Traditional methods and materials are essential to good collections care at a railway museum. So over the last nine months, Volunteers and full time staff at the Northwest Railway Museum have been learning to hot rivet. Hot riveting was (is) used to attach two or more metal parts and was widely used in car and locomotive construction prior to the widespread introduction of electric welding. It is labor intensive and is almost a lost art.
The riveting crew recently had an opportunity to try out their skills. The Museum has contracted to perform some rehabilitation work on Issaquah Historical Society’s former Weyerhaeuser caboose. A damaged section of side sheet needed to be reattached to the side sill. So approximately 36 replacement rivets were required.
A gas-fired forge was moved from the Conservation and Restoration Center to the Issaquah Depot. An air compressor, a rivet gun, and some hand tools also made the trip. And on a cool September morning, all the tools were set up to begin riveting.
The replacement section of side sheet was welded to the existing car side a few days prior. Holes were predrilled and aligned with the side sill. The gas forge was lit and rivets were set inside to begin heating. Meanwhile, the rivet gun was oiled and connected to the air supply. Allan W. volunteered to do the honors and climbed under the caboose to operate the gun.
When the rivets were orange, Roger S. picked up a rivet with the tongs and inserted it into a hole in the caboose side. Clark M. alternating with Bill W. “bucked” the rivet with a second unpowered rivet gun while Allan W. operated the powered rivet gun. The die in Allan’s gun shaped the now red hot end of the rivet into an oval head to secure it on the inside of the caboose frame. As the rivet cooled, it shrank and pulled the side sheet very tightly against the side sill.
Check out this video showing the process:
The tender tank rehabilitation and restoration work for Northern Pacific Railway 0-6-0 steam locomotive 924 is drawing to a close! The 19th Century Rogers-built locomotive is the subject of a major collections care effort inside the Northwest Railway Museum's Conservation and Restoration Center in Snoqualmie where the first order of business is the tender and its badly deteriorated water tank. The
building of a new riveted cistern for a steam locomotive is a lot of hard work,
and is not often undertaken at heritage railroads. 
Erecting major components such as sides, ends, and slope sheets
can usually be accomplished quickly. In the non-museum world, a similar vessel
would be put together using modern fabrication techniques such as welding, and the
project would have been completed months ago. However, in order to adhere
to the Secretary of the Interior Standards for Treatment of Historic Properties,
façadism is not an acceptable practice. Instead, it is critical to reuse
original fabrications and components to the greatest extent practicable, and
when infeasible, faithfully recreate the missing or irreparably damaged
fabrications using materials and techniques consistent with the original. So for the tender cistern, every rivet has
been or will be duplicated using the technologies of the era. For
instance, each corner seam is riveted to an angle iron on both sides of
the angle with 1/2 button head rivets on a 1 1/2" pitch requiring
literally thousands of precision drilled holes. 
Since the last report, the top deck of the tender tank has been
fitted and installed. Historically, for this portion of the tank, flush
head "Liverpool" style rivet heads were used for the majority of the
work. This was done so that coal could be scooped from the top deck
without hitting the higher "button head" style rivets. This
feature has been faithfully reproduced on the new tank. 
In addition to the structural riveting, the tank continues to receive
original castings and forgings with the installation of tie down brackets and
hand rails. The side coal boards were also added, giving the cistern that
iconic 19th Century everted lip tender look. Moving forward, this coal
board will soon be extended and wrap completely around the rear of the top
deck, and the original water hatch will be rehabilitated and installed. 
In addition, to the ongoing cistern work, the tender frame has
received attention for its return to service. This frame had been
extensively rebuilt in the 1970s due to an encounter with a runaway freight car
while being stored in Centralia, WA, and most of the wooden framework remains
in remarkable condition. However, aesthetically the timbers exhibited
surface weathering and other effects which would not present well in the final
product. In order to rectify these issues and assure many decades of
trouble free service, the surfaces have been sealed and filled using epoxy-based
fillers and sanded to fill any minor cracks and surface blemishes. (This technique
was extensively applied to chapel car 5 Messenger of Peace.) The frame will be
primed with epoxy-based primer Awlgrip 545) and top coated with a finish coat
of black. Once this work is completed, the tank can be installed on the
frame and bolted down. Following this step, the tender trucks will be
rebuilt so as to assure like-new performance from the tender. 
The 924's tender will be completed this summer. At that time, work will shift to the locomotive boiler, running gear, and cab. And the 924's tender just might see some early service in support of the Museum's steam program.
