Many display locomotives have lost their boiler jackets in recent years, when the asbestos lagging was removed. A proper cosmetic restoration should replace the jacket, usually over strips of wood, styrofoam or other material to replace the lagging thickness. Where an identical sister locomotive still retains its jacket, the sections may be removed, flattened, and used as patterns to cut new ones.

For those engines that have no other identical sisters with a jacket still on, however, jacket replacement is more difficult. I believe the Pere Marquette 1225 folks used a computer to develop patterns, but still had to do some cutting and fitting afterward. Short of obtaining original locomotive plant drawings, can anyone suggest good methods to develop patterns for boiler jackets that are long removed and thrown away?

bobyar2001@yahoo.com

The KRM's L&N 4-6-2 #152 had a badly deteriorated jacket when the restoration took place. Most pieces were unusable, even as patterns. I believe we had a seamstress help us figure out what the pattern would be, and it was fairly accurate.

wilkidm@wku.edu

I believe the Pere Marquette 1225
> folks used a computer to develop patterns,
> but still had to do some cutting and fitting
> afterward. Short of obtaining original
> locomotive plant drawings, can anyone
> suggest good methods to develop patterns for
> boiler jackets that are long removed and
> thrown away?

Cutting and fitting, beginning with a cardboard pattern, is the only way. For Pere Marquette 1225, our engineer used a CAD file of the engine's boiler to create the pattern. Beginning with the boiler drawing, it was a simple matter to add the thickness of the insulation (variously 2 or 3 inches as measured from the studs and spacers found on the engine), and draw in the boundaries of the sheets (each course was in six segments, with sliding overlaps at the 12:00 and 6:00 o'clock points, and lock joints at about the 3:30, 8:30 and 5:00 and 7:00 points). The CAD system can be told to add extra material for the joints. The main benefit to this is that it gave us the correct outer dimensions of the large pieces, which must be tapered to match the boiler. We felt this saved enough time to be worth doing, as opposed to starting with cardboard and scissors. The resulting patterns fit pretty well.

The output from the CAD plotter was taped together, and then traced onto big sheets of cardboard. These were used to mark the locations of the many holes for studs and pipes and brackets. Once the cardboard was made to fit, it was copied in metal.

We had the Lima/AMC specification for the jacket, which called for various thicknesses of steel. Generally, the bottom segments were light. Some upper ones, which are subject to getting walked on, were quite stiff. Some are so stiff they had to be rolled, including the smokebox jacketing, which is unlagged and is evidently for appearance only.

Aarne H. Frobom, editor
The Steam Railroading Institute

froboma@mdot.state.mi.us

We fit cardboard patterns on to the locomotive first, then cut metal ones to match.

robsterne@hotmail.com

> Where an identical sister
> locomotive still retains its jacket, the
> sections may be removed, flattened, and used
> as patterns to cut new ones.

Many large sheet metal shops that do jacketing and ductwork for industry will be able to jacket a locomotive or provide a consultant who can make drawings, or at least give advice, depending on what you can afford. Dismantling an existing jacket would be time consuming and would damage the original jacket.


runner@i-55.com

Thanks to all for this information. It would be a very good subject to post in more detail, if anyone is interested. While straight sections of boiler should be no problem, the tapered ones are more problematic. The common method of laying out funnels in shop class don't really work here due to the size.

Dismantling an existing jacket on another locomotive should not be a problem, however, as it would likely still have asbestos lagging in place, which should be removed anyway. As such, it would be an ideal time to begin restoration two locomotives.

Many large sheet metal shops that do
> jacketing and ductwork for industry will be
> able to jacket a locomotive or provide a
> consultant who can make drawings, or at
> least give advice, depending on what you can
> afford. Dismantling an existing jacket would
> be time consuming and would damage the
> original jacket.


bobyar2001@yahoo.com

> Cutting and fitting, beginning with a
> cardboard pattern, is the only way.

I've gotten pretty good results from using heavy brown wrapping paper (for mailing packages, etc.) laid directly over the insulation on the boiler. After the locations for studs, washout plugs, brackets, anchors, etc. were marked, the sheets were laid out onto the sheet metal, the info transferred, and everything cut to shape. The boilers I've dealt with were relatively small in diameter compared to locomotives such as the #1225, so using cardboard probably would not have been an option, as it would have buckled too much.

Brian T. Wise


sugarpine71@yahoo.com