Question for Hobby Bob

**Sidney Schwartz** · #1 08-27-2023, 02:49 PM

Bob I'm building your HO scale 4-4-0 American loco. Can you tell me if I got the boiler put together correctly? Also, the instructions for building the stack reference parts that I can't find, specifically the spark arrestor, cap and ring. Can you tell me where these are on the sheets? Thanks again for the models.

**HobbyBob** · #2 08-28-2023, 08:28 AM

Hey Sidney! Your technique is perfect (better than mine)! However, on the larger diameter tube, the space for the dome should be towards the front rather than the back. This isn't a fatal flaw though, because the cab should cover up the dome marking.

I simplified the stack for UP 119, because the dual-cone spark arrester would be devilishly hard to build. However, looking at it again, I think I could design one. Hang tight on the stack, and I'll add one today.

As an interesting note, I used modeling techniques from my old model rocketry days to design this model... it's funny how things come around sometimes!

**HobbyBob** · #3 08-28-2023, 08:29 AM

Just snuggle the rear dome up to the transition and you should be fine...

**Sidney Schwartz** · #4 08-28-2023, 12:16 PM

Thanks much, Bob!

**HobbyBob** · #5 08-28-2023, 03:40 PM

I've uploaded a new file of UP No. 119 with an "accurate" stack. It's too tiny for me to build; however, given how well you built the boiler, you should be able to do it. If you'd like to see how those conic sections are designed, the formula is included in the undecorated version...

**HobbyBob** · #6 08-28-2023, 03:41 PM

Quote:

Originally Posted by Sidney Schwartz

Thanks much, Bob!

Glad to be of service!

**Sidney Schwartz** · #7 08-28-2023, 07:18 PM

I've downloaded the revised 119 and will have a whack at it.

**HobbyBob** · #8 08-29-2023, 08:22 AM

Great! Please let me know how it goes!

**Sidney Schwartz** · #9 08-30-2023, 03:28 PM

Does this look correct so far? I know the cow catcher isn't right...I haven't yet decided what I want to do with that.

The collar pieces for the stack were not long enough to completely encircle it. I doubled them up in length and then cut off the excess.

**Sidney Schwartz** · #10 08-30-2023, 03:53 PM

I'm having trouble figuring out how put the cylinders/rods together. Do you have a photo of a completed model that shows that? Thanks.