I recently decided to learn how repair my broken bandsaw blades, but am having some trouble getting a good joint. Everything lines up well and the solder seems to be well connected, but when I grind down the new joint, it becomes very weak and breaks again after a few secconds of cutting. I realize this is a vague question, but any suggestions. I am using a small butane torch and metal working solder.
Thanks, Richard
Wrong stuff, in my opinion. You need to be using silver solder or braze. They require higher heat, but the strength difference is substantial. You need to scarf the joints to increase the bonded surface.
Here is decent article:
Way back when, DoAll provided a butt welder for blades as part of the saw.
Doubt a soft solder joint will work.
Lew
Interesting, I would never have thought of doing it that way. Perhaps because many, many years ago, in using a large metal cutting band saw, we had a blade welder built into the band saw.
It worked this way. We would square the but edges, then mount them into the welder. One end clamped on one side and the other end clamped on the other side, each to a set distance apart. Then we moved a lever which moved the two ends together and spring loaded them to force them together. Next we pushed a button and electric current passed through the blade between the clamps and caused the blade ends to go to white hot and the spring pushed them together to make the weld. There was an automatic cut off of current. Then after it cooled slightly, we pushed another button and it then passed an annealing current through the weld joint. Then we would be able to take it out of the welder and grind the weld flat on each side on an adjacent built in grinder. The came out perfect every time.
I have no idea how much one of those blade welders cost today, and I am sure that I would not have enough use for one to warrant buying one. So I like your idea of braising, but would shy away from silver solder as being two weak for a but joint.
Even so, I still see a need to anneal the joint after braising it, else the blade will be too brittle in that spot, and will bread again soon.
Zap
Thu, Nov 30, 2006, 12:13pm (EST-3) snipped-for-privacy@msn.com (Richard) doth lament: I recently decided to learn how repair my broken bandsaw blades, but am having some trouble getting a good joint.
Apparently you're using the wrong recipe.
From WordNet (r) 2.0 (wn) braising n : cooking slowly in fat in a closed pot with little moisture
JOAT I am, therefore I think.
Look for information on "brazing", not "braising" and I think you'll have more luck than you've had. You can find blade welders for as little as
130 dollars however they don't automatically pass the annealing current, you have to anneal with a torch, and of course no built-in grinder.Hi J. Clarke,
Thanks for the spelling lesson. I needed that, since I never finished grade school, they wouldn't let me past the 3rd grade so I quit when I turned 16. And They didn't teach the difference between those two words when I was in school 60 some years ago, then again I just may have been sleeping the day they taught the difference between Brazing and Braising.
I guess I will have to give my spell checker 100 lashes with a wet noodle to teach it how to tell the difference. Or maybe not, for all I have to do is to post it here, and YOU will correct all my spelling errors for me. That will be easier than blaming my spell checker. And my arm will not get so tired beating my spell checker with that wet noodle.
I hope that next time that you will also do the grammer checking for me also.
Thanks again for the spelling correction.
Zap
J. Clarke wrote:
Nope, only those that will get you bad results in a search engine, and then only if I am in the mood.
Oh Woe is me, I guess I will just have to go on and give my spell checker those 100 lashes with the wet noodle after all (grin)
Zap
J. Clarke wrote:
That's not a spelling correction, both words are spelled correctly. JC was just (politely IMO) telling you that were using the WRONG word. I'll have to check it out, I bet if you DAGS on "braising bandsaw blade" some of the returns will have to do with butchering techniques, cuts of meat, and cooking. If you search of "brazing bandsaw blade" you are much more likely to find the information you are looking for.
What's the solder and what's the bandsaw size?
IMHE, you aren't going to have much success using hard-soldered joints on a bandsaw with small diameter wheels. On a bigger machine (18" upwards), particularly for metal cutting rather than wood, they have less flexing and might survive longer. If it's a small machine though, you need those think butt welds.
As to solder, then silver solder is really the stuff to use (easiest too and doesn't need any more ehat than a butane torch and a firebrick). Soft solder really hasn't got the strength or the fatigue life. Brazing tends to give a bigger lump.
So don't grind it down. If you're having to solder, then live with the lump. Constant thickness really demands a strong resistance butt weld.
Lets not get too serious about this. I believe that both JC and my self were both writing with "Tongue in Cheek". That is just having a bit of fun with each other. I did not take it serious, and I don't think JC did either. I recognized from the beginning that it was all in fun. And I hoped that everyone else did also. The fact is that I did enjoy JC's emails.
Zap
At 16, you must have been the biggest 3rd grader in history.
Happy to help.
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