Panel beating advice please?

[JerryBill]

Although I've been subscribed here a while it hadn't occurred to me to try asking here about panel beating until a search on the topic gave a few hits here.

In my spare time over the past 25 years or so I built a 55-foot steel yacht. The hull was more or less finished six or seven years ago.

For storage of all kinds of stuff including a lot of wood I built a shed next to the boat. A while back a cheap Chinese power tool set fire to it and burned it to the ground. Serves me right for leaving it plugged in I suppose.

Not as bad as it could have been by a long way but things inside the boat did catch fire. Some of the boat's hull plating was glowing red by the time the fire brigade arrived.

They turned the hoses onto it. It made a hell of a lot of noise cracking some of the tack welds that hold the plating to the frames. The hull survived otherwise pretty much undamaged.

Next morning, when it was all cooled down, some of the plating was obviously buckled here and there and I want to try my hand at panel beating to make it fair again.

I've never done it before. Is there anyone here who can point me in the right direction to learn how to do it?

The hull is mild steel, the plating is 3mm on the deck and mostly 5mm on the hull. There's some 1/4" and 1/2" around the keel but thankfully that doesn't seem to have been warped at all.

Thanks very much in anticipation for any suggestions.

 

[CompoSimmonite]

Just my opinion but "panel beating" such thicknesses isn't going to be easy - if at all possible. I can see the only option may be to cut out the warped sections and let in fresh metal. Might be worth visiting a boat yard where they build, repair etc narrow boats to get their views ? All the best.

 

[voipio]

Spot heating on the convex side of the steel panels can be used to pull them straight. There is a knack to doing it well.

See e.g. here:

Distortion - Corrective Techniques

General guidelines are provided on 'best practice' for correcting distortion using mechanical or thermal techniques

www.twi-global.com

 

[Redsailor]

Panel beating in the usual sense is not really going to be any good here as you will most likely be using a sledge hammer. Possible way forward is to use some sort of hydraulic ram set up or perhaps weld some temporary struts across the frames and use levers or hammered wedges to coerce the plating back into shape. The plate will have suffered expansion due to the heat and will be difficult to force back to the original shape. All depends really on how bad the distortion is and how much area it covers, so possibly best course of action is as suggested by CompoSimmonite above.

 

[addjunkie]

Depending on the issues you could weld a bolt on a use jacks and strong backs to pull it out, but heat will probably be better

 

[tom2207]

the shipyard here used to have a squad of men whos job was to flame shrink / stretch things back into place , ive seen pictures of maybe thirty big rose bud torches on a beam on wheels being moved about , its all very spectacular ,,, but some wood and a porta power may be easier ,, cut a few tacks and flex things , sounds like a lot of experimenting lays ahead
looking forwards to the pictures though.

 

[GRW]

This is just a random thought - with no science or experience behind it (so hopefully someone clever will be able to say if it's got legs or is a terrible idea)....

If the section has buckled through heat expansion & distortion (& is sort-off too big now to sit neatly in its place)...

Could you not disc cut several straight long vertical cuts next to each other to alleviate the stress on the plate & create some small amount of space and also make it easier to manipulate the steel?

Then, once the shape is back, weld up the cut lines and grind back to flush?

A) Would that work?
B) Is it too much faff or just a dumb idea?

 

[tom2207]

This is just a random thought - with no science or experience behind it (so hopefully someone clever will be able to say if it's got legs or is a terrible idea)....

If the section has buckled through heat expansion & distortion (& is sort-off too big now to sit neatly in its place)...

Could you not disc cut several straight long vertical cuts next to each other to alleviate the stress on the plate & create some small amount of space and also make it easier to manipulate the steel?

Then, once the shape is back, weld up the cut lines and grind back to flush?

A) Would that work?
B) Is it too much faff or just a dumb idea?

no reason why not , except it can lead to the starved cow look ,,, not great on a new hull. But its a last resort to fall back on I guess.

 

[JerryBill]

Thanks for all the ideas folks, a lot to think about there. I've done a few tweaks using the disc cut idea in the past - I didn't cut right the way through, just made a groove - but it's kinda labour intensive to make a tidy job and I was hoping not to have to go that way. It did work well enough.

My idea of panel beating was based on something somebody said about a similar boat to mine that got caught on some coral in the Indian Ocean and bent out of shape in places. Apparently the owner shipped it back to Norfolk where I'm told it was "panel beaten" but I know no more than that and the guy who told me about it died a while back so I can't ask for more info.

I'll look into the spot heating idea next, that TWI-Global link looks really useful.

Thanks again, I'll be back!

 

[Morrisman]

the shipyard here used to have a squad of men whos job was to flame shrink / stretch things back into place , ive seen pictures of maybe thirty big rose bud torches on a beam on wheels being moved about , its all very spectacular ,,, but some wood and a porta power may be easier ,, cut a few tacks and flex things , sounds like a lot of experimenting lays ahead
looking forwards to the pictures though.

In a shipyard in Japan I saw guys curving and shaping 2" thick steel into unbelievable shapes using nothing more than huge torches and fixtures to hold the steel. It's a dying art, nobody learns it any more. Creating the curves of a bulbous bow on a ship is not something you can mass produce in a press brake.

I'm sure there's a Youtube video showing some Japanese artisan curving thick steel plate, not seen it for a while though.

 

[Morrisman]

Thanks for all the ideas folks, a lot to think about there. I've done a few tweaks using the disc cut idea in the past - I didn't cut right the way through, just made a groove - but it's kinda labour intensive to make a tidy job and I was hoping not to have to go that way. It did work well enough.

My idea of panel beating was based on something somebody said about a similar boat to mine that got caught on some coral in the Indian Ocean and bent out of shape in places. Apparently the owner shipped it back to Norfolk where I'm told it was "panel beaten" but I know no more than that and the guy who told me about it died a while back so I can't ask for more info.

I'll look into the spot heating idea next, that TWI-Global link looks really useful.

Thanks again, I'll be back!

The idea behind heat shrinking is that you heat a spot cherry red, it expands and crushes the cooler steel around it a small amount. You let the red spot cool down, and it shrinks back to its normal size, pulling in the squeezed down steel around it, thus the immediate area is smaller than it started out as.

 

[Bullet2012]

or use one of these for panel beating

 

[addjunkie]

Come on guys hes only been on 25 years, might as well start again….only joking

 

[Morris]

Dogs, wedges, a BFH and a large rosebud torch.

 

[8ob]

Could you not disc cut several straight long vertical cuts next to each other to alleviate the stress on the plate & create some small amount of space and also make it easier to manipulate the steel?

Then, once the shape is back, weld up the cut lines and grind back to flush?

A) Would that work?
B) Is it too much faff or just a dumb idea?

Its how I would do it, maybe cut a large cross through the middle of each dished/concave section which would give four workable flaps to fettle. In the absence of some serious heating/pulling equipment you would stand more chance of getting it right.

Bob

 

[Seadog]

 

[arian]

Although I've been subscribed here a while it hadn't occurred to me to try asking here about panel beating until a search on the topic gave a few hits here.

In my spare time over the past 25 years or so I built a 55-foot steel yacht. The hull was more or less finished six or seven years ago.

For storage of all kinds of stuff including a lot of wood I built a shed next to the boat. A while back a cheap Chinese power tool set fire to it and burned it to the ground. Serves me right for leaving it plugged in I suppose.

Not as bad as it could have been by a long way but things inside the boat did catch fire. Some of the boat's hull plating was glowing red by the time the fire brigade arrived.

They turned the hoses onto it. It made a hell of a lot of noise cracking some of the tack welds that hold the plating to the frames. The hull survived otherwise pretty much undamaged.

Next morning, when it was all cooled down, some of the plating was obviously buckled here and there and I want to try my hand at panel beating to make it fair again.

I've never done it before. Is there anyone here who can point me in the right direction to learn how to do it?

The hull is mild steel, the plating is 3mm on the deck and mostly 5mm on the hull. There's some 1/4" and 1/2" around the keel but thankfully that doesn't seem to have been warped at all.

Thanks very much in anticipation for any suggestions.

I remember reading in Model Engineer(?) about fettlers on newbuild railway engine boilers, who would turn up with an OA torch and a hammer and make everything good. Whole new skill to re-create