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1920s Delco Combination Switch Contact Plate Rebuild


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I'm working on rebuilding a Delco 1238 combination switch for a 1923 Moon. The contact plate was in poor shape, about ready to fall apart, so I made a new one. I'm sure it's been done by someone else, but here are some pictures and an explanation of what I did.


Here is a picture of the switch in case you don't know what I'm referring to.KIMG1244.JPG.5ded1c8ba98763520cbc96ba7d1bda91.JPG


Here is what I started with for the contact plate.KIMG1263.JPG.a9f86da7c103980b88957e5f23dfd2ff.JPGKIMG1264.JPG.2883bff6fa2803ef795057edab585db2.JPG


I started out by drilling and punching out all of the rivets. All of the steel parts then went into a tub for electrolysis. Then everything metal was wire wheeled.KIMG1265.JPG.1e979425b9085334be748c574b86502e.JPG


Then I used my circle cutter to cut a disc of 1/8 inch black paper micarta.KIMG1268.JPG.565852011b73c973c1b04c5035ad6227.JPG


The new disc was then clamped to the back of the original so that each hole could be transfer punched. Each hole was then carefully drilled so that the material didn't blow out the back side. Holes for the rotary contacts were countersunk so that the rivet heads could be flush.KIMG1266.JPG.7d8809236d72f2ef9323007e4048ebf0.JPGKIMG1267.JPG.7ee1a6ee33c34c6698c888d5fd2099e7.JPGKIMG1269.JPG.9aff9fe4a7e3a8a03c456ceabd1bb98f.JPG


Pure copper tubular rivets could not be found, so I used brass brake lining rivets. Each one got chucked in my drill, so that the heads could be filed to the right diameter. The large steel piece needed welded up and reshaped since one of the bridges was cracked. The copper plate was made to replace the original brass one that cracked when I was working with it. Many of the holes were carefully filed with needle files to get the rivets to line up. I used a regular brake relining tool to hammer the rivets. I did have to make a custom setting tool for it that had enough clearance to get around the steel parts. All of the contacts were numbered with normal number punches. The trick to not cracking the phenolic was to use light blows while oscillating the punch so that each blow focused on a different part of the number. New machine screws will be here soon to finish it off. I am happy with how it turned out.



Edited by ryan95 (see edit history)
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  • 5 months later...

Thank you, I'm not sure how yours goes together, or if it is even Delco. I haven't seen one like that before, so I can't help, but if it is anything like the Delco ones, the whole switch has to come apart to replace the knobs.

Edited by ryan95 (see edit history)
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