Looking for a Repair on Corner of Cab Roof Prewar Shell

Yes, but you have to do a skinny underlayment of fiberglas cloth.  It makes the roof slightly thicker, but you bevel the underside to hide it.  Use JB Weld as the binding epoxy.  When the area is finally built up to the perfect contour, you can glue on the beading and add plastic "rivets" by drilling small holes, and filling them with very skinny dowel.

The underlayment should attach to bare metal, roughened with a coarse file.  Good luck.

I have made casts of original missing pieces with moulding clay before and cast replacement pieces out of resin or pewter. The scale Hudson roofs were quite thin so a support piece maybe needed under and this can be done with a piece of sheet tin/brass. There is a technique for "welding" pot metal but this is risky and only do with restore as heat will damage surrounding paint, but is done to repair pot metal emblems on old cars.  

does anyone have some examples they may have done like this?

would really like to see a picture of repairs like this if someone has one.

I will see if I have any pics. I have also done this to repair plastic fragment  that was missing

I had started a thread a while ago for my prewar Lionel steam switchers. My friend and I worked on the cab roof that was mis-shaped from some serious abuse before I had custody of it.

https://ogrforum.com/...rewar-steam-switcher

In trying to reshape the roof to make it rounder, the corner broke off. Now, my situation is different than yours, but maybe some of this can help you. We used a scrap piece of a tuna can to create a reinforced area to glue (with JB Weld) the corner piece that broke off. If you look closely, you can still see the crack, but that's OK by me. I'm happy to have it running and think of it as a reminder of  how bad it originally looked vs. now. In your case, you should be able to still use the piece of the can to provide the reinforcement underneath. Depending on the size of your missing piece, maybe you can use some copper or brass or some Bondo (for car repair) or a combination of either of those metals and the Bondo. The Bondo worked on another switcher that had a chunk of its headlight missing. You would never know the difference looking at it. 

Good luck and post before and after pictures when you can.

Tom 

OK so here's what I have done.  Get an equivalent piece of equipment to make a mold from.  Get vinyl casting material from your dentist.  Its used to make molds for temporary crowns.  Use the vinyl molding material on the good piece corner.  It sets in a few minutes.  The mold can now be attached to the damaged cab roof with the missing corner.  I mix up 2 part epoxy and add some xerox toner (it is black styrene powder actually).  Pour the mix into the mold extending the mix beyond the missing corner.  When the epoxy cures remove the mold.  You now have a finished corner; some sanding and filing is required.  Paint as necessary.

Lou N

Lou gave the best solution for once the corner is broke off even if you have the piece that broke it will never fit properly. The point where it mates with the main casting is bent. The lesson is NEVER try and cold bend a roof corner back into position, you may get lucky, probably not.  I have straightened bent cab roofs for myself and friends too many times to count. the way I do it is to take a 1 x 4 or a 2 x 4 and hold the rear edge of the cab roof up side down against it and trace the curve with a pencil now cut out the board along the line and then reverse the board so that the bent side of the cab is on the good side of the board. Now clamp it all together so nothing can move and use an old fork and a torch. Heat along the bend while applying light but steady pressure with the fork as soon as it drops against the board remove the torch and hold the pressure on the fork a couple more seconds. Let it cool for 5 -6 minutes before moving anything.  Sometimes I have to touch up the paint sometimes not.  On the occasion when I have to cast a new corner I always use spring steel shim material epoxied to the under side of the cab as a stiffener .010 is more than thick enough.  Some good auto parts stores have it and Manhattan Supply has it.  Make sure to rough it up , as well as the underside of the cab it will be glued to.  It is much stiffer than common can material, or fiberglass,  and not likely to bend with a small blow.  I have used several materials to make molds with good results but the handiest is common modeling clay I heat it in the microwave till it is soft but not runny then press it into the item that is to be the master.  THEN, I put the clay and in this case the master loco body in the freezer for a hour or two. When it comes out the clay will be quite hard and you can giggle it off your master without bending it. The thicker the clay the better. I usually file / grind a couple thousandths off the edge of the cab roof that is to be repaired to get the bent edge off before I attach my mold.  A jagged edge makes a stronger joint.  Once you have attached your mold use a small brush to wet the edge of the cab roof where the joint is with your epoxy to make sure all the little facets of the broke edge have epoxy on them.  And say your prayers !    j

thanks for all the ideas, I think I have a good idea of the process. But now to come across another with that corner to take a mold of. If I can come across a shell with that corner I probably wont need to do this anyway but maybe a 773 shell will work for the mold. I have one packed away somewhere. If any of you have time to dig up a photo I would love to see the results. Thanks guys!

JohnActon posted:

 I have used several materials to make molds with good results but the handiest is common modeling clay I heat it in the microwave till it is soft but not runny then press it into the item that is to be the master.  THEN, I put the clay and in this case the master loco body in the freezer for a hour or two. When it comes out the clay will be quite hard and you can giggle it off your master without bending it. The thicker the clay the better. I usually file / grind a couple thousandths off the edge of the cab roof that is to be repaired to get the bent edge off before I attach my mold.  A jagged edge makes a stronger joint.  Once you have attached your mold use a small brush to wet the edge of the cab roof where the joint is with your epoxy to make sure all the little facets of the broke edge have epoxy on them.  And say your prayers !    j

I like the clay idea.  I will try it next time.  Any particular brand?  We have Michael's and Hobby Lobby nearby.  I also remember the machinists at work using a green colored clay that they used to make dams around a part that would hold coolant/lubricant.

Thanks,

Lou N

Lou, Not sure about a brand  I have been using the clay so long and when I purchase new it just ends up mixed with the old.  My original batch, long before Michaels or Hobby Lobby ,   was from the toy dept at Kmart with several colors that ended up mixed together.  One thing that I noticed is the older it gets the stiffer it is at room temperature which is a good thing as you can still get it plenty soft in the microwave. Basically modeling clay is Kaolin clay mixed with mineral oil and coloring. The more oil the softer it is.  As it gets older the VOC in the oil gas off and the clay gets stiffer.  My grandaughter just gave me a tub of natural colored Crayola clay in a plastic tub and it is so soft and tacky to be useless for making the kind of mold we are talking about. I guess I could roll it thin and cover it with an old rag and let it sit out a few years to stiffen up.  Problem is at seventy one I may be a stiff before it is.  You can purchase dry Kaolin clay powder on line and mix your own to what ever consistency you desire.  Another favorite use I have for clay is to take a big wad 1.5~2" thick and push Xacto knives into it keeps them shiny , sharp and handy.  j