Not sure, anybody interested?

[AURktman]

Amazing as always!

[sdennison]

So, the Former #3 has proven to be a challenging three piece structure but the LH side is now nearly finished. Lots of put and take in the fitting of this. When you have the individual old piece to "remake" I'd think it would go a bit easier but I am trying to fill space from nothing other than a whole assembly and drawings. Maybe I should be smarter but I got what's I got.



Three pieces to make the one final #3 former.








In the fixture, original sample.

[sdennison]

Continuing to develop the fixture as I see the need to improve location. Just to improve the orientation of the formers.



While the original is back in the fixture, a chance to drill rivet pilot holes that couldn't be accessed in the fixture.



Sitting on its own on a bench makes it look like a real assembly.



Back in the fixture and fitting more components. Tedious put them in, take them out, tweek, put them in. Repeat.

[Pogo]

Tedious put them in, take them out, tweek, put them in. Repeat.

Yep, been there before!

[sdennison]

For a little change of pace, chip makin... There are two steel blocks, LH shown...yada yada. They tie the upper center intake section to the lower via a Tee extrusion in the area of the partition separating cooler air from intake air. As with so many parts, there are multiple methods of manufacture. In this case a forging or machined from a block of 4130. No forging here so put the mill to use.



Squared up the blanks on Saturday. Rough machined today and now into finishing stages. The next challenge will be to find the "rivnuts" that get installed in the blocks. They are a press fit but have a thread lock feature. I'll find the part number but not sure I'll find a source.

[sdennison]

Still need to taper the sides and do a little fluff n buff. Won't drill until I can fit to our plane. Also, in search of CVC-1110-4 splined nut inserts. I call the Vought parts department but they didn't answer. Don't happen to have some lying about do you?

[mustanglover]

We use MacLean-ESNA splined nut inserts. You can try them and see what they have to as ESNA was from the 1930 aerospace time frame and probably made the parts you are referring to.

http://www.macleanfoggcs.com/products/maclean-esna-nylon-insert-lock-nuts/

[sdennison]

We use MacLean-ESNA splined nut inserts. You can try them and see what they have to as ESNA was from the 1930 aerospace time frame and probably made the parts you are referring to.

http://www.macleanfoggcs.com/products/maclean-esna-nylon-insert-lock-nuts/

Perfect! This is why I love the WIX brain. They are stock catalog items from the legacy catalog. Thanks Mustanglover!

So, finished these today with the exception of drilling to fit our plane and now, installation of the lock nuts. Sides have a 7 degree draft as well as a taper front to rear. No scanner or CNC mill. Just old school chip production.

[Pogo]

Too pretty to stick in some greasy old airplane...

[sdennison]

Ha, I'll paint them and then the oil will be a preservative...

[sdennison]

So, another how'm I gonna do that? There are four elliptical tube braces in the inlet section main rib that were removed. So, I have to take round tubing and squash it down to the ellipse shape. I am making a set of dies to do that. Channel iron that I am going to fill with Bondo and create the form. Then, I have to make a swedge die set to crimp the ends for the fittings. The braces are all different lengths and the fitting boss lengths are different. Whoops, one more twist, there are two different starting tube diameters, 7/8" x .049" wall and 1" x .049" wall. Oh yeah, the fittings don't exist either. Surprise!

[sdennison]

Continued the forming dies. Made end caps with the finish contour and then attached alignment tabs to the channels.





So, I filled the channel form with Bondo and fit the 2" diameter tube until the Bondo set up.



Trim, sand, repeat.





Next, test samples.

[Rod Schneider]

It is absolutely fascinating to see and learn some of your techniques!!! Awesome work!

[sdennison]

Test tube day...not chemistry but let's see if this die set works. There are two different sizes of elliptical tubing needed. One starts with 7/8" OD x .049" wall and the other with 1" OD x .049" wall. The dies were made off of the 7/8" version. I took a test piece of 2024 and annealed it in the shop (carbon torch method) not to use the oven annealed good stuff. Coated with a little WD40 just because.



Let the "Chalkie" put the squeeze on. The tube just lays in the dies self centering and the guide tabs align the top and bottom.



Pressed until the edges of the die set touched and, guess what? Yup, ellipse. I am within .010" on the width and .005" on the thickness.





So, I tried a sample of the 1" to see what I would get. It is close but too tight in the corners I think. .050" too thin and .030" too wide. I will play with shimming the die for closing thickness to see if I can get the piece to meet print.

[sdennison]

Well, it took three tries to get the proper shimming figured out but happily, with .100" shims in place, the tube squashes to the exact size needed and well within the tolerance. Kind of surprised how simple it was to do. The annealed tubing takes little effort to conform. Even though I cracked the bondo form and the surface finish of the die was not perfect, no issues with the final forms.

The next step is to create the end swedge tooling and process to fit the end brackets. The tube will require heat treating prior to the final fit and drilling for riveting. Oh, by the way, of the four struts per side, each one has a different OAL center to center of the brackets. Sure why not? That makes it real easy for mass production.