Do-it-yourself restoration: Reproducing parts

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Part 10 of the 10-part 2010 Old Cars Weekly Restoration Series


Above top, Dennis Bickford and Jeff Weisbrod teamed up to reproduce these sill mats for 1942-1948 Story & photos by Angelo Van Bogart

What do you do when you can’t find a part? If you’re Dennis Bickford, you make it yourself. When that’s not possible, Bickford teams up with those with the equipment to make the parts he and his customers need. And he’ll be the first person to say, “You can, too.”

Along with his wife Kathy, Bickford owns Vintage Woodworks, a restoration shop with work previously featured in Old Cars Guide to Auto Restoration. Vintage Woodworks completes many aspects of restoration, but in its 35 years, the business has evolved to focus on wood and upholstery in Chrysler Town and Country models from the 1940s. However, the process for reproducing out-of-production parts to be covered here extends beyond those dazzling wood-bodied cars to any type of automobile with rubber components.

The part to be reproduced here is a rubber sill mat for 1942-’48 Dodge, De Soto and Chrysler convertible and two-door coupes, and is only visible when the door is opened. There are essentially two parts to these sill mats: a metal base and the rubber that forms around it. In the six decades or so since Chrysler Corp. built these mats, the rubber has cracked and the metal bases have rusted. As as result, those mats that have survived are not up to the aesthetic standards of a freshly veneered Town and Country, nor are they up the functional standards of a Dodge or De Soto coupe or convertible that is driven.


 
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The original mats have an inner core made of metal with studs that often rust. For
this project, new cores are made to the original shape by Weisbord and then molded.

To begin reproducing a component, Bickford breaks it down into its parts. In this instance, he started with the metal core, which was essentially made from sheet metal upon which the factory welded studs. Using an original core as a template, a new core was cut in the proper shape from sheet metal and studs exactly like the originals were welded on, then the whole part was powder coated.

Bickford does not maintain the equipment to mold rubber, but word of mouth has led him to someone with this capability. Even though Bickford operates in central Wisconsin, a very rural area, he found someone with such skills within 10 miles of his door. Jeff Weisbrod of Weisbrod Model and Machine makes relatively small runs of parts for medical and furniture companies, computer companies and other businesses, such as Vintage Woodworks. He equates the process of reproducing this sill mat to rapid prototyping (the automatic construction of physical objects using additive manufacturing technology). Best of all, he’s able to produce the tooling and part at a reasonable cost that justifies small runs, such as those in the restoration of cars less common than 1957 Chevrolets and two-seat Thunderbirds.


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The finished core is attached to a back plate, which will suspend the core in the
mold while urethane is poured around it.


Using the method to reproduce the part shown here, Weisbrod estimates the tooling cost to be less than $5,000, a bargain compared to the $15,000 or more it would cost to tool the sill mats using injection molding or a CNC machine. At $15,000, it would be nearly impossible to cover the cost of the tooling and the materials to create the part, unless 1940s MoPars suddenly became more popular than 1971 ’Cudas.

“It’s probably the least expensive way to get tooling, but it’s also durable and you still have the masters — the original part still exists,” Weisbrod said.

At this point, Bickford passes the reproduction process over to Weisbrod. His first step to reproducing the rubber portion of the sill mat is repairing an original mat. Bickford presented the best original mats he could to Weisbrod (one for each side), and Weisbrod repaired them by filling in the cracks and replacing any chunks of rubber that may have been missing. The goal was to have a part that looked OEM, and any flaws in the original will be duplicated in the reproduction process. Therefore, these flaws must be eliminated.


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Once the original part’s surface has been restored as new as possible, it can be used to make the tooling. In this instance, Weisbrod placed the original mat in an aluminum frame to hold it in place, then poured a two-part castable material over the part. The original part can be removed once the mold hardens. A mix of a special urethane can be poured into this mold to create the new sill mat. The urethane can be whatever color is desired, but in this case, a simple black is used to replicate the original rubber mat.


Above, Before the urethane is poured, a release agent is sprayed in the mold. Below,
The backing plate suspending the sill mat’s metal core is lowered. The black clips
hold the metal core. Once the urethane is poured into the mold, the top platen can be
lowered and pressure can be applied to solidify the urethane so it becomes rubber-like.

To do so, Weisbrod places the new metal core to a wooden backing plate, which will suspend the metal core and allow liquid urethane to vulcanize around it and solidify in the mold, thus forming the rubber portion of the mat. Through a process of trial and error, Weisbrod has determined the proper amount of his urethane mix to pour into his mold. Once the urethane is poured into the mold, it is placed under pressure and heat using a machine of Weisbrod’s own design.


Above, When the metal core is place, the heated top platen can
be lowered and turned on. This machine applies both heat and
pressure. Below, Twenty minutes later, the urethane has solidified
into a solid, rubber-like substance and is ready to be removed.
Note how the rubber is now vulcanized to the core.


A timer is set, and after approximately 20 minutes, the new mats are formed. Excess flash is then removed with a razor and sandpaper, and the mats are ready to be installed, or sold to fellow hobbyists in need.

Although these steps are specific to one part, they can be followed to reproduce or create an infinite number of other parts. If a source for mats, trim, upholstery or any other item does not offer the part you need, contact them about reproducing the part. Or, work with someone like Weisbrod to make the parts you need. You may end up starting a new business.


Above, the excess flashing can be removed with razor or fine sandpaper. Below,
The close-up shows how cleanly the urethane can be made by removing the extra
flashing. This part is now ready to crown a concours restoration.




Considering a restoration project? Check out Old Cars Guide to Auto Restoration CD Volume 2

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