Straightening Bent Die-Cast Cab Roof August 1, 2021 Update

Your suggestion seems like a good idea.

Auto body shops have various shaped metal forms that you back the metal and hammer it back in shape.

Your clamp idea is worth trying. I have "fixed" this kind of damage a couple of times. Can be done. I have generally approached it with pliers/Vice-Grips, gently, slowly. Gentle tapping can be used, also. Some like to heat the metal with a torch; it does help, I imagine, but I have not tried it.

If it breaks, brass and epoxy become your best route; add a brass shelf and "rebuild" the broken area.

Don't expect perfection - I am sure that you do not - as it is essentially impossible and sometimes that "just one more tap/squeeze..." can be one too many.  You are going to have to address the surface scars anyway, with epoxy or filler and files or some such.

Coach, your plan is solid, and that’s what a lot of us do to make this repair,.....use hardwood, not pine or birch, those soft woods will just conform to the dent,.....cut your forms with flat ends, so a sturdy C clamp can do the work,....I use a little heat on stubborn offenders, ......that works magic,.....just warming the work piece works, ....no need to blister paint, .....small butane torch, or map gas bottle is fine,...heat from the underside, this way if you do need to touch up, it’s concealed to the inside of the cab area,....

Pat

Coach, I would recommend using a hair dryer to heat the area. Better control and much less chance of paint damage. Your wood block and clamp is a great idea. Good luck.

Heat and vise grips, gently. Operative word is gently.

I also use the wood clamp method but rather than cut your blocks in the exact finish contour, use a slightly larger radius. The metal will spring back some unless you actually melt it. I have used both a high temp (800F) heat gun and a propane torch held some distance away and moving back and forth constantly. Heat it , bend a bit, heat, bend, heat bend a little at time. Straightening the deflectors will be the hard part to get right. You may have to grab them with smooth jaw pliers and get it pretty hot.

Pete

Thanks for all the replies so far.  Pat it's good to know that what I planned to do is what you would do.  Thanks for the tip about the hardwood.  Norton your advice is sound however not knowing what that larger radius should be and as D500 said, I'm not expecting perfection I'll proceed as planned with the addition of some heat.

I'm not in a rush so it will be interesting to see if anyone else chimes in with something different.

To add a bit of color on the “take your time” comments: after perusing every thread on this forum I could find (lots) I settled on the wood block method. Have used it twice with near perfect result.  See photo for my setup and note the two screws.  Once snugged up I tightened those screws literally no more than a half turn twice a day. Repairing a 75 degree corner bend on a postwar 2034 it took almost a month total.  I started bending to a 3.5 diameter arc first (which I read was the arc size Lionel used) and once I got there I went to a larger arc of 4 3/8 and just spot bent the corner only. The only heat involved was warming the whole shell on the hot Texas summer sun. I used hole saws chucked in a drill press to cut the arcs.

I read everything posted here related to postwar stuff and it is amazing what one can learn.  Thanks.

GOOD LUCK! :-)

Someone did this before. do a search he did a compleate breakdown of  how they did it came out very nice search the Forum you will find it about 6-8 months ago

So the time has come to try to straighten out this roof.So, I used a contour gauge to transfer the curve of the roof to a piece of 1 x 3 oak.  Using hardwood as suggested by harmonyards.  The first attempt at cutting out the pattern did go well so a second pattern had to be made.Pretty good using a jig saw.  I had to use a rasp to round out the straighter area on the lower right.  Then using two 4" C clamps  to mount the forms and apply some pressure.You can see from the second photo the top and bottom don't line up perfectly because of the overhang of the roof and the deflectors on the trailing edge.  Now for the hard part, the squeeze with patience.  I think 1/4 turn per day using a heat gun prior to tightening.

Way to go Coach!.....you’ll have it licked in no time!..

Pat

So today was the unveiling.  I went from thisto this

From thisto thisI think it came out pretty good.  The deflector is a little chewed up but I don't think there is anything I can do about that. I did touch up the chipped paint with a Sharpie.  The only thing I was considering was turning my form around and pressing again.

Due to my poor skills using the jig saw the curve of my form is not perfectly symmetrical but made up of several arcs of different radii.  The left side a little more shallow and the right side a little deeper.  This is the way it was originally used.  I wonder if I turn it around with the shallower curve on the right and the deeper curve on the left if the final result may be even better than what I have now.  Any thoughts would be appreciated.

Excellent work coach joe!!

Nice job.

Close enough !

That came out great, Joe!

Nice job.

Jim

Vast improvement Joe, excellent.  If you don't mind a little touch-up, you could carefully take some of the chewed up nicks out with a fine file and then touch it up.

Looks good Joe. Some fine (600 +) grit silicon carbide sand paper may help smooth the drip edge to an acceptable level.

Bob

Thank you all for your comments.  I could try to smooth out the deflector a little  but I don't think it will ever look quite right.  My plan is to turn this AT&SF version of a NYC Mohawk into the proper NYC livery.  I'm hoping to accomplish that with out a total repaint but just removing the lettering from the engine and the very large number from the tender.  Maybe while I'm doing that I'll work on the deflector.  Any one ever strip the lettering of an MTH steamer?  Any hints would be appreciated.

@coach joe posted:

Thank you all for your comments.  I could try to smooth out the deflector a little  but I don't think it will ever look quite right.  My plan is to turn this AT&SF version of a NYC Mohawk into the proper NYC livery.  I'm hoping to accomplish that with out a total repaint but just removing the lettering from the engine and the very large number from the tender.  Maybe while I'm doing that I'll work on the deflector.  Any one ever strip the lettering of an MTH steamer?  Any hints would be appreciated.

A light wipe with lacquer thinner does the trick,.....it won’t remove the black,...just do light wipes until the letters or digits disappear,..

Pat

Joe, I think you could straighten the deflectors some with heat and some smooth duck bill pliers, grabbing a bit at a time.

As for the lettering, lacquer thinner will have it off in seconds. Wipe on, wipe off.

Pete

If I use the lacquer thinner do I have to neutralize it somehow once the letters and numbers are gone?

@coach joe posted:

If I use the lacquer thinner do I have to neutralize it somehow once the letters and numbers are gone?

Nope, it will evaporate so fast your head will spin Coach,...

Pat

Coach I am curious did you still apply heat prior to each squeeze as originally planned? Turned out great and is a big improvement.  

Rich I used a heat gun on the low setting for a few minutes to warm the end of the roof before each new turn of the screw.  Nothing crazy just to warm the metal slightly.

Thanks for this post Coach.    I wouldn't have thought something like this would have worked on the diecast metal.

Looks like a successful outcome to me  🤓. Nice.

Okay I couldn't leave well enough alone and put the cab roof back under pressure.  This time I flip my mold around  to expose both ends of the roof to my less than perfect arc.  I feel it did make it a little better, especially the right side that was bent to a sharper than original curve.I even worked on smoothing the deflector a little with a tack hammer.  No to get some lacquer thinner to rid this Mohawk of the ATSF markings and dress it properly in NYC decals.

Looks good Coach!....keep hold of your newly made tool set, ....I’ll be sending you a box of bent up boiler shells!......you're hired!....great work!.

Pat

Another one rescued from a life of deformity, good job.

Thank you both.  It means a lot coming from craftsmen like you.

So it has been six months since I finished straightening out the bent cab roof and stripping the Santa Fe markings from this MTH RailKing Mohawk.  The plan always was to dress this engine in proper New York Central livery.  I found a wonderful article on the Late Mohawks on the NYCHS web site.  This RailKing engine is creditable representation of an L3A Mohawk, however the size of the tender is closer to those pulled by the L2Ds.  I got some NYC steam decals and began planning the transformation.  The set of decals had a 3056 number in series.  This was an actual Mohawk road number, however it was an L3C, but I wasn't about to start piecing together a number for an L3A.  As I started looking through photos for proper placement and size of lettering it became apparent the decal set was for O scale engines and the selective compression employed by MTH to make a good looking engine in less than scale dimensions started giving me problems.  The engine numbers appear larger than those on actual Mohawks.  The tender lettering came in two sizes, I guess one for road engines with longer tenders and one for short tenders or switch engines.  The available number for the back of the tender appears small than actual.  Pictures I've sen have that number the same size as the numbers on the cab.  Actual L2D tenders had a 28 ton coal capacity, the closest I could come is 21 tons.  But she's finally in the right livery and can finally be put into revenue service.  Further details added are a water scoop, an engineer and fireman on some homemade seats, painted the valve handles red, should have used a brighter shade, paint the gauge faces and built a fire in the fire box to get it under steam.

Coach!….WOW!!….looking good!….sure is a nice representation of a NYC Mohawk!..great job!..

Pat

Looking good, I like the firebox.

Joe,

Very nice. All the lettering looks fine to me. How about some pictures of the completed engine and tender - say 4 views of each?

MELGAR

Nice work Joe. Looks great!

Very nicely done, Joe! I did something similar to a 2018 2-6-4 a while back - my right rear corner of the roof had about a 60 degree deflection which I straightened over approx 2 months using a large vice grip and 2 blocks of oak and a strong hair dryer for preheating. I did daily adjustments but found that as things got closer to the normal shape, the progress slowed considerably. I finally quit tweaking it, fearing a very slightly bent corner looks much better than a broken corner! Sorry, no pics to show.

I do have one question - the numbering on your cab, was it stamped, heat stamped, painted on somehow, or what? I know heat stamping leaves an impression in the underlying black paint, making numbering changes a bit more obvious. Yours looks really good, hence my question!

George

George the original numbers and lettering were painted on.  I used Pat's, Harmon Yard's, suggestion and a quick wipe with lacquer thinner and I had an undecorated MTH RailKing Mohawk.

John, I like the way the firebox turned out also.  Found a picture on the interweb, some resizing and a two test prints and voila, almost as good as firebox glow.