Machine Shop / Locomotive Drive Work

[ScaleCraft]

yes, but can't remember where I've seen one.
Probably 30 years ago at Bob Hall's.
Boy, that worm is toast!
I'll check my files.

[bob turner]

Yes. Henry Pearce. Check with Stevenson for parts. One of the best gearboxes - something horrible must have happened.

The Mod 0.6 from NWSL is a good replacement if you cannot get the parts, but new production cases need some careful rework. The older ones are "glass-filled" and easily recognized. Newer ones are glossy black - as I recall, it is a number J drill and some sandpaper to get the case to settle in on the axle bearings.

[E7]

RFT,

In deference to our mates on the forum, we can take this offline to work out the details. Don't want to bore anyone with this silliness.

Jay

No need. I think most of us find this stuff interesting!

[Jay Criswell]

Yeah, I have some of those if Bob S. can't help you out.

Jay

[R.K. Maroon]

Bob appears to be correct. The early Pearce Tool flyers I have don't mention an enclosed gearbox, but it appears in the 1990 flyer:



It apparently was only offered with the Mikado chassis:



The one I have has a 25:1 ratio -- Good for a 4-4-2, I would think.

Thank you for the offer, Jay. I may take you up on that offer someday, but for now.....there is more to this story, as follows:

There is good news and bad news with this gearbox. The good news is that, while it looks like heck in the photos, close inspection indicated that it was still serviceable. It had a layer of hard dried grease on everything that was something of a bear to remove, but with some effort (and chemicals) it cleaned up nicely.

The bad news was related to the hole that can be seen at the top of the gearcase:



I am guess that somebody did this to allow lubrication without disassembly. Unfortunately, they were, uh, just a little heavy handed, and managed to drill into the worm. And not just a little bit:



That worm is steel. Drilling that deep took some effort. *sigh*

After some inspection, I realized that one face of the worm was mostly unscathed. I decided to JB Weld the drill damage, sand to match the profile, and then install the worm so the best face was contacting the fiber gear when operating in the forward direction. This may seem like an unwise approach, but, in its favor, it allowed me to proceed directly with a repair without delay and without having to pull the gear from the axle. Also, this is a road locomotive, not a switcher, so it runs forward almost all the time. It is also 4-4-2, not a 4-8-4, which will be only used for light duty, and which, like all my models, will only see occasional run-time. Is it a bet? Sure, is it a good bet? Time will tell. Fortunately the consequences of losing this bet are small -- there is always plan B.

Having said all that, I am curious to see if Bob Stevenson has replacement gears. His website does not list them but I will call him to see what he might have in back stock.

Jim

[bob turner]

Axle gear look ok? If the JB Weld doesn't hold up, the worm could act as a hob on the worm gear.

I had a buddy who liked to take a Dremel to his models. By the time he would finish, one would need a new main frame and a lot of brass to patch the boiler belly. He would occasionally nick a driver as well. Some folks should not be allowed around power tools.

[Jay Criswell]

Jim,

You're a lot braver than I. That worm looks more like a viper waiting to devour a worm (gear). If said worm gear isn't already destroyed I assume it will be soon. Once that occurs, your little project will get a little uglier.

If I were you, I'd toss everything.

Just my thoughts @ 5:45AM.

Jay

[E7]

I had a buddy who liked to take a Dremel to his models. By the time he would finish, one would need a new main frame and a lot of brass to patch the boiler belly. He would occasionally nick a driver as well.

Bob, could you explain what it was that this guy was trying to accomplish?

Some folks should not be allowed around power tools.

Some folks should not be allowed around ANY tools!

[E7]

Jim,

You're a lot braver than I. That worm looks more like a viper waiting to devour a worm (gear). If said worm gear isn't already destroyed I assume it will be soon. Once that occurs, your little project will get a little uglier.

If I were you, I'd toss everything.

Just my thoughts @ 5:45AM.

Jay

Jay, Looking at those parts (and I use that term loosely) what does Jim have to lose but his time? One caveat, if he is able to repair that mess, we might ask him to change his name to Mandrake!

Rich

[bob turner]

The case is ok. The bearings are ok. The worm is shot. Maybe the axle gear as well, but not sure. Replacing the worm should be trivial - in fact I bet it is stock Boston Gear. But their prices for onesies and twosies make them not a good option. Stevenson, then Jay.

A slightly damaged worm wheel (axle gear) will probably work fine with a new steel worm.

[Jay Criswell]

A pig with lipstick is still a pig. Toss the crap and do it right. Why mickey mouse it when you don't have to?

Jay

[bob turner]

Yes, but what are the options? I am always happy to press a gear and re-quarter for Jim, but the big question is can he buy these parts, or indeed a suitable gearbox if it comes to that?

[Jay Criswell]

Geez Bob! Are you not paying attention? I have everything required, all unused, but I wanted to give Bob S. a chance first. Don't want to cost him a sale.

Glad you're not my airplane mechanic.

Jay

[bob turner]

The customer should drive the mechanic, not the other way around. Took my wife's Ford Ranger with 100,000 miles in - mechanic found about $5,000 worth of work, including replacing all suspension parts including the rack and pinion steering stuff, and said the timing chains should have been replaced at 60,000. He bid $3000 extra for the chains, then backed up and said his facility was not equipped to do that.

Think I should have all that done, to a truck worth $5,000? Especially when Ford says the timing chains are good for the life of the engine?

But you are correct - you do not want me as an aircraft mechanic. If I get a soft cylinder, I replace it or get it fixed. Most shops now will opt for what is called a "top overhaul," replacing all of the cylinders and pistons with new at the hint of a weak cylinder. The difference in cost for airplanes the size of my Cubs, is about five grand. My cylinder guy was doing exhaust valves for a hundred bucks.

But you are correct in that it is easy to replace both gears. It is truly neat that you have the parts - and I am sure that Jim will support Bob's efforts when he can. But you and Bob are both in this for love of the hobby, not big bucks. Both of you appear to be happy to help whenever you can. I wasn't trying to steer Jim to you at Bob's expense.

[R.K. Maroon]

It turns out that Jay had a used gearbox with a good worm but no worm gear. The existing worm gear on the 4-4-2 appears to be in excellent shape. As noted, there is a risk that my repaired worm would eat up that worm gear. Though my curious self would like to know if the repaired worm would work if put into service, the existence of a replacement worm changes the calculus on this. Jay offered to send the replacement worm (and gearbox -- with no hole!) and I gladly accepted. I will report back.

In the meantime, here is something different: The worm shaft on the model has a second worm:



I will give somebody else a chance to figure this one out. I do find the construction here interesting. How in the world did this get fabricated? It looks like the worm and the two shafts on both sides are one piece, but the worm has a much larger diameter than the shaft, so that can't be right. That means the shafts were bored and the worm turned to fit (and brazed?) or vice versa. And that was easier than simply using a larger worm with a hole the size of the shaft? Anybody got any insight into this thing?