Author Topic: How to shape the built up leading edge on a Ringmaster (Read 6560 times)

Mike Griffin · « **on:** May 31, 2014, 04:26:15 PM »

I am going to post several pictures showing how to do this after you have glued up the wing. The first two I will post here show the leading edge before any shaping is done.
Click on the pictures to enlarge them.

Mike

Mike Griffin · « **Reply #1 on:** May 31, 2014, 04:29:42 PM »

These pictures show how I use the Great Plains Razor Plane to do the rough shaping and then I start sanding with the shaping tool that is included with the kit. I have 80 grit in the moulded shaper box.

Mike Griffin · « **Reply #2 on:** May 31, 2014, 04:32:39 PM »

This shows another angle of using the balsa box shaper and the "shoshine" technique of finishing. Using 180 Grit paper to do the shoeshine with.

Mike Griffin · « **Reply #3 on:** May 31, 2014, 04:34:28 PM »

These last two shots simply show the Wingtip weight box and adjustable lead out guide installation which I put in all my pre built Ringmasters whether they be Take apart or just regular..

Mike

Douglas Ames · « **Reply #4 on:** May 31, 2014, 04:48:54 PM »

Very nice!
I never liked the 11 piece leading edges on the modern RM's.
Are you saving any significant weight?
Granted, the vintage baseball bat leading edges can be heavy,
but replaced with a good grade of balsa I think it's easier to build a straight and reasonably light LE.

Bootlegger · « **Reply #5 on:** May 31, 2014, 04:56:17 PM »

Mike I looked at the bolt holding the adjustable L/O guide in place, and have a question, do you "bugger" the bolt threads so it can't back out?
Thanks

Mike Griffin · « **Reply #6 on:** May 31, 2014, 05:21:06 PM »

Quote from: Bootlegger on May 31, 2014, 04:56:17 PM

Mike I looked at the bolt holding the adjustable L/O guide in place, and have a question, do you "bugger" the bolt threads so it can't back out?
Thanks

Gil I am not sure what you are asking me, but the guide is two pieces. The sliding part with the two brass eyelets, is loosened and tightened with that 4-40 bolt which is screwed into a blind nut. You simply insert a small Phillips head screwdriver through the wingtip slot to loosen the guide and move it toy he desired position and then tighten it again.

Mike

Bill Little · « **Reply #7 on:** May 31, 2014, 05:34:36 PM »

Quote from: Mike Griffin on May 31, 2014, 05:21:06 PM

Gil I am not sure what you are asking me, but the guide is two pieces. The sliding part with the two brass eyelets, is loosened and tightened with that 4-40 bolt which is screwed into a blind nut. You simply insert a small Phillips head screwdriver through the wingtip slot to loosen the guide and move it toy he desired position and then tighten it again.

Mike

Hi Mike,

Gil is asking if you do anything to keep the bolt from backing all the way out. I have seen it happen. A pair of dykes and some crimping of the last threads keep it from doing so. That's "buggered up".

Bill

Mike Griffin · « **Reply #8 on:** May 31, 2014, 07:48:41 PM »

Thank you Bill . I didn't understand what Gil was asking. I have never done that on any of my own models and have never had one unscrew all the way.

What I have done is put a nut on the end with thread lock.

Mike

Jim Kraft · « **Reply #9 on:** June 03, 2014, 08:49:42 PM »

I use a nylon insert aircraft type nut on the back side of the bolt. It is probably overkill but I have never lost one either. And I have had them come loose.

Sean McEntee · « **Reply #10 on:** June 03, 2014, 10:02:59 PM »

I'm digging your LE sanding block. How bout a how-to thread on how to make those?

john e. holliday · « **Reply #11 on:** June 04, 2014, 08:16:31 AM »

Well thanks to Eric, the kit I have from him I used the rib to verify the rib shapes. I built my own leading edge and trailing edge on my latest S-1 and the Super Ringmaster. I have plenty of time so it was a job/task I enjoyed.

Gerald Arana · « **Reply #12 on:** June 05, 2014, 10:35:05 AM »

Here's how I do it.

Anybody want to know how to cut a perfect parabola on a table saw?

Jerry

Bill Little · « **Reply #13 on:** June 05, 2014, 10:52:13 AM »

Quote from: Sean McEntee on June 03, 2014, 10:02:59 PM

I'm digging your LE sanding block. How bout a how-to thread on how to make those?

Hi Sean,

First, let me thank you for your service to our country! Second, the parts for the LE sanding block come in the RSM kit. It's a good idea!

BIG Bear
RNMM/AMM

RknRusty · « **Reply #14 on:** June 08, 2014, 09:35:20 PM »

I'm trying to figure out how to make a shaped sanding block to shape the square stick used on the leading edge of my Skyray kit wing. The kit comes with one 1/8" thick wood plate as a gauge with the shape cut into it. I've been freehanding it so far, but now I'm getting close enough that I need the shape to finish right.

I have all of the ply kit ribs I guess I could stack together and mold some sort of goo over them and line it with sandpaper after it sets. I just don't know what that goo would be. I only have rudimentary power tools for shaping balsa blocks including a scroll saw, 1.5" belt sander, and a drill press. Maybe if I use a 1/2" forstner bit and bore through a block long ways and cut it in half. Maybe I'll try that.

Or I take that shaped plate to a carpenter and see if they can make a block for me. I guess Sig figured it's not too critical.

BTW, maybe you guys can tell me some place to get rolls of adhesive backed sandpaper, 220 would be nice. I see Sparky using it all the time in his videos.
Rusty

john e. holliday · « **Reply #15 on:** June 09, 2014, 06:50:54 AM »

Try Tower Hobbies or go to your local wood working store. I have one that used to carry Shop Smith stuff until a call back by Shop Smith. After I get back home maybe I will take time to pull the pictures of how I make a replica of a S-1 Ringmaster leading edge that according to the one from an original kit is exact copy.

Dane Martin · « **Reply #16 on:** June 29, 2014, 02:07:19 AM »

Quote from: Gerald Arana on June 05, 2014, 10:35:05 AM

Here's how I do it.

Anybody want to know how to cut a perfect parabola on a table saw?

Jerry

Yes!

Brett Buck · « **Reply #17 on:** July 07, 2014, 09:21:28 AM »

Quote from: Dane Martin on June 29, 2014, 02:07:19 AM

Yes!

Run the part across the blade with a skew angle. Instead of sliding it along a fence that is parallel to the blade, slide it along a fence that is at a 15 degree (or whatever it takes to get the desired parameters) angle. Take shallow cuts and raise the blade a little bit at a time.

Someday, I will tell you how I cut a true elliptical wing out of foam with a hot wire.

Brett

Dane Martin · « **Reply #18 on:** July 07, 2014, 09:26:49 AM »

Quote from: Brett Buck on July 07, 2014, 09:21:28 AM

Run the part across the blade with a skew angle. Instead of sliding it along a fence that is parallel to the blade, slide it along a fence that is at a 15 degree (or whatever it takes to get the desired parameters) angle. Take shallow cuts and raise the blade a little bit at a time.

Someday, I will tell you how I cut a true elliptical wing out of foam with a hot wire.

Brett

that would be a cool thread with pics when you got time to kill.

Kevin Ferguson · « **Reply #19 on:** July 07, 2014, 10:01:01 AM »

elaborating on table saw techniques:

A pedant would insist that Brett's method gives a elipse,
rather than a parabola. A pragmatist will know that over the range of interest, the two are nearly indistinguishable.

Another way:

If you have a way to precisely control the fence and depth, you can make a stair step approximation of any curve, then sand the corners of the steps off. If you try to make the steps very fine you will find most blades do not cut a rectangular groove...the angles of the teeth leave an inverted vee.

One way to set the fence in equal increments is to clamp a block behind it, the add one more 1/8" shim for each cut. The height can be set with a machinist's height gauge or with a template.

For convex curves, If a thin amount of stock is left between the kerfs, it will support the block on the table for subsequent cuts, then broken out at the end.

Dave Harmon · « **Reply #20 on:** July 09, 2014, 10:32:28 PM »

I use a router and slide the block along the fence....works great and quick.

Dave
AMA 5053

Mike Lauerman · « **Reply #21 on:** September 05, 2014, 02:40:39 PM »

I have a router I bought for some 'deck finishing' on our back porch. I toyed with the idea of shaping a leading edge for my scratchbuilt S-1.

This is a perplexing step in an otherwise 'walk in the park'!

Brett's idea with the table saw is very realistic! I have a block of soft pine that is about to get 'tried'. Thanks, all!