Stories of Naperville

Jul 30

[ARCHIVED] Threshing About – A Blog about a Thresher

The original item was published from July 29, 2019 1:43 PM to July 30, 2019 1:15 PM

Hi!  I’m Louise Howard, Curator of Collections at Naper Settlement in Naperville, IL.  I serve as the project director for the conservation treatment program for the museum’s threshing machine.

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Return of the thresher

Welcome home!  After nearly 2 ½ years the Wood Bros. thresher, an iconic piece of Naperville’s 20th century agricultural history is finally home.  The macro artifact made its way back to Naperville this past March, after undergoing extensive conservation treatment at the workshop of Kennedy Furniture and Historic Objects Conservation in Mt. Carroll, IL.   

What the thresher conservation treatment entailed

Cleaning and Conservation

The conservation included thorough cleaning of the macro artifact’s exterior portions and interior compartments.  Disassembly of major units of the machine was necessary to reach interior areas not easily accessible.  These areas include the tailing elevator tubes and cast-iron corners, open link chain and rakes as well as the first section of grain pans and other smaller metal covers and panels.  A hot pressure wash with soap and disinfectant was performed before machine reassembly began.

Areas of loss were evaluated for reversible repairs and plans were developed and executed for replication and installation of grain pans, split wagon tongue and conveyor belts.

Details of conservation treatment for the thresher conservation based on individual sections follows:


The self-feeder is essentially a specialized conveyor.  Its principal components are a folding trough with outward projecting flanges, open link chain, metal rakes attached to the chain at 19 inch intervals, canvas attached to the chain by use of wooden slats across the canvas, and a series of chain drive sprockets on both sides of the tray. 

Treatment of the self-feeder involved minor repair, cleaning and painting.  The canvas material was damaged and severely deteriorated with major losses throughout it.  The entire canvas was replaced with new canvas from an identical weave and weight from Chicago Canvas.

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Conveyor, folded, front view – pre-treatment                                     
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Removed Conveyor for treatment

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Preparing to install rakes onto cain and new canvas

Tailings Elevator

The tailings elevator consists of two long tubes, a crossover trough at the bottom, a top crossover with open shoot for dumping grain back into the machine to be recovered, four cast iron two-piece elbow corners, three idler sprockets, one belt-drive drive sprocket, and a continuous open chain with paddles for transporting grain from the bottom trough to the top return dump crossover.

The tailings elevator contained grain still in place within the in-feed tube and the crossover trough.  Due to grain remaining in the machine, there was extensive damage because of rodents making homes on the paddles and in the cast iron elbows.

Treatment included the removal of the elevator from the machine and complete disassembly. Damage to the grain receiving trough was so severe it necessitated replacement of a replica trough.  Tube damage was repaired with sheet metal plates and ferro metal steel.  Severe rust was trimmed away.  Eight-gauge metal plates cut to fit where needed and were fastened in place temporarily on the interior walls of the tubes using a small application of ferro metal to the fitted pieces. These were then secured and drawn tightly against the interior walls of the tube with sheet metal screws. When the ferro metal had set and cured, a thin layer of ferro metal was applied to secure new sheet meal to a level equal to the outside wall of the tube.  Elbows and sprockets were wire brushed and scraped to remove rust and debris. Sprockets were cleaned and oiled; cast elbows were primed on the interior surfaces and primed and painted on the exterior faces.  Chain and paddles were power washed and wire brushed and painted with primer. 

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Tailings elevator removal – pre-treatment      

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  Damaged tailing elevator tube

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Tailings tube repair with ferro metal

Hart Grain weigher and elevator

The Hart Grain weigher is made of galvanized sheet metal which had several areas of staining and rust due to exposure to weather.  Grain enters the elevator from the crossover grain auger.  The elevator is made to open link chain drive by top and bottom sprockets.  Small metal cups are integrated into the chain at 7 inch intervals and carry the grain to the weigher where it is dumped.  A counting device records each dump of the weigher to identify the total number of units of grained produced with the process.  The auger carries the grain through an open grain trough set up to deliver the grain to a wagon or sacking machine by gravity.  Removal from the thresher began with the delivery trough and the elevator funnel. 

During the treatment process, it was discovered that the infeed side of the elevator grain pans had become home for rodents.  Nest material was removed along with other debris and components washed, sanitized, scraped and wire brushed. Most of the painted parts of the grain weigher retained their original painting.  This paint was washed and cleaned with both brass and bristle brushes and dried.  None of the Hart Grain weigher parts were repainted.  Galvanized metal was washed with automotive soap. 

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Cleaning grain cups and drive chain         
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Cleaning drive for grain weigher
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Cleaned galvanized metal on grain elevator           
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Elevator reinstalled           

Machine interior and grain pans

Damage to the corrugated grain pans and funnel straw bin was extensive.  Treatment involved removal of the fanning mill, grain pans and grain pan wooden frame structure and one sieve to complete all needed cleaning and repairs.  Badly rusted sheet metal was trimmed and new fitted metal panels were fabricated for both the interior and exterior surfaces of the straw bin.  Replacement grain pans were fabricated by Schmidt Machine Co. in Upper Ohio.  The pans were reproduced as closely as possible to the originals.  Surviving original aged paint of the interior was cleaned, waxed and received no further treatment.

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Pre-treatment interior view from machine rear

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Pre-treatment interior, noting deterioration to grain pans

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Damaged grain pans, removed 

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New replicated grain pans ready for installation

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Net return grain pan: pre-treatment

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during treatment

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Repainted interior painted with rust inhibitor

Frames, axles, iron wheels

The structural steel of the thresher was in good condition.  It was scraped, sanded and cleaned with a surface grinder prior to application of rust inhibitor primer, followed by a red paint primer and red paint finish coat.

The machine’s wheels and axles did not require disassembly.  Areas of paint loss to these components were scraped, power wire brushed, primed, and repainted with red paint to match the surviving red.  Some natural wear was simulated on the wheel faces.

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Wheel and hub grease cup, pre-treatment        

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Axle grease cup, post-treatment

Wagon Tongue

The wagon tongue on the thresher was badly damaged at the hitch end prior to treatment and there was no hitch hardware attached.  Research revealed use of a spliced wagon tongue with the machine that would accommodate farm equipment being pulled by either a tractor or a team of horses or other animals.  Further research uncovered a 1919 patent for spliced wagon tongue hardware.  With information from the patent a full set of mechanical drawings and full-scale pattern were produced along with one set of hardware.  The replica hardware was finished and installed on a two-piece replacement wagon tongue. 

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Prototype of vintage spliced wagon tongue hardware

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Fabricated hardware

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Final install of spliced wagon tongue and hardware

Straw stacker

The function of the straw stacker or wind stacker is to allow straw and other debris to be blown by the silo fan through the tubes onto the ground and away from the thresher. To facilitate treatment of the straw stacker it was completely removed from the thresher and disassembled.  Damage was evident and lost parts were also noted on the straw stacker.  A canvas dust shield on the discharge hood was also badly damage.  Springs on both sides of the hood were broken and inoperable.  There were rusted and dented areas on the extension and main tubes.  Lettering on the extension tube was in poor and damaged condition.  Dents, metal and rust damages on the tubes were repaired and letters were repainted.  Metal repairs were completed using the Abatron ferro-metal process.  Prior to repainting the extension tube, lettering positioning was mapped and measured for location.  Tracings were produced to guide repainting. 

Replacement of the yoke (end connectors) required research and a trip to Mount Pleasant, IA to the Old Timers and Thrashers Museum.  At the museum at 1931 thrasher was examined and several measurements and photographs taken of the yoke.  A pattern was created and two yokes were then fabricated by Cattail Foundry in New Holland, PA. 

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Pre-treatment – stacker removal

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Pre-treatment – stacker removal

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Scope exam of paint on stacker

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Relettering of stacker 1

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Relettering stacker 2

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Remounting of stacker onto machine

Drive belts and pulleys

The thresher has seven drive belts.  Six were badly damaged and could not be put back into service.  The largest belt, which was fitted onto a steam or gasoline powered tractor, supplied power to a main drive pulley.  That belt is suitable for exhibition use and is correctly placed on the machine in a static position.  A second large belt carries power from the main drive shaft to all other pulleys and shafts through a complex series of pulleys and drives.  These drives are powered by the other four small belts.  All pulleys are old and likely original.  No treatment was done to the pulleys.  New drive belts were made at the Apache Company of Cedar Rapids, IA in their Cincinnati, OH plant and installed on the thresher.

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Belt slack adjuster – pre-treatment

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Cleaning of belt slack adjuster

Painted finish

A review and analysis of the thresher’s paint finishes were conducted and a selection of finishes was made for final application to the thresher. The final finishes reveal a silver machine outlined in red.  A short length of frame rail behind the tool box on the thresher exterior has not been repainted.  This section serves as a document piece for previous original and/or later paint layers.

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Reveal of paint profile on self-feeder

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Paint reveal on self-feeder chains

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Original paint on interior side of an access panel

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Primer residue on side frame indicates assembly prior to
final paint color application

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Gray primer paint on tube edge

Treatment challenges

The most challenging aspect of the treatment process was the desired final appearance to be an “in service, well-cared for” farm machine.  Extensive surface damage and general degraded condition of the exterior and interior of the machine combined to create the challenge.  The final finish treatment chosen was to minimize the treatment of the parts on the machine that moved, functioned or performed certain actions and received service wear and tear.  In repainting the steel panels and structural elements of the thresher the results followed the “well-maintained” concept. A “new” appearance was modified on the new canvas used for the conveyor part of the self-feeder.  Other new canvas, some hidden from view, was either not aged or only slightly. 

Project educational component

The conservation project also included a field study workshop, held last April, hosted by Naper Settlement.  Workshop participants include a total of 24 students from North Central College DePaul University, Lewis University and DeKalb County History Center.  The workshop included presentations by staff from Naper Settlement, North Central College and DePaul University, providing historical importance of the thresher.  Workshop discussions also touched on integrated vision with exhibits and interpretive plans as well as the importance of telling accurate stories through exhibition.  Workshop participants took field study trips to Naper Settlement, Garfield Farm and Village in La Fox, Heritage Prairie Farm in Elburn, and Nachussa Grasslands in Franklin Grove.  The workshop concluded with a visit to the Kennedy Conservation workshop of lead conservator, Ralph Kennedy, where he and macro artifact consulting conservator, Brian Howard, walked the group through the thresher’s treatment program. 

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Naper Settlement session – April 27, 2018

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Naper Settlement session – April 27, 2018

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Garfield Farm, La Fox, IL session:  April 27, 2018

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Garfield Farm, La Fox, IL session:  April 27, 2018

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Heritage Prairie Farm, Elburn IL session:  April 27, 2018

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Heritage Prairie Farm, Elburn IL session:  April 27, 2018

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Nachussa Grasslands, Franklin Grove, IL session:  April 28, 2018

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Kennedy Conservation presentation and visit to workshop, Mt. Carroll, IL session:  April 28, 2018

Naper Settlement’s future plans to share Naperville’s agricultural history

Naper Settlement’s Cultivate Center - a new 5,000 square foot exhibition space - will showcase Naperville's rich agricultural history, connecting it to the farming story of the region and the nation. This center will provide an immersive opportunity to learn about Naperville's agricultural history and how it connects to the farming story of the region and nation today.