast when it's time to fly.

 

Happy building!

[TMann]

I typically use large ziploc bags filled with sand for wieght when I need it. Easy to adjust the weight etc.

 

When I did this bulkhead, I used a vacuum bag process and let the atmosphere provide the required pressure to the part.

[argoldman]

I typically use large ziploc bags filled with sand for wieght when I need it. Easy to adjust the weight etc.

 

When I did this bulkhead, I used a vacuum bag process and let the atmosphere provide the required pressure to the part.

If you get some sink cutouts (formica type)from kitchen counters (ie from Hme depot-- very cheap), lay it on top of your structure, you can use whatever type of weights that you want to, including buckets of water.

 

I have found these mini-countertops to be of invaluable help in many of the construction tasks. If you contaminate them with epoxy and don't want to clean them up, discard them.

[aviator_edb]

I wanted to thank everyone for the tips. I just got done cleaning up after finishing the font side layup on f-22. I did the aft face /doubler on friday.

 

The 9 ply UNI/BID layup on the sides was a lot fun. I did the wet out on hd aluminum foil, rough trimmed then laid the whole thing in place carefully. Wash, rinse then repeat one more time and I was done. I got smart a bought a fresh blade for my rotary cutter and it made cutting out the correct shape from the layup super easy.

 

The real fun will be cutting off the excess once the cure is done. I'll be tackling that next weekend. Than goodness for the Fien multimaster.

[mfryer]

The real fun will be cutting off the excess once the cure is done. I'll be tackling that next weekend. Than goodness for the Fien multimaster.

The Fien is a wonderfull tool, however trimming ecces glass when it is partially cured (dry but gummy) with a razor is far eisier and will save you some life of your Fien blades.

[aviator_edb]

yah, I'm still working on my timing for doing knife trimming..

[Lynn Erickson]

yah, I'm still working on my timing for doing knife trimming..

If you trim the next day when the glass seems to be to hard you can use a heat gun and it will soften it enough to knife trim.

[argoldman]

If you trim the next day when the glass seems to be to hard you can use a heat gun and it will soften it enough to knife trim.

After what seems like miles and miles of knife trimming at just the right time, waking up at 3:00 in the AM so that I can get the trim exactly at the right time, the Fein tool was a godsend (or whatever "send" prefix you prefer to use).

 

When caught at the right time, knife trimming is, as Garrisson Keillor says, "Tasty and Expeditious", however getting it at the right time can be difficult as it depends on the thickness of the layup many times.

 

Although heating and trimming works, it is a great deal more work than simple knife trimming. I have no idea of what the reheat, cutting (and pulling the fibers) has on the final layup--probably none.

 

Best to get the sleep and use your Fein. One blade, possibly 2 will last for the entire build and make your life so much easier. Easier and in a time frame that fits your schedule is more bettttter.