Author Topic: How to put spar cut outs in ribs 4/13 completed new pics another question (Read 3182 times)

Leester · « **on:** April 10, 2007, 06:17:10 PM »

I just finished stack sanding a set of ribs. This was my first attempt at it and everything went well. Now I need to make the cut outs for the spars, according to Randy P. you place the spar at or near the high point of the ribs. I still have them bolted together so whats the best way to do this at this stage of the project ? Thanks

Keith Spriggs · « **Reply #1 on:** April 11, 2007, 01:00:47 AM »

If you know anyone that has a mill/drill it works real well to cut the notch for the spar. In your case, since it is a tapered wing, you would need to make two tapered pieces of wood to put between the "rib stack" and the vise jaws so the top of the ribs would be "level". In the picture the ribs I am notching were all the same size so the blocks were not necessary. I used a 1/8 inch router bit and run the mill at the highest speed. The highest speed that a mill/drill will turn is far short of the optimum speed for a router bit, but it still works fairly well. A sharp bit is a necessity. It can also be done on a table saw, but it is more difficult to get a really good fit.

Bill Gruby · « **Reply #2 on:** April 11, 2007, 03:57:34 AM »

Lee;

Keiths' idea is a good one. You might be able to get by with a good "Drill Press" also.

On the occassion that I have to do "Stack Ribs", when I fabricate the root and tip templates I cut all notches in the templates ie Leading edge, spars etc. After I cut and sand to shape I just use a few files to cut these out. Just another way to do it. I am sure there are more.

"Billy G"

It is early bring on the Danged COFFEE.

Dick Fowler · « **Reply #3 on:** April 11, 2007, 05:59:22 AM »

Keith, tell us more about the "wing jig" in the second picture. Looks like a slotted piece of pine.

dave siegler · « **Reply #4 on:** April 11, 2007, 07:27:32 AM »

For constant cord wings it is easy. Just use your band saw while still in the stack. It is easy to nibble out a slot that is slightly undersize then glue some 120 grit to a short section of your spar, or a small file to finish the slot. You can trial fit the spars and LE while still bolted together. This is easier that it sounds. Just keep the slot under size to start.

Practice on the stack of outcuts you have to get the technique down

I also use the outcuts and stack cut triangle gussets. that way I always have a stock of them at hand. I use gussets a lot more when I have them precut.

I use a scroll saw for this operation. ( I don't have a band saw.)

Also a zona saw will do it well too. make multiple cuts an break out the chips. I use a zona saw on tapered rib sets.

Dave

Paul Smith · « **Reply #5 on:** April 11, 2007, 08:00:00 AM »

I just include the spar notches in the templates and cut the stack with an X-Acto saw, with a file as the final cleanup.

Big holes are drilled with sharpened brass tubing in a power drill. No laser, no CNC. Just #11 blades and finesse.

No big whoop.

Leester · « **Reply #6 on:** April 11, 2007, 09:38:16 AM »

Thanks guys: I am making a built up wing from a foam wing design so there is no guide for where the spars go. I used Sig C grain 1/16th balsa and drilled the bolt holes with my drill press. The holes turned out perfect, didn't screw up the wood at all. I guess I'll put jig holes in the ribs put the rods in and mark for the spars and go from there.

Bill Little · « **Reply #7 on:** April 11, 2007, 09:43:14 AM »

Quote from: Leester on April 11, 2007, 09:38:16 AM

Thanks guys: I am making a built up wing from a foam wing design so there is no guide for where the spars go. I used Sig C grain 1/16th balsa and drilled the bolt holes with my drill press. The holes turned out perfect, didn't screw up the wood at all. I guess I'll put jig holes in the ribs put the rods in and mark for the spars and go from there.

Lee, I would bolt the ribs back together at least to mark the front edge of your spars. You can decide where you want them, then use a straight edge and draw the lines where the front and rear of the cutouts need to be. Bill <><

Leester · « **Reply #8 on:** April 11, 2007, 09:50:32 AM »

Bill, I haven't unbolted them yet, so mark the front and rear now ? Then take apart and make the notches ? Almost forgot, with the ribs tapered at the front and rear do I square them off or or just make sure there all angled in the same dirrection inboard to out ?

Bill Little · « **Reply #9 on:** April 11, 2007, 11:04:22 AM »

Quote from: Leester on April 11, 2007, 09:50:32 AM

Bill, I haven't unbolted them yet, so mark the front and rear now ? Then take apart and make the notches ? Almost forgot, with the ribs tapered at the front and rear do I square them off or or just make sure there all angled in the same dirrection inboard to out ?

I make the cutouts in the root and tip templates like someone else pointed out, then take a razor saw and cut down the templates.

Pick where you're gonna put the spars (high point of the airfoil is good) then make the width of the cutout marks on the ribs before you unbolt them. Of course, you can do that, leave them bolted together and use the scroll/bandsaw mwthods the others talk about. I have hand cut each spar cut out before........ I used a single edge razor blade and "chop cut" them.

Bill <><

bill marvel · « **Reply #10 on:** April 11, 2007, 01:46:52 PM »

Quote from: Leester on April 10, 2007, 06:17:10 PM

I just finished stack sanding a set of ribs. This was my first attempt at it and everything went well. Now I need to make the cut outs for the spars, according to Randy P. you place the spar at or near the high point of the ribs. I still have them bolted together so whats the best way to do this at this stage of the project ? Thanks

Lee
My low tech method for cutting spar notches as well as leading and trailing edge notches is to use a couple of pieces of fine toothed hacksaw blade separated with a slice of plywood of the appropriate thickness. I think I read this in "Air Trails" back in the 1950's!!! Make sure the teeth are down so it cuts on the pull. Experiment with several thicknesses of ply. Stack some scrap balsa and make some cuts until you get the spar thickness. Epoxy the blades to the ply and you will have a slotting tool that will last forever. After you have made 2-3 of these with varying separations, you'll never have to make another.
regards,
bill marvel

Paul Smith · « **Reply #11 on:** April 11, 2007, 01:47:32 PM »

Here's a hot tip from the free flight world.

Before you start the stack-sanding, brush a little clear dope across the edges of the stack. This will keep the ribs lined up so they don't shift during the work. Most of the dope gets sanded off in the process, and you can use a razor blade or acetone get the ribs a part later.

Tip #2 - Dubro 4/40 threaded pushrod stock to make the long bolts.

Keith Spriggs · « **Reply #12 on:** April 11, 2007, 11:03:28 PM »

Quote from: Dick Fowler on April 11, 2007, 05:59:22 AM

Keith, tell us more about the "wing jig" in the second picture. Looks like a slotted piece of pine.

There are many ways to do almost any job. I happen to use the mill drill to cut the spar notch since I was also going to cut the leading edge notch and the elongated holes in the ribs all at the same time. The router bits made very smooth notches and everything ended up within a few thousandth of an inch.

For the wing jig I used the first piece of wood that I happen to see which was a rough 2x2 of some undetermined specie. I ran it through the jointer until all sides were straight and parallel It actually ended up about 1 1/4 inch square. I laid out where the ribs went and selected a saw blade that would cut a notch that the 1/16 th inch ribs would fit in snugly. I cut kerfs through where the ribs were located. I then ripped the board in half which gave me two identical "jigs". I clamped them down and checked both for level and square. I located one next to the spar notch and one at the trailing edge of the ribs. If I was doing it again I would locate the rear jig far enough forward to install the trailing edge at the same time with it still in the jig. As it was I had to move it forward and recheck fer level and square again. It worked very well and the wing ended up very straight. A tapered wing could be built with a slight variation of the same type of jig. It cost nothing but the number one reason was that it was fun to do.

Leester · « **Reply #13 on:** April 12, 2007, 12:09:14 PM »

I got the jig holes in and the spar notches. I just have to set up the jig and I'm ready to "Rock'n Roll" Thanks again for all the tips, I did learn alot from this.

Leester · « **Reply #14 on:** April 13, 2007, 11:23:21 AM »

I've got them all finished and jiged up. This is a tapered wing as you can see and I made all the ribs at once. I put the larger rib 1,3,5 etc. on the inboard side. The Inboard panel is bigger than the outboard, because of this the leading edge and spars don't match at the center line of the wing. The inboard side is 1/16 more forward than the outboard ? I did square up the trailing edge. This wing will go in a profile fusalage. Is this going to cause a problem or not ? Thanks

Steve Helmick · « **Reply #15 on:** April 13, 2007, 10:26:52 PM »

Hidden inside the fuselage, it shouldn't be noticeable. Aerodynamics won't mind. Post pics.

Steve

Author Topic: How to put spar cut outs in ribs 4/13 completed new pics another question (Read 3182 times)

Leester

How to put spar cut outs in ribs 4/13 completed new pics another question

Keith Spriggs

Re: How to put spar cut outs in ribs

Bill Gruby

Re: How to put spar cut outs in ribs

Dick Fowler

Re: How to put spar cut outs in ribs

dave siegler

Re: How to put spar cut outs in ribs

Paul Smith

Re: How to put spar cut outs in ribs

Leester

Re: How to put spar cut outs in ribs

Bill Little

Re: How to put spar cut outs in ribs

Leester

Re: How to put spar cut outs in ribs

Bill Little

Re: How to put spar cut outs in ribs

bill marvel

Re: How to put spar cut outs in ribs

Paul Smith

Re: How to put spar cut outs in ribs

Keith Spriggs

Re: How to put spar cut outs in ribs

Leester

Re: How to put spar cut outs in ribs

Leester

Re: How to put spar cut outs in ribs 4/13 completed new pics another question

Steve Helmick

Re: How to put spar cut outs in ribs 4/13 completed new pics another question