Fabricating A Steam Dome - Take 2

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Fender
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Fabricating A Steam Dome - Take 2

Post by Fender » Sat Mar 30, 2013 6:21 pm

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:
Dome Prototype.jpg
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:
Dome Mixing Bowl.jpg
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:
Dome Form 2013-03-24 10.14.56 resize.jpg
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:
Dome Form 2013-03-24 10.15.37 resize.jpg
Dan Watson

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Fender
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Re: Fabricating A Steam Dome - Take 2

Post by Fender » Sat Mar 30, 2013 6:54 pm

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.
Dome Spinning Tool 2013-03-30 16.55.26 resize.jpg
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:
Dome Spinning 2013-03-30 13.18.44 resize.jpg
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:
Dome Spinning 2013-03-30 14.00.47 resize.jpg
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!):
Dome Spinning 2013-03-30 16.48.58 resize.jpg
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!
Last edited by Fender on Mon Apr 01, 2013 10:47 am, edited 6 times in total.
Dan Watson

Spiner
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Re: Fabricating A Steam Dome - Take 2

Post by Spiner » Sat Mar 30, 2013 7:03 pm

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.
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Lovesthedrive
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Re: Fabricating A Steam Dome - Take 2

Post by Lovesthedrive » Sat Mar 30, 2013 7:23 pm

Very nice!
1952 John Deere model 60

Wanted: Half size steam tractor. Will trade land in Maine

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Fender
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Re: Fabricating A Steam Dome - Take 2

Post by Fender » Sat Mar 30, 2013 7:45 pm

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.
Dome Cylinder 2013-03-10 14.38.59 resize.jpg
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:
Dome Cylinder 2013-03-10 14.52.25 resize.jpg
Yours truly sawing off the excess straight ends on DaveD's DoAll bandsaw:
Dome Cylinder 2013-03-10 15.03.01 resize.jpg
Here is one of the dome sides tack welded together using Dave's TIG welder.
Dome Cylinder 2013-03-10 15.44.57 resize.jpg
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jb bergman
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Re: Fabricating A Steam Dome - Take 2

Post by jb bergman » Sat Mar 30, 2013 9:32 pm

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

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Pipescs
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Re: Fabricating A Steam Dome - Take 2

Post by Pipescs » Sun Mar 31, 2013 8:08 am

How did you hold the ball to bore it for the two bearings?
Charlie Pipes
USMC Retired

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Fred_V
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Re: Fabricating A Steam Dome - Take 2

Post by Fred_V » Sun Mar 31, 2013 8:14 am

Fender wrote: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

Fred V
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Re: Fabricating A Steam Dome - Take 2

Post by FLSTEAM » Sun Mar 31, 2013 8:52 am

Fred

I liked the video.

John B.
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Trainman4602
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Re: Fabricating A Steam Dome - Take 2

Post by Trainman4602 » Sun Mar 31, 2013 9:10 am

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.
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Re: Fabricating A Steam Dome - Take 2

Post by JBodenmann » Sun Mar 31, 2013 2:28 pm

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

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Trainman4602
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Re: Fabricating A Steam Dome - Take 2

Post by Trainman4602 » Sun Mar 31, 2013 5:22 pm

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.
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