ORIGINAL: Campgems

What happened was you tried to drill through the old CA hinge. The drill wanted to go on one side or the other but not down the center.

When you cut out an old hinge, you have to move the new hinge to fresh wood. It doesn't mater what type hinge you use, you can't put a new on over an old one. If you had a friend with a mill, they could use a 1/8'' mill and drill a new hole over the old hinge, but you are going to have trouble shapping the hole top to fit the shoulder of the hinge. Find fresh wood and have a go there. If you are going to use the Robart hinges, they will give you a bit more leeway on where to drill the new holes. Just make sure that you have enough wood on the other side of the hinge.

I aquired a Twist 150 that had never flown. When the guy was assembling it, he used the wrong CA and on a couple places on the ailerons, he didn't get CA into one side of the hinge. I cut them out and the drilled and fitted for Robart hinge points. Then I got to wondering if there was enough wood for them. I made a little wire with a 90 degree on one end that would go through the 1/8'' hole and I could snag the back side of the wood to tell how long the hole was. Fear confirmed, so I cut the covering off bottom of the wing and ailerons and then glued in and inch and a half piece of wood the same thickness of the wood in the ailerons. Re drilled the holes and now I have a full three barbs in wood. While you have the covering off, it may be a good time to plan on doing this. You can also fill the hole you drilled, just make a dowl of balsa and use white glue and push it through. Cut and sand smooth.

I looks is if the balas next to the hole has been broken. If so, I would cut the entire piece off and replace it with new wood. I wouldn't trust a butt joint there, especiall close to a hinge.

Don

ORIGINAL: MinnFlyer

Ok, I've got a few things to say on this...

First, you said you can't move the hinges because they would go into the cross bracing - So what? That's not going to hurt anything.

Next, cutting the LE on the black tape would not normally be the way to do it as you would want to avoid a seam in the LE at all cost. However, in this case you could get away with it because if you are going to use Robart hinges, the LE will need to be wider to accomodate the longer hinge.

So you can kill two birds with one stone by doing this:

Remove a section of LE and replace. Now cut a longer piece and glue it in behind the cut section so that it braces all cut lines.

Now the cuts are reinforced and you have plenty of thickness for the longer hinges.

ORIGINAL: Campgems

I'll add one more thing also. I really like Minnflier's recomendation. I would tack glue a strip flull length of the surface about 1/2'' behind the Leading edge prior to makeing the cuts. That will keep from squeezing or spreading the LE when the replacements are put in place. You could also do a serious pin job on a building board, leaving the width of the LE hanging over the edge. You don't wan't to build a twist into it with the repairs. Once the LE repairs are made, then remove the strip.

Don

ORIGINAL: MinnFlyer

Ok, I've got a few things to say on this...

First, you said you can't move the hinges because they would go into the cross bracing - So what? That's not going to hurt anything.

Next, cutting the LE on the black tape would not normally be the way to do it as you would want to avoid a seam in the LE at all cost. However, in this case you could get away with it because if you are going to use Robart hinges, the LE will need to be wider to accomodate the longer hinge.

So you can kill two birds with one stone by doing this:

Remove a section of LE and replace. Now cut a longer piece and glue it in behind the cut section so that it braces all cut lines.

Now the cuts are reinforced and you have plenty of thickness for the longer hinges.

ORIGINAL: RCKen

If you're using CA hinges, then you need to use thin CA. If you are going to use hinge points then you want to use epoxy.

Ken

ORIGINAL: Campgems

OK, another trick. I hate CA, I always get to much on and have these razor sharp fillets that you just can't sand smooth without cutting the balsa away around it.

I used to be a jeweler and one my ''tools'' was craft sticks, IE popsicle sticks'' that I glued wet or dry sand paper onto. I started at 280 and went up to 1000 grit. I could use an Xacto knive and cut them to thin strips and modify the sides for getting into tight spots.

I was working on a 4*60 and Sig recomends Ca for just about everything. Come time to cover, there were enough knife egdes of Ca to make me question if the covering would hold up. I tried garnet paper and other stuff and was successful in screwing up a couple ribs in the process. In frustration, I grabbed a 320 grit stick and what a susprise, It eats CA. It is also so fine that it really doesn't do much damage to balsa unless you dig in an edge. They make a great little tool to get into the tight corneres and cut the CA back to where you want it and round the edges.

Just take a sheet of wet or dry and lay it face down on some news papers. Spray the back with some 77 adheasive. Don't skimp. Then lay out the craft sticks in a nice pattern for best coverage. Press them down tight and then the next day, use your Xactor knife to cut the sticks from the wet or dry sheet from the stick side. As long as you cut from the back, you can shape and taper the stick as needed and keep the wet or dry active right to the edge. When the edge gets a little worn, put it face down on some scrap wood and cut a new edge on it. A great and inexpensive tool to sand the tight spots and clean up the hardened CA. They don't work on Epoxy though.

Don