Metal forming motorcycle hugger

[Screwdriver]

You've missed the part where you trap the tuck. It will still work without but not as effective.

I have no idea how you'd do that in this case. I rely on the grippy "anvil" which constrains the material. If I bolt it down somehow I can see how that would be bettr but that is a very awkward shape to work with. When you hammer inside for example, it's difficult not to foul the edge with your hammer or the occasional finger.

A sand bag would be a much better bet. I have to move the position of the workpiece constantly so fixing it would be extremely tedious, be very interested to hear of some tips and tricks though. This is fun!

 

[Screwdriver]

Trapping the tuck

Well that is interesting. I could see how the technique works but my tucks formed naturally due to the compound curve shortening the edge. I think the part is now much too hard to tuck as shown, I may have to run with it as-is.

Need to make another hammer because I am interested to try a "proper" technique as shown. I can hardly believe my approach worked without knowing this "trapping" business.

 

[Screwdriver]

Duralumin age hardens.

Does it also work harden?

 

[MattF]

Not sure.

I simply recall the age hardening bit from somewhere. A search online should give all specifics regarding its characteristics.

 

[Screwdriver]

From Grok:

"Yes, duralumin does exhibit work hardening (also called strain hardening or cold working), but this is not its primary strengthening mechanism.

Duralumin is a classic early example of a precipitation-hardenable (age-hardenable) aluminum-copper alloy (typically in the 2000 series, like Al-Cu with additions of Mg and Mn). Its famous and revolutionary property — discovered by Alfred Wilm around 1903–1911 — is that it can be significantly strengthened through heat treatment: solution treatment (heating to dissolve precipitates), quenching, and then natural or artificial aging to form fine precipitates that block dislocations.

Sources describe duralumin as relatively soft and ductile in the annealed or as-worked state, allowing it to be rolled, forged, extruded, or drawn. Like essentially all aluminum alloys (and most metals), it undergoes work hardening during cold deformation — plastic deformation increases dislocation density, raising strength and hardness while reducing ductility.

However, the dominant way to achieve high strength in duralumin is precipitation hardening (age hardening), not work hardening."

Next question: do we think this actually is Duralumin? Got a massive sheet off @hotponyshoes (thanks Luke!) but I merely assume that's what it is...

 

[tom2207]

This ^ "shrinking" thing, I've watched a good few vids, but damned if I can see how it works - anyone else?

once it clicks its simple ,,, try it with a lump of blue tac in your hands first using a table as a backer and it will all make sense .

 

[Agroshield]

I have no idea how you'd do that in this case.

One of the YT I saw (tuck shrinking fixture billsmetal), he has two pairs of long jaw mole grips welded to a fixture. You grip the material either side of the tuck and flatten it. The grips stop the material moving sideways.

For making the tucks, a set of slate cutters with modified jaws can work (courtesy of Trev's Blog on YT).

Slate Cutter

Strong steel construction with spring loaded handles and soft grips. Coated for rust resistance.

www.toolstation.com

These work on thin stuff:

https://www.amazon.co.uk/MAXPOWER-Crimper-Stainless-Ductwork-Downspout/dp/B0C23JZ4PF

 

[Morris]

From Grok:

"Yes, duralumin does exhibit work hardening (also called strain hardening or cold working), but this is not its primary strengthening mechanism.

Duralumin is a classic early example of a precipitation-hardenable (age-hardenable) aluminum-copper alloy (typically in the 2000 series, like Al-Cu with additions of Mg and Mn). Its famous and revolutionary property — discovered by Alfred Wilm around 1903–1911 — is that it can be significantly strengthened through heat treatment: solution treatment (heating to dissolve precipitates), quenching, and then natural or artificial aging to form fine precipitates that block dislocations.

Sources describe duralumin as relatively soft and ductile in the annealed or as-worked state, allowing it to be rolled, forged, extruded, or drawn. Like essentially all aluminum alloys (and most metals), it undergoes work hardening during cold deformation — plastic deformation increases dislocation density, raising strength and hardness while reducing ductility.

However, the dominant way to achieve high strength in duralumin is precipitation hardening (age hardening), not work hardening."

Next question: do we think this actually is Duralumin? Got a massive sheet off @hotponyshoes (thanks Luke!) but I merely assume that's what it is...

Having had a quick search on Duralumin one thing I noticed is that the last production was in the 70's. It was replaced by 2000 series alloys and then 6000 series. So if what you have is Duralumin it's old. It also has poor corrosion resistance so probably would not have survived this long.
I'm no expert on it though, just an interested bystander.
I asked about the wire edging earlier because that is how you prevent stress cracking from the edge. Duralumin is sensitive to notches.

 

[Screwdriver]

One of the YT I saw (tuck shrinking fixture billsmetal), he has two pairs of long jaw mole grips welded to a fixture. You grip the material either side of the tuck and flatten it. The grips stop the material moving sideways.

Yes but it was the "trapping" that I was unfamiliar with. The tuck just wants to flatten out so something other than the mere presence of the side material needs to constrain it. I assume a good grippy anvil surface must work up to a point because that's how I go this far. I'll be making up some tucking forks in a minute though because that looks like the best way to form this hugger.

Then I may also 3d print some inserts for a screw face mallet. That will test the durability of a PETG print!

 

[Maxakarudy]

Yes but it was the "trapping" that I was unfamiliar with. The tuck just wants to flatten out so something other than the mere presence of the side material needs to constrain it. I assume a good grippy anvil surface must work up to a point because that's how I go this far. I'll be making up some tucking forks in a minute though because that looks like the best way to form this hugger.

Then I may also 3d print some inserts for a screw face mallet. That will test the durability of a PETG print!

It's quite a complex technique to get the best results, metal on metal stretches, unavoidable, metal on hardwood is better as it allows compression, not stretching, the "tuck" has to be flattened at the outer edge aswell, so it can't escape, so then you are left with a bulge (), then it's case of flattening it out, you are therefore reducing the surface area of that piece of metal, thus shrinking.

 

[minimutly]

Complex to do, complex to understand as well.. will have to dedicate an afternoon to it.

 

[Misterg]

Does it also work harden?

Any of the likely grades will anneal & work harden.

It'll go dead soft when annealed, but as soon as you start working it, it will stiffen up quite a bit and allow you to work it for quite a while before it needs annealing again. By the time you've shrunk the edges a bit it'll be reasonably hard again. Just be cautious of hitting it too hard immediately after annealing.

 

[Maxakarudy]

A wee tucking fork I made with 2 centre punches & flat bar

 

[Screwdriver]

I will carry on practising with this piece but the customer has changed their mind. Now he wants a flat sheet bolted between the frame rails but interestingly, easily removable. Interesting because it gives me something to think about but also somewhat annoying not to have anywhere to fit this.