My '48 Int. KB-7 (Sanford)

[Joey Mack]

So here is my new field kit. No instructions with it.  My guess is I have to weld the copper tab to the back of the power stud.  Will solder withstand the amps, or will it melt ? I do have lead on hand if that is what I need. 

[Geoff Weeks]

I have used solder but I suspect silver solder would be better. At least you starting with all new and clean parts.

[mowerman]

it looks like it spells out good,,lol.ithink thier glued in,,,,,im sure someone has better advice,the main thing is they were available,,,

[Joey Mack]

Silver solder ?  I will buy some. I have a common solder, but dont know what it is made of. 

[mowerman]

try UTUBE someone might mention them

[Joey Mack]

Yes Bob,  I guess I can go to You Tube University. 

I prefer the Goeff Weeks Vocational Technical Institute when it comes to my KB-7...  

[mowerman]

well i dont blame you i just poked around and yes many guys cover them,,,good luck

[tjc transport]

normal solder is lead and tin. electronics solder has a flux core, plumbers solder does not and needs flux added to the surface before applying the solder to make it stick.

[Joey Mack]

I have all of those solders.. I just need to pick the one that wont melt when I crank the engine, on a day when it starts hard...  🍻

[Geoff Weeks]

Joey, If I were to do it over again. I'd buy a "jeweler's" air-acetylene  torch and a small tip. You need heat but in a smaller area then the typical oxy-acetylene, and go with silver solder. 

 I think that way you'll have the best chance of a permanent repair regardless of what voltage/current draw passes through the connection. 

 The key is the small, concentrated heat source. 

[Vladislav]

There are two basic kinds of solder. 40% tin with 60% lead and opposit - 60% tin with 40% lead. The 1st is generally used for electronics. It melts about... hmm, sorry guys, about 200C. That's that solder you find with flux put inside. The other kind has higher melt temp and higher mechanical strength. Here it usually sells as thick sticks. It's more for mechanical jobs and can be used with solder acid for work with steel and SS. But for some reason I haven't had much luck using it (not enough skills?) 

[Geoff Weeks]

Silver Solder is a bridge between brazing and soldering. Silver content can vary with higher silver content having a higher melt point. In this application both the ability to hold the pole windings to the stud when heated and the ability of silver to conduct better then "soft solders" are a benefit. 

[Joey Mack]

I have solder with silver, and a small  propane torch. Will my brazing tip be better ?

[Joey Mack]

Ok... so I was also thinking about drilling a hole in the windings strap and the center of the power stud and tapping it to accept a small bolt, then soldering it... Thoughts ??

[Geoff Weeks]

There isn't a lot of room in there, so I don't think there is a mechanical means to tie them to the stud.

 I tried propane and found it wasn't hot/concentrated enough. I used my smallest oxy tip and worked fast, but as I said, If I had to do over I'd use a jewelers torch.

The way I did it worked, but was less than ideal. some of insulation wrap got hotter than I'd like.  Mine still work just fine. Every time I have to crank a bit to prime, I cringe thinking "you dummy, you should have silver soldered it"!

 I'd "dry fit" the field to the stud then push the stud away from the case and insulator (to minimize the heat transfer to the case) and solder.

Edited 1 hour ago by Geoff Weeks
typo

[Joey Mack]

Thanks GW.. how about , I line it up in mock up, mark it and take it to a jewler and pay him to weld it ?? 

[Geoff Weeks]

The issue /question is can you get the stud in place with the field welded to it? I hadn't pulled my field pole shoes, so there was very little room to work. 

 With the pole shoes out you should a lot more room/options, but I didn't do it that way, I was just trying to repair a connection that had broke loose.

With the pole shoes bolted in there isn't enough movement in the ends of the windings to do much more than depress the stud away from the case. 

So not having done any repair with the pole shoes out, I can't give concrete advice on what is possible.

[Joey Mack]

got it.. yes it is tight and the strap may not bend enough to allow the stup to be installed with its insulators...   I will use my silver solder and propane torch on a practice piece 1st. If it is not hot enough I will get a MAP GAS cyl.