locking down pots

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dr_when
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locking down pots

Post by dr_when » Mon Sep 08, 2008 8:02 am

Does anyone know what is used in industry to "lock down" trim pots after they are adjusted. I know that nail polish can work but is there an actual product used professionally?

Thanks!!

Bob
"Who is John Galt?"

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Dave Dixon
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Post by Dave Dixon » Mon Sep 08, 2008 9:58 am

In the aircraft instrument industry we used to use a product called "glyptol", or alternate name of glypt insulating varnish. Another place I worked at used - literally - Red Barn Paint - super heavy insulating paint!!! I am sure that nail polish, or any thick enamel paint would look and perform just as professional. Hope this helps, Dave

Edit: Add: Whoops, it is spelled glyptAl. Here is a link, but it isn't cheap!http://www.eastwoodco.com/shopping/prod ... uctID=2297

Dean Huster
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Post by Dean Huster » Mon Sep 08, 2008 7:12 pm

For the larger and older pots with 3/8-32 bushings and 1/4 inch shafts, there were special nuts that you could spin on with extended split bushings over which a lock nut could be tightened to lock down the shaft.

If you're interested in such a thing for new design, I'd suggest instead using multi-turn trimmers designed for a fairly narrow adjustment range. Rarely would these need any sort of lock-down. Most well-designed circuits these days do not have lock-down adjustments nor do they use any kind of "holding" paint on the shaft.

Dean
Dean Huster, Electronics Curmudgeon
Contributing Editor emeritus, "Q & A", of the former "Poptronics" magazine (formerly "Popular Electronics" and "Electronics Now" magazines).

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dr_when
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Post by dr_when » Tue Sep 09, 2008 4:40 am

Thanks Dean,

I am primarily looking for a recommendation for trimmers and surface mount potentiometers. Once set, they need to be "locked" with something like nail polish, etc. I believe nail polish would actually be fine but it's hard to get an MSDS on nail polish and quality folks like to see that everything is WEEE/ROHs compliant. I thought perhaps there was an actual electrical product available.

Thanks!!!!

Bob
"Who is John Galt?"

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Dave Dixon
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Post by Dave Dixon » Tue Sep 09, 2008 5:04 am

Here goes... One of the mfgs that we are an authorized repair station for specifies Glyptal #1209 for their products with a thinner number G-1500 (also Glyptal Brand). We specify Resin Lab part number BM-RED for similar usage. You should be able to find it at resinlab dot com. You should be able to locate further info and MSDS's on these two products. Hope this helps,
Dave
BTW - Here at work, "Glyptal" is like "Kleenex" or "Xerox" we refer to "glyptalling" pots, even if we use a different brand of product. I would use Glyptal if you can afford it! I'll see if I can find any other specs later today for any other recommendations!

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Post by Dave Dixon » Tue Sep 09, 2008 5:24 am

Follow up. I just went to our parts room and found bottles of GC Bond 10-4302 used for the same purpose. I'm not sure which manufacturer specifies it, but the bottle is marked RoHS. I'll bet it was always lead free, but probably now costs more with the extra labelling :) It might also be a good idea to check with a Loctite representative. They seem to be everywhere these days. I think that is all I can come up with for now. Happy "glyptalling"!!!!!!

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dr_when
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Post by dr_when » Tue Sep 09, 2008 6:38 am

Dave,

Thanks. I think Glyptal is the ticket and for some reason rings a bell (from the past). I will look into it further. Thanks also for all the related info!!!

Bob
"Who is John Galt?"

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