Nichrome Wire Connectors

[RyanP]

Does anyone know where to get the connectors used to make a mechanical
connection to the nichrome wire? I'm planning to rebuild my PLA
extruder nozzle assembly (AGAIN) tomorrow and I'd like use better
connectors. Right now I'm making due with the smallest crimping
connector that I found at radioshack--cut in half, but it takes up a
lot of room on the heater barrel. I'd appreciate any suggestions on
where to find better ones.

I'll be replicating Rick's instructions for a nozzle assembly this
time: http://www.makergear.com/pages/printing-with-pla Seems pretty
straight-forward and I'm pretty close right now. Finally printed two
parts yesterday before failing today. The only other issue is that I
may have somehow torqued the heater barrel with all the teardowns and
tightenings.

[Nick Ames]

I've gotten excellent results by tying the nichrome and wire together in
a huge knot and flooding it with solder. Much stronger than a ferrule,
and less risk of corrosion. (All my previous heaters died from the
ferrule-nichrome connection getting exposed to the air, corroding, and
breaking. I've been running the knotted wire heater for far longer, and
I haven't had a problem.)

[Steven Dick]

I just redid my heater today....  I wrapped the nichrome around the copper wire a couple of times with a plyers, and then folded the copper wire over that, and soldered the mess together.  Ask me in about 3 weeks if it's still holding.  :)

I also put 3 layers of kapton tape between the washer and the thin m6 nut.  (Also through the washer, so its not touching the barrel directly either.)

I'm not sure if the kapton tape helped or if I did a better wrapping job, but my heater seems to be coming up to temp more than twice as fast.

[Matthew Wilson]

I use a 1/8" long bit of 1/8" copper tubing. I loop the nichrome
through and then crimp it down onto the copper. No need for solder at
all.

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[Johnny]

For my last rebuild I used the small red butt connectors from a cheap
crimp set. I just tore the plastic insulation off and used the ferrule
inside.

[RyanP]

Okay, I got good results by just wrapping the wires around eachother
and filling it with soldier. I wouldn't suggest this to anyone
without a multimeter though. I did have to redo one connection
because it didn't come together that great.

Ryan

[Rod Davis]

Im not sure if this will help, but they sell high temp connectors on
ebay.

You can see them here:

http://stores.ebay.com/caseyelectricsupply

Hope this helps!

Rod

[Oren Beck]

Nichrome has some inherent connection factors. It's not easily
soldered at all= nearly non-wettable so commercial connectors are
often mechanical clamping/compression based. With tricky details of
expand/contract fatigues. Wide,flat surfaces with bellville washers
made from heat resistant ally have been used by Conveyor toasters for
connections to their nichrome ribbons.

I have used a truly ghetto hack to repair open coil nichromes like
dryer/air handler heaters. Self Arc Welding by using some almost
Darwin Baiting wooden or similar tooling for touching one broken end
to the other. SNAPPING
arc and an often quite reliable connection results.. Not recommended
for the faint hearted.

Alternative production methods like welding in an inert gas by spot
Resistance or Laser seem to be tied with some esoteric stunts like
explosive deformations or magnetic collapse sleeves. Whole classes of
such process details are closely guarded "Trade Secret" with NDA's et
all to keep them locked down. Not paranoia- just a flawed, "Closed
Source" capitalist reality.. I do suggest some Toaster dissections as
both education and material sources

[Nick Burrows]

I found the best way to attach a wire to nichrome is to use a crimping connector as the base. This has worked for the several months I have had my 'bot.

1. Lay nichrome wire across connector

2. Wrap component lead around nichrome wire above crimping part

3. Fold nichrome wire back over itself.

4. Crimp connector (Pliers can work for this)

5. Solder wire to connector

6. Cut off unused portion of connector.

See attached drawing for what it should look like. You can solder your wire to the back of the crimping area to reduce length of connection if needed.

[Steven Dick]

My wrapped wire connection is still holding 7 weeks later...

The trick with this method is to wrap the nichrome around the copper wire and then wrap the copper wire around the whole mess and then solder the copper wire to itself through the nichrome.

In more detail, use about 3cm of nichrome and about 2cm of copper wire.
Start with the ends pointed towards each other, and wrap the nichrome starting half way up the bare end of the copper wire, and tightly wrap it at least twice with some spacing between the windings, then twice more going back towards the nichrome so the windings cross each other.  Make sure the loose end of the nichrome is tucked well into the mess so it doesn't poke out and make a sharp spot. Then fold the loose end of the copper over the wrappings and twist it around a bit.

Use your favorite solder/flux to tin the exposed copper (I prefer rosin core), and once it is tinned, use silver solder that solders with a high viscosity, so you can heat it slightly and move it around to make sure that it totally covers the entire joint including all the exposed nichrome.

Then I wrap the whole blob in kapton tape until the tape seals the fiberglass threads on the nichrome to keep them from shreding or creeping up.

Next time I make one (which will hopefully be never) I'll have to take some pictures.

I wonder if a wire wrap technique (with a wire wrap tool and a square pin) could work even better...

[Jordan Miller]

Nick and Steven,

Can you post your excellent recommendations and details for soldering wire to nichrome onto the MakerBot wiki? I think it will help a lot of people!

http://wiki.makerbot.com/plastruder-mk4-assembly#toc24

jordan

[wulfdesign]

I like Matthew's solution but here is what i did
for my Heated Build Platform and it worked pretty good.

just put a small loop with a pair of needle nose pliers
in the end of the nichrome and copper leads
loop them together and solder.

-L