crash bandicoute

im getting ready to start my first scratch build and was trying to think of a way to keep all the notches in the ribs and bulkheads the same size for my stringers and sparsinstead of having some a little too loose and too tight. you can get a small piece of brass square "tubing"in the size you need for spars andsub-sparsand sharpen the edges and use it for a type of punch, if the wood you're using isn't too thick,lining the edge of it up withthe edge of the piece of wood after you get it cut out. if it is too thick to go through, at least you get a marking of where to cut it instead of guessing.even for bulkheads orformersor WHATEVER...the link to it...http://www3.towerhobbies.com/cgi-bin...?&I=LXR847&P=0. and it's in different sizes.

kdc

Good idea. The tube ( round or square ) is of course sharpened on the inside.
There was a whole 5 page article on making proper punches from silver steel by Alec Whittaker in the English magazine RCME January 2009.
Lots of info including the important point of having a soft pine wood underneath as an anvil. Also could be punched halfway and the wood turned over to complete the cut to cut cleanly. Some people wet the wood to soften before punching in kit production it seems.

ARillos

For ribs, I use the sandwich method. Build two rib templates from 1/16 or 1/8 hard plywood, drill two holes and use two long 3/16 bolts for clamping the ribs. Cut the rectangles for the ribs (half wing at a time) drill the ribs using the template, bolt them together and sand them to match the template. For any additional notch use the X-Acto saw and or no.11 traditional blade. Good luck! Alex.

yel914

I've also cut out those notches with short lengths of fine toothed hacksaw blades, stacked together for the proper thickness and taped on the ends. A few passes makes a good fitting notch.

Edwin

My Feedback: (2)

I use a hardwood sanding block the width of spar with some 80 grit stick on sand paper. It makes the slot the exact width.
Edwin

Jim_Purcha

My Feedback: (8)

I've done this too. Use the same size of spar with sand paper. Works great. Used it on tapered spars.

Jim

Laird SS

Jim's method of sanding the slots is the way we did it back in the days of rubber powered models like those from Cleveland Model Supply. It worked well. Also, as Jim said, it works well on tapered wings where the slots may not be perpendicular to the sides of the ribs.

BMatthews

You've got the right idea but the wrong tool with the brass tubing. At least it's the wrong tool unless you want to put the spars into the middle of the ribs. The brass tubing will tend to crush the wood and produce oversize holes unless it's extremly sharp. I cut holes with round tubing that I sharpen but in that case I can twist the tubing to aid the cutting. But with the retangular or square tubing you're stuck with a pure push.

For normal three sided notches the methods mentioned above work out far better. For myself I prefer to make my own spar "rasps" by gluing together fine tooth hacksaw blades. The final size being achieved by stoning off a little of the tooth set to get a light but firm push fit for the spar wood. That makes for a good glue joint. The less glue the better.