I am trying to recreate a section of the CNJ from the 40s and 50s and I have a couple of very vintage (early 60's) AHM CNJ Camelback 4-6-0's that I would like to try and restore and re-power. Unfortunately, my fixed income budget doesn't allow me to purchase any of the brass camelbacks available on eBay, etc. And w/o those Camelbacks, well... you really don't have the NJ of that era.
The AHM models were enturely zinc casting from the frame up and including the tender. I have a couple on which the cracks in the boiler castings are pronounced but could perhaps be healed with some sort of filler.
Somewhere I read that zinc castings can be repaired with some sort of low temperature solder or maybe it was even a type of solder used for aluminum. (Does that even exist???)
Could one use some type of modelers filling putty?
Does anyone have any experience or advice for this type of repair?
Many thanks,
Ed
the solder for aluminum and zinc that you refer to is probably Sal-Met. I have not seen any for sale for years. I have no idea if it is still made. I think at best it would be a temporary top gap.
The general view seems to be that zinc rot (or zinc pest) is not curable or even really delay-able. There have been some urban legends about boiling in vinegar and such but I am not aware of anybody who claims and can show genuine success. the strangest part about the phenomenon is that the zinc actually expands as the process contintues - someone from Walthers told me that they actually had some plastic shells "explode" because the zinc in the frame expanded as it deteriorated.
The other thing is that in my experience the process accelerates once it has begun.
Just this weekend I saw a flatcar being sold at a train show with a zinc underframe which had curved into a tight radius. The plastic body of the flatcar was curved right along with it. It was hilarious and I thought of buying it as a comedy "prop" for my clinics but the guy wanted $8 for it.
The best advice MR could give 40 or 50 years ago when guys first started to complain about the problem was to try to make a pattern or impression from a part and cast it in cerro-bend or other low melt temperature metal. That might work with a truck sideframe but for an entire locomotive it seem impractical. Perhaps someone super involved with advanced 3D printing could scan the boiler/cab and spin out a copy? That is about all I can think of.
Mantua/Tyco had some camelbacks in plastic maybe 25/30 year ago (and some even earlier some 65 years ago). There were also some in the Aristo-Craft line but I think those too were zinc alloy castings.
Dave Nelson
Sometimes zinc pest/rot doesn't take years to develop. These Trix, by Märklín, box car floors are severely infested and they were manufactured maybe ten years ago or less.
Trix4 by Edmund, on Flickr
You could crumble the die-cast floors as easily as crushing a Saltine cracker. Replacement was the only option.
Trix2 by Edmund, on Flickr
I wish I could give a better prognosis on zinc-rot.
Good Luck, Ed
While the "Search" function here yielded nothing, a google search for "RDG Casey - Camelback locomotives- Model Railroader Forums" was more fruitful:
LINK
He has more threads here showing how he converts well-running, and currently available, locomotives into models representing Camelbacks from the various roads which used such locomotives. You may be able to find more with a similar search
Perhaps he'll chime-in here with some links to his extremely well-executed conversions.
Wayne
I have been casting an eye to my two Trix products, a Mikado 2-8-2 and a GG1, both now about 16 years after manufacture. Alas, my eyes have flitted across unmistakable signs that I won't be enjoying these otherwise fine locomotives for more than perhaps the next ten years...at most.
selectorI have been casting an eye to my two Trix products, a Mikado 2-8-2 and a GG1, both now about 16 years after manufacture.
The Zinc pest that affected the Märklín manufactured products affected only products made at one Asian factory during a specific time period. It did affect some locomotives but I don't recall any cases of the GG1 or Mikado having the problem.
I bought a Trix Mikado less than a year ago and I'm getting almost daily use out of it. An excellent model.
Regards, Ed
Fill the cracks with Bondo glazing putty and sand smooth. You could also fill those cracks with super glue and baking soda for strength.
Modeling the Baltimore waterfront in HO scale
One of my first HO locomotives was the AHM CNJ 4-6-0. It was a good looking smooth runner and a good puller but the casting were not very strong even when new. I had several pieces break. The motor was also troublesome. Commutator segments would come loose and the coil connections would break.
Mark Vinski
i repaired a couple of zalmac loco castings with devcon titanium putty, its a bit on the expensive side but when cured it's machineable and tapable.what i used was a leftover from a xmision case repair.
j. c. i repaired a couple of zalmac loco castings with devcon titanium putty, its a bit on the expensive side but when cured it's machineable and tapable.what i used was a leftover from a xmision case repair.
Very interesting. Thanks for the tip!
Jumijo Fill the cracks with Bondo glazing putty and sand smooth. You could also fill those cracks with super glue and baking soda for strength.
Could you explain a bit more on combining super glue and baking soda??
Thanks,
Wayne --
Wow. That's some pretty cool modeling. I'm not sure I am up to it skill-wise, but I've seen other examples of scratchbuilding locos with styrene and it's really interesting. Thanks very much for the link!
Mel -
The way you did the frame in brass is very cool and it is very analagous to the original AHM zinc cast frame in configuration. I'm tempted to try something like that but unfortunately I imagine one needs a drill press.
Weird thing is that the frame of the old AHM seems to be of a cast composition because it is in perfect shape. Its the boiler, cab and tender that are cracked.
Mnay thanks for taking the time to show your details!
cnjman721 Mel - The way you did the frame in brass is very cool and it is very analagous to the original AHM zinc cast frame in configuration. I'm tempted to try something like that but unfortunately I imagine one needs a drill press. Weird thing is that the frame of the old AHM seems to be of a cast composition because it is in perfect shape. Its the boiler, cab and tender that are cracked. Mnay thanks for taking the time to show your details! Ed
cnjman721 Jumijo Fill the cracks with Bondo glazing putty and sand smooth. You could also fill those cracks with super glue and baking soda for strength. Could you explain a bit more on combining super glue and baking soda?? Thanks, Ed
Put enough thin super glue (not gel) in the crack to fill it, and then pour baking soda on top. It hardens instantly and creates a strong bond that can be shaped, filed, sanded, etc,.