Power wire ends - anyone soldered?

I am getting very close to having my Ormerod up and running, but the crimp ends on the power cable will not go in the screw terminals on either board.
I have used a good quality crimping tool and the crimp is nice and compact, but there is no way I can get any of the 4 crimps into any of the terminals.
So it looks like I am going to have to cut off the crimps and tin solder the wires instead.
This is mentioned in the instructions, but I don't understand why my crimps won't fit.
Anyone else had to do this?
Or is there a trick I am missing?

When I found they wouldn't fit I soldered the crimps and then filed them until they fitted. In some places I ended up filing right through the crimp into solder/wire

The crimps didn't work for me. I just soldered the tips to keep the strands together.

Kim

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I tinned the wires, then fitted the round ends - plus a little more solder.
With a little careful force, the round ends WILL go into the terminal blocks. If they ever come out again, I guess they will be a little square!
Greg

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Ormerod #17

I soldered the tips like Kim. I then periodically check that they do not loosen.

I soldered them too. If you do this, bear in mind that the solder will soften with time. I suggest using unleaded solder (it should soften less than leaded solder), and check at intervals that the terminal block screws are still tight.

I believe the ferrules supplied will fit the terminal block if they are crimped into a square shape.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Just twist the bare copper wires tightly and put into the terminal blocks, ensuring that pretty much all the strands are clamped under the screw. It is not a good idea to tin wires that go into screw terminals, they end up quickly deforming and becoming loose, and at those currents a loose terminal can end up with a fire - as happened to someone in another thread. Check the terminal screws are still tight every week or two. Tinning the end of a wire that is not securely supported (clamped) near the tinned section will also lead to the wire fatiguing and breaking if subjected to any sort of vibration or movement.

Dave
(#106)

Thanks all for replies, glad its not just mine that don't fit.
The crimps were done by a professional electrician with decent crimp tool, it left it as a pretty tight square, but still nowhere near going to pass into the terminal.
I will make sure I regularly check screws.

Dave, you say its NOT a good idea to tin wires, but the instructions specifically say TO tin them, to stop the loosening. Any reason for the contradiction? (sorry if that sounds rude, its not meant to)

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balidey
Thanks all for replies, glad its not just mine that don't fit.
The crimps were done by a professional electrician with decent crimp tool, it left it as a pretty tight square, but still nowhere near going to pass into the terminal.
I will make sure I regularly check screws.

Dave, you say its NOT a good idea to tin wires, but the instructions specifically say TO tin them, to stop the loosening. Any reason for the contradiction? (sorry if that sounds rude, its not meant to)

It's a classic "gotcha" - as already mentioned, the soft lead relaxes (moves around) over time and the clamping force is then lost. Tinned leads look nice and neat and prevent stray strands misbehaving, but the professional way to terminate stranded wire is always using a "bootlace ferrule".

I did something a little different when I found the crimped leads wouldn't fit - I used the ferrules as a solder cup, that is, I placed them on the bare twisted wires then end-fed solder into the ferrule (being careful not to get any on the outside). Then I used flat pliers to squeeze the ferrule into a square that would fit in the terminal clamp. The solder deforms to the new shape but retains a low-impedance connection and the ferrule casing stops the solder moving over time.

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RS Components Reprap Ormerod No. 481

I used simple 9 pin SUBD connectors. You can buy them everywhere, easy to solder, easy to disconnect when necessary.

Would it be a problem to use solid copper cable of appropriate diameter?

I found the original cable a bit short and a bit lacking in colour coding, I could crimp it, but the ferrules wouldn't fit through the holes in the case, so I used some 20A multi-strand figure 8 from maplin (black/red) - this twists nicely and is held properly by the terminal blocks, and with the extra inch I allowed myself, it clears the Z post nicely

On the whole, I'd go with DMoulds advice on soldering versus crimping, the automotive industry is crimping all the way as far as I can see. Solder leads to embrittlement of multistrand cable when flexed.

There are two types of terminal blocks aimed at different terminations - one is the direct screw, which makes a "pressure weld" by direct force into the wire (designed for solid cores as used in UK household cabling, or multistrand wire encased in a ferrule - the individual strands could otherwise be cut by the screw action, as anyone rewiring a UK plug will have noticed), the other has a spring leaf under the screw and spreads the load of the screw end, as well as having some give, and is designed for clamping multistrand wire without cutting it (I think this latter is what is soldered to the board, but I didn't look inside - maybe I will tomorrow )

Ray

As the supplied crimps wouldn't fit through the aperture I used some insulated crimps with long pins, these were long enough to go through the aperture and connect, I have attached a pic showing the original ferule and the readily available crimp I used together with a longer tab type that is also available, the original crimp is approx. 8.5mm the ones I used are 11.5 mm and the long tab type at the top are 18.4 mm long.
I cant recommend where best to buy as my previous supplier JPR electronics seem to have reduced the range available.

best regards

mike

Well I had to cut the original crimps off, then tinned the wire, but my soldering iron is crap, so I made a pretty bad job of it. In trimming it short the cable is only just long enough, some would say too short. So I will be re-doing the cable and will hunt out some slightly smaller diameter crimps.

You really can fit the supplied, round, ferrules into the square holes.
Feed the lightly tinned wires into the ferrule - feed a little more solder into the open end
Make sure the clamping screws are fully out of the way. Make sure the Duet is not fixed in position. Hold the ferrule with pliers and press firmly into the connector - with your other hand taking the pressure on the connector.
Finally tighten the clamping screws and fix the Duet into position/

I have had no heating issues in the terminal blocks
Greg

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Ormerod #17

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GregL
Feed the lightly tinned wires into the ferrule - feed a little more solder into the open end

And I should have added that if solder does flow around the outside it's easy to clean off by applying your iron for a few seconds and wiping over the molten solder with a stainless steel pan scourer (these make magnificent soldering iron tip cleaners too - much better for the iron than wet sponges)

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RS Components Reprap Ormerod No. 481

Quote
GregL
You really can fit the supplied, round, ferrules into the square holes.
Greg

If you have access to a ferrule crimper you will. They are a snug fit but they do go. However the proper crimpers are £80+. Luckily for us we have some at work. Try RS no 399-2031

[www.ebay.com.au]

alternatively, strip the earth and live strands from a main ring cable and be done with it. It is solid copper and non flexible. That way you get a nice fat wire that bends into a shape and stays that way for ever.