Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => AmpTools/Tech Tips => Topic started by: cwood3 on December 02, 2008, 06:45:38 am
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When I make my own chasis, I drill a small hole timed right for the little tab that sticks out on an Alpha pot. When I buy a chassis, it's just the hole for the pot shaft. Do most of you guys snip off the tab on the pot or make up the distance with washers so that the pot tightens correctly (flat/square) against the chassis.????? May be a silly question, but I'm always the curious one.
Thanks. :P
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I just break it off using needle nose pliers.
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I always add the anti rotation holes. It makes things really easy.
If you add a faceplate on top of the chassis, you may need to trim the anti-rotation stub a bit. Otherwise the faceplate won't sit flat.
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Yeah the anti-rotation holes are handy....Just line up the pot where you want it...mark where the tab will sit and drill a small hole for the tab. (I drill one even smaller than the ones LC has shown, but I can't remember the exact drill bit size I use off hand.) The pots will almost never come loose and spin the whole pot with the knob when the hole is used. That said. I only use the anti-rotation tab on new builds, I snap that tab off when I'm using alphas as replacements on existing gear.
2yen
-j.
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Yeah, only new builds!
I lay everything out on a piece of graph paper, punch through to the chassis. The measurement from the center hole for the large Alpha pots is 7/16". I use a 1/8" bit for the holes and is the smallest size I drill for pilot holes too.
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Kinda what I figured.........thanks!
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Sorry, I thot this was another kinda pot.
> Just line up the pot where you want it...mark where the tab will sit
MARK??
I just shove it and rotate. Puts a scratch in the metal.
You will pick a knob to cover the tab, and that will hide the scratch.
Yeah, you will mount the pot from behind, but drill from the front. So shove the pot in the front. First set it in back and note which side the tab will be on, then from the front rotated to keep the tab at that side of the hole.
The scratch is a curved line, you want a dot. Well, 99.9% of the time, you want the pot square to the chassis, and 97% of the time, tab is in-line with the row of holes. So lay your ruler down the center of the 3/8" holes, make a tick where it crosses each tab-scratch, that's your spot.
I bust them off too, but sometimes regret it later. Nuts always loosen, especially modern junk. Anything I will keep forever or loan to idiots, I prefer to have something to prevent roundy-round rotation.
Geometry geeks will note that if the pot is tilted while scratching, the arc runs wide of where it will be when pot is set snug. Fug it. I never hit the mark anyway, so I use a large slop-factor on drill-size, and it goes in.
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depends.. if the amp user is likely to go relentlessly digging for "11" on the dials, then drill the tab holes. :)
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toothed washers don't work for you guys? :(
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Toothed washers work pretty good and use them when there is no anti-rotation hole or I can't make one.
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toothed washers and loctite...a little dab will do ya
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toothed washers and loctite...a little dab will do ya
you ever own a harley? or something w/ a -twin? ;D
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Notice that the little anti-rotation tab has a brother
180 degrees across from it bent down against the
pot face. Instead of breaking it off, bend it down like
the other, and you can just pry it back up if you
later change your mind.
Happy Holidays!
bnchwrmr
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>Notice that...
Depends on the brand. Some are cast metal as part of the pot face and not part of the stamped back.
Like some others here, I try to use them when I can, but usually only if a separate faceplate will be used to cover that chassis side. The one time I drilled them into a chassis that wouldn't be otherwise covered, I screwed it up and had them 180 degrees out. I use a Dremel to get them short enough not to interfere with the way the separate faceplate lays on.
Otherwise, I either bend them, snap them, or grind them off - depending on the pot in question.