I am trying to referbish one of my old locomotives.
I discovered the axels on the drivers are 2 metal rods connected by a plastic piece. Is anyone familiar with these locomotives that would know if I can punch out the axel and replace it with a solid metal one? It’s not clear how the axel is connected, one piece or a press fit.
It is a Bachmann 0-6-0 from the 90s with a pancake motor. Its an inexpensive model, so probably I shouldnt be bothering, but I figured it would be a good learning experience.
One axel does have a gear which will make things a lot more fun, but the other 2 I would like to replace. My experience bwith trains is limited. I just came back to the hobby after a 20 year haitus. However, I have spent enough time working in a machine shop, I am confident I have the general skills required.
Over the years I’ve owned several Bachmann steam locomotives (8) with that same axle arraignment. Most were 4-8-4s and every one with the pancake motor had the wheels fall off. I replaced many of them early on until I started using CA/Super Glue to just reattach them. The CA/Super Glue fix was a permanent fix and much better than replacement wheel sets from Bachmann.
The chief worry about substituting a one-piece axle is that you will have to gauge the wheels AND quarter them all consistently to a precise degree ( they don’t need to be accurate at 90 degrees like the real thing, but they have to be the same) AND you need to do both those things at the same time while any adhesive is setting up. The thing I would advise is to make or buy a quartering jig and do as Mel does: cement the stub axles so they are quartered and gauged at the same time. (And drill the gear to an epoxy or glue fit so it won’t be as likely to crack when it gets old?)
This is very common. The axles are in halves to accommodate installation of the plastic drive gear. The non-drive axles do not need to be solid. If you fit a solid axle you’ll also need to provide for electrical insulation of one wheel from the other, split axles do this automatically.
Friction fit plastic axle connections, with or without gears, provide more than enough friction to do the job. These models cannot haul anything close to prototypical weights. The drive wheels spin on the rails long before the axle halves could slip.
Remember the metal stub axles are power pickup on insulated center axle wheels. The older Bachmann frames are also insulated halves to pickup power from the stub axles.
Thanks for the reminder. I had forgotten that important detail, which does complicate things.
I’m not to worried about gauging and quartering them. It will take some time to get right, but I can be patient sometimes. I do have a quarter from NWSL, but it won’t actually work with wheels of this design.
It is 20+ years old and the cracking is already an issue. One of the axels has a big crack and the gear is starting to crack. The gear is just a hairline crack on one end that I am hoping I can patch. I think I got lucky and caught it early.
It does have the split frame, but the wheels are isolated and there are wipers for the contact to the met
You should not need to glue the plastic gears or axle connectors. The reported failures were thought to be due to the type of plastic used. Replacements are made from a different plastic.
One video post suggests reaming out the axle holes in the plastic to a more precise fit. I don’t know about that but I point out that these gears and connectors are technically an interference fit, that’s how they grip the axle shafts. You want to avoid reducing the interference dimension unless they really won’t press fit onto the axle halves. If you can press them onto the axles with your hands then there will not be enough internal forces to crack the plastic.
In machining, differential heat and hydraulic pressure are used to insert parts for a secure interference fit. Indeed, steel tires on steam locomotives were fit by using differential heat. As it cooled the tire contracted around steel wheel for a very tight fit indeed. I’ve used this technique using only hot water to expand plastic to fit steel. Cooling just the steel in a fridge or even a freezer also works. Opening glass jars which have metal screw on lids by running the lid under hot water uses the same phenomenon.
I seriously doubt whether these methods need to be used for axle assembly. Hand pressure should be enough as the torque forces an HO locomotive wheel can exert on the axle are very small.
