Mounting pots in a thick chassis/faceplate situation....

[dehughes]

Alrighty....the build is beginning.... I have the chassis, the trannies and choke mounted, the tube sockets all mounted too, and the faceplate just arrived. However, when I try to mount the jacks and pots, I find that the shaft of the pots and jacks isn't quite long enough to allow for a lock washer on the inside of the chassis. The chassis is .080" aluminum, and the faceplate is about .0625" thick. I can get the nut on, but no washer or lock washer. I didn't even think of this when I ordered the faceplate, but I'd really like to put a lock washer inside the chassis to keep the pots from loosening up after use, etc...it just seems like a nice, solid build idea.

Any ideas? I know that some of the pots (Alpha, specifically) have a little peg that you can set into a hole on the side of the pot hole in order to keep the pot from rotating out and loosening up, but I'd like to use CTS pots or other "nice" pots, and they don't have this option. The goal is to use high-quality parts and to secure them well...

Many thanks.

[mlp-mx6]

The Mil-spec 2W pots (like Allen-Bradley Type J, PEC from Digi-Key) have a longer threaded area, and they will fit that scenario. A little pricey for some, but scouring the surplus sites and Ebay could net some relatively low prices for GREAT quality pots. Good luck!

[Allynmey]

Skip the lock washer or replace the pots I really is the only choice. OEC, AB, or clarostat pots are pretty expensive. Try www.apexjr.com to see if Steve has your values in stock cheap.

Allynmey

[MarkB]

The above answers are probably best for you. There is another way to use your current parts - depending on how much space you need.


http://en.wikipedia.org/wiki/Counterbore


I don't know what one would cost - I used them at work. Your face plate would hide the counterbore.

[dehughes]

You guys are so kick ass. Many thanks....

It looks like I'd need a threaded shaft length of about .5"...that should be perfect. Please pass on any links you may have for a nice place to find good quality pots (1M, 500k, and 250k) that have a .5" threaded shaft length. I have some links, but have only managed to find the 500k value (www.s2amps.com).

HOWEVER, it looks like West Labs has some made for them by Clarostat, to the RV4 style Mil-spec. Has anyone purchased and used these pots from West Labs? They might be the ticket for my situation...


THANKS.

[Moose]

I use west's clarostats. Damned good pots. They're conductive plastic RV4 2Watt jobbers and of significantly higher quality than alphas, CTS, or other carbon wafer pots.

The one complaint SOME people have is that the feel when you rotate them is inconsistent. The PEC (hot molded carbon, also RV4 and superhigh quality -- get 'em from Digikey) have a little more drag and are more consistent as well as a little smoother. Personally, I don't notice it.

One thing to keep in mind. If you want to do a ground bus, you can't solder to the back of the clarostats so you can't do it like KF did in the franchesca pics. I don't know if you can solder to PEC pots.

[mlp-mx6]

+1 on Steve at Apex Jr. He had several (but not all) of the values I needed. We spoke via email and phone and he was great to deal with.

I had bought some 250K aud. from David Allen a couple years ago, so I had those already. The only ones I had a hard time finding were 1M Audio (could've gone to DigiKey or West, but $10 each is pretty stiff). Solution - I found some AB 5M lin pots on Ebay for cheap. When you "taper" a 5M with 1.2M you get a 990K quasi-log pot, but with a very smooth curve. On average I guess I paid under $3 per pot. Not all the same brand, but all the same style (Type J and the like) and they look like they'll last thru a nuclear winter!

FYI - my ODS chassis is a whopping .125 thick(!) and with a lock washer I have threaded shaft length to spare.

[dehughes]

Nice nice nice. Thanks guys. I won't be soldering to the back of the pots, so that's no worry. I looked around for the PEC stuff, but figured I'd give West's pots a go. He seems nice, and people seem to dig his services.

Many MANY thanks my friends!