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Old 03-31-2017, 05:32 AM
Maxakarudy Maxakarudy is offline
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Default Power hammer on aluminium

I've seen the very impressive work achieved on m/s with a power hammer, can the same be done on 1.5mm/16g 3003/1050 aluminium, I was thinking mainly about shrinking die work.
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Old 03-31-2017, 11:47 AM
AllyBill AllyBill is offline
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Works fine but don't overdo it or it can work harden and crack.

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Old 03-31-2017, 10:12 PM
crystallographic crystallographic is offline
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I'm no expert on this, but there are those who set their Hammer for stretching, and then re-set the Hammer for shrinking. And, there are those who have one Hammer set for shrinking, and others are set for other things. Power is great to have, unless it undoes what you did, and when those "thumbnail" dies come together too hard, they undo the shrink - and you go nowhere fast. And the same thing can happen in a Pullmax - set the dies too tightly and you get lots of motion, but zero shrink action.
One thing about "fatigue failure" is that when the metal is humped up and then flattened a bunch of times, it shows itself very prominently. 1100, 1050, 3003, 3005 are all less prone to fatigue failure with those shrink dies humping and flattening. But, 6061, 6063, 5052 and 5005 are much more susceptible to fatigue failure, with those dies.

Be careful out there,
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Old 04-01-2017, 02:08 AM
Maxakarudy Maxakarudy is offline
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Thanks for the replies,

My thoughts concern the controlability of contact between the dies on a powerhammer and I'm not sure how much there is, whereas with a pullmax you have more control.

Just curious what any of you guys with Baleigh MH19 use to shrink, do you set the machine to rigid mode or spring hammer action?
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Old 04-01-2017, 09:15 AM
crystallographic crystallographic is offline
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Quote:
Originally Posted by Maxakarudy View Post
Thanks for the replies,

My thoughts concern the controlability of contact between the dies on a powerhammer and I'm not sure how much there is, whereas with a pullmax you have more control.

Just curious what any of you guys with Baleigh MH19 use to shrink, do you set the machine to rigid mode or spring hammer action?
Sometimes the dies are a bit loose on that machine.
The design of the shrink dies can help, gradations of effectiveness, as it were.
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Old 04-01-2017, 01:48 PM
John Buchtenkirch John Buchtenkirch is offline
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Quote:
Originally Posted by Maxakarudy View Post
Thanks for the replies,

My thoughts concern the controlability of contact between the dies on a powerhammer and I'm not sure how much there is, whereas with a pullmax you have more control.

Just curious what any of you guys with Baleigh MH19 use to shrink, do you set the machine to rigid mode or spring hammer action?
Initially I had my share of trouble shrinking edges of panels (but not further in) on the power hammer. Scott Knight told me on the edges you have to be careful to only lay the tuck down, if you hit the edges too hard you will stretch them. He also double shrinks edges, in other words he goes right back in on a tuck for a second time. To help myself I also installed a vari-speed motor on my hammer and caped the SPM at 500 or 600 which helped me, as I gained on mastering the foot clutch I turned it back up to 900 SPM.

Shrinking dies (thumbnail style) in a fixed stroke machine (Pullmax type) surely take less time to master, however an experienced operator with a power hammer will certainly outperform the fixed stroke machine.

Someone could probably write a book just on thumbnail dies & hit points (not me, still have more questions than answers) because some dies shrink more aggressively than others and some mark up the metal more than others. Then there is the opinion / argument that unless you use a fixed stroke machine at less than zero clearance (some owners wouldn’t, feel it’s too hard on the machine) you’re not really hammering down the metal so you have a less stable panel when welding it. I was even told that shrinking with thumbnail dies was outlawed by the aircraft industry or at least by some aircraft companies, I’m sorry I can’t even remember who even told me that but consider it just another tidbit of information regarding thumbnail dies.

I have zero experience on Baleigh hammers so it would be unfair for me to comment on them. ~ John Buchtenkirch
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Old 04-01-2017, 02:39 PM
Gareth Davies Gareth Davies is offline
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Martin, I'm sure there's a good few videos on YouTube with Mark Gerisch using the Baileigh machines to shrink and shape thin alloy panels. He is also featured in Bill Longyard's power hammer book, which is worth a read.
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Old 04-02-2017, 11:10 PM
crystallographic crystallographic is offline
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Quote:
Originally Posted by John Buchtenkirch View Post
Initially I had my share of trouble shrinking edges of panels (but not further in) on the power hammer. Scott Knight told me on the edges you have to be careful to only lay the tuck down, if you hit the edges too hard you will stretch them. He also double shrinks edges, in other words he goes right back in on a tuck for a second time. To help myself I also installed a vari-speed motor on my hammer and caped the SPM at 500 or 600 which helped me, as I gained on mastering the foot clutch I turned it back up to 900 SPM.
Shrinking dies (thumbnail style) in a fixed stroke machine (Pullmax type) surely take less time to master, however an experienced operator with a power hammer will certainly outperform the fixed stroke machine.
Someone could probably write a book just on thumbnail dies & hit points (not me, still have more questions than answers) because some dies shrink more aggressively than others and some mark up the metal more than others. Then there is the opinion / argument that unless you use a fixed stroke machine at less than zero clearance (some owners wouldn’t, feel it’s too hard on the machine) you’re not really hammering down the metal so you have a less stable panel when welding it. I was even told that shrinking with thumbnail dies was outlawed by the aircraft industry or at least by some aircraft companies, I’m sorry I can’t even remember who even told me that but consider it just another tidbit of information regarding thumbnail dies.
I have zero experience on Baleigh hammers so it would be unfair for me to comment on them. ~ John Buchtenkirch
Thanks, John.
I watched Leo for hours at a time, over several years. He had a distinct rhythm when shrinking steel. I'd copy his rhythm and get the same results he did, as my part came around at the same speed he was doing. He did complain about his "dull dies" because they would not grab as much as they would when sharpened up. But he said they were fine on aluminum.

I've heard that same rumor regarding "not for use on airplanes" but funny thing, I've done a fair amount of work for the big companies and they never mentioned a prohibition on tool or method but they have made positive machine recommendations for some parts I've made, so I go along with the flow.
I've seen the tracks of those dies on some round cowls from the 1930's, so whatever "prohibition" was certainly not in effect then. And - Jim Younkin used both his Yoder and his Pullmax (with my dies in it) to make up the round cowl for the H-1 replica, and it was doing 375+ and no signs of problems in the 6061 at 80 hours on that airframe.

Variations will happen, in both machines and the craftsmen on those same machnes ....
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Old 04-03-2017, 10:44 AM
John Buchtenkirch John Buchtenkirch is offline
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Kent, I honestly can’t even remember who told me about the ban but I can certainly see where the specification people in the aviation business could be happier with push together Erco, Marchant, Eckold type shrinking compared to thumbnail type shrinking that disrupts / reshapes the metal so much to accomplish the same linear shrinking. I’d also just think that cracking would be less of a concern with the stipple type shrink jaws but I saw at least a dozen of the small shrinkers with teeth being sold off at the Fairchild Republic auction after the A10 contract finished so who really knows . I am not a metallurgist . ~ John Buchtenkirch
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