1932 Pierce Arrow Club Brougham 53 part
A friend of mine owns this:
Pebble beach concourse quality, but unfortunately it was missing the accelerator linkage part. It has to integrate both the steering wheel manual accelerator and the foot pedal. He borrowed one from another car and had the brass arm part cast. Pretty rough, but good enough. I had to machine that part, add the tip roller, make the cast iron base and pins. Assembly of the tip roller and the locking of the brass to the pivot shaft had to be done in the original fashion - solid pins and beat the pin ends until they mushroomed! No easy disassembly.
I lost all the early photos of machining the arm... but needless to say it was a PITA to figure out what to hold and get everything in plane. In the end I machined the hub flange (eyeballed the axis), grabbed that in soft-jaws and drill/milled away. Sketchy, but it's only soft brass so low forces involved.
The cast flange threw me some curve balls. At first I tried to fake it and just measure/make manually. Problem was that nothing was "quite right" and every error magnified somewhere else. Not surprising considering it was probably a wooden mold pressed into sand, hand-ground for cleanup and manually drilled. So... I flopped it on my scanner, used that as a background image in my cad and overlayed what was most likely the original design with measurements on 1/16ths. Hey... it worked!
Note the bottom left hole position. It's just plain wrong. I talked to the owner and he agreed there is no point in copying the sample errors so I corrected it to what I thought was the original intent. Then I made adjustments as necessary to allow for the casing tapers etc. Result (over-dimensioned with excessive accuracy, but I like it that way for CNC entry and checking):
I could have exported it as a dxf to my CNC BP but it was easier to just type in the few coordinates and let the Conversational mode Geometry Calc figure the arc and other intersections.
Getting started :
Last edited by lakeside53; 02-14-2017 at 01:34 AM.
Roughed out. No.. I didn't scrape the block prior to machining - it's Durabar left over from a scraping class I attended; time to use it for something worthwhile! BTW... Durabar machines wonderfully. 1/2 inch 3 flute carbide at 3000 rpm and 20 IPM feed. Chips everywhere, but they are nice little curls not black grit.
Vertical work done :
Final base and original :
The pivot pin hole was reamed to 1 thou over nominal for a "nice fit' on the 0.3125 TPG shafting.
Done... original assembly plus mine. I wanted to grind and polish all the brass but the owner wanted it as rough as the original. lol.
Last edited by lakeside53; 02-14-2017 at 12:04 AM.
Now he can hand grind my nice machined base (for authenticity) and throw it in a urinal for a month to age
Oh.. I made him a spare base (about 1.5 hours)... so now there is one more than the entire market for that part.
I figure I had about 20 hours and 4 versions into that before I got it right... he was very happy with the result.
Last edited by lakeside53; 02-13-2017 at 11:21 PM.
Very nice. Congrats to BOTH of you on a job well done.
Nice car, but why did you take a picture of your friend taking a whiz?
Originally Posted by lakeside53
He sent me the pic! Not sure it's him or what he's doing.
Last edited by lakeside53; 02-14-2017 at 12:08 AM.
My god looks like it could double as a door hinge,,, think about what it took back then just to operate the throttle weight wise,
then there's the under the hood stuff --- all replaced awhile back by a cable and now just some wires and little plastic boxes...
nice work making it work though...
Ha.. good point. Maybe they did re-use a door hinge part!
As a data point, that car has a V-12 that put out 132hp... Spark advance and manual throttle on the steering column. Times have changed.
Last edited by lakeside53; 02-14-2017 at 12:21 AM.
Nice work. I love doing stuff like that, and wish I could find more work like that sometimes. You did a good job.
I use my scanner for work like that all the time, then import the picture into cad to trace around the lines. It's amazing the accuracy you can achieve, as well as being able to pick up on things like the manufacturing error you noticed. It works especially great for engine case side covers on motorcycles.
A nice piece of "reverse engineering". One needs to look at the dimensions on the drawing to get an idea of the actual size of the parts. A camera and an optical comparator is another method to reverse engineer. As usual your workmanship is first rate.