Help with crimping

[ceraunic_level]

Am I doing this right

I over lap the stripped conductors

View media item 3426
then crimp twice, with the imprint of both dots from the ratchet to the centre of the crimp.

I can get nice strong connection like this, however the spec say

Red 0.5mm-1.5mm². Blue 1.5mm-2.5mm². Yellow 4.0mm-6.0mm².s say

I can't get two 2.5mm conductors to overlap in a blue butt which makes me think I am doing this wrong and the conductors should 'Butt' up to each other not overlap
With this method my joints are really weak

any advice would be great
Thanks

 

[fattony]

You dont actually overlap the conductors as you said they butt up t each other, so half the amount of copper you are inserting into the crimp. You are correct in what you say i.e red for 0.5mm to 1.5mm

 

[JohnD]

the "tubes" in the crimps usually have a slight "dimple" inside to prevent you pushing either wire beyond the midpoint. If you can push the cores in enough to overlap it sounds to me like the crimps are too large (you are using single-core or standed cable, not flex?)

You want to strip back the insulation enough so that the copper fully enters the metal tube, but the insulation is covered by the plastic tail and you couldn't touch or poke the copper, even with a bit of wire.

 

[ceraunic_level]

Ok yes thanks for that

Had another go, only striped off about 7mm of insulation which butts up to the metal tube and conducter is half way in then crimp

Could you tell me if I m crimping in the right place, should the dots be closer together?

The joint feels quite strong but each wire has a little bit of movement when pushed and pulled, is that right??


View media item 3427

 

[mattylad]

This is why they are commonly called a "butt crimp"

There should be no movement in the crimps when correctly crimped.

 

[Spark123]

What size is the wire you are crimping? If it is 1.5mm then use a red crimp. For 2.5mm use a blue crimp. You need to compress the metal in the middle of the crimp with the ratchet crimpers.

 

[skenk]

I don't know if you're supposed to?? but I crimp more than twice, like 6 times or something all along the length of the crimp and it's solid. You are using ratchet crimpers, yeah?

 

[ban-all-sheds]

I don't know if you're supposed to??

No, you're not.

but I crimp more than twice, like 6 times or something all along the length of the crimp and it's solid.

If you put the crimp in the right way round, and line it up properly, I can't see how it would even be possible to put it in 6 times. Once at each end - job done.

Try adjusting your crimper.

 

[Spark123]

I think he means applying the crimping pliers 6 times along the length of the butt crimp to ensure it is adequately squashed onto the wires?

Should only need to do apply the crimping pliers twice, the metal part inside the crimp isn't really that wide.

 

[ColJack]

the wires will feel like they move a little if you hold onto the plastic part and pull the wire.. it's the metal moving inside the plastic..
the wires shouldn't pull out and any more movement than a mm or so is too much..

stranded wires can be doubled over if needed to make a secure crimp ( ie using 0.5 or 0.75mm flex in a red crimp.. )

 

[ban-all-sheds]

Oh no - not more confusion over the word "each"....

Should only need to do apply the crimping pliers twice

Once at each end - job done.

 

[Spark123]

Oh well, I thought you thought the 6 times was for something different, if you see what I mean.

 

[skenk]

I think he means applying the crimping pliers 6 times along the length of the butt crimp to ensure it is adequately squashed onto the wires?

Yeah that's what I meant, had a feeling you were only meant to do it once/twice for butt. Thanks for the tips all, esp lining up the seam. Had some practice and it's working better now.

 

[kwikfix328]

It will depend on which type and brand of crimp you use , but I was trained to bare enough cable so that the bare wire is crimped to the inner metal part of the crimp, then the plastic outer sheath crimps down onto the Cable insulation to secure that .

At my work i mostly use Tyco AMP PIDG crimps, these have 3 parts; an inner crimp that secures to the wire , a thinner middle metal sheath that crimps to the cable insulation , and an outer plastic part that covers the whole lot.

The wires should not crossover in the middle, they should butt up against a divider at the halfway point, if you look down through the crimp you should see it. I normally strip the wire and then lay it alongsid e the crimp so you can judge whether you have stripped of the correct amount of insulation.
The way to test it physically was to bend the cable to 90 deg where it enters the crimp , then straighten it and see if it will pull out by applying 'reasonable' force. Don't forget you are making an electrical connection , not building a railway bridge..

If the crimp was something like a ring tongue, or spade, etc then you should do a milli-volt drop test across the connection , (That was an exam answer by the way , I've never actually done a milli volt drop test on a crimp connection - don't quote me on that though... )

 

[ceraunic_level]

Thanks for the replys

Kwikfix,tried your testing technique and was disappointed to find that one half of the crimp came out. Still not mastered yet.

Agree with your comment about the railway bridge though, i am giving it some serious pulling