marshg246
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- Jul 12, 2015
- Messages
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The original 8 Rocker End Plate Screws (06.3124) are 1/4' BSW in a 72 and later Commando head (not sure about pre-72). 1/4 BSW is the only thread pattern (that I can think of) that is nearly the same as unified threads. 1/4 BSW and 1/4-20 UNC are the same diameters and threads per inch and with effort UNC screws will screw into the head.
A Few years ago, in a "senior moment" I forgot that they were BSW and ran a 1/4-20 UNC tap threw them. Of course, 1/4-20 UNC now worked but much to my surprise, so did 1/4 BSW. This is because BSW has 55-degree threads that are not as deep as UNC which has 60-degree threads. Tapping with 1/4-20 UNC removes almost no metal. Yes, the holding power of 1/4 BSW is slightly reduced but not much is needed for the end plates.
The nice thing about 1/4-20 UNC is that chrome hex head, polished stainless hex head, and polished button Allen head screws are available at my local hardware store and if I use plain Zinc hex 3screws, they are almost free.
A Few years ago, in a "senior moment" I forgot that they were BSW and ran a 1/4-20 UNC tap threw them. Of course, 1/4-20 UNC now worked but much to my surprise, so did 1/4 BSW. This is because BSW has 55-degree threads that are not as deep as UNC which has 60-degree threads. Tapping with 1/4-20 UNC removes almost no metal. Yes, the holding power of 1/4 BSW is slightly reduced but not much is needed for the end plates.
The nice thing about 1/4-20 UNC is that chrome hex head, polished stainless hex head, and polished button Allen head screws are available at my local hardware store and if I use plain Zinc hex 3screws, they are almost free.