SteamPower4ever

Fixed the screw that was causing trouble and after a bit more work with the saw and drill, the frame construction is now done. Now I just need to mount the belly tanks with the speaker, attach the wires to the decoder and it should be ready to growl Notice the decoder is sitting on nylon stays to isolate it from the new metal frame. I may need a few drops of glue to secure the screws in those nylon stays. They feel kind of "not entirely fastened" and I'm afraid to overtighten them.

Glued and screwed. Got the last parts needed to begin the assembly of the engine. One of the screws is acting up of course, so I need to figure out how to get it out But in general, it's looking good.

The trucks are still incomplete. I need to figure out how to design the lower axle box braces. However, the entire project is on hold for the time being. Jens

I'm waiting for parts, but meanwhile I've assembled the trucks. The screws go in from below and I've made hex holes for the nuts, so the assembly is fairly easy. Having considered pros and cons I decided that the smoke unit should be attached to the body part. The smoke outlet connects to the duct assembly with a small piece of rubber tube that comes with the smoke unit, and fitting those parts at the same time as matching the body to the frame is simply a no-go. There's no room to guide the parts in place and no way to assure they're in the right place after assembly. So - after a few failed designs I've made some hanging brackets that should work well. The ducts are redesigned slightly giving more room below for the smoke unit. When assembling the engine, I just need to plug the connector from the decoder to the smoke unit.

Thank you for watching

Thanks, Chuck. I'm quite proud of the design myself I've designed the smoke ducts that fit the ESU smoke unit. The part fits onto the screw posts in the MTH body and the exhausts match the MTH smoke stacks. MTH has opted for a semi-open system with soft gaskets between the body and the smoke system, which is why they've designed that drain pipe to drain condensed smoke fluid away. I'm going for a closed system where I glue the part in place at the smoke stacks. Mostly to seal the system. Mechanical stability comes from the screws. Here's the complete design. I can fill smoke fluid in either stack. I lowered the smoke unit (red) a bit, which makes me think that maybe it should be attached to the frame after all. I'll have to think about that. I've noticed on several videos of the ESU smoke unit that at low speed the smoke flows too smoothly for my taste. Looks like the smoke simply escapes unforced. To stir up the smoke I've added some internal bulkheads in the ducts. Hopefully they provide some turbulence even at low speed. Here's a cross section of the duct unit:

The first parts arrived from Shapeways. Out of the box, the NWSL trucks come with a small retaining ring that is supposed to secure the king pin to the frame. I think that's a bit too flimsy. Because of difference in height and king pin location between the MTH and NWSL trucks I've made adapter sets for the trucks. They're in two parts and one part attaches to the NWSL truck like a saddle. The space between the tabs on the truck and the saddle are designed to fasten the truck sides. Four screws and it's done. The other parts go in the frame where I've cut the square holes. I still need to cut holes in the MTH frame, but four more screws at either end and I'm done here also. The trucks are then attached to the frame by inserting the tabs at the top of the saddle at a 90 degree angle and turning the truck to the right position. The frame then rests on the shoulders of the truck saddles and when the crew stairs are in place, the trucks can't turn back to the detach position. And the real beauty is that for the next four units I can simply order the parts ...

They do, yes. Once attached, the frame/body assembly is fairly rigid and stable.

The pieces are coming together. A 3D CAD program can also be used for lighter duty such as rough planning of an assembly. I've made models of the outlines of the MTH body and frame and crude models of the stuff I'm going to use, and it fits well together now. Below is a model of the interior of the F7A: - Light grey is the MTH frame (brass plate not shown, but included in the dimensions) - Dark grey is the MTH weight blocks - Blue is the speaker and truck mounts - Amber is the brass supports - Green is the ESU decoder - Red is the ESU smoke unit The two floating pieces above the model are the smoke stacks. Next I need to design some sort of duct work from the smoke unit to the stacks. There's room for the cab, except for the staircase at the rear of the cab, which has to go. I've managed to use the MTH weights without modification, and now I just need to figure out how to make threads in them. The look and feel like they're made from more than just black iron. Steel or something. Here's the truck mounts as ordered from Shapeways. The upper part mounts in the frame and the lower part attaches to the NWSL truck, attaching the truck sides with the same four screws. The two parts fit together like a simple key, which is turned 90 degrees to lock. Once the truck is in place, it can't swivel that much, so it stays in place and the frame rests on the crest of the lower part. As I said earlier, I think I need to strengthen the frame after weakening it at the openings for the speaker and the truck mounts. Here's the frame support with a 1mm brass plate cut to shape and the brass profiles soldered to the plate. Once attached with screws (I haven't made up my mind about glueing it yet), the entire frame will be totally straight and rigid. That gives me peace of mind, as the MTH frame itself is warping, even before I started working on it. Jens

Hmm - that Daylight GS-4 sure is tempting Does anyone know if the 2017 model will feature a close coupling between engine and tender? If you look at the small pics it looks like the tender is hauled on a string. The pics must be a smaller scale. Then look at the small pic of the Big Boy. The tender is very close to the engine as it should be.

Go ahead - I'd love to see that We've mused over the subject several times at my former club, but we never got around to it.

Ahh, you know - I'm a tinkerer. It's fun - that's really all the reason. Basically I want to get rid of the sliders. I always imagined I would do that, and after test runs on the layout(s) that for now will be the home turf, I'm right in doing so. They are causing shorts in some turnouts. Next is to improve pickup as the MTH trucks have tires, which means that without the sliders I have reliable pickup on only two axles. Hence new trucks. I have good experience with NWSL in the past, although in smaller scale, so time will tell. Edit: I'm powering the B units too, and they'll get NWSL trucks. I like to have the same drives in all units. I too think the forked tube is some kind of condensate drain, but it doesn't originate from the smoke pipes but from the chamber surrounding the smoke stacks. Anyway I'm arranging my smoke system so any condensate drains back into the smoke unit. To get the best sound I've chosen the largest speaker possible. It's actually a Visaton FRS 8. It doesn't fit in the MTH frame, so I've cut an opening for it in the plastic frame. That of course weakens the frame, so I'm adding a brass plate, which first of all must have a similar hole for the speaker, and I'll reinforce it with brass profiles. I'll arrange those so that I can close the speaker chamber. I'm also going to build some new mounts for the trucks. I'm working on a design for 3D printing.

Well, if I can program CV17 and 18, I can program CV29 also, so it shouldn't be a problem. But again, it's mostly out of interest, as I'm fitting ESU decoders in the F7s anyway.

Hmm ... Have to try that, even though it doesn't matter much. Thanks.