Ideas on shaping aluminum

[Brian]

After searching to no avail for a pre-shaped aluminum piece, I have decided to make my own firewall bump-out. Does not have to be much really, but it does have compound curves.

I took a piece of aluminum, marked it up and started whacking it with a body hammer and found that it shaped rather easily, and here is a pic of the prototype.

My question is, how do I go about making the final piece in a manner that ends up with a more presentable finish? Should I cover my hammer with leather? Use a plastic mallet? use heat? use thicker ali and file it to shape?
Any thoughts would be appreciated.

Many thanks

Brian

 

[Bill D]

The best way is to use an English wheel. Eastwood sells them but they're big $$$

 

[Richard Timte]

Bill,

your close but a English wheel is used to make the shape, a planishing hammer is used to smooth out the finish. Here is a link to some hand ones for sale. Planishing Hammer

 

[Bill D]

Thanks for the clarification RT

 

[JimmyMac]

Richard,
A planishing hammer won't do it either.
This is how it's done.

 

Here is a link for a pneumatic planishing hammer. Planishing Hammer by Eckold Very pricy though, but will give professional results. Here is a more economical choice, Eastwood Company: Auto Tools, Body Repair, Classic Car Restoration, House of Kolor Paint, Powder Coating

 

[Jac Mac]

If you have not had much experience in this field go to www.metalmeets.com
You will find most info you require there, even how to fab your own air planishing tools which you need for your project. If you have not annealed the alloy yet after your work to date do so as even the softest of alloys will have work hardened at this stage. Two old tricks for doing this( try on a piece of scrap alloy first);
1. Scrawl all over the alloy with a felt tip marker pen, then use a neutral oxy acetylene flame to heat the alloy until the marker pen ink is just gone ,no more, do not get flame to close to alloy so that sheet is heated evenly. then dunk in a bucket of water or if working with the panel on a vehicle use a wet sponge to cool rapidly.
2. Use an excess acetylene flame and allow the carbon/soot to cover the area of alloy you wish to anneal, now change to a neutral flame and heat until the carbon/soot disappears as in 1 above and cool.

Depending on how much you work the material you may have to repeat this process several times.
Jac Mac

 

[Mark Worthington]

Brian, I have an aluminum "blister" that came with my RF kit that I don't need, because my engine has the shortened water pump. You are welcome to it.

 

[Brian]

Deleted because Mark stepped in with his kind offer..........

 

[Brian]

WO-WEE!! That's sweet Mark, many thanks for the offer. I'll take you up on it and save my fingers..

Brian

 

[JimmyMac]

One day you might get as good as this guy with a planishing hammer !
LOL


YouTube - Peugot

 

[John Fitzpatrick]

That's almost as funny as the "un-pimping" VW commercial! Thanks for the smile!

 

[Randy]

This is what I'd do, First graet job so far. Shrinking around edge will straighten it.then use a planishing post (doly welded on post fixed in vise) then hammer on doly will smooth and raise center. Check my work at www.Blastolene.com,
Randy

 

[Randy]

Or you can mail it to me and I'll finish. I have english wheel, planishing hammers, shrinkers.ect, Or come to Grants Pass and I'll show you how!
Randy

 

[Pat Buckley]

I love your style Randy.

Fantastic.

 

[Lynn Larsen]

Jac Mac,

You 'da man. I was wondering if someone was going to mention annealing to remove the work hardening, especially with aluminum. I could just see the little cracks starting to form as the shape approached the final form.

 

[Rob]

Hey JacMac,
I thought the idea after warming was not to quench, as that affects the mechanical properties and hardens the material again.

My understanding has always been that the "quench cooling" or "rapid quenching" produces hard and brittle grain structure due to formation of metastable, aka martensitic beta.

In doing the same kind of activity I do the high soot warm up, but then let it come down naturally (no forced cooling).

Thoughts....?????

 

[Rob]

Back to top....really looking for input from JacMac. thanks...

 

[Jac Mac]

Hey JacMac,
I thought the idea after warming was not to quench, as that affects the mechanical properties and hardens the material again.

My understanding has always been that the "quench cooling" or "rapid quenching" produces hard and brittle grain structure due to formation of metastable, aka martensitic beta.

In doing the same kind of activity I do the high soot warm up, but then let it come down naturally (no forced cooling).

Thoughts....?????

Sorry Rob, I,ve been away chasing race cars for the last few days and missed this one,

With aluminum ( And I am quoting Ron Fourniers book here as he puts it quite simply)--A controlled process of heating metal to 640 deg F(338 deg C) and cooling rapidly to 450 deg F (232 deg C) until recrystalization occurs to soften the metal.

With Steel heating then Cooling slowly ( Temps reqd vary with different grades and conditions of steels).

Was talking with a fellow GT40 addict this weekend and he mentioned that for aluminum he use's soap as a temp indicator with the difference that the soap turns black when the correct temp has been reached prior to quench.

I should stress that care should be taken not to overheat aluminum during this process, if you think you have done so allow to air cool for a minute or so before the quench and you may save it, but have a close look at the surface for any cracks, tearing etc in the suspect area ( magnifying glass ) before further work. Once you have 'overcooked' it there is little option but to start again.

Jac Mac

 

[Rob]

Hey Jac Mac,
Thanks for the info. Very interesting.
I have considered for a while picking up an infared pyrometer. This would come in quite handy in this situation too I would presume. Possibly another argument to get one. The guess work on the temp is always the worst part of the process.

I will try your process the next opportunity.

thanks again.....