Railfan.net Home Railfan Photos ABPR Archives Staff Safari Photos Railfan Links

Railfan.net Forums Railfan.net Forums Railfan.net Forums
Welcome, Guest. Please Sign In or Register. Jul 22nd, 2017, 2:55am
Categories •  FastIndex •  LongIndex •  Help •  Search •  Members  •  Sign In •  Register


Making A Steam Dome
   Railfan.net Web Forums
   Model Railroading
   Live Steam and Ride on Scales
(Moderators: moose_the_caboose, Brian Tusin)
   Making A Steam Dome
« Previous topic | Next topic »
Pages: 1  ReplyReply     EMail TopicEMail Topic   PrintPrint
   Author  Topic: Making A Steam Dome  (Read 449 times)
Dan Watson
Historian
Posts: 354
Making A Steam Dome
  Dome_Spinning_2013-03-30_13.18.44_resize.jpg - 125649 Bytes
« on: Mar 30th, 2013, 10:28pm »
Quick-Jump   Reply w/Quote   Modify

Thought I would post a few pictures of the steam dome I'm making for a friend's loco. First is the hemispherical top of the dome.  This is being spun on a lathe from sheet steel over a wooden form.

http://Forums.Railfan.net/Images/LiveSteam/Dome_Spinning_2013-03-30_13.18.44_resize.jpg
Click Image to Resize

Logged
Dan Watson
Historian
Posts: 354
Re: Making A Steam Dome
  Dome_Spinning_Tool_2013-03-30_16.55.26_resize.jpg - 114983 Bytes
« Reply #1 on: Mar 30th, 2013, 10:30pm »
Quick-Jump   Reply w/Quote   Modify

Here is the roller tool that goes in the toolpost.  The roller is made from a trailer hitch ball and rides on two ball bearings.  The idea is to deform the metal over the wooden form as it spins, a little at a time.

http://Forums.Railfan.net/Images/LiveSteam/Dome_Spinning_Tool_2013-03-30_16.55.26_resize.jpg
Click Image to Resize

Logged
Dan Watson
Historian
Posts: 354
Re: Making A Steam Dome
  Dome_Spinning_2013-03-30_14.00.47_resize.jpg - 118673 Bytes
« Reply #2 on: Mar 30th, 2013, 10:32pm »
Quick-Jump   Reply w/Quote   Modify

Almost there, after quite a lot of spinning and massaging the steel sheet with the roller.

http://Forums.Railfan.net/Images/LiveSteam/Dome_Spinning_2013-03-30_14.00.47_resize.jpg
Click Image to Resize

Logged
Dan Watson
Historian
Posts: 354
Re: Making A Steam Dome
  Dome_Spinning_2013-03-30_16.48.58_resize.jpg - 255093 Bytes
« Reply #3 on: Mar 30th, 2013, 10:35pm »
Quick-Jump   Reply w/Quote   Modify

The dome top has arrived!  I parted off the ragged edge and also bored a hole in the top of the dome while it was still between centers on the lathe. (This is Pivo Patio, North)
A side note: metal spinning actually shrinks the metal and makes it thicker!  When I started, the steel sheet was .060" thick.  When finished, the outer part of the dome top was actually .065" thick.


http://Forums.Railfan.net/Images/LiveSteam/Dome_Spinning_2013-03-30_16.48.58_resize.jpg
Click Image to Resize

« Last Edit: Mar 30th, 2013, 10:57pm by Dan Watson » Logged
Dan Watson
Historian
Posts: 354
Re: Making A Steam Dome
  Dome_Cylinder_2013-03-10_14.38.59_resize.jpg - 125283 Bytes
« Reply #4 on: Mar 30th, 2013, 10:40pm »
Quick-Jump   Reply w/Quote   Modify

Here are the dome sides being run through a slip roll.  I'm making two in case one of them goes wrong.  Several passes through the slip roll are needed.

http://Forums.Railfan.net/Images/LiveSteam/Dome_Cylinder_2013-03-10_14.38.59_resize.jpg
Click Image to Resize

Logged
Dan Watson
Historian
Posts: 354
Re: Making A Steam Dome
  Dome_Cylinder_2013-03-10_14.52.25_resize.jpg - 113052 Bytes
« Reply #5 on: Mar 30th, 2013, 10:42pm »
Quick-Jump   Reply w/Quote   Modify

Here are the cylinders out of the roll.  The ends overlap because the slip roll won't put a curve into the last inch or so on the ends.  The straight part on the ends will be trimmed off.

http://Forums.Railfan.net/Images/LiveSteam/Dome_Cylinder_2013-03-10_14.52.25_resize.jpg
Click Image to Resize

« Last Edit: Mar 30th, 2013, 10:44pm by Dan Watson » Logged
Dan Watson
Historian
Posts: 354
Re: Making A Steam Dome
  Dome_Cylinder_2013-03-10_15.44.57_resize.jpg - 147944 Bytes
« Reply #6 on: Mar 30th, 2013, 10:47pm »
Quick-Jump   Reply w/Quote   Modify

The dome sides are tack welded together with a TIG outfit.  Eventually the dome top will be welded on and the seams ground flush.

http://Forums.Railfan.net/Images/LiveSteam/Dome_Cylinder_2013-03-10_15.44.57_resize.jpg
Click Image to Resize

Logged
Dan Watson
Historian
Posts: 354
Re: Making A Steam Dome
  Dome_Prototype_resize.jpg - 50651 Bytes
« Reply #7 on: Mar 30th, 2013, 10:53pm »
Quick-Jump   Reply w/Quote   Modify

This is what the dome is supposed to look like when I'm finished.  Right now I'm taking a break to work on another project, so stay tuned!

http://Forums.Railfan.net/Images/LiveSteam/Dome_Prototype_resize.jpg
Click Image to Resize

Logged
moose_the_caboose
Moderator
Historian
Posts: 1478
Re: Making A Steam Dome
 
« Reply #8 on: Mar 31st, 2013, 11:47am »
Quick-Jump   Reply w/Quote   Modify

hey dan!
 
nice work!  glad to see you back at it again.  i'm also thankful that you were able to make the unmeet this year...just wish the time hadn't flown so fast that we didn't get much 'talk' time in.  may be next year?
 
the steam dome looks wonderful....but, what's the back story?  since you were spinning steel, did you have to aneal?  how long from start to finish in the spinning process?  did the spinning form deform from the pressure used?  if so, what wood did you use?  if not, same question...what wood did you use?  does the forming ball also smooth the finish or is additiional finishing required or desired?
 
btw, the 'nba' is a nice addition to pivo north!
 
 
moose


Logged

pockets
Historian
Posts: 1224
Re: Making A Steam Dome
 
« Reply #9 on: Mar 31st, 2013, 5:27pm »
Quick-Jump   Reply w/Quote   Modify

Very nice, Dan. I particularly like the trailer hitch ball. I've used ball bearings and wood, but all of my spinning, so far, has been non-ferrous.
 
Greg B.


Logged


Mechanical engineers build weapons, whereas civil engineers build targets.

When the man at the door said," Alcohol, Tobacco and Firearms", I, naturally assumed it was a delivery!
Dan Watson
Historian
Posts: 354
Re: Making A Steam Dome
 
« Reply #10 on: Mar 31st, 2013, 5:37pm »
Quick-Jump   Reply w/Quote   Modify

Hi Moose,
I did a little research before starting this project.  The 1008 steel sheet is recommended for deep drawing operations like this.  It has only .08 percent carbon and is quite ductile.  It seems like it work hardened a little during the spinning process, and the finished dome top will ring like a bell.  But no annealing was required.  In my book this is a distinct advantage over copper, which would have needed to be annealed several times.  Also, the cost was much less with steel vs. copper.
 
As to how long it took, I was working at a very deliberate pace since this was the first time I've tried this, and I was continually adjusting the roller tool, taking the workpiece out of the lathe to mash out wrinkles, etc.  Were I to make another, the spinning could be accomplished in less than an hour. My 16" lathe has a top speed of about 500 rpm, but this is too intimidating for me.  I think I ran it at about 80 rpm.  The faster you spin the part, the less time it takes.  Someone with experience could probably make this in about ten minutes.
 
The wood is cherry.  Most any type of seasoned hardwood would work OK.  The wood doesn't deform much under the pressure.  But one unexpected result was that I had a devil of a time hammering the dome off the former when it was finished!  The steel heats up from being deformed under the roller, and when the last bit was completed, the edge of the hot dome was up snug with the wood form.  And what does hot metal do when it cools?  Why, it shrinks!
 
One point I still don't have sorted out in my mind is how the metal is both stretched and shrunk during the spinning process.  The dome top has a diameter of 7.5 inches.  Now, if you multiply 7.5 times pi (3.14), you would get roughly 24 inches. And to go around a hemisphere this size, you'd need 12 inches of material, right?.  But I started off with a disk of steel sheet 10" in diameter, and it was just enough to complete the top of the dome.  So clearly, the metal had to stretch from 10" to a little over 12" to cover the former.  However, when I started the steel was .060" thick.  When I finished, it was .065" thick, so the metal had to shrink!  Go figure.
 
I plan to retire about this time next year.  Hopefully will have more free time for things like the unmeet after that.


« Last Edit: Mar 31st, 2013, 5:44pm by Dan Watson » Logged
Henry
Historian
Posts: 6098
Re: Making A Steam Dome
 
« Reply #11 on: Apr 1st, 2013, 10:01am »
Quick-Jump   Reply w/Quote   Modify

Dan, thanks for the explanation and pictures, I found it very interesting. I wish I had a reason to try it!
 
Henry


Logged
Dan Watson
Historian
Posts: 354
Re: Making A Steam Dome
  Dome_Welded_2013-04-07_16.44.03_resize.jpg - 163454 Bytes
« Reply #12 on: Apr 16th, 2013, 5:10pm »
Quick-Jump   Reply w/Quote   Modify

Here is the dome top after being welded to the side.  TIG welding (or any other type welding, for that matter) is not my strong suit so a friend did the welding.  The next step will be to start hammering out the flare at the bottom.  Wish me luck on this; I've never tried this before!
Welding requires a different brand of beer from rolling or spinning


http://Forums.Railfan.net/Images/LiveSteam/Dome_Welded_2013-04-07_16.44.03_resize.jpg
Click Image to Resize

« Last Edit: Apr 16th, 2013, 5:18pm by Dan Watson » Logged
Dan Watson
Historian
Posts: 354
Re: Making A Steam Dome
  BoilerTemplateB.jpg - 100603 Bytes
« Reply #13 on: May 27th, 2013, 4:04pm »
Quick-Jump   Reply w/Quote   Modify

Here's some photos of how the bottom was flared out.  I made a mock-up of the boiler from scrap lumber by sawing out sections of 2X6 on the bandsaw, then screwing them together with deck screws.  This gives me something to fit the dome to.  The bottom of the dome was cut out to rough shape with the ubiquitous 4.5" angle grinder.

http://Forums.Railfan.net/Images/LiveSteam/BoilerTemplateB.jpg
Click Image to Resize

Logged
Dan Watson
Historian
Posts: 354
Re: Making A Steam Dome
  DomeStretching.jpg - 171165 Bytes
« Reply #14 on: May 27th, 2013, 4:09pm »
Quick-Jump   Reply w/Quote   Modify

In order to flare out the bottom of the dome, the metal must be stretched.  After experimenting with different methods, the one that worked best was to put a piece of channel in the vise facing upwards, and hammer on the sheet metal between the flanges of the channel, where the sheet is unsupported.  After it is stretched out, I replaced the channel in the vise with an auto body "dolly", or hand anvil.  Then I hammered out the dents from the stretching operation.

http://Forums.Railfan.net/Images/LiveSteam/DomeStretching.jpg
Click Image to Resize

Logged
Dan Watson
Historian
Posts: 354
Re: Making A Steam Dome
  DomeHammeringC.jpg - 162796 Bytes
« Reply #15 on: May 27th, 2013, 4:11pm »
Quick-Jump   Reply w/Quote   Modify

After much hammering, here is where we are on this project.  Next step is to sandblast the dome and put on some auto body filler.

http://Forums.Railfan.net/Images/LiveSteam/DomeHammeringC.jpg
Click Image to Resize

Logged
Dan Watson
Historian
Posts: 354
Re: Making A Steam Dome
  DomeBondo.jpg - 262866 Bytes
« Reply #16 on: May 27th, 2013, 4:14pm »
Quick-Jump   Reply w/Quote   Modify

I'm not so good with auto body work so I'll leave the final sanding and finishing to my friend David, whose loco this is for.  Besides, I'm ready to move on to the next project!

http://Forums.Railfan.net/Images/LiveSteam/DomeBondo.jpg
Click Image to Resize

Logged
Boulder Creek
Chaser
View Profile   WWW  

Posts: 61
Re: Making A Steam Dome
 
« Reply #17 on: Jun 13th, 2013, 3:57am »
Quick-Jump   Reply w/Quote   Modify

Fantastic work there Dan! Thanks for sharing the pictures with us!

Logged

Visit the Boulder Creek Tramway at: www.smex.net.au/bouldercreek
Dan Watson
Historian
Posts: 354
Re: Making A Steam Dome
 
« Reply #18 on: Jun 13th, 2013, 1:05pm »
Quick-Jump   Reply w/Quote   Modify

Thanks!  Actually I wasn't satisfied with the finish, and went over it again with more bondo and then sanded it with a power sander.  However I shipped it off to my friend in Mississippi without taking another picture.  He promised to send me a photo of the dome once it's painted and installed on his 4-6-0, and I'll post it here.

Logged
Pages: 1  ReplyReply     EMail TopicEMail Topic   PrintPrint

« Previous topic | Next topic »