wire seal to resist potting - Page 1
Forum section: electronics / projects

author: Simon
author_rank: Unknown
timestamp: September 29, 2015, 08:19:39 pm
content: I need to put wires through the bottom of a box and then pot the box. The potting must not leak through. Other than a cable gland (and a good one at that as thes are 2x 16-20 AWG cable) ?

author: m98
author_rank: Frequent Contributor
timestamp: September 29, 2015, 10:46:12 pm
content: What's wrong with a cable gland?Maybe you could try to apply some sealant before potting to avoid leakage.

author: lewis
author_rank: Frequent Contributor
timestamp: September 29, 2015, 11:42:13 pm
content: Superglue on the inside of the box works well as long as you have one hole per cable. cable gland is better as it offers some amount of strain relief and is good for multiple cables. The ease of installation offsets the gland's cost. And you can use a cheap gland because you're not worried about long term ingress of water, it only needs to seal for as long a the resin takes to cure.

author: John Coloccia
author_rank: Super Contributor
timestamp: September 30, 2015, 02:37:30 am
content: Can you turn the box upside down and pot from the bottom?

author: calexanian
author_rank: Super Contributor
timestamp: September 30, 2015, 06:33:07 am
content: I have used two things successfully. Chemtronics peelable solder mask (Latex I believe) and I have also used silly putty.http://www.all-spec.com/products/cm8.htmlThere are several different masks available now. We used the basic pink one around dip switches that poked through a front panel where upon the PCB was potted into a recess molded into the back of the panel. Worked well. We would apply the mask and pot it the next day and it peels off cleanly. Also you can use good old hot glue. if you hit it with IPA you can sometimes crack off the hot glue from plastic cleanly.

author: Simon
author_rank: Unknown
timestamp: September 30, 2015, 07:50:34 am
content: Basically this would be an open top potting box so can't be potted the other way around. I just need to screw it in place with the wires coming through the bottom and pot it without the potting leaking through. I don't need to mechanically retain them as athat happens in the potting so it's a shame to go to the extent of a cable gland, it's not cheap and large and cumbersome.

author: KL27x
author_rank: Super Contributor
timestamp: September 30, 2015, 10:31:54 am
content: RTV silicone or hot glue?

author: Ian.M
author_rank: Super Contributor
timestamp: September 30, 2015, 11:15:24 am
content: If its a one-off or very small volume and you are using an epoxy potting compound, use epoxy putty on the inside. Pour the potting compound after the putty has set firm, but before it fully hardens to get a good chemical bond.

author: Simon
author_rank: Unknown
timestamp: September 30, 2015, 11:50:05 am
content: I am talking with the main part supplier to see if we can get the cables sealed to the body that way there won't be a problem. I guess the alternative is as said the hot glue. It's for a couple of hundred at the moment so worth getting right which is why I'm also talking to the manufacturer or the main part.

author: John Coloccia
author_rank: Super Contributor
timestamp: September 30, 2015, 11:53:08 am
content: For just a couple of hundred, hot glue is probably the quickest and easiest solution. I can think of more exotic solutions, but I can't think of anything quicker or easier.