There are more ways of building Ringmasters on this Earth, Horatio, than are imagin'd in your philosophies.

You can stack hacksaw blades to get a kerf width to match the ribs.

You can make a built-up leading and trailing edge (no slots, but lots of surface area for gluing).

You can use a razor saw, make two parallel cuts, and chip out the wood between with a narrow chisel or a screwdriver.

I stack cut my ribs, and I hold the stack together with jig holes.  For my Ringmaster project I used a wood bit of the appropriate size, and drilled two round holes to mark the spar location.  Then when the stack was apart I used one of the templates to locate the spar hole relative to the jig holes and cut out spar holes with a #11 blade.

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Thanks my friend for the useful information, I guess you are very right about cutting slots in the leading and trailing edges I will try that plan of attack on building my new Ringmaster. Thanks Edward

I prefer the table saw with two blades in it. Makes a nice neat 1/8" cut.

Good luck, Jerry

A small band saw is what I use.  Select a blade with the right amount of kerf.  Better than a table saw because you can easily see what you're doing.  I doubt that a small notch would cause a weak spot if the wood is 1/2 to 1" thick.

Floyd

Maybe you'd doubt that, but that's where they always break. So it's better to avoid it. Kit makers like Sterling were wonderful at putting the notches in the wrong place, as a bonus. Maybe Floyd never crashed a Sterling kit? Steve

The reason for the notches was so a novice could put the kit together without plans. Anyone could do it. I built them with out a table. I would not notch them today.
Ed

Exactly, none of the Sterling kits came with traditional plans, only assembly drawings and instructions.
Word is it was to prevent copying and replication. They wanted you to buy another kit!

I make a punch - a chunk of 1/4" square tubing. Sharpen the end and punch out spar slots. Works for me, anyway.

I clamp a 1x-whatever scrap board to the scroll saw table, with the edge behind the blade.  A cut at each edge of the slot to the depth where the leading or trailing edge is flat against the board, another cut on the other side of the slot, and a quick pass in the middle to remove the waste.  It cuts the slot to depth, the table and the makeshift fence ensure the slots are square.  Assuming the ribs are cut square, it basically snaps together.

Is a Ringmaster without a notched leading edge really a Ringmaster at all?   

I get all the pairs of ribs cut and sanded, then use a needle file of the correct thickness, to make notches in the leading and trailing edges and spar and bellcrank mounts. Works for me, and I scratchbuilt two of them in a week and a half. That was from plans, to ready-to-fly. Just my 2 cents, and an easy task to perform.

I have always tried to replicate the original kits with less iron-like wood however! My method of notching the LE for ribs has been has been to tape tow or three, depending on the stock used to make the ribs, coping saw blades and pull this tool across the formed LE until the saw blades just run flush the stock. When using Ambroid Glue I'd pre-glue each rib's mating surface so that the glue would penetrate the the wood and from a very strong joint. I still have a scratched out P-51 and S1 Ringmaster which were made in 1975 and 1985 respectively and both are still sound and in flying shape. Would have flown the Ringmaster today if it wouldn't have been for the darned hurricane with its wind and rain.

Phil Spillman