Hot Glue Legal to Glue PWM cables ?

[Al Skierkiewicz]

Alan,
In practice I have seen hot glue on plastic that can only be removed with a razor blade. When applied to the PWM connector of a speed controller or RoboRio, the glue also migrates into the connector body and interior of the device. On a Victor, this would be a permanent solution IMHO.
Al

[Alan Anderson]

Originally Posted by Al Skierkiewicz

In practice I have seen hot glue on plastic that can only be removed with a razor blade. When applied to the PWM connector of a speed controller or RoboRio, the glue also migrates into the connector body and interior of the device.

You have definitely seen some variety of hot glue that doesn't match anything in my experience. The kind I use doesn't come close to being able to "migrate".

When I say "hot glue" I mean the kind that comes in clearish/whitish finger-sized sticks and gets extruded through a hollow heating element, coming out as a skinny thread of sticky squishable plastic with the approximate consistency of gel-style toothpaste. It quickly cools to a slightly pliable solid form, sticking to whatever it is contact with. When hot, it does not flow into cracks; one would have to force it there intentionally as if spackling a hole.

[Ether]

Originally Posted by Al Skierkiewicz

In practice I have seen hot glue on plastic that can only be removed with a razor blade. When applied to the PWM connector of a speed controller or RoboRio, the glue also migrates into the connector body and interior of the device. On a Victor, this would be a permanent solution IMHO.

Al, It almost sounds like you are talking about 2-part epoxy, which reacts exothermically (gets hot) when the 2 parts are mixed. Many formulations of 2-part epoxy tend to wick and migrate during the curing process. When cured, it is permanent and quite difficult to remove.

[Al Skierkiewicz]

The hot glue I am talking about will run like a warm milk shake letting gravity take it where it wants. The tools I have used act like a 'runny nose' and drip constantly while hot. While I was writing this, I remembered that there is a product you can buy at Office Depot that is intended for tacking posters to a wall. That should do the trick, be easily removable, and will not contaminate electronics. It looks a lot like Playdough.

[AdamHeard]

We use standard hobby low heat (white gun, not blue) hot glue.

What Al is describing isn't comparable at all, we've never had issues with hot glue. Only the smallest dot is needed anyway. It doesn't flow, it's very viscous when hot.

[MasterMentor]

We use a drop of red nail polish - it creates a non-permanent bond that is easily breakable when necessary, holds the PWM connector in place, and the team moms usually have a ready supply of it. I got the idea from a post here on CD.

MM

[Alan Anderson]

Originally Posted by Al Skierkiewicz

The hot glue I am talking about will run like a warm milk shake letting gravity take it where it wants. The tools I have used act like a 'runny nose' and drip constantly while hot.

Now your extreme aversion to the stuff becomes understandable.

I'm also now pretty sure that what you're referring to isn't what anyone else in FRC wants to use. While the usual craft-style hot glue guns do drip at times, what falls from the nozzle has a consistency closer to warm peanut butter than to warm milk shake. Think beeswax, not honey.

While I was writing this, I remembered that there is a product you can buy at Office Depot that is intended for tacking posters to a wall. That should do the trick, be easily removable, and will not contaminate electronics. It looks a lot like Playdough.

Plasti-Tak and similar materials are neither sticky enough nor solid enough to have the desired effect on a PWM connector. They adhere well to paper, and the typical amount used gives a large area of contact to spread out the force, but if you try to use them to do something like affix a PWM connector to a Spike it'll stretch and/or tear and/or simply roll off the part.

[IKE]

Originally Posted by AdamHeard

We use standard hobby low heat (white gun, not blue) hot glue.

What Al is describing isn't comparable at all, we've never had issues with hot glue. Only the smallest dot is needed anyway. It doesn't flow, it's very viscous when hot.

Any chance you can send a picture of it "being applied as a little dab". I have always considered this a "best practice" to use a small dab of hot glue or RTV between the PWM connector and the housing to act as a anchor for impacts and shock.

That being said, when inspecting, I have obeserved several connectors that it was clear someone thought "more is better" and flooded the: CAN, PWM, Ethernet... connector. I typically see a couple of these per competition towards the end of the season. Often for an ethernet or JAG CAN that someone has brocken a tab on. Once the team gets to that state, they tend to have some sort of issue during most matches.

Googling "hot glue electrical connector" or "RTV electrical", I saw a lot of images of hot glue being used as some sort of conformable coating/filling which is not recommended for these connections.

[MrRoboSteve]

There's nothing wrong with properly applied hot glue. The problem is that it's very easy to improperly apply it, and then you end up with a big mess that is sometimes unrecoverable. Al's observation, based on looking at more robots than (nearly) everyone here, is that many teams can't apply small amounts of hot glue.

The approach I suggest (combination of adhesive backed cable base, tie wrap, and small amount of electrical tape [please use fresh 3M brand tape]) is one of several that a) work, b) are difficult to screw up, and c) don't end up with an unrecoverable mess if executed wrong.

[ArtemusMaximus]

"to glue or not to glue, that is the question"

In my opinion it's as simple as this: rules do not prohibit, so you can do it.
You can do it - yes, but should you, that's another question to answer.

In my experience, hot gluing is not a precise method, accompanied by multitude of "glue hair" strings. So at the end of the day, it's a matter of managing benefit/risk ratio.