[TIPS] Strengthen the diy/self made hook probe's join using hot glue gun  - Page 1
Forum section: electronics / projects

author: BravoV
author_rank: Super Contributor
timestamp: October 12, 2011, 06:20:29 pm
content: Recently I grabbed bunch of el-cheapo "OneHungLow" dmm probes cables which have nice banana connector at the other end, and decided to make my self a nice short banana to hook clip probes like below image, not pretty though but it works. Btw I ran out of black one, so blue looks fine too.Usually the problem with this kind of self made/soldered hook clip is the weak join at the solder join inside the head of the clip. It is normal after few rough usages like twisted or pulled hard at the cable, the join between the fine stranded copper wires from the cable with the probe copper tip inside the clip's head will be snapped easily, and it will be a pita to fix since it needs to be dismantled the whole assembly and redo the solder. Also the thin soft copper hook at the tip doesn't react too well if bended too many times to make that "J" hook shape, it will break easily.Here what I did, using hot glue gun to make a strong bond between the cable to the clip's head, so the solder join inside the head will not be exposed to the mechanical stress cause by the movement during normal use. The glue material once cured and cooled fits this purpose quite well since its elastic and will stick quite hard even to plastic surface like the cable surface or the head assembly, trust me, you can not easily peel away the glue once set from the cable or the head.The head of the blue clip, you can see there are lots of scratches made by sharp cutter knife to ensure the glue will stick and grab strongly at the head's surface to form a really nice bond.Another view, that spot was not finished yet, just to show it before I put the glue on it, and it will be applied thinly, cause too thick, the bulging glue will affect the push movement.The red one with the ugly glue, but it will turned into strong bond yet flexible once its cured.Another angle, this side is thinly applied.Side view.Another shot on both.Finally, our hero.Thats all.

author: Balaur
author_rank: Unknown
timestamp: October 12, 2011, 07:19:22 pm
content: Hey, nice presentation!It's true that the cable on this kind of hooks is particularly weak in that area. Thank you for the idea!I'm also using something like this for the 9V battery clips. I recover the clips on a used battery and reuse as a connector.In addition to the initial glob of glue deposited by the glue gun, I'm using the hot air station to keep the glue hot and malleable in order to be able to work with it.

author: tnt
author_rank: Regular Contributor
timestamp: October 12, 2011, 10:31:32 pm
content: sugru !

author: BravoV
author_rank: Super Contributor
timestamp: October 13, 2011, 04:03:20 am
content: Quote from: Balaur on October 12, 2011, 07:19:22 pmMy pleasure, glad you like it.What a coincidence, I made that exact 9v batt clip too, and using hot air to smooth out the surface, but for this clips I'm not using it, I can live with that ugly looks.Quote from: tnt on October 12, 2011, 10:31:32 pmYeah, probably that will work too and can be shaped better, just make sure it will stick to both the cable and the pin surface, cause I remember sugru does not sitck on some plastic type, while this glue just works, tried it on so many type of connectors and different materials from various cables.

author: Rufus
author_rank: Super Contributor
timestamp: October 13, 2011, 07:10:49 am
content: I find hot melt glue to be electrically speaking exceptionally good all round. Very good insulator, very good sealant on most materials and I've read a good low loss dielectric at high frequencies. Obviously lacking at higher temperatures where it melts again - lol.I find it useful with heatshrink sleeving, effectively making your own adhesive lined heatshrink. Put a little on what you are sleeving and it will melt and flow when you shrink providing better strength, insulation and sealing.I once soldered a couple of bits of PVC hook up wire to the leads of a 10M resistor and gave the resistor and joints a generous coating of hot melt glue. I poked two holes in the lid of a jam jar, threaded the wires through and sealed around them with hot melt so the resistor sat at the bottom of the jar. I half filled the jam jar with concentrated salt solution. I accurately measured the resistance between the wires and wrote it and the date with an indelible marker on the lid then stuck it on a window ledge.I occasionally measured the resistance and it didn't change at all until after about a year the sun had completely erased the writing so I no longer know exactly what the original value was or when I put it in there.That was about 5 years ago and it is still on the window ledge. The inside looks a bit disgusting, the lid is getting rusty and will probably disintegrate in another year or two. I measured the resistance between the wires today and it is still 10.1 Megs. So, 6 years submerged in concentrated salt solution exposed to sunlight and temperature cycling and the hook up wire insulation and hot melt seal around the resistor and joints is still intact - I continue to be impressed.

author: BravoV
author_rank: Super Contributor
timestamp: October 14, 2011, 03:10:22 am
content: Quote from: Rufus on October 13, 2011, 07:10:49 amNice trick, never thought about that, thanks !Quote from: Rufus on October 13, 2011, 07:10:49 amDoes the glue turned into hardened or brittle plastic ? or it maintains the soft plasticity feel ?Curious why you did this ?

author: Rufus
author_rank: Super Contributor
timestamp: October 14, 2011, 09:56:42 am
content: Quote from: BravoV on October 14, 2011, 03:10:22 amI haven't opened it so I don't know. I imagine it hasn't changed. There are some debris in the water, the glue seemed to shed thin layers of 'skin' early on, maybe it still is and will fail eventually.Quote from: BravoV on October 14, 2011, 03:10:22 amIf I remember correctly it was after a discussion about the difficulty of getting reliable water tight seals on cables feeding underwater pumps for fish ponds. I thought hot melt glue might work well and decided to test it. I didn't imagine the test would still be running 6 years later.

author: BravoV
author_rank: Super Contributor
timestamp: October 15, 2011, 06:43:33 pm
content: Hey Rufus, if one day you decided to open it up and to inspect it, please make a new thread to share your finding.This little experiment, although looks minor and trivial, but I think its valuable, 6 years thru thermal cycle, in constant wet & salted environment and also UV light exposure from the sun, should someday I want to make a circuit that will be exposed to sea environment, damn sure I'm interested in this information.

author: sonicj
author_rank: Frequent Contributor
timestamp: October 18, 2011, 05:54:23 am
content: i've done this on a number of projects to reduce wire fatigue at a joint / crimp / etc. i've found that hot glue tends to release after some handling though. could be the glue im using or the surfaces im adhering to, but anywho, i usually add a spot tie to avoid disturbing the glue.