Hi, what is a good way to run a switch shaft extension through the front panel of a chassis? I see pictures of peoples projects that use shaft extensions but it's almost impossible to see from the pictures how anybody does it. I'm worried that there will be play in just about every direction since the switch is no longer mechanically coupled to the front panel.
I've seen a couple mentions of bushings which are secured to the front panel with threads and a washer. This takes care of forces in the rotational direction but I would still be worried about the "thrust" direction. The other issue is that I cannot find these bushings from standard suppliers such as McMaster.
I'm inclined to try the shaft going straight through the hole in the front panel without anything else. The hole would hopefully be tight enough so there isn't noticable play. The other thing to try is to use a rubber grommet which, if done right, could limit the play better than a metal bushing since it would be "grippier".
Thoughts?
I've seen a couple mentions of bushings which are secured to the front panel with threads and a washer. This takes care of forces in the rotational direction but I would still be worried about the "thrust" direction. The other issue is that I cannot find these bushings from standard suppliers such as McMaster.
I'm inclined to try the shaft going straight through the hole in the front panel without anything else. The hole would hopefully be tight enough so there isn't noticable play. The other thing to try is to use a rubber grommet which, if done right, could limit the play better than a metal bushing since it would be "grippier".
Thoughts?
nickm1:
You want to use a shaft bushing and a properly-sized extension shaft. There is no lateral play when properly sized and the extension shaft will rotate freely in the bushing. With a decently-weighted knob, you can get a lovely, smooth rotation. A decent source for the bushing is Surplus Sales (see Shaft Bushings & Bearings - Surplus Sales of Nebraska). They also sell shaft couplings (Shaft Collars & Solid Couplings) but I prefer the rather nifty CNC'd shaft couplers found on ebay (for example, 6 35x6 35mm CNC Flexible Coupling Motor Shaft Coupler 1 4" to 0 25" Shaft | eBay).
The bushing suggested above mounts in a 3/8" hole and has an internal diameter of 0.25", so you'll need a 0.25" extension shaft and knob with a similarly-sized mounting hole. If the attenuator you're using has a 6mm shaft, you'll want a shaft coupler with 6mm on one end and 6.35mm on the other; they're surprisingly easy to find on ebay.
You won't regret it.
Regards,
Scott
You want to use a shaft bushing and a properly-sized extension shaft. There is no lateral play when properly sized and the extension shaft will rotate freely in the bushing. With a decently-weighted knob, you can get a lovely, smooth rotation. A decent source for the bushing is Surplus Sales (see Shaft Bushings & Bearings - Surplus Sales of Nebraska). They also sell shaft couplings (Shaft Collars & Solid Couplings) but I prefer the rather nifty CNC'd shaft couplers found on ebay (for example, 6 35x6 35mm CNC Flexible Coupling Motor Shaft Coupler 1 4" to 0 25" Shaft | eBay).
The bushing suggested above mounts in a 3/8" hole and has an internal diameter of 0.25", so you'll need a 0.25" extension shaft and knob with a similarly-sized mounting hole. If the attenuator you're using has a 6mm shaft, you'll want a shaft coupler with 6mm on one end and 6.35mm on the other; they're surprisingly easy to find on ebay.
You won't regret it.
Regards,
Scott
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