Sheet Metal Forming

[Broken-Wrench]

[quote="Rossco"]Hammerforming or rolling around a die might be the way..Had similar dramas with the Spitfire frame cappings.[/quote]

I'm trying to understad Australian. Just trying to understand

Shot bag and hammer? Hammerforming?

Rolling around a die? English wheel?

What is a frame capping? a doubler?

[Broken-Wrench]

I like radius tools also,, You just stick it in the machine and bang perfect radius everytime..

[262crew]

Hammerforming or rolling around a die might be the way..Had similar dramas with the Spitfire frame cappings.

I'm trying to understad Australian. Just trying to understand

Shot bag and hammer? Hammerforming?

Rolling around a die? English wheel?

What is a frame capping? a doubler?

i.e. using a hammer to persuade the metal into shape.

[quicksilvermustang]

The big problem with forming 2024-O around a form block/ strecthforming/or whatever the hell else you use is when you got to heat treat it, it will warp and potato chip on you. The way the parts in the war were made were drop formed using 2024-O, heat treated, then put back in the drop form and hit again another time sometimes more. if you can make it out of T4 or even 2024-T351 it will give you the desired thickness and strength for the part

[Rossco]

Hammerforming... click here and watch the first post...
http://spitfireprojecta58-27.blogspot.com/
Rolling...

and capping is the blue bit....

Any questions??

[Broken-Wrench]

Thanks for the post!!!

[RyanShort1]

Good stuff!

Ryan

[A2C]

The big problem with forming 2024-O around a form block/ strecthforming/or whatever the heck else you use is when you got to heat treat it, it will warp and potato chip on you. The way the parts in the war were made were drop formed using 2024-O, heat treated, then put back in the drop form and hit again another time sometimes more. if you can make it out of T4 or even 2024-T351 it will give you the desired thickness and strength for the part

That sounds about right. You can possibly also age harden T-0, and possibly heat treat and quench after ageforming w/o deformation

[Rossco]

I,m missing some info in my old text books but is it possible to anneal T3 back to 0 for hammerforming?Some of our frames were cut in the wrong stuff and I don,t want to waste material.Some of the Spit frames do have tight curves around them..

[OZFURYFAN]

Yes Rossco,you can do a partial anneal or a full one,a partial uses a temp of around 340 deg c and then air cool the parts,after you finish forming resolutionise the work back to temper using 488-499 deg c and then age harden(96 hours).You can even re cook it to T4 or T6 if you like baking!!!Mil-h-6088 is the spec if you want accurate info on temperature & heating times,cheers,Pete

[Rossco]

Cheers mate,thats given me a huuuuge relief knowing I can soften the frames to do a good job on them..Now to approach Boeing out at the base and see if I can grab some time in their salt bath..

[muddyboots]

As shocked at BW's posting such an interesting thread, I must also say that it would be really neat to build your own Airacobra in your barn using nothing but wood patterns. I know next to nothing baout metal working, so this has been a really bried but interesting inro to it...Could somebody maybe use this as a intro to aircraft metal working? What are the metals you use for sheet metal, and framing, and stringers, and such? what do all those numbers mean?

[262crew]

As shocked at BW's posting such an interesting thread, I must also say that it would be really neat to build your own Airacobra in your barn using nothing but wood patterns. I know next to nothing baout metal working, so this has been a really bried but interesting inro to it...Could somebody maybe use this as a intro to aircraft metal working? What are the metals you use for sheet metal, and framing, and stringers, and such? what do all those numbers mean?

You have asked a question that requires a lot of detail but in short the numbers 2024-T3 refer to the material type (aluminum) and condition of heat treat. T-3 is "softer" then T-4 and 7075-T6 is "harder" then T-3 or T-4. Different areas of an aircraft require the different material and is dependant on what the engineer calls out in the drawing. Generally the harder the material the more stress it can take. 7075-T6 could be used in a wing spar web and the attaching angles, and the spar cap might be made of 4130 chrome Molly steel. Think "I" beam in shape. On commercial airplanes the skin is usually T3 or T4, but in high heat areas it might be stainless steel, titanium or inconel. On Boeing airplanes floor beams are T4 the skins are T3 and the frames are T6. I have made frames for an F-104 using the hammer forming method. I started with the original frame traced it onto maple then compensated for bend radius, and material thickness. The aluminum was 7075-T6 as the final condition but I had to use 7075-T0 and that means the material was very soft (T0) for forming. After I beat the S H ! T out of it I sent it out to be heat treated to the final condition of T6. I have also made frames and structural pieces for a BF-109 using original drawings, back then they used a lot of duraluminum and had to convert it into modern standards since duraluminum is not practical. Basically the equivalent material was T4. Confused? Me too?!?

If engineers had to build aircraft they would be designed differently

[Cvairwerks]

Muddy: A good place to start might be taking one of the EAA weekend workshops. They have a number of them thoughout the year on various subjects. There are also a couple of tinbashers that are of ultra-high quality workmanship that do some workshops. A couple of guys have some really good CD's too. It just takes practice and the desire to become good at it.

[Rossco]

Hammerforming is fun but hard work,even in 0 (annealed) temper.Important thing is to polish your edges and work quickly (heavy hits)to prevent work hardening,which will end up cracking...How do I know this???...errrr ummmm...
Errr watch here for some of our efforts...
http://au.youtube.com/watch?v=M7rXV4tdw ... re=related
To start out go down and grab a tinmans mallet,one with radiused ends,a sandbag,not the army hide behind type but a round leather bag filled with sand or lead shot and a panelbeating kit.Best aluminium to start out with is straight commercial grade half hard .9mm or about .040",or 3000 series marine grade.Also a lot cheaper than aircraft grade.Now start hammering the ally into the sandbag with the big end of the tinmans mallet,overlapping each hit in a circular pattern.Next thing is to keep hitting and "WATCH" what the metal is doing.Manipulate it like a sculpture works his clay.Play with it and let it stretch and shrink. Let the metal LIVE!!!!!!