Author Topic: solder joints in coils (Read 6351 times)

Keyman · « **on:** October 30, 2007, 11:35:59 AM »

I went to out local electrical shop and they sold me all the #15 wire they had from spools that are too low for them to use ... The wire all adds up to 6lbs which should be sufficient to wind my ten coils for my 8ft. Hugh Piggott turbine. Is it acceptable to splice wire in a coil? And what is the best method to do so? I have 5 coils with varying amounts of wire on them. The chances of not needing to splice are remote at best. He sold me the wire this way because I told him I was trying to save money. 2.50/ lb seemed like a very fair price to me .

Keyman

tecker · « **Reply #1 on:** October 30, 2007, 06:03:07 AM »

I wouldn't do it because of a few reasons but it's not a good idea as a general rule . You'll have to get it cleaned to get a good solder joint that leaves you with a big ? mark and the resistance is not high enough to get a test on a completed coil. If you have no choice in a first stator situation bring two ends out lable them and solder together out of the winding with all the other interconnects .

TomW · « **Reply #2 on:** October 30, 2007, 06:19:12 AM »

tecker;

Good advice on bringing the splice outside of the "coil".

I would not personally splice magnet wire but I think of that kind of option as "desert island" stuff. It will probably work but is not ideal. Since the coils can be and usually are wound as single units and connected together later he might get lucky and get use of most of it without splices. The price is right so a bit of effort in working around the material on hand may be worthwhile.

Cheers.

TomW

Keyman · « **Reply #3 on:** October 30, 2007, 06:47:47 AM »

They gave me a stick of what looks like silver solder but they called it something else ... they claimed that it would make an acceptable connection for a coil.

wooferhound · « **Reply #4 on:** October 30, 2007, 07:48:50 AM »

I think it will work just fine except for lumpy coils and a slightly higher resistance. Here is what I would do.

Put a small 1 inch long Heat Shrink Tubing over one of the leads to be soldered.

Scrape the thin insulation off of the Magnet wire about 1/8 inch (3mm).

Clean the two scraped ends very well.

Tin or presolder the ends and trim the ends back to 1/8 inch again.

Melt some solder onto the tip of the soldering Iron.

Hold the 2 wire ends together and Inline as straight as possible

Tack them neatly together with the soldering iron

Make the connection as Small and Smooth as possible.

Slide your Heat Shrink tubing over the connection and Shrink it with a lighter.

Finish winding your coil and enjoy the power

HomegrownPower · « **Reply #5 on:** October 30, 2007, 08:56:35 AM »

I was wondering the samething . See lots of wire on ebay at good prices but in like 100 ft lenghts . Not knowing about using a solder connection I opted for a bigger spool that I was sure to wind my coils in one piece .

Let us know how it goes

Lonnie

Flux · « **Reply #6 on:** October 30, 2007, 09:44:05 AM »

The stuff they gave you that looks like silver solder is probably "Silphos" or some other trade name in your part of the world. It is a self fluxing braze that is used to make end connections in motors. It makes a totally sound connection that will stand more temperature than you need worry about. It needs at least oxy-propane to reach weld temperature, you will not need to clean the wire, it will burn the enamel and braze to the hot copper.

The big snag is that it will burn the enamel about 1" either side of the join and you will need to somehow insulate it. You can use sleeving but it will make a mess in the middle of a coil and take up lots of space.

If you can manage to join between coils that is fine, if you have to join in a coil then with care it will be ok but make sure the sleeved area is towards what will end up as the outside of your coil where you have plenty of winding space. If the bulky join happens to occur where the coils nest together towards the centre you will run out of space.

If they charged you for the Silphos it may have been cheaper to not use short ends of wire but if they gave you it then fine.

Flux

TomW · « **Reply #7 on:** October 30, 2007, 10:16:33 AM »

flux;

The big snag is that it will burn the enamel about 1" either side of the join and you will need to somehow insulate it.

Its been a few years but when I needed to solder something and didn't want the heat wicking into the part ~~I would clip either an alligator clip or hemostats just beyond the soldering point on the lead / wire. The clip prevents the heat from going past it at least until the clip gets hot.~~

Might be a good way to reduce the heat run up the wire.

Cheers.

TomW

Keyman · « **Reply #8 on:** October 30, 2007, 10:29:10 AM »

All great ideas .. thanks you all so much for taking tome to respond I will let you know how it goes.

Keyman

Flux · « **Reply #9 on:** October 30, 2007, 10:47:06 AM »

Good advice for soldering Tom, but I think the material he has is a self fluxing braze that works at dull red heat, it makes a far superior join to soft solder.

I would be slightly reluctant to suggest soft soldering connections in these coils if you are going to run them close to class H temperatures that some are certainly aiming at, a well made soft soldered lap joint would be ok if the thing was not pushed to crazy temperatures but I think some of these coils are pushed beyond the melting point of 60/40 solder.

Flux

TomW · « **Reply #10 on:** October 30, 2007, 11:36:38 AM »

flux;

Another good point. I never brazed and only used silver solder rarely so my experience is with lower temp materials. I had a cheap inverter that desoldered a pair of ballast resistors that were under the board. Was a simple fix after I figured out where they fell out of the board. So, indeed, circuits can easily exceed the melting point of standard solders. Bringing the connection ~~outside of the coil should eliminate the extreme heat inside the stator simply because it has access to cooling air.~~

Its never "that simple" in this stuff it seems. Probably why it is never boring.

Cheers.

TomW

picmacmillan · « **Reply #11 on:** October 30, 2007, 01:54:25 PM »

hi keyman...first of all...good thread...when i buy wire....its usually 6 pound rolls....its about 45-50 bucks canadian....i get enough wire(14-15 guage) to make one stator...there is some left over for about another coil...i make 12 coils in mine and 16 magnets per rotor...dual rotor....one tip i have that has worked for me is to twist the wire ends together to join them...then solder them, and check the resistance...i dont recommend this cuz...if you look at the big picture...the wire is a real inexpensive thing to buy new...you are guaranteed there isn't any knicks or damage...and the coils will be flatter(very important the air gap),depending on the magnets used...getting back to the coils of used wire...the reason i say this is that...we do the work, make the coil winder get the wire,..solder blah, blah, blah....and then we spend some real time making the stator mold...getting things right...get the fiberglass, the resin..(or whatever your using)...we get it all done.....and then we find out we have a short somewhere.....there is tons and tonsof these posts here...about getting 1/3 or the power(3 phase)..now we have a junk stator...and trust me keyman...i can mail you a couple...my advice is to learn off the one your doing....then buy new wire ...hope this helps...good luck with your project...pickster

veewee77 · « **Reply #12 on:** October 30, 2007, 07:08:08 PM »

I do agree with other here about making connections inside a coil. But I disagree with some of the methods. Holding the two wire ends together and putting solder on the iron then on the wires in not a good connecting method.

You can't reliably 'paint' solder onto a connection.

Also, make a good 'mechanical connection' before you add solder. Then heat the connection and add the solder to the connection, not the iron.

A good mechanical connection of the 'inline' type you are wanting to use is to strip and clean the wire about 1/8 to 1/4 inch using fine (finer the better) emery cloth and not 'across' the wire but 'inline' with it. Then lay the wires side by side and twist them securely.

not like this =====xxxxxxxx

like this______XXXXXX_____

Measure ^ and ^ with the meter.

One wire one way and the other wire the other way, not both ends the same way, then twisted. . .if you can understand that. . .Make the twist as tight as you can without breeaking the wire strand and don't score the wire, if possible. Use your fingers (after a good washing to get the oil out of them) to help keep scoreing to a minimum. Once the connection is twisted securely, check resistance with the lowest setting your meter will do on the ends of the connection (not the ends of the wires). If your connection is open, cut it out and redo it. (open meaning no current will flow from it (the meter will not move)). Once you get a secure mechanical connection, then heat the joint with the iron and then apply the solder to the joint, not the iron. Use a rosin core solder not acid core! Clean off the excess rosin residue with the finest emery you have. Once this connection is finished, borrow the highest quality enamel nail polish the spousal unit has and coat the connection with it. At least 5 layers. Don't allow drips or runs in it, light coats are best. Wait for several hours for it to dry then wind your coils. This will be as reliable as it can get for this type of application and the space compromise will not be too bad with the nail enamel since it will be relatively thin compared to the heatshrink tube.

I said all that to say this, though. . . This is a "desert island" thing as others have said. What you will likely find, though is that your coils will wind with very few of these connections needed. Splicing inside of a coil is not recommended unless absolutely there is no other option.

Doug

pepa · « **Reply #13 on:** October 30, 2007, 08:57:34 PM »

hi keyman, what worked for me on one stater that i made with wire pieces was to burn and clean about a half inch of the ends to be spliced. next slip a shrink wap over one side then flatten the ends of both wires on a anvil or other metal object with a hammer. tin the wires and make a overlap joint. take your pliers and shape the joint back as round as possible and shrink rap. it does not make to bad of a hump and its tight. even if the coil heats to the point of melting the solder, you still have contact until the shrink rap fails and everything shorts. pepa

coldspot · « **Reply #14 on:** October 30, 2007, 09:12:16 PM »

"a "desert island""

thought,

Use some tiny copper tube,with just enough clearance for the wire to enter, rosin flux coated after cleaning off with emery or fine file and just pushed end to end inside and soldered with enough heat and heat sinks, (one I use often is a gator clip with a wick type tail sitting in same ashtray as foam oven cleaner type pad kept wet for cooling the iron's tip between joints and end cool down. The gator clip stays cooler longer with the moist tail).

This joint is nothing I've tried but might be workable.

When custom building the memory water blocks for my system, I picked up some very small tubing from the R/C type hobby store and have made many things and had many ideas with.

Mary B · « **Reply #15 on:** October 30, 2007, 09:31:36 PM »

good post. I totally agree that a strong mechanical joint is needed before soldering. A side by side joint may be smaller but as the wire heats and contracts that solder connection will eventually break and cause problems. They do make rosin core silver solder which is higher temp than standard 60/40. I would recommend at least that.

Keyman · « **Reply #16 on:** October 30, 2007, 10:08:06 PM »

I did some expiramenting with small lengths of wire. I filed a narrow groove in the top of a piece of a fire brick. Just large enough to lay two wires side by side . I used welders vice grips ( the kind with the split jaw turnd at a 90 degree angle to hold the wire in place. Then used the high temp silflos with a very small tip on my oxy acetylene torch and brazed the joint. the heat did not go beyond the jaws and the joint is rock solid. Any thoughts on using high temp engine spray paint to recoat the wire instead of heat shrink tubing?

Flux · « **Reply #17 on:** October 31, 2007, 01:32:54 AM »

The join will be absolutely fine and will cause you no trouble. Don't play with any spray on coating it will never work.

In theory you don't need to insulate the joint, you just need to be careful to make sure it doesn't scratch the neighbouring turns. Make sure there are no sharp edges and if the silphos has run decently it should be nice and smooth.

I wouldn't suggest that you leave it bare but I don't think it will be as stressed as the centre connection that others seem to bring out over the coil with no mechanical protection. Heat shrink sleeving will probably be the easiest to use and will shrink down to occupy little space. Alternatively if you have some thin Nomex you could fold that over the join so that it protects both sides, it is incredibly strong mechanically even at high temperature and will not cut through. Kapton would also do but is more expensive. If you don't intend to push the coils too hot Mylar would also be suitable but I think you are limited to 160C.

The man who let you have the wire and silphos may be able to help you with Nomex ( it is a trade name " Dupont" I think and there may be other brand alternatives, It is "aramid" based. I just aren't familiar with what you have available in N. America).

If you are careful I don't see any problem if you keep the bulges somewhere on the coil where you have plenty of room.

Flux

iamdewayne · « **Reply #18 on:** October 31, 2007, 06:15:59 AM »

Flux said:

I just aren't familiar with what you have available in N. America).

C'mon Flux, we have everything!!! ( except a car that gets descent gas mileage...)

Dewayne

patelvinod · « **Reply #19 on:** October 31, 2007, 07:12:04 AM »

How about this?

tecker · « **Reply #20 on:** November 02, 2007, 06:06:11 AM »

With all the work and money that goes into the stator it makes no sense to put solder joints in coil windings . Just make the connections outside the coil and your done,It's every bit as solid as any other winding.

Keyman · « **Reply #21 on:** November 02, 2007, 10:38:31 AM »

I have been leaning that way since your first post. Makes no sense to weaken the potential of the coil with a solder joint in it. Thanks for your input. I will be winding the coils next week maybe I will get lucky and not have to have any.

Keyman

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Author Topic: solder joints in coils (Read 6351 times)