Need Input

I have a copy of the original factory drawings (from when I was planning on doing the project).

Mine was to be stamped pieces to be welded together. Yours are to be machined I take it.

I'd sure hope yours are lighter weight than the brass ones. The brass advantage: It lowers the front of the C/K without further mods.

Dave: I'm currently having some reproduction bumper guards for the M5 trucks (and '41 cars) made by investment casting stainless steel. The stainless will be polished and buffed so they won't need chrome plating, but they could be plated if someone wanted to - and the hard work of the buffing will already be done. I had a pair of originals to make the molds, but I also supplied the original drawings so that the dimensions could be checked. Since the molds will made from original stamped parts, the cast copies will come out a little smaller due to shrinkage during cooling of the metal. On a small bumper guard, shrinkage won't show. I'm expecting prototypes in the next week or so. And, no, they are not being made in the U.S.

For a part as large as the '53/'54 side grills, shrinkage during casting is really an issue. For brass, the shrinkage will be about 5%. If the grille shells are 20 inches wide, that means that a copy cast from an original might turn out 1 inch short! Ideally, you would use the original drawings, make a pattern 5% oversize in all directions, and use that for molding. For small quantities of parts, you might be able to use stereo lithography (SLA) to "grow" one set of left and right parts out of plastic and use those as casting patterns. See

. A good CAD designer could use the original drawings to make one 3D model on the computer and just flip it to make the other side (assumes they are mirror images).

How did the brass ones that Dave Thibeault made fit? Were they the right size, right hole locations? I know I've seen the raw brass parts, but have never seen a finished set.

If Dale (Lark Parker) has copies of the original drawings, they must be at the Stude National Museum. So, get a set of the drawings from Dale or the Museum (call/email Andy Beckman with part numbers). But, you really need to hook up with a foundry/plater who would be willing to take the job on at reasonable cost before diving in beyond the drawings.

What I have is the full size drawing(s) that Andy copied for me. It was a big effort on Andy's part as it is so large that he had to take them to a special copier. It is about 3 ft high by 15 foot long. Took about three months to find, copy and ship. Andy said that there was only one drawing for both sides, right and left. If Dave doesn't want it I thought it would make nice den wallpaper. It's pretty interesting and artistic if you can ignore all the numbers. All I'm looking for right now is a discount on an early pair of surrounds. ( It keeps with my philosophy of losing money on every Studebaker deal.) I would sell to anyone that has an interest. If Dave has no need I will probably sell on eBay as a work of art/curiosity.

I might be willing to model the parts in solidworks in exchange for a set of the finished grill surrounds for my 54 coupe. This parametric model could be used to create a SLA part for a pattern with however many% larger dimensions to account for shrinkage.

I would have to look at the original print to determine how difficult this modeling will be to take a guess as to how long it would take. Maybe 2 days +/?- Cheers, Brian Roseville MN

Lark Parker wrote:

I might be willing to model the parts in solidworks for a set of the finished grills for my 54 coupe. The model could be used to create a SLA part for a pattern with however many% larger dimensions to account for shrinkage.

I would have to look at the print to determine how difficult this modeling will be to take a guess as to how long it would take. Maybe 2 days? Cheers, Brian Roseville MN

Lark Parker wrote:

Dave may not be concerned about shrinkage if he is doing them in plastic. I will compare my drawing dimensions to measurements on an actual surround and see if the Studebaker drawing has finished dimensions --- or a dimension that precalculated the shrinkage. I assume that pot metal had such shrinkage.

Even with plastic, shrinkage is a very real consideration. Depending on the plastic used, shrinkage could be anywhere between .005 and .040 inch per inch of part.

It was always a challenge when building or repairing plastic injection molds because most our customers did not furnish tool drawings when we took one of their jobs in house. Most times, the best I was given was a 'good' part and had to build new components from that by figuring the typical shrinkage rate of the material used. It was really a bitch as some of the Delrin compounds we used (per customer spec) had a shrinkage rage of .015-.035 in/in and we were to hold tolerances of .002 on a finished part.

Most metal brightwork castings are designed to be larger than actual requirements (often based on clay designs etc.) to accommodate the finishing process such as rough grinding, polishing and finally plating.

However, as you state, plastic is another story as the plating IIRC is the first thing to be applied to the mold followed by the plastic filler material at elevated temperatures. A whole lot less wiggle room here.

Trial and error can get real costly in a hurry...

JT

Lee wrote: