Lid won't close

I made a strongbox to give to my nephew and his wife. They won't know what to make of it, but I never know what to give them either, so it comes out about even. I made it out of a 6" long piece of 8" square tubing with 1/2" wall thickness. The floor is also 1/2" plate, and the lid is 1/4" plate. The lid has sides that fit over the box so that it can't be pried open, and the hasps (one welded to the lid and the other to the box) are also protected so that when the box is locked with a padlock, the shackle is inaccessible to bolt cutters. There are holes in the floor of the box so that it can be attached to the floor, if desired. The lid is hinged to the box with two large hinges which are welded so that the heads of their removable pins are touching. The hinges are welded to the lid and back of the box as completely as it was possible to weld them. Therein lies the problem.

When I first tacked the hinges to the box and the lid, the lid fit tightly against the top of the box. Now that they are welded completely, the lid stops closing about 3/4" above the front edge of the box. I can close it more by leaning on it, but I think it would take a pipe clamp to close it all the way. That's not going to be convenient.

Two things I've thought of doing are: 1) building up the front and sides to the height that the lid stops, which I can't imagine being able to make look good, or; 2) clamp the lid closed and then heat it and the hinges with a rosebud until it takes the stress out of it. I'd welcome any better suggestions.

Stan

I would try lowering and beveling the front edge of the box , the lid's arc of travel will be causing the inner face of the front lid side to rub onto the front wall of the box . Lowering the front will create space between the front edge and the travel arc .

Just simply grind off some of the end nearest to the hinge, that will let the lid close. It should not take much if you're that close to making if tight now.

Is the lid scraping or the hinges binding? Different solutions to each.

If it is scraping you should be able to see the effects of that. Then I would grind as appropriate.

If the hinges are binding, you might be best to try stress relieving with a rosebud. As if you get the hinge side cherry red, you may be able to bend it back straight. The goal being to realign the hinges.

Cliff(VA)

You should have put some spacers under the lid before you welded the hinges on to raise it up a few thousands. Metal shrinks when you weld it.

Hit it with a hammer Got dern it ! Just Kidding Stan . You'll get it

Hi Charles;

The lid isn't scraping anywhere or hitting any part of the box. What I now think happened is that the large amount of welding (and grinding) I did to make the hinge plates appear to be nothing more than slightly thickened areas at the back of the lid and on the back of the box, warped the lid so that it is cupped down in back. When the lid closes now, it comes in contact with the top edge of the box in back while the front of the lid is still 3/4" from closing. I can grind the contact surface at the back of the lid fairly easily---the additional thickness of the hinge plate on top should prevent that from weakening the lid to any significant extent. I'd like to be able to take the metal off the top edge of the box in back but I haven't been able to do that without scoring the inside of the lower hinge plate. It would definitely reduce the security of the strongbox if I cut through the hinge plates.

Stan

NOW you tell me. IIRC, I did leave some space between the bottom of the lid and the top of the box in back. Quite a few thousandths, in fact. What went wrong, I think, is that the lid warped in a slightly cupped shape---probably because the hinges butted together in the center so they got less weld metal there than at the outside edges. Anyway, I'm fairly confident now that I can fix it with some careful grinding.

Stan

Of course I tried the BF hammer first, Dave. Well, maybe not so much. Speaking of big hammers, I once started making a collection of useless tools for a local art show. One tool I finished before abandoning the project was a 90 pound hand sledge with a 19/32 box end wrench for the handle, which made it a multi tool. The only other tool I completed was a precision hammer with crosshair gun sights on top, but I had ideas (or "concepts" as we untalented artists like to call them) for several more. One was a four person garden rake with four handles 90 degrees apart. I couldn't decide whether to call it a gang rake or is that would just have been in bad taste.

Stan

You're exactly right, but see my response to Charles in Aus. below to read why I had to go with the 2nd best solution (grinding metal off the lid there instead).

Thanks, Stan

Hi Cliff;

Grinding turned out to be the appropriate action. I'm almost sorry not to have gotten a chance to try the rosebud on it, though. I'd be interested in seeing what that would do.

Thanks, Stan

Heating would have caused you a lot more work, you would have been chasing that heat warp all over the lid. I do short welds and let the metal cool, then do another short weld. I repeat this until the weld is complete. When I am welding 1/2" plate hinge tabs I have to alternate from one side to another. The heat pulls the tab 3/8" both ways until I have it welded half way down on both sides.I know just how to heat warp metal.lol

Well Stan it seems you got the lid fixed by grinding it. You also stated the lid had a bow in it from where you welded the hinges to the lid. Steel will draw when welded along on axis very far. You have to counter this when you weld thinner stuff. Meaning you sometimes make a jig that bow it the opposite way so when the weld cools/contracts it will be straight. So on your lid all you needed to do was lay some weld on the inside opposite of where you welded the hinges on. That would take the "bow" out of the door.

I made a roll back bed many years ago. I really laid the welds on the cross members. When I was done with the top half it had a six inch bow in the 24 feet of length. My Father is a mechanical engineer. He looked at it and told me to just turn it over and make a long bead of weld the full length of the long beam. I did and it straighten it right out. I then ground the weld off and it stayed straight.