Boston & Maine B15 2-6-0 Scratchbuild

[garethashenden]

Nice to see you back on this project, but remind me: why didn't you use the standard low-friction pointy axle tender wheels riding in bearing cups in the sideframes?

The tender is transferring weight to the back of the locomotive. This will aid with traction and counteract a heavy smokebox. To do this the tender under frame is rigid, rather than a pair of trucks and attached to the tender body by a pivot near the back. I could have done all that and have pinpoint axles, but it would have been a lot more work and more excuses for procrastination. I’ll try to take a picture tonight, but the middle two axles are actually sprung, and all of them spin freely.
At some point after I finish this, I want to model a T1 2-8-4. That’s big enough that I shouldn’t need weight transfer from the tender and it will probably have pinpoint axle trucks. But I want to finish the Mogul first.

[peteski]

The tender is transferring weight to the back of the locomotive. This will aid with traction and counteract a heavy smokebox. To do this the tender under frame is rigid, rather than a pair of trucks and attached to the tender body by a pivot near the back. I could have done all that and have pinpoint axles, but it would have been a lot more work and more excuses for procrastination. I’ll try to take a picture tonight, but the middle two axles are actually sprung, and all of them spin freely.
At some point after I finish this, I want to model a T1 2-8-4. That’s big enough that I shouldn’t need weight transfer from the tender and it will probably have pinpoint axle trucks. But I want to finish the Mogul first.

I see. While you could have easily made a rigid 4-axle pinpoint bearing tender, the wheels would have been rigid (not lateral movement). In your design you probably have some lateral play (to compensate when the tender traverses curves).  Will all the tender wheels pick up electricity?  Remember what Victor Miranda said:  maximize your electric pickup, especially in models of  steam locos. 

[Chris333]

Do you have a gearhead on that motor in the tender?   

My 'go to' combination on my own 2-6-0 was a Kato 12v. 11-105 motor and a Gizmoszone gearhead on the front.   Similar mount though, used NWSL universals and shafting.   Mine only had 48" drivers and is smaller.   

When Chris built his logging 2-6-2 (Jerry DeBene has it now) I don't know if he used a gearhead or not in his tender drive, but it sure ran well.  At that time we were using Faulhaber motors from Motorman (RIP).   I tried several motor and gearhead combinations in my tender including a Faulhaber 0816, Max's Mashima, and my own 1105+gearhead custom blend, it easily won. 

That frame is still one sweet piece of work there.

I had a Faulhaber with a 4:1 gearhead, but I think Mark has done up a Atlas 2-6-0 with a Gizmozone gear head. @Mark W

Found this too:

[garethashenden]

In not sure if the leading wheels with both pick up power, but it will have at least 15 wheel pickup. The motor is a 7x16mm coreless from eBay. The 2mm guys were raving about these, so I grabbed a five pack while they were available. The gear reduction is 40:1.

[mmagliaro]

Looks really nice!  I do have one concern.  Is that really how you are going to join the motor to the gearbox up in the locomotive.  The way it is pictured here, the wire comes off the outside edge of the brass bit on the motor shaft, and I would expect it to vibrate in very weird ways.  Is that just temporary for the photo?

So glad to see you back on this one!

Well, after umm, three years  , there has been progress!!!

I spent three years procrastinating on making wheels. I bought a lathe and made a couple, but they weren’t very good and then I got distracted. Then I bought an Alco S3 from Lee with a couple of cracked gears. I ordered replacements from NWSL, and while I was poking around the site I noticed they sold 33” N scale wheels without axles. So I bought 10.
I mounted 8 on half axles and put them under the tender. Then I made a drawbar and a bunch of other little things and the motor is now connected to the gearbox! There aren’t any shorts, so it should run, but I have to go to work now so I won’t get to find out for sure until I get home.

Here are the pictures.

[Rob B]

OH MAN! I just clicked on Railwire and see another build like this. SMH Now if it wasn't for the lack of time I'd start a Ma & Pa 4-4-0 #6.

[garethashenden]

Looks really nice!  I do have one concern.  Is that really how you are going to join the motor to the gearbox up in the locomotive.  The way it is pictured here, the wire comes off the outside edge of the brass bit on the motor shaft, and I would expect it to vibrate in very weird ways.  Is that just temporary for the photo?

So glad to see you back on this one!

 Maybe both? This driveshaft is temporary because I didn’t make it very well, but it is also how it will look. If I make it properly the straight part of the wire will be concentric with the shafts and it should work like any other u-joint.

[Mark W]

I had a Faulhaber with a 4:1 gearhead, but I think Mark has done up a Atlas 2-6-0 with a Gizmozone gear head. @Mark W

Found this too:

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Interesting, I see that I put the motor and gearhead are from Gizmoszone in that video's description, but I always remembered swapping out the gearhead onto a Kato 11-105 motor, à la @randgust.   

[randgust]

One of the big advantages of tender drive is that you can really sock the boiler and cab area full of lead.   You might not need to transfer as much tender weight to the locomotive frame as you think.   Your tender pickup is critical. On my 2-6-0 I built it on a shortened Kato caboose frame so that I got 8x8 end-axle pickup and the equalizing ears via the contact strips, I've done this a couple times before as well and it's really,really good but you still need the motor weight on the tender to make it worthwhile for pickup, and the tender has to be as free-rolling as possible.

The tender has to be really stable and have some kind of three-point suspension or it's going to either vibrate or twist or both, that was more of a challenge that I thought but the pickup wipers dampened mine pretty well.    Mine is also very quiet, and with that gearhead, the speed control and torque is outstanding.   It will go to full slip and never drop rpm's or budge the ammeter.     

I've become a big fan of tender drive on small steam, I think it worked far better than I thought it would.   Heck, I had a Tyco 4-4-0 "General" in the 1960's as a kid in HO, and it didn't work all that well, now I know it was purely due to pickup issues.   With 8x8 pickup it's much better.   I give credit to my design to Chris333, he provided me with details on how he did it on his Atlas chassis using NWSL universals and shafting, get 'em while you can.   My only contribution is my Frankenmotor of the Kato+gizmozone gearhead.

[garethashenden]

The last time I worked on this I realised that I had a problem with the frames. I hadn't included anywhere to attach the cylinders.  The easiest solution would be to make a new chassis, which I have now done. This also allowed me to fix a couple of other things I wasn't really happy with. The locomotive now has a separate gearbox, rather than being integrated with the chassis and better connecting rods made from steel rather than brass. They're thicker, stronger, and much better all around. I'm now back to approximately the point I was in April, but in better condition to continue. Next up will be finishing the rods, then I'll start on the cylinders and main rods.

[mmagliaro]

I really like the separate gearbox.  Now that I see that, I wish I had done that on my 0-6-0.
It makes it much easier to get the gearmeshes all good, and mount it independently of the motor.  Plus,
with worm in its own carrier, that eliminates yet another place where you would have to worry about precision alignment and it isolates the motor armature from the fore/aft shifting forces of the worm.

[garethashenden]

I really like the separate gearbox.  Now that I see that, I wish I had done that on my 0-6-0.
It makes it much easier to get the gearmeshes all good, and mount it independently of the motor.  Plus,
with worm in its own carrier, that eliminates yet another place where you would have to worry about precision alignment and it isolates the motor armature from the fore/aft shifting forces of the worm.

Thanks Max. The only thing I’m not 100% satisfied with is that I used square tube between the two sides. Bar would have been better, both for more bearing surface and extra weight. I’ll probably stuff it with lead at some point.

[peteski]

I really like the separate gearbox.  Now that I see that, I wish I had done that on my 0-6-0.
It makes it much easier to get the gearmeshes all good, and mount it independently of the motor.  Plus,
with worm in its own carrier, that eliminates yet another place where you would have to worry about precision alignment and it isolates the motor armature from the fore/aft shifting forces of the worm.

The brass model manufacturers have been doing this for a long time.  I think that every brass N scale steam loco I have ever worked on (which is not all that many) has a separate self-contained floating gearbox.  It does have benefits, but it also does add complexity to the mechanism.

[randgust]

After what I've stumbled on in my steamers, I'm looking at where your drawbar attachment point is on the locomotive frame.   At this point, it's not impossible to see if you can fabricate a drawbar to move that pivot point down and closer to the rear axle.   That will keep it from 'torquing' the front axle against the outside rail when entering a curve and greatly reduces the likelihood of derailments, as well as the tendency to 'lift' the front drivers under full slip because of a higher pull point under the cab.    I'm not sure if you're still trying to weight-transfer from the tender to the locomotive via the drawbar, but I've never tried that myself, frankly, without the motor in the locomotive I've been able to add so much weight where it would have been it's just not an issue.

I really like your gearbox.   I've always been torn between all-gear drives in N vs. rods and crankpins.  The gears are a PITA but wearing out crankpins is bad too.   I think it depends on how much use you think this will actually see here.   I don't doubt your ability to precisely quarter the drivers though after looking at your workmanship here.

Your tender truck frames look really solid.   On my tender drives I've really had to make sure the lead tender truck had something to restrict too much twist looseness to lessen vibration and and the rear truck was really loose, that was really an issue with my 2-6-0 but not hard to solve.

[mmagliaro]

I wouldn't worry about the choice of square tube vs solid bar for the spacers in that gearbox.  For the tiny bit of airspace inside that tube, you are talking about fractions of a gram of lost weight at most.

As for rods vs gear driven drivers, again, if I had it to do over, I would have bit the bullet and mounted idlers and geared all the drivers in my 0-6-0.   I think on a short wheelbase engine with small drivers, it's a lot harder to get the quartering perfect, and overall the mechanism is more robust if the wheels are all gear driven and the rods just go around for show.  When you move to an x-8-x coupled mechanism, it makes more sense to do something like the Kato Mikado, where some drivers are gear driven and some are propelled only on the rods, to allow for freer movement through curves, and to eliminate all those idler gears.