Author Topic: Cutting a set of Ribs (Read 10730 times)

Joe Hamorski · « **on:** October 05, 2015, 08:33:20 AM »

Greetings Fellow Scratch Builders

I need some suggestions regarding cutting a quality set of ribs. On my last attempt, building a Ringmaster for the Fly-A-Thon, I realized there are better and more consistent ways to get set of ribs. Of course, there is always the 'buy a set' option, however I would consider that a last resort. Currently, I'm most interested in the Magician and Cavalier for my next scratch builds.

Thank you for your time
Joe

john e. holliday · « **Reply #1 on:** October 05, 2015, 09:05:57 AM »

This is what I do. Get a second copy of rib patterns and cut the out. On constant chord wings you only need 4 patterns, main ribs and center ribs. Tapered wings need pattern for each rib. I cut the patterns up and proceed to glue the pattern to plywood. Constant chord wings I use 1/8 ply mostly I use 1/16 ply. I cut them out and sand down to the outline. I don't cut the spar notches in the pattern. If you are going to use a rod jig make sure the holes are in correct spot. The hard part, cut the balsa sheets up for the ribs. Stack them between the templates and sand to the pattern. When done take magic marker and mark one side, top or bottom, doesn't matter as I have yet to get airfoil the same top and bottom.

Now is time to mark spar locations before unbolting the stack. You did get bolts long enough from your friendly Ace Hardware store, right. I didn't mention the leading and trailing edge. The trailing edge is easy, the leading edge depends on if it is a notch or squared off. I forgot about marking center line of the rib. Once ribs are done there are several ways of assembling the wing. I have built several wings in my lap with no jig other than masking tape and rubber bands. Most are built using the rod jig, but some how when rods were removed I had a twist. My jig sits on a surface that has been checked each time I use it. I blame it on the stresses of the sheeting when applied while in the jig. Now do I have you confused enough that you will go with laser cut ribs from a CAD drawing???

Randy Powell · « **Reply #2 on:** October 05, 2015, 10:20:00 AM »

Or, send the templates to Pat Johnston as have him laser cut them.

Tim Wescott · « **Reply #3 on:** October 05, 2015, 10:42:16 AM »

The old school way to cut straight-tapered wings is to cut a pair of templates, one for the root rib and one for the tip rib, then bolt a bunch of balsa blanks in a stack between 'em, then use a long straight knife and a touch of sandpaper to cut the stack. Each rib will have an angled edge -- you fix that up for spars and whatnot as you go, then you knock off all the high spots with an idiot board when the wing is assembled.

It's harder to describe than it is to do.

I don't have a picture of a stack bolted up, but here's a picture of two stacks of rib blanks waiting to be bolted up, and a wing in the process of being built from the ribs thusly made.

Jim Kraft · « **Reply #4 on:** October 05, 2015, 08:42:02 PM »

On constant cord wings like the Magician I sometimes just cut a ply template and glue to a block of balsa. I then cut out the block to match the ply template on my band saw. Then I put an angle iron fence on my band saw set to the width of the ribs I want to cut. Then lay the block on its side and cut off the ribs like slicing bologna. You can also do it with stacked blanks put together with 1/4" dowels through them and the ply template. Then when you get the stack cut out on the band saw you are done. Here is a set of Magician ribs.

Motorman · « **Reply #5 on:** October 05, 2015, 09:33:37 PM »

Just trace them on the wood and cut them out with a #11 blade.

MM

Bill Johnson · « **Reply #6 on:** October 06, 2015, 05:43:02 AM »

Quote from: Tim Wescott on October 05, 2015, 10:42:16 AM

The old school way to cut straight-tapered wings is to cut a pair of templates, one for the root rib and one for the tip rib, then bolt a bunch of balsa blanks in a stack between 'em, then use a long straight knife and a touch of sandpaper to cut the stack. Each rib will have an angled edge -- you fix that up for spars and whatnot as you go, then you knock off all the high spots with an idiot board when the wing is assembled.

It's harder to describe than it is to do.

I don't have a picture of a stack bolted up, but here's a picture of two stacks of rib blanks waiting to be bolted up, and a wing in the process of being built from the ribs thusly made.

I've noticed on a couple of older plans that you only get a print of the root and tip rib so you have to do it that way. It doesn't look too hard.

GregArdill · « **Reply #7 on:** October 06, 2015, 05:48:56 AM »

Quote from: Motorman on October 05, 2015, 09:33:37 PM

Just trace them on the wood and cut them out with a #11 blade.

MM

This is also what I mostly do.

Makes me wonder, Do minor imperfections and irregularities matter much? Especially on a more basic model, like a Ringmaster.

Dane Martin · « **Reply #8 on:** October 06, 2015, 07:17:41 AM »

Quote from: GregArdill on October 06, 2015, 05:48:56 AM

This is also what I mostly do.

Makes me wonder, Do minor imperfections and irregularities matter much? Especially on a more basic model, like a Ringmaster.

Nah, they're covered... You can't see them! Lol
I would tell the beginner just try it! What's the worst that can happen? You may have to cut more. But you're already cutting some any way.

Phil Krankowski · « **Reply #9 on:** October 06, 2015, 07:25:25 AM »

On a constant chord wing take your ribs, cut them out via your choice, stack and bind via your choice taking care that they won't slip against each other, lightly sand them to straighten the edges, then unstack and flip every other rib, re-stack and lightly sand again. If all went well enough the ribs will be both nicely profiled and symmetrical.

I never tried this with a tapered wing.

Phil

Larry Borden · « **Reply #10 on:** October 06, 2015, 08:22:03 AM »

What Randy said.

Balsa Butcher · « **Reply #11 on:** October 06, 2015, 09:24:30 AM »

I do the stack and sand method but with a few differences. Blanks are scrap (medium to hard) 3/32 sandwiched between the hardwood templates, carved, and shaped. Keep them oriented and note the high side of the angled edge. Apply thin CA to the edges to harden them up.
Use these as templates to individually cut the actual ribs out of 1/16. High side of the angle goes down. Spar notches are left off of the templates but added later to the actual ribs. If one is careful and doesn't cut into the templates they can be re-used to replace a rib damaged during the build (it happens) or to construct rib sets for additional wings.

john e. holliday · « **Reply #12 on:** October 28, 2015, 11:28:28 AM »

Here's what I did with ribs I just finished sanding for the Vagabond. Ply template and cut ribs with new Ex-Acto blade. Scrap to align the ribs and sanded to get them even with each other. Was offered a set of laser cut ribs, but this way passes time and relaxes me.

Bob Hunt · « **Reply #13 on:** October 29, 2015, 03:57:50 AM »

I've come up with (a long time ago...) a method of making a set of ribs for a tapered wing that produces ribs that are not only accurate in planform (side view), but also have the correct thickness taper (front view), and leading edge taper (top view). This method of rib making is part of a total wing building system that I call the Lost-Foam process. In actuality, no foam is "lost." I just use the foam parts for templating and fixturing. I'll not go into a full explanation of the Lost-Foam process (which, by the way, I wish now that I'd named "Foam Form" building...), but I will post a few photos that show just a part of the sequence. In this case the photos depict the steps required to make as perfect-fitting ribs as I know how to produce. This will require that I post the photos in several responses...

If, after perusing the photos, you'd like a booklet that explains the entire Lost-Foam process, please drop me an email and I'll send you my Lost-Foam Instruction manual in PDF form at no charge.

Later - Bob Hunt

Bob Hunt · « **Reply #14 on:** October 29, 2015, 04:04:04 AM »

Next group of photos...

Bob Hunt · « **Reply #15 on:** October 29, 2015, 04:09:19 AM »

and the next group...

Bob Hunt · « **Reply #16 on:** October 29, 2015, 04:24:32 AM »

More yet...

Bob Hunt · « **Reply #17 on:** October 29, 2015, 04:28:43 AM »

and the last ones...

eric rule · « **Reply #18 on:** October 29, 2015, 02:51:18 PM »

Or just "loft" them in AutoCAD 3D and let the laser do all the hard work.

All of the suggestions above work well. What is important is that you end up with a rib set that is accurate and will do the job for you. Also something that you will enjoy working on. After all this is a hobby! Have fun!

Bob Hunt · « **Reply #19 on:** October 29, 2015, 03:23:21 PM »

I don't look at it as "hard work" Eric; to me its model building, and I enjoy all of it. Creating all the pieces that make up my model by hand is how I get my kicks.

Later - Bob

Randy Powell · « **Reply #20 on:** October 29, 2015, 04:56:01 PM »

I'm with Bob.

Motorman · « **Reply #21 on:** October 30, 2015, 08:02:52 AM »

Is this the legend of the 'Old John Henry? The difference is it's a hobby so to each his own.

MM

eric rule · « **Reply #22 on:** October 30, 2015, 10:06:56 AM »

Bob; I did not make the comment based upon anything you posted nor did I think that anything I said was a negative comment about any of the posts. All I was attempting to point out is that there are many methods folks use to accomplish the same goal.

What I did say was "All of the suggestions above work well. What is important is that you end up with a rib set that is accurate and will do the job for you. Also something that you will enjoy working on. After all this is a hobby! Have fun!"

If you or anyone else took that to mean I was saying what I do is the only way to do the job then you and they are reading into the comment something that is simply not intended. As I said this is a hobby. We all do it in a way that makes it enjoyable for us. Whatever makes you or me happy is therefore a good thing!

Eric

john e. holliday · « **Reply #23 on:** October 30, 2015, 11:14:47 AM »

But laser cutting is making me lazy.

Bob Hunt · « **Reply #24 on:** October 30, 2015, 12:49:47 PM »

Quote from: eric rule on October 30, 2015, 10:06:56 AM

Bob; I did not make the comment based upon anything you posted nor did I think that anything I said was a negative comment about any of the posts. All I was attempting to point out is that there are many methods folks use to accomplish the same goal.

What I did say was "All of the suggestions above work well. What is important is that you end up with a rib set that is accurate and will do the job for you. Also something that you will enjoy working on. After all this is a hobby! Have fun!"

If you or anyone else took that to mean I was saying what I do is the only way to do the job then you and they are reading into the comment something that is simply not intended. As I said this is a hobby. We all do it in a way that makes it enjoyable for us. Whatever makes you or me happy is therefore a good thing!

Eric

Hi Eric:

I don't know what prompted you to think that I thought there was anything negative in your comments. I just responded that I personally like to make all my own parts. Did you not see the "smiley face" at the end of my comments? I think we are all getting a bit too touchy. Perhaps it is time for me to retire from "forum life" if I cannot make simple, and non-agressive comments. I have plenty to keep me busy, so I will not miss this part of my life.

It's been mostly fun. Later all - Bob

john e. holliday · « **Reply #25 on:** October 31, 2015, 01:42:33 PM »

Hey Bobby, don't let some one get your shorts in a tight wad. Every one has opinions and ideas. I'm remember Dad saying people like to criticize, just ignore it, consider the source and let it flow like water off a ducks back. You do too much for us guys on here and else where.

RknRusty · « **Reply #26 on:** October 31, 2015, 09:48:10 PM »

All of the above methods fascinate me, and some I'll try, some I won't. I clicked up and thought about every picture posted, I'm a visual learner. My first attempt at stacking between hard templates and shaping came out so well I surprised myself. I thought it was the most professional looking thing I had ever done. Bob's method it the most ingenious hands-on I've seen, and Eric's is the fastest, after the software input, I suppose. Both produce stunningly perfect results. I detected no negativity, just a statement of comparison. I'm not wired to pick up on negative vibes easily, and probably sometimes miss them when they really are there. I just appreciate that y'all take the time to show us what you do.
Rusty

PerttiMe · « **Reply #27 on:** November 01, 2015, 04:02:22 AM »

There's more than one way to skin a cat...

... I see that people have got conscious about "the devils of the internet". So much so, that they worry about their own posts being misconstrued

Does anyone have more methods or variations?

eric rule · « **Reply #28 on:** November 01, 2015, 08:55:21 AM »

Hi Bob;

Sorry I missed the smiley face at the end of your comments.

You know how much I appreciate all that you have done for the hobby and how much I respect you. I did not want you to think I was discounting your method.

My Bad!!!
Eric

Bob Hunt · « **Reply #29 on:** November 02, 2015, 06:52:17 AM »

Hi Eric:

No apology necessary; I know you didn't mean anything untoward. You are a total class act, and even though we often don't agree on things, I respect you highly for all you have done for the hobby/sport.

My last comments are more of frustration with forum life in general. It seems that everyone is looking for something to gripe about - myself included... The forum (all forums really...) could be a great place from which to learn, but it seems that many just want to snipe at each others comments and thoughts. Can't we all just read the constructive posts and take away from them what helps us, and then refrain from going any further?

Sorry for being so sensitive; I've had a lot on my plate of late and I guess I just vented at the wrong time.

Peace - Bob

Tim Wescott · « **Reply #30 on:** November 02, 2015, 10:34:29 AM »

Quote from: RknRusty on October 31, 2015, 09:48:10 PM

Eric's is the fastest, after the software input, I suppose.

Speaking as a guy who both writes and uses software -- "after the software input" can be pretty loaded. If I'm building a pure one-off airplane it's often faster for me to sketch a few outlines on butcher paper, newsprint, or balsa sheet and just build than it is to draw up "nice" plans in CAD and proceed from there. If I do draw up plans it's either because I'm unsure of myself and I want to ponder on how everything will fit together, or because I think that other people may want copies and I want to share.

If you're doing 3D CAD for your day job then yes, that route is going to be the quickest way to a finished airplane.

BillP · « **Reply #31 on:** November 02, 2015, 11:28:31 AM »

When I first started scratch building I cut everything individually with a blade and later changed to making templates for stacking and cutting by hand or band saw. After a few years of doing it that way I concluded cutting individually was more satisfying (I'm a slow builder) and I reverted back to tracing each rib and cutting it out with a #11 blade. I stack all the ribs and sand to even them...then cut the spar notches and sand them evenly using home brew sticks of different sizes with sandpaper glued to them. For small holes I stack the ribs and use a drill press. For large holes and curves I use drafting templates and a blade. I make no claims that this is a better way to do ribs but it works for me and that's all that matters.

Bill P.

Bill Little · « **Reply #32 on:** November 02, 2015, 04:56:41 PM »

I find it very interesting to cut I Beam ribs. Before I saw the video that Bob did of Billy building an Ares, I just made a one sided template and cut each rib. Then I saw Billy's "jig" for cutting ribs! Since I was going to make more copies than just one of the model, I made a jig like Billys. It IS a much faster means of cutting the ribs, and highly recommended if making more than one model using that airfoil.
Bill

Target · « **Reply #33 on:** November 03, 2015, 11:27:10 PM »

What are ribs?
Lol.
As long as you get usable sets, it doesn't matter how you get there. And there are lots of options.
Pick one method you like, and either stick with it, or change it up each time.
Have fun building whatever you do.