Hi all, firstly, no laughing.
I'm a woodworker not a metalworker (although I'm trying)
Secondly, this is my first attempt to post a mini tutorial on this forum, so bear with me.
Here is a band saw blade holder for when I used to have a small band saw and break blades frequently.
These are your basic ingredients:
Basically a piece of square tubing with a slot cut out in it and some flat metal, both about the same length.
Drill some holes to match whatever size bolt you wish to use and use a tap to make a thread in the tubing only.
Place in a vice to hold the jig steady.
You then simply break a blade or two (I was getting quite proficient at that!) then file/sand/grind the two ends to form a scarf joint.
Solder away until your heart's content or you finish the solder joint
As you can see from my soldering, I am a woodworker
Judicious use of a grinder will smooth the blade after soldering and make you look like a better metalworker, but don't be fooled.
Hopefully this post works. Feel free to ask questions - somebody more skilled than me will be able to answer
By the way, this was from many years ago - I now have a much bigger industrial band saw and have never broken a blade. Just as well, since I can't find the jig anywhere.