I’m looking at adding Robart hinges to a 1/4 inch thick Fin/Rudder assembly and also in 1/4 inch thick Ailerons. I'm debating using the 1/8 points, which only leave 1/16 of wood on each side at the top and bottom of the hole. Obviously, there is more material and therefore more holding power further away from the very top and bottom of the hole, but I was wondering if I should be using 3/16 inch hinges instead for this thinner material.

I’ll be drilling the holes which are in the 1/4 inch thick material (Fin/Rudder/Ailerons) in a drill press before I assemble or cover the parts, so I’m not too concerned about staying within the material for the full length of the hinge. I can’t get the entire wing in the press, but the trailing edge material in the wing is thicker, so I can hand drill them to match the aileron.

Bottom line - I am concerned that the 1/8 hinge is too big for the 1/4 inch material, but have not seen any conclusive information on sizing the hinges for the material thickness, fi the hole can be drilled successfully.

Does anyone have good guidance? Has anyone had good or bad experiences with thin balsa?

Thanks in advance,

Jack
p.s. - Yes, I've thought about Dubro hinge and CA hinges, but I've built with both of them and wanted to try the Robarts this time.

Have used 1/8" hinge points in 1/4" sheet stock with no problems. If you want to be extra sure, you can glue (using thin CA) 1" squares of light weight fiberglass cloth above and below the hinge holes. That would be totally bullet-proof. Use some filler on the 1" squares and they will be virtually invisible under the covering.

It really won't be a problem. And rather than using a drill press, the Robart Drill Jig is the way to go

3/32, not 3/16 hinges

Dubro makes some small hinge points and if you are worried about the wood breaking out with the 1/8" ones, you could add one or two hinges and use the smaller ones. It would give you the same pull strength, maybe more, and give you some extra meat to hold them.

The issue with the 1/8" points in 1/4" wood is that keeping the hole straight becomes absolutely mandatory. A drill press and a good vise are a must. THe drill jig can center, but you need something to make sure it doesnt run off center of the piece being drilled. Also as you are pushing into a blind hole, the hydrilic pressure could blow out the side if you are not careful and use a very light coating of glue/epoxy. IF the hole is straight and the fit is good, the thin material will hold up OK as long as it isn't damaged in the setting of the hinge. Once the glue dries up, the hole is reinforced by the glue.

Don

Before I use them I also add another 1/4 inch block behind the areas to be drilled just so I have A better/bigger gluing area. I use the jig/guide and hand drill. I have A drill press but it's over kill if you have the jig/guide.

As others have said, 1/4" is plenty thick for Robart hinges. Again, use the Robart drill guide for accurate centering. The trick to staying centered is to drill slowly and to hold a finger on either side of the surface being drilled. You will be able to feel the bit through the wood if you start straying off center, then you can correct for it.

Make some practice holes in a piece of scrap balsa. You'll be surprised by how well you can tell where the bit is going and how well you can correct it.

Dave

Great info! I really appreciate the help. I figured it would be fine, but wanted to verify.

I'll practice with the Robart jig and a spacing jig, but since I have a drill press and the vice to support it, I can't image a more accurate way to stay centered in the thin material, especially in the Aileron

In true RCU fashion, you've managed to educate me further than I anticipated.

Thanks again,

Jack

I quite useing ca on hinges, I now use Gorilla glue. It expands and fills all the ridges.
john