Rocket Surgery on the PRB brass ATSF 3400 Pacific

[randgust]

So I just had to jump ahead and try to run the thing, ah, yes, back to reality.  Soldered up the wiring harness to the tender.   Good news, bad news.

Well, it does run.   But there are issues here.

It's surprisingly noisy, and I suspect it's all coming from the tolerances to the worm and nylon spur.  It's tight down on that.  I think I'll shim up the front of the motor about .005 until there's a hair of daylight in the gears, see how that goes.

No hitches or jumping at all in the running gear.   That's a blessing.

I wired the motor backwards for DC, easy fix...

Without the pilot truck on it, Ron, you're right.  It's surprisingly poor pickup on the right side (locomotive side).  If you're in a situation where the axle with the traction tire is touching, and the second and third aren't, or over a switch frog at low speed, dead stall.   The tender is surprisingly good on the left side. 

I have Dirk's ATSF trucks on order, that should get me 12x12  pickup on the tender so I'm not freaked out, yet.

The trailing truck derails constantly going in reverse.   It looks like narrow gauge, have to fix that for sure.  And if it's picking up on the right side, not doing it very well.

I can see that relocating the drawbar on the locomotive end is going to be necessary, it's crabbing pretty well and also jacking off the tender to the outside rail - not always derailing, but under load it certainly will.

At higher speeds, the flywheel actually kicks in and it gets past some of the pickup glitches.

As the only locomotive pickup that is truly solid is on the #3 axle, if that's not touching on the RH side, well, there you go.  Or not go.

Well, I've seen worse, but I was hoping for better, particularly surprised by the gear noise.  It was about silent in the drive cradle.

[randgust]

OK, well last nights effort was to attempt to solve the gear noise problem.

Yeah.   Well, it's bad.   Really bad.

I raised the gear tolerance between the worm and the idler slightly and reassembled.  Wow, even noisier.  And then I saw the worm hopping around.  Yuck.   Oh no.

The bearing bracket on the left side of the frame that holds the idler gear broke loose.   On study, a light and very cold solder joint on the frame.   But this is a critical fail.  The frame is all painted, requires a total teardown and wheel removal (like Max's) to get in there.   And like any brass locomotive, trying to resolder stuff properly always risks something else coming unsoldered or damaged.   And tolerances are rather critical, as well as structural strength.

I think I have a repair plan.  I can drill and 'stitch' it back on with .010 wire reinforcement on both sides, then solder the wire loops to hold it and 'maybe' get the original joint to hold as well.  But holding the thing in exact place during soldering is a bear, as well as overheating, and everything has to be removed of paint that I'm working on too.  The idler gear is nylon, that has to be out during the repair and then replaced, but the steel idlr gear shaft can hopefully go back in as an alignment tool during repair.

It's not a fatal, but it's a solid 8 on the degree of difficulty scale.   And I want to think about it as well.   I've stitched frames together with brass wire before, it's a technique that works if there is inside and outside clearance for it, and there is.

Ron, you dodged a bullet.  I think it just broke, didn't arrive that way, but it was most certainly a cold solder joint from original assembly.

The trailing truck wheelset was tight, easily fixed the gauge on that, as well as reversing the motor wires.   The only good thing is that this is hip-deep in screw assembly that all comes apart.  The Jamco actually had the entire frame box soldered, it was literally impossible to drop the wheelsets out.

[peteski]

Ouch!

Resistance soldering  setup would probably be helpful in this repair as it concentrates the heat directly on the solder joint.

[randgust]

That would seem to be a good idea....until....

Got the very careful teardown done, and you can see what happened.   But here's the situation.

The nylon spur gear is SOLID on that shaft.  Won't come out.  Press may break the gear.   Only way to reassemble is to put it in place and then secure the bearing bracket with it in place.   So any soldering heat will carry into the shaft and possibly overheat that gear.  And if that happens, done like a dinner, that gear is irreplaceable.  No idea how they assembled that, probably a dedicated press fixture.  I 'thought' it would come out.  It won't.

So securing it back with wire stitching and soldering the stitching, seems a whole lot safer, lock down with some ACC or JB Weld.   I can tinker with the set and fit until it's right.   

And you can see how cold and light that original solder bead was.



Link:  http://www.randgust.com/PRB342908.jpg

[Chris333]

Maybe a plate (2 small plates) of .005" brass sheet over the gap?

[peteski]

To me it looks like that shaft should come out of the gear using any type of a press (like even a drill press).  You just have to come up with some sort of fixture that it will hold everything securely and square.  But it is not my model either  . . .

[mmagliaro]

I had BOTH of those problems.  On this exact 4-6-2, I had to shim the motor to relieve the tight gear mesh.  Just .005" under the motor
is exactly what I did and it was smooooth.

And on a Precision Scale K4, I had a broken frame solder joint.
While a resistance soldering station would be awesome for repairing such a thing, I assume you don't have one (and I didn't either).

I went with drilled #78 holes, wire pins, and epoxy.  It will work.  As you know, drilling holes and inserting wire pins with the epoxy
is a million bajillion times stronger than just epoxy.

[nkalanaga]

And, you can pin it together without the epoxy, see if it works, then epoxy it.

[randgust]

Well, I think I got it.   

Step 1 was to drill the ear and the frame horizontally, .022, and at an angle for the reinforcements.   And thoroughly clean it.



Link:  http://www.randgust.com/PRB342909.jpg

Step 2 was to 'band' the repair using some vintage .010x.018 flat brass bar, solder it up first to the top 'ear' as a separate part, then align to the main frame, bend and stitch to the bottom frame by bending it bar and pulling it tight, after inserting the plastic gear.  A little bending and shifting for perfect alignment was possible.

Then bend over the bar, trim, hold with a hemostat, and solder the bar ends together. 



Link:  http://www.randgust.com/PRB342910.jpg

Then file the solder joints down to .010 flat.   Then, after that, hit the original joint and the drilled holes with a light touch of ACC.   It's certainly solid, the gear spins, and was not damaged.   Whew.   

Now I can start reassembly.  After my pulse comes back down.

Late update - got it roughed back and the motor on, it works, and it's much quieter.   So I didn't kill it.  Reassembling was a bear though.

[ATSF_Ron]

Great job on the surgery, Randy!!  That's all way beyond my skill set.

ATSF_Ron

[mmagliaro]

Yep. Well executed, man.  It is tedious, but strong, and it works.

[randgust]

I'm waiting for my tender trucks here.   I think I'll amuse myself with the new drawbar.

Which gets me into tracking theory.  Traction tire is on the front axle of this one, that's unusual, and the lead slug in the boiler is all the way front.    So that weight distribution may be deliberate.

With my LL 2-8-4 with the drawbar rear mount under the cab, it had a terrible reputation for climbing the outside rail on curves until I relocated the drawbar to behind the rear driver.   Did the same stunt to the Jamco 4-6-2, but it has no traction tires and is brick heavy, and deep flanges.

I'd think theoretically that adding more boiler weight further back might make it worse, but right now it's NOT heavy enough on the back axle to keep it in constant electrical contact.  If it was, the front axle with traction tires would lift instead.  So if I beat the contact problem with the 12x12 tender, may leave it alone.....

You'll note that the Kato 2-8-2, possibly the best design, did the same stunt with the drawbar mount to the same point at the trailing truck mount.   My goal.  https://hoseeker.net/katoinformation/katospartscatalog1997pg17.jpg

[Chris333]

There is a guy who makes 3D ATSF models. Doodlebugs, steam, and boxcars. He might have the tender trucks you need and they have axle point pickups with brass strips.

[randgust]

Oh, I've been corresponding with Dirk and the trucks are on the way.   He's having shipping, supply, and medical issues as well, but he's still hanging in there.

I did his tender for the Jamco, that got me the 12x12 fix on that as the brass tender was really a POS all the way around.   His was incredible in appearance and performance.   And I've done some of his car kits.  Probably the best guy out there for blending 3D prints, etched brass, and commercial into the right material for the right job instead of always trying one material for everything.

The other 'theory' I've experimented with is that lead truck without springs or centering, just weight.   Jamco did it that way, Micro-Ace did it that way on the 4-4-0, I did it that was on the D16, and I also did it that way on the Decapod.   On the Dec, with the scale flanges, just hated facing-point Kato turnouts on Ttrak, had to go to a wider tread and deeper flange.  That has me worried on this one.   We'll see.  "In Theory" you aren't loosing any tractive effort that way.

[randgust]

Update as of now - first, I got the new drawbar fabricated from brass and got it tested with the stock trailing truck.   I 'think' it's going to work.   Photos coming.

But even after reassembly, pickup remains the problem, even with the stock tender trucks polished up for better contact, it constantly stalls.  I can see why Ron got frustrated.   You'd think with all that weight and contact points it would be bulletproof, and it is anything but.

And I got Derk's (ATSF Models) tender trucks in - made it here OK, and look good.  More rocket surgery on the tender.