Deck repair

Hi Joost, While you will get good responses here, you may also try rec.boats.building. For the job you are describing, you neednt be too accurate with the rolling. For a job like this, what we would usually do is just put it through a roller to 'break its back' as the technique is known. Once you have put even the slightest roll in the plate, it will flex more easily. Once you have rolled it, it doesnt matter too much if you went slightly under or over; this is only 4mm plate. tack the 'straight' side on, then put one tack on either curved side. Now use dogs and wedges to progressively pull the pate and tack it in place an inch at a time. You may even find you can just tack some pipe or whatever to one end of the plate and use that to leverage the plate instead of dogging.

Shaun

Related the rusty boat deck described in my previous question "Cutting bolt with minimal heat" I encountered a new problem.

Most of the steel of my 4 mm mild steel deck is fortunately still there, but there is one place where a section of about 20x40 cm is completely eaten away by rust. I´m planning to cut out this area as far until the surrounding steel is again 3-4 mm and weld a new piece of metal in there. Only complication is that the deck is slightly curved. Not much, but enough to make a flat piece of steel plate look ugly there.

What I would like to ask is what the normal procedure is to fit a new

4 mm mild steel piece in the hole following the curve of the surrounding area. The curve is mainly in one direction and in the middle approx 1 cm away from the "straight line". Perhaps there is also some (much smaller) slight curvature in the other direction.

I thought about preforming the metal on a roller, but measurement is not easy for that. I´d rather take some in-situ approach. Only the material is too thick to deform with simple tools. Perhaps welding some sort of long lever on the plate and use that to curve it while tacking every spot that is on the right position? And cutting the lever away afterwards? Or is it possible to use a propane burner to heat the material and have it bend itself?

Related to this I´m also not sure if any problems might occur after the piece is tack welded in the perfect position. Can it deform while make the final welding all around? I´ve heard that in bad repair jobs like this, the curving "flips" inward.

I´d be very happy with any comments on this.

Joost

Related the rusty boat deck described in my previous question "Cutting bolt with minimal heat" I encountered a new problem.

Most of the steel of my 4 mm mild steel deck is fortunately still there, but there is one place where a section of about 20x40 cm is completely eaten away by rust. I´m planning to cut out this area as far until the surrounding steel is again 3-4 mm and weld a new piece of metal in there. Only complication is that the deck is slightly curved. Not much, but enough to make a flat piece of steel plate look ugly there.

What I would like to ask is what the normal procedure is to fit a new

4 mm mild steel piece in the hole following the curve of the surrounding area. The curve is mainly in one direction and in the middle approx 1 cm away from the "straight line". Perhaps there is also some (much smaller) slight curvature in the other direction.

I thought about preforming the metal on a roller, but measurement is not easy for that. I´d rather take some in-situ approach. Only the material is too thick to deform with simple tools. Perhaps welding some sort of long lever on the plate and use that to curve it while tacking every spot that is on the right position? And cutting the lever away afterwards? Or is it possible to use a propane burner to heat the material and have it bend itself?

Related to this I´m also not sure if any problems might occur after the piece is tack welded in the perfect position. Can it deform while make the final welding all around? I´ve heard that in bad repair jobs like this, the curving "flips" inward.

I´d be very happy with any comments on this.

Joost

Hit it with a hammer. You can stretch a piece of 4mm into a hemisphere with a hammer and some patience. It's how woks and steel drums are made. Doesn't really take a lot, just tap-tap-tap where you want it to stretch.

"BillM" wrote: (clip) I thought about preforming the metal on a roller, but

^^^^^^^^^^^^^^^^ If you have a set of rolls, and measurement is what's holding you back, this is my suggestion: mold some plaster of Paris to the deck adjacent to the hole, and take this into the shop. You know that you will need a bigger piece than the hole, because rolls don't work on the ends.

I think the usual way to shape ship plates is to make a wooden template from the hull or frames and fit the plate to the template. Trace and cut the curve of the deck next to the opening on the edge of a piece of plywood. You can block up the edges of the plate and apply the weight of your car to the center with a jack to curve it, or just drive over it.

I've had better results slightly overbending a curve by crude means, then straightening it to fit with a hammer or by jumping on it.

Jim Wilkins

Yeah, lay it on the ground and work it with a three-pounder, pretty easy to get just the curve you need.

John