Post by stevewf on Dec 19, 2022 18:15:27 GMT -5
Here are the few photos I snapped while modding a Bourns Push/Pull minipot in order to make it a four-pole switch.
I started with two complete Bourns units and ended up with one unit plus parts.
Here's the finished unit I made, with some annotations:
Here's a photo of a Bourns unit in pieces:
This photo could be useful as a glossary for this post.
And here's a close-up of the new link I made:
This is Block "A" after adding the new link, which is obviously a screw. The screw's head must fit into the existing slot in Block B; I highlighted the slot in Block A just to illustrate how the screw head must be shaped. In my case, the screw head was a good diameter, but it was too "tall" and had to be flattened; I did that with a metal file. Of course, the screw must also be inserted to the correct depth as dictated by the gap between the two Blocks when finished.
Using this setup caused the loss of the detente in Block A, as the screw collided with the detente spring. Even though Block A no longer contributes to the detente, Block A's detente slider was inserted back into place because it helps keep Slider B in place. In my opinion, detente B does the job well, solo.
So basically, the operation required:
-Disassembly of two Bourns units. I've labeled the two switch bodies for ease of reference.
-Removal of part of Block B's metal cover
-Drilling Block A for the link screw
-Shaping of the screw head and insertion of the screw into Block A
-Rebuilding Switch B with its detente slider and spring, and Switch A with only its slider
-Soldering the two switch covers together
-Reassembling the pot/switch coupling and bending tabs back into place
The savvy may observe that I swapped a second wafer into the pot, making it a dual-gang; that's incidental and independent of the 4-pole mod, but it means that at least one of the original Bourns units that I started with was a dual-gang Push/Pull - needed for its special nylon wiper carrier, which is dual-gang and allows a flatted shaft to slide through.
Those familiar with Bourns P/P pots know that they're easily disassembled and reassembled by bending/straightening tiny metal tabs. This 4P switch can thus be moved to other Bourns pots; but there's a limit to how much abuse the tiny metals tabs can take before they break.
The resulting unit is about 42mm (1-5/8") tall, from the bottom of switch B to the top of the pot body, and needs a pretty deep cavity.
The one I made works.
I started with two complete Bourns units and ended up with one unit plus parts.
Here's the finished unit I made, with some annotations:
Here's a photo of a Bourns unit in pieces:
This photo could be useful as a glossary for this post.
And here's a close-up of the new link I made:
This is Block "A" after adding the new link, which is obviously a screw. The screw's head must fit into the existing slot in Block B; I highlighted the slot in Block A just to illustrate how the screw head must be shaped. In my case, the screw head was a good diameter, but it was too "tall" and had to be flattened; I did that with a metal file. Of course, the screw must also be inserted to the correct depth as dictated by the gap between the two Blocks when finished.
Using this setup caused the loss of the detente in Block A, as the screw collided with the detente spring. Even though Block A no longer contributes to the detente, Block A's detente slider was inserted back into place because it helps keep Slider B in place. In my opinion, detente B does the job well, solo.
So basically, the operation required:
-Disassembly of two Bourns units. I've labeled the two switch bodies for ease of reference.
-Removal of part of Block B's metal cover
-Drilling Block A for the link screw
-Shaping of the screw head and insertion of the screw into Block A
-Rebuilding Switch B with its detente slider and spring, and Switch A with only its slider
-Soldering the two switch covers together
-Reassembling the pot/switch coupling and bending tabs back into place
The savvy may observe that I swapped a second wafer into the pot, making it a dual-gang; that's incidental and independent of the 4-pole mod, but it means that at least one of the original Bourns units that I started with was a dual-gang Push/Pull - needed for its special nylon wiper carrier, which is dual-gang and allows a flatted shaft to slide through.
Those familiar with Bourns P/P pots know that they're easily disassembled and reassembled by bending/straightening tiny metal tabs. This 4P switch can thus be moved to other Bourns pots; but there's a limit to how much abuse the tiny metals tabs can take before they break.
The resulting unit is about 42mm (1-5/8") tall, from the bottom of switch B to the top of the pot body, and needs a pretty deep cavity.
The one I made works.