Oops, I did it again!

I have 3 electrical cabinets that I have emptied of all the useful
bits and would like to make them into lock-up cupboards. They are 2
mm. mild sheet and stand about 6 ft. high and 3 ft wide with a depth
of about 9 inches.

The doors are having a folded and welded edge for strength, but
because there were a lot of switches and lights etc. there before they
left a lot of holes which needed to be filled. I made some disks of
the correct sizes and thickness and MIG welded them in the holes. This
was in the first door. Smashing, all I needed was to grind down the
welds smooth, a bit of filler and paint. Oh no! The panel has now got
two stable states, both wrong. The panel is distorted and I am
dismayed. Is there any way I can relieve this and make it flat again?

Does anyone have a solution? I would be very happy to try anything.

Thanks and regards George.

On Wed, 22 Apr 2009 11:12:25 -0700 (PDT), George
wrote:


The doors are having a folded and welded edge for strength, but
because there were a lot of switches and lights etc. there before they
left a lot of holes which needed to be filled. I made some disks of
the correct sizes and thickness and MIG welded them in the holes. This
was in the first door. Smashing, all I needed was to grind down the
welds smooth, a bit of filler and paint. Oh no! The panel has now got
two stable states, both wrong. The panel is distorted and I am
dismayed. Is there any way I can relieve this and make it flat again?

Does anyone have a solution? I would be very happy to try anything.

The welds shrank as they cooled. Try peening them to stretch them back
out. The work'll go faster hot, but doing it cold is safer and less
prone to surprises. A good heavy dolly to back up your hammering is a
must.

Are the two stable states warped with the corners out of plane?

--
Ned Simmons

Ned Simmons wrote:
The welds shrank as they cooled. ...

I suspect that the welding heat expanded the sheet & the welded-in patch
locked it in the expanded state. There are 2 methods that I know of to
shrink metal:

1. with a torch, heat a spot of the expanded metal to orange (red?) hot
& immediately quench with a wet rag. Repeat as needed.

2. using a soft mallet (wood, plastic, rawhide), beat the expanded
metal with a steel backer. The key is that the mallet is softer than
the backer.

So, if it shrank, do as Ned says. If it expanded, do as I suggest. If
you guess wrong, it will make things worse.

Good luck,
Bob

On Apr 22, 6:32*pm, Bob Engelhardt wrote:
Ned Simmons wrote:
The welds shrank as they cooled. ...

I suspect that the welding heat expanded the sheet & the welded-in patch
locked it in the expanded state. *There are 2 methods that I know of to
shrink metal:

1. *with a torch, heat a spot of the expanded metal to orange (red?) hot
& immediately quench with a wet rag. *Repeat as needed.

2. *using a soft mallet (wood, plastic, rawhide), beat the expanded
metal with a steel backer. *The key is that the mallet is softer than
the backer.

So, if it shrank, do as Ned says. *If it expanded, do as I suggest. *If
you guess wrong, it will make things worse.

Good luck,
Bob

Generally if part of a panel expands it becomes convex, if it shrinks
the distortion will be saddle-shaped, ie rippled or dished
alternatingly outward and inward, centered on the shrunken area which
is where to hit.

"George" wrote in message
...
Oops, I did it again!

I have 3 electrical cabinets that I have emptied of all the useful
bits and would like to make them into lock-up cupboards. They are 2
mm. mild sheet and stand about 6 ft. high and 3 ft wide with a depth
of about 9 inches.

The doors are having a folded and welded edge for strength, but
because there were a lot of switches and lights etc. there before they
left a lot of holes which needed to be filled. I made some disks of
the correct sizes and thickness and MIG welded them in the holes. This
was in the first door. Smashing, all I needed was to grind down the
welds smooth, a bit of filler and paint. Oh no! The panel has now got
two stable states, both wrong. The panel is distorted and I am
dismayed. Is there any way I can relieve this and make it flat again?

Does anyone have a solution? I would be very happy to try anything.

Thanks and regards George.






I would bevel the plug and the hole so the plug does not fall through the
hole.
I wounld then spot the plug from the back on three points, grind the spots
flat and then sand the front. A can of primer surfacer and a sanding will
cover up any flaws.

John

On Wed, 22 Apr 2009 18:32:18 -0400, Bob Engelhardt
wrote:

Ned Simmons wrote:
The welds shrank as they cooled. ...

I suspect that the welding heat expanded the sheet & the welded-in patch
locked it in the expanded state. There are 2 methods that I know of to
shrink metal:

1. with a torch, heat a spot of the expanded metal to orange (red?) hot
& immediately quench with a wet rag. Repeat as needed.

2. using a soft mallet (wood, plastic, rawhide), beat the expanded
metal with a steel backer. The key is that the mallet is softer than
the backer.

So, if it shrank, do as Ned says. If it expanded, do as I suggest. If
you guess wrong, it will make things worse.

That's why I asked about the shape of the distorted door. If it's
saddle shaped (Jim's description) the welds shrinking caused the
distortion. If it's oil canned (a bi-stable bulge) the middle has
expanded.

--
Ned Simmons

On Apr 23, 2:04*am, Ned Simmons wrote:
On Wed, 22 Apr 2009 18:32:18 -0400, Bob Engelhardt





wrote:
Ned Simmons wrote:
The welds shrank as they cooled. ...

I suspect that the welding heat expanded the sheet & the welded-in patch
locked it in the expanded state. *There are 2 methods that I know of to
shrink metal:

1. *with a torch, heat a spot of the expanded metal to orange (red?) hot
& immediately quench with a wet rag. *Repeat as needed.

2. *using a soft mallet (wood, plastic, rawhide), beat the expanded
metal with a steel backer. *The key is that the mallet is softer than
the backer.

So, if it shrank, do as Ned says. *If it expanded, do as I suggest. *If
you guess wrong, it will make things worse.

That's why I asked about the shape of the distorted door. If it's
saddle shaped (Jim's description) the welds shrinking caused the
distortion. If it's oil canned (a bi-stable bulge) the middle has
expanded.

--
Ned Simmons- Hide quoted text -

- Show quoted text -

Thanks a lot, It is saddle shaped so it has shrunk. The problem may
be the fact that there are a total of about 8 holes of 1/2 inch to
about 2 1/2 that I have plugged. It is a big door too. The holes are
mostly at the top of the door, but I do have a big panel repair kit
which includes several dollys so with the approprate hammer, I am in
with a chance. It's a pity I was a bit enthusiastic with the welding.
A few spots would probably held OK, without so much shrinkage.

I got a message this morning that this had not been posted so - as I
did it again there may be another posting. Sorry.

Once again many thanks and regards. George

Speaking of welding distortion; knew a guy that did an extraordinary
amount of welding repair on a '34 Ford truck cab. When he was done, the
doors and glass didn't fit any more. He SHRUNK the cab! Major bummer....
JR
Dweller in the cellar

George wrote:
Oops, I did it again!

I have 3 electrical cabinets that I have emptied of all the useful
bits and would like to make them into lock-up cupboards. They are 2
mm. mild sheet and stand about 6 ft. high and 3 ft wide with a depth
of about 9 inches.

The doors are having a folded and welded edge for strength, but
because there were a lot of switches and lights etc. there before they
left a lot of holes which needed to be filled. I made some disks of
the correct sizes and thickness and MIG welded them in the holes. This
was in the first door. Smashing, all I needed was to grind down the
welds smooth, a bit of filler and paint. Oh no! The panel has now got
two stable states, both wrong. The panel is distorted and I am
dismayed. Is there any way I can relieve this and make it flat again?

Does anyone have a solution? I would be very happy to try anything.

Thanks and regards George.





--
--------------------------------------------------------------
Home Page: http://www.seanet.com/~jasonrnorth
If you're not the lead dog, the view never changes
Doubt yourself, and the real world will eat you alive
The world doesn't revolve around you, it revolves around me
No skeletons in the closet; just decomposing corpses
--------------------------------------------------------------
Dependence is Vulnerability:
--------------------------------------------------------------
"Open the Pod Bay Doors please, Hal"
"I'm sorry, Dave, I'm afraid I can't do that.."