Wednesday, September 21, 2011

Soldering connectors

This post contains many links to other sites.  Some are businesses.  I have no vested interest in the businesses.  I post for your convenience.

I am home schooled in soldering.  Steve showed me how he solders copper pipes (not the same) and how he has soldered wires together using the same flux and solder that he uses for copper pipes.  Not exactly correct.  I read on  the vintagesingers yahoo group  ( a wonderful post by N. Rain Noe ( on re wiring a 201 motor.  Look in the files for Motor rewiring.  I simply bought all the supplies he suggested and practiced A LOT.   I studied various sites on the internet and practiced some more.  Soldering is not hard.  It is tedious.  Patience is the key.  The most important thing to remember is to heat the WIRE and let it melt the solder.  You can create a joint by touching the solder to the soldering iron and dripping it onto the wire, but that is considered a cold joint and not strong, nor correct

 About wire.  Gauge refers to the heft of the wire, or its thickness.  12 is heavier than 14 which is heavier than 16 which is heavier  than 18.  By the way this is not true for sewing machine needles, is it?  But it is true for needles I have used to give injections to human beings.  Go figure.

SPT refers to the insulation.  I don't have a clue what it stands for but with insulation rating the higher number, the thicker the insulation.  Therefore,  SPT-2 is thicker than SPT-1.  For most sewing machine wiring repair, if you can use the SPT-2 it is probably better.  If you don't need protection from abrasion, the SPT-1 is adequate.  You can find it all somewhere out there on the internet with the help of GOOGLE.  Or just order it from Sew Classic, and buy it by the foot.

 I have used common 16 gauge SPT -2 wire to re wire lights and foot pedals.  Truly I like the 18 gauge   wire much better.  It is easier to handle and the same "weight" as original wire on the singers.  Some people think that 16 gauge is better, and that is fine.  I just like the 18 gauge stuff.  Again, if you can, use the SPT-2 insulation.

About safety.  The soldering iron is hot and the solder is hot.  Wear eye protection and work in a well ventilated area.  This stuff has lead in it.  Keep your work area un-cluttered and watch how the iron is positioned.  For me it is all about positioning.  I don't start to solder until I am all set up.  Even then I have to watch what I am doing.

The first thing I do is gather my tools and plug in the iron and wet the little sponge that fits in the helping hands base.    I have been using a Weller 25 watt soldering iron that I bought for 20 bucks. It has been just fine.  I did buy an iron with higher power and a rheostat at Radio Shack,  on the advice of another customer shopping there that day.  I don't like it as well.  I did use it for today's project and I like it a little better.  I think that I should have saved my money and stuck with the Weller.
Weller soldering iron, "helping hands," 37/63 resin core solder, crimping/stripping tool
I also recommend another blog  My Sewing Machine Addiction ( all about the complete restoration of a Singer 201.  She gave me the idea to make ring connectors from the end of the wire itself.  This is a nice tidy way to create terminal ends for easy connection to almost anything.  Ten years ago, maybe even as recently as five years ago, my grip was strong enough to crimp terminal ends to wire.  But not now.  Maybe I need a better tool......

I do think that crimping is a good, certainly quick, method for installing new connectors.  Since I cannot crimp, I solder.    I remove the little insulators from the connector and turn them around and use them after I have soldered the joint.
AWG= American Wire Gauge  

  I   gently, every so gently, squeeze the plastic end of the connector with the pliers.  This loosens it from the metal ring so that I can then switch and hold the metal part with the pliers and twist the plastic part off of the ring.  You might have to squeeze that plastic insulator more than once, but it will free up eventually.  Sometimes I will use my hemostats to hold the ring and twist it as I gently hold the plastic with the pliers.  Once loosened I can then twist it off.
Gently squeeze the plastic part of the connector to loosen it.  Be very gentle and squeeze only the plastic part.
This demonstrates that the insulator is coming off.   I hold the metal ring in the pliers and twist the plastic off with my fingers. 

Today I put new connectors on new wire for Syracuse Gramma's foot pedal.  I measured the new wire against the old, to be sure I had the same length.  Then I very carefully scored the wire length wise, just a bit, so that I could separate the two wires from eachother but preserve the insulation.  Once I got a little bit of the wire free from itself, I just pulled it apart as far as I needed to.

Then I stripped the insulation from the wire.

It is important that you don't break the wires when you strip the insulation.  The crimping/stripping tool is calibrated, I use the largest hole that will get the job done and not cut the wire.  I do have to grip well and pull hard, but the insulation comes off quite nicely.  For this particular project, the insulation does not need to be stripped this long but you get the idea.
Once the wire is stripped and my connectors are free of their insulators, I set up the wire and connectors using the helping hands (HH). You can see that I did remember to put the little plastic insulator on the wire before I soldered the connection. Note how the fat end is oriented toward the connector.  This will allow you to pull that insulator back over the soldered joint when done.    You can also see that I am at risk of melting the other wire because it is too close to the iron.  I fixed that problem, tout suite.  
Even though I am about to melt the insulation in the above picture, you can see that the iron is positioned on the connector and the wire.  Most of the heat is in the bevel of the iron, not the tip, so you want to have the bevel connect to the items to be heated and soldered.

 When soldering, it is important to have clean wire and clean soldering iron.  There is a tip cleaner product, which I have not purchased.  Instead I heat the iron and "tin" the tip, meaning I melt solder all over the end of the iron.  I then rub the tip on the damp sponge in the base of the HH stand.  This might be more expensive than tip cleaner, solder isn't cheap and this wastes solder.  Next trip to town, I will check out tip cleaner

Here I am holding the solder on the wire itself and waiting for the hot wire to melt the solder.  It happens quick, once it happens.  Obviously it hasn't happened in this photo.  I used the self timer on the camera for this shot, clever me, and of course with all of that setup the wire wasn't hot enough.
Don't disturb the connection until the solder has cooled.  Once it is cooled it is strong like bull and you can do anything to  it , almost. 
I slipped the insulators down over the soldered joint and that finished this little project.

I am not a professional sewing machine mechanic  but I am mighty pleased with this outcome.  If you notice, the connectors are not identical and I am not going to tell you why, except that it has to do with memory, blue insulator and wire that is shorter than it was originally. ( # 22-16 AWG is irrelevant in this photo.  )

Coming up in a future post, how to make a terminal ring out of the wire itself.  It's fun and EASY.

1 comment:

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