PRR D16sb research for a build

[Ed Kapuscinski]

I want to crowdsource a "machine shop in a box" for projects like this: a good mini-mill, a good mini-lathe and maybe a surface grinder that can travel around for worthy projects.
I guess we'd also want to include a 1:160 Keith Rucker or a full size @narrowminded for good measure, lol.

[randgust]

Well, no normal swiss file I had would even touch those old Bachmann axles, so that's how I figured it was steel.    I actually ended up using the side of the Dremel diamond cutoff wheel as a file, which is absolutely flat on the side.   Worked great. 

The problem that I had without a proper press is getting those wheels (with plastic centers) squared up against the new axle.   First wheel can be put on with a drill press, but pressing the second wheel on is a lot harder.    I still think I can tweak it as long as a)  its properly in quarter, and the rods aren't binding against the gear drive (which they are not) and 2) I have a really good micrometer to check the variance of the inside dimensions to find the wobble areas.   I didn't bother to do this until I could see if this entire wacky drive train idea was actually going to work, which apparently it will.

When I twisted the driveshaft with my fingers it looked OK, but running at low speed under actual power you can see the wobble.

If I had really good tools here I probably would have left the Rivarossi axles alone and set up a brand new frame, just sayin'.

[randgust]

Well, here's where I'm at.    I decided that although the one driver isn't perfect, it means I need to snag another Rivarossi 4-6-2 main driver, which I don't have.   I have about everything else including extra Bachmann axles.   But, I can always swap that out in the future, meanwhile, I have kept building this thing as there are a lot of other mechanism, fit, and drive issues to solve.

I made a raw brass boiler out of K&S tubing and tapered it with Squadron, filed smooth.   The cylinders are the original Rivarossi, filed to shape as they are the right dimensions but need tapered to the inside.

The pilot truck is 'good enough', particularly when it has to clear the cylinders.   While I've turned the driver flanges I haven't bothered with the pilot truck yet, that can be later as well.

Today I fit the brass pilot deck, cylinders, and test fit the brass boiler on the heavily cut-down Bachmann chassis.   And I test fit the resin copy of the Trix cab, which is too long, but you get a feel for the overall dimensions pretty quickly.

The key dimensions - wheelbase, wheel diameter, boiler diameter, top of rail to top of boiler....are all dead-on to my PRR drawings.   As well as the tender wheelbase and length from the rear driver.

There's lots and lots of room in the boiler to add weight and rebalance it to the axles.    So... I'm roughing out the critical issues here and test-running it to see how this goes.   The one good thing is that the pilot truck clears the cylinders down to a 9 3/4 curve.

[peteski]

Well, here's where I'm at.   

The pilot truck is 'good enough', particularly when it has to clear the cylinders.   While I've turned the driver flanges I haven't bothered with the pilot truck yet, that can be later as well.

I hope that you reconsider.
Those look comically small. They are bout 25" in diameter (with the flange being 36" diameter!). Turning the flanges down will make them look even weirder.  If those tiny wheels with huge flanges clear the cylinders, larger wheels with smaller flanges should too, and would look 1000% better. I think that low flange 28" or 33" wheels would work and look more realistic.

It pains me to see someone spending all that time to  almost scratchbuild a model while leaving somethgin very visible  (like pilot wheels) looking so unrealistic.

[mmagliaro]

Randy,
Do you still need a Rivarossi 4-6-2- main driver?  (the one with the threaded post insert on it)?
PM me. 

-- Max

[randgust]

I just scored a broken junker 4-6-2 on the auction site last night, which will give me a bunch of parts, including another main driver set and another pilot truck.

The main driver is already planned to go to Narrowminded (Mark) so that he can do a better job of mounting the driver on the Bachmann axle than I can with what tools I have.

The second pilot truck, or more accurately the frame, allows me to experiment with putting in bigger pilot wheels with smaller flanges and see if they will still work.    I wasn't sure how much room I would end up with under the pilot deck; I think it will work, worth a try anyway.  But even on an 11" curve, the deflection of the pilot truck laterally is ...wow.  It's really moving around under there.   Nothing against improving appearance, but the darn thing still has to run well or it's just not worth doing.

Shapeways has nice stuff like the slatted pilot front, water scoop, and other details for down the road.

Now that I have the cylinders finalized for position and alignment I'm trying to figure out how to do a single (top) crosshead guide and crosshead.   It's got to have enough lateral movement to handle the bigger drivers and not be completely fragile, but I can't believe I can't do better than the Rivarossi one.   Even the Trix one off a junker 4-6-2 would appear to be an improvement.    I can fabricate/modify a new main rod here, that's the easy part.    Steam parts are hard to come by; I'm open to suggestion here about what else might work.   

I was trying to figure out what to do for a smokebox front as that's actually a bigger boiler; turns out the old Rapido 0-6-0 has a smokebox front that will work nicely if I don't come across something better in the meanwhile.  Problem with RLW is that you're guessing on dimensions.

Another thing that sorta bugs me is that I'm looking at 1046 as it would have appeared in 1926-28; that's when PRR was in the middle of modernizing things on this class.   Shots I have of it are earlier or later.    I do have to admit that some of the real oddball stuff on these appeals to me like the tilted piston valves to work with the original inside Stephenson valve gear.   Was there any other class that designed custom cylinders tilted like this to use older-style valve gear?

[Point353]

Another thing that sorta bugs me is that I'm looking at 1046 as it would have appeared in 1926-28; that's when PRR was in the middle of modernizing things on this class.   Shots I have of it are earlier or later.    I do have to admit that some of the real oddball stuff on these appeals to me like the tilted piston valves to work with the original inside Stephenson valve gear.

In what ways would the appearance of the 1046 in 1926-28 differ from what is shown in this photo?

[randgust]

That's the locomotive at Oil City near the end of service about 1937.    From Stauffer's book, the 'original' features were rather obvious in that the class originally had the 'big' drivers, oil headlights up on top of the boiler, no turbogenerator, and early on, slide valves instead of pistons (different cylinders).    The headlight is kind of the big deal to me in terms of appearance issues.    It looks to me like PRR took their sweet time in converting everything over to electric headlights.   I'm pretty sure I'm going with the electric 'modern' version, unless somebody produces a shot of 1046 in that year range with the other details.    Here's a similar class at Olean (other end) with the older headlight) in 1916 but the drivers and pistons redone:

http://www.northeast.railfan.net/images/prr6217.jpg

Also note the difference in the pilot; this may be locomotive specific or a standard modification.  I'm a PRR greenhorn, really, other than my immediate local area.

Oh, and I don't know that I mentioned it, but I did score a 1930 Official Guide (first quarter, so the depression hadn't hit the schedules yet) and it proved what my father had related.   There were two trains a day up and down the river Oil City-Olean; both locals, and one pair was identified as a motorcar and the other was not.    So his comments that 'the first year they had a doodlebug and the second year they didn't' proved out.   I'm assuming the 1930 schedule wasn't much different from what he rode, and that explained it.    By the last run in 1937 the doodlebug was gone with only the  4-4-0 remaining, all the passenger service was dropped up the valley that year.

[Ed Kapuscinski]

The Pennsy DEFINITELY took its time doing headlight conversions.

For example, the first Ka4s and I1s (their massive 2-10-0s) came with oil headlights.

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[mmagliaro]

Randy, when I made my SP&S 4-4-2 out of one of those Rivarossi frames, I put Fox Valley 33" wheels into the original pilot wheel frame.   I did have to ream out the circular passages in those little "fingers" that hold the axles in, because the FVM axle is thicker than the original Atlas axle.    You need to be really careful there, because there isn't a lot of metal to spare in the fingers.  I think I used a little 1.5mm chucking reamer and just twirled it inside the circular openings with my fingers.

I had to add an insulating washer behind the "dead" wheel in each wheelset, because it kept finding a way for the back of the wheel to graze the frame and short out.  I buzzed off the pointy ends of the axles with a Dremel as well.

Here's a pic.  It does fit, and it can definitely make it around 15" curves.  I don't know how much tighter it could go.   11" is probably pushing it.

[randgust]

I don't need 9 3/4 but I do need 11" for the modules and my reversing loops.   But with a second (expendable) pilot truck we'll give something like this a shot.

[Chris333]

Once or twice I have notched the back of the cylinders to clear wheels, but sometimes you'd be surprised what will work as is.

[randgust]

I got a set of those Fox Valley wheels from somewhere, at least I think they are Fox Valley by studying the dimensions and photos.   Also have some of the narrow-tread BLMA that have thinner axles.   When I studied it, I think it will work, at least worth a shot here when I get the second pilot truck in.  If nothing else I'll then have two interchangeable pilot trucks, one with wheels that Peteski can tolerate looking at without pain and another one for when I actually have to run it!   

Anyway, great suggestion Max.  But I've got a long way to go on this thing.  The one thing that is proven, now, at least to me is that the tender drive with the gearhead is 100% solid as a concept here, just like in my 2-6-0.   Great speed range and torque.

[peteski]

The one thing that is proven, now, at least to me is that the tender drive with the gearhead is 100% solid as a concept here, just like in my 2-6-0.   Great speed range and torque.

True.  It is used on some N scale European steam locos (mosty by Arnold).  But it doesn't leave much room for a sound decoder, and a decent-size speaker enclosure. Not a problem if it is a DC model.

[randgust]

It is with great reluctance and with tongue firmly in cheek that I feel obligated to announce that....

Peteski was right.   

I was highly skeptical that this would work; the spare junker pilot truck was modified with the FVM wheels and the points ground off per Max.   When I first tried it, it derailed on about everything (ah-HA!) and I decided to add just a little slip of lead on top of the lead axle.

Damn.  Works great.   Now this is a pretty crude test of the idea, but it's still a tracking test at this point, and I put it through the entire layout and it neither hung nor derailed.   So....  I have to admit it.  It worked.



Mark (Narrowminded) now has my spare driver set now and is attempting to make a more cocentric set than what I could with my tools.   

This really runs pretty well.  After I get the wobble out of the lead driver set I think I have a winner, at least for the drive.

I have to admit I'm still stumped by finding a suitable single crosshead guide and piston with enough travel - any NKP 2-8-4 assembly would work but when Bachmann's part website opened back up, yup, out of stock.  Can't find much of anything else so far.