There were a couple of comments on the custom tack strip I made for my 29 roadster.. here's how I did it; As you already know, the part of the body that the tack strip mounts to is pretty irregular at best. I knew I didn't want the seat upholstery to wrap over the body, and i didn’t want to put the effort in to making the area presentable on its own. i envisioned something sleek and subtle. A perfect place for custom mounding! Originally I thought I could just shape an original wood tack strip. Unfortunately the aftermarket tack strips fit so poorly that it was easier to start from scratch.. with Bondo! I put some blue tape over the area of the body that the tack strip mounts too, then applied a coat of wax onto the tape(this helps to release the bondo) Next I started building up the area with fiberglass reinforced bondo. In hindsight I should have embedded some armature wire into the bondo. This would have made the master a little stiffer. Once there was an adequate amount of bondo applied I got to shaping. Personally i enjoy using vixen files whenever i can, using my favirite files and blocks along with a pair of dividers and a ruler I got to work. The shape of the car was used as a guide to shape the tack strip. This process took me some time, as there was a lot of back and forth, adding and removing bondo. Once I had the shape I was after , and using a plastic scraper and some air i carefully popped the bondo off the car. Surprisingly it came off easily, and held it's shape. The master was then taken to the foundry. With sandcasting there is always some shrinkage , generally around 10%. I've found that determining what the exact shrinkage is going to be is nearly impossible without actually making one. Since this was a one off, I just rolled the dice, figuring that I would just ad material aftwards. As suspected it shrank. The amount was about 1.5 inches.. the part was cut in half , drilled and tapped with 1/4-20 threads & studs , then mounted to the car. A piece of aluminum was cut and welded in place while the part was attached to the car(this was before there was any bodywork done to the car). Sandcasting is never perfect, so it took a lot of fileing, sanding, welding and welding pinholes , filing, sanding, etc.etc. etc.... this took a while, probably 12 hours , and I could have easily spent another 20 hours making it "perfect ". The chrome shop did a fantastic job, BUT there is some subtle pitting from the irregularities in the aluminum casting.. Ideally this would have been cast in bronze. A bronze casting could have been copper plated and all porosity could have been delt with. Personally i'm pretty happy with the end result. The part ads a nice and unique touch to the car..
Real nice! I some how feel cheated, you could have had one of the best build threads here on the HAMB. I really like the bracing you place behind the seat, must really make the body stiffer and allow for nice door fitting. That feature will be stolen my myself and others. Bob
I started a build thread, but honestly I couldn't keep up with doing both. The process was heavily documented and I've thought about doing post build thread... The bracing your referring to is made from 1" .090 DOM. It's welded to the sub frame in 4 spots and into bracing for the top iron brackets. You're correct in that it really stiffens the body up, as well as a structure for the interior body panels that I made.
I clicked onto your site, very impressive stuff you make. Is there a special meaning behind the Spragwerks name? The only thing sprag brings to mind is the early pre 1905 anti roll fixture on Horseless carriages.
Thanks! I'll spare you the long story.. But.. Along with that anti roll fixtures sprag is used in a type of clutch.. a one way clutch. Before I ventured into the world of custom fabrication I worked for Dereoit Diesel mainly rebuilding off highyway engines. When I transitioned to a my new career I wanted the name of the business to vaguely references my mechanical past. Somewhere along the way I heard about this "Sprag" clutch.. that stuck in my head.. then friend suggested I put Werks on the end.. it worked for me as I felt it was another vauge nod to well made industrial products.. so that's the how and why about Spragwerks!
Man that came out slick ! Very nice project overall , thanks for sharing w us. My Grandfather & Uncle retired from Detroit Diesel too.
You're welcome! Working for Detroit Diesel, and being a Local 15C Union member was a life changing experience.. My dad also worked there.
Not to derail your thread but I have a great collection of DD memorabelia. Even a few back when it was still GM diesel.
The Jalopy Journal
