Fabricating A Steam Dome - Take 2

[Fender]

Earlier, I posted a question on this subject and received many helpful responses. So I decided to take the plunge and learn how to do metal spinning. Also, to start a new thread on this subject.
As a refresher, my buddy David Price wanted a "Schenectady" style steam dome shell for his RGS 20, as it was originally built. The prototype RGS 20 had acquired a Baldwin-style steam dome shell at some point, and this is the style provided by Tom Artzberger. Here is a photo of the original Schenectady steam dome:

Originally I was going to take the easy way out and use a stainless steel mixing bowl for the hemispherical part, and bought this bowl, but it turned out to be the wrong diameter:

The first step is to make a wooden former that is the right shape. A fellow live steamer provided a chunk of cherry firewood that was the appropriate diameter. Charlie Pipes helped me turn it down on the Atlas lathe:

This chunk of cherry was about the largest diameter (finished size 7.5") we could turn on the Atlas lathe. Even then we had to use a boring bar. Here's a photo of the former almost finished:

[Fender]

Here is the metal spinning tool I made out of some scrap and a surplus trailer hitch ball. The ball rides on two ball bearings.

I transferred the wood former, still mounted on the Atlas faceplate, to the four-jaw chuck on my 16" lathe. I mounted the spinning tool in a lantern toolpost, and then placed a piece of 16 gauge (.060") 1008 cold-rolled steel about 10" in diamter on the form, supported by a live center in the tailstock. The sheet was drilled with a center drill to keep it in place:

Here is the spun dome a little further along. I took it out of the lathe and "massaged" it under the arbor press to smooth out the wrinkles on the edges:

Here is the finished dome top. The dome is actually pretty smooth; the filing marks make it look like it has ridges. (time for a break!):

What's interesting is that the metal started out .060 thick, but when I measured the finished dome it was .065 thick at the outside!

[Spiner]

Here are some pictures of the steam dome we are working on right now. it started out as a 4" stainless pipe cap that has been turned, welded and shaped into the dome.

[Lovesthedrive]

Very nice!

[Fender]

With the help of DaveD, the sides were rolled from the same 1008 sheet. I cut two pieces (one for the dome and the other to mess up on!) about 7" X 26" and ran them through Dave's slip roll. Because the slip roll doesn't curve the last inch or so, they had to be made a little longer.

Here are the sheets out of the slip roll. As you can see, they overlap a little because of the straight part at each end. These will be cut off:

Yours truly sawing off the excess straight ends on DaveD's DoAll bandsaw:

Here is one of the dome sides tack welded together using Dave's TIG welder.

[jb bergman]

I like New Castle! Was there something else in that picture?
JB

[Pipescs]

How did you hold the ball to bore it for the two bearings?

[Fred_V]

Here is the finished dome top. The dome is actually pretty smooth; the filing marks make it look like it has ridges. (time for a break!)
What's interesting is that the metal started out .060 thick, but when I measured the finished dome it was .065 thick at the outside!

Very nice job. How will you make the bottom part?
here is a vid on making a stack base that may be of interest.
http://www.youtube.com/watch?v=7AYKQmpaUqE

[FLSTEAM]

Fred

I liked the video.

John B.

[Trainman4602]

Just another point of view

This is pretty much the standard way of making a one off dome.

The last two pictures are how I formed the flange .

I made a reverse form of the boiler and bored out a hole for the dome to fit into . I then rounded the edge and "copper Bashed" the edge to the form flange.

[JBodenmann]

Hello My Friends
Very cool thread on making a stem dome.
Jack

[Trainman4602]

As a follow up to the dome spinning. I then had to add the detail of the whistle and the other pipes that were attached to the dome. I think most of these were an afterthought and not part of the original design.

In the first picture I added an addition ring that I could tap the dummy piping into. This then simulates the piping coming thru the dome cover rather than taking the easy route of attaching it to the cover. Just another small detail that adds a realistic look to you model.