By
Alan Lewis
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I NEED D-SHAPED BUMPER STRIPS, BUT ALL I HAVE IS O-RINGS! |
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The game originally had D-shaped bumper strips along both sides of the playfield. They were 3/8" wide X 3/16" tall half rounds. |
The first question was what rubber
was used for this D-strip? It was white for sure but at 60 years old is was
crusty and mushy. Click on the above image to see
the FTIR analysis of the original 60 year old rubber compared to a new white
rubber pinball o-ring. From this analysis plus a "burn" test on the old and new rubber I determined that the original ring was made from the same rubber as a typical new pinball rebound o-ring. In addition I determined that these o-rings are most likely SBR rubber approximately 50 durometer. |
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OK, so you are saying "what
else is new, this FTIR stuff is old hat to the pinball restorer". To
what length will a budget minded pinball restorer go to work around a
challenge? I had some of the new large size white pinball o-rings hanging
around so I figured that since they were the right rubber material I need to
use them. I had to cut an o-ring in half
along its' length! Slice the round cross section into two D shaped cross
sections. A skiving die was made out of wood and an X-Acto blade. |
A standard o-ring is cut in one
place so it is straight. The end is hand split in half for about an inch so
it can go through the die. Soap is used as a lubricant. Once threaded through the die
the rubber is pulled all the way through producing two D shaped strips. That's all there is to it! (OK, so I am leaving out all the hard parts, nothing is ever that easy!) |
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The old vs. the new D-Strip. The new one is smaller but will look and work just like the original. Same shape, same rubber. |
Installed |
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This tool will save you a lot of headaches when fastening the rubber strips to the side rails. It is a Brad Setter and only costs $10. |
The brad is held by a magnet and is gently pulled into the rubber and wood. No muss, no fuss! |
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Copyright
2007 by Alan Lewis
No
copying without written permission from Alan Lewis