Author Topic: Using the right bolt?  (Read 120 times)

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Offline soundasleep

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Using the right bolt?
« on: February 27, 2014, 12:16:58 AM »
90's era Williams/Bally machines. More specifically the carriage bolts used for attaching the hinges to the backbox itself.

4320-01123-24B is the original component: 1/4-20 1.5" long.

However according to the PBSP website you can use these instead:

4320-01123-20B which is the 1.25" long - the ones used on the coin door and level assembly.

I just tried using the smaller bolt on a Bally Gameshow and it does work, but the bolt stops about 1mm from the top of the nut, rather than sticking out the 1/4"

The smaller bolts are almost half the price, so long term it would add up.

My question to those with much more experience is - does it actually make any difference?

Surely the bolts aren't going to give way during transport just because they are a bit shorter. Right?

Offline swinks

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Re: Using the right bolt?
« Reply #1 on: February 27, 2014, 08:17:15 AM »
it is good engineering practise to have at least 1-2 threads hanging past the end of the nut so then the nut is taking a maximum load - the less threads engaged between the bolt and nut means a higher risk of stripping which every one is weaker. In addition the last thread on the bolt is slightly chamfered so it isn't a full thread.
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Offline soundasleep

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Re: Using the right bolt?
« Reply #2 on: February 28, 2014, 03:42:00 PM »
Which begs the question, why is Pinball Life recommending the wrong bolts? (The text on PBSP is a copy/paste from PL)