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+--- Thread: Bandsaw blade soldering (/thread-4389.html)
Bandsaw blade soldering - JScott - 01-28-2022
My BIL here in Colombia has a pretty large bandsaw in his wood shop. They go through a lot of blades and to help out I offered to start soldering blades for him. They have to run to a town 2 hours away to have blades repaired so this will help him a lot. I've never tried soldering like this before, but after researching, reading and watching some videos it didn't look too difficult. We picked up the needed materials on our last trip to the big town (Monteria). We bought new blade stock, silver solder (don't know the composition), flux and a torch head with two bottles of MAPP gas.
I was planning on building a fancy jig to hold everything in position nicely but my brother was in a hurry and said "C'mon let's test this stuff!" although he said it in Spanish. I made up the jury rigged arrangement below and took a run at it. As you can see we are outside in a windy, dusty environment so results were a little inconsistent. The first attempt didn't work because we were working on an old, rusty, 1/4 inch blade and it was hard to get it down to clean metal. I used a broken C clamp to hold the blade on the left hand side and a pair of vise grips to hold the blade on the right hand side. The skarf bevel was done by hand and eye on the side of the bench grinder stone. The blade was aligned by eye.
[attachment=17579]
The second attempt was better and a tip of the hat to TomG for tips from his YouTube video. This joint lasted for two days of hard use on wood varying from 2 to 6 inches thick. Pretty good for a 1/4" blade!
[attachment=17580]
I didn't have a sander, grinder or file to dress down finished braze so I very gently ground down the surplus with the bench grinder. It looks terrible but it worked. I did another blade yesterday which was a new 3/8 inch blade. I used the same jig and it was a struggle to get a good joint. I think the issue is working outside in the wind and dust. I finally got a decent bond and it was running when I left! We'll see how long it lasts. I gathered up some pieces of angle iron to make up a proper jig and I'll try doing the soldering here in my clean dust and wind free shop.
One of the interesting asides is that this band saw has been in use for several years. They have never brazed/soldered any of their own blades. As soon as I started with my attempts everyone had advice on how to do it. I should be using a different flux. Use brass/bronze instead of silver solder. The blade joint should be vertical instead of horizontal so the solder would run differently. The joint should be a lap joint instead of a skarf joint.
It's a cultural thing here and I find it cute. It used to be annoying but I'm retired now and pretty much have all the time I need and can ignore all the static and keep doing what I have seen in every illustration, video and article on blade soldering until I get it right. I'll add a picture of the Mark II jig when its finished.JScott
RE: Bandsaw blade soldering - vtsteam - 01-28-2022
Good for you.
I just silver brazed a bandsaw blade on my Duplicarver 24" 3-wheel bandsaw a few days ago. Three wheel saws go through blades faster than 2 wheelers because the bend is sharper, and they bend three times per full blade revolution instead of two. It would be expensive to keep this saw in 11' blades if I had to buy them instead of make them up.
RE: Bandsaw blade soldering - awemawson - 01-29-2022
I'd have thought you'd have a blade welder by now Steve.
RE: Bandsaw blade soldering - JScott - 01-29-2022
Roger that on the cost of the blades. These blades are just over 12 feet long so the cost to get them made up is pretty high. We're going to order blade in bulk rolls from Medellin which will really help save some money.
RE: Bandsaw blade soldering - vtsteam - 01-30-2022
(01-29-2022, 03:26 PM)awemawson Wrote: I'd have thought you'd have a blade welder by now Steve.
My working metal shop is 6' by 8', Andrew. I braze a blade maybe once a year.
RE: Bandsaw blade soldering - awemawson - 01-30-2022
ah - fair do's .
I thought that you had quite a large wood mill set up to service the blades from - was that just while you were building you house?
RE: Bandsaw blade soldering - vtsteam - 01-30-2022
(01-30-2022, 01:30 PM)awemawson Wrote: ah - fair do's .
I thought that you had quite a large wood mill set up to service the blades from - was that just while you were building you house?
I do Andrew, a homemade sawmill, but that is outdoors -- I don't repair those blades -- I've never broken one, and they used to be quite inexpensive -- by comparison with blades for the smaller saws I own.
I do sharpen those sawmill blades, but never have had need to weld one. Not sure I'd want to take the risk of brazing blades that big vs. buying a new one for $25.
RE: Bandsaw blade soldering - JScott - 02-11-2022
As promised here is the picture of the second soldering jig. It's my design but I didn't do the welding. I left that to my BIL. Looks a little rough but everything came out square and straight.
[attachment=17694]
And the update. Bad news. The silver soldering was not a success. I tried everything with the materials on hand. I used a flux call Flux-4. I used straight borax. I used paint thinner, Scotch Brite and sandpaper to make sure everything was clean. The soldered joint just would not hold. My deduction is that the silver content in the rod they sold us is too low. The rods are rectangular in cross section and about 1/16 x 1/8 inches. They are marked TW-O. No clue what that is or what it means and google was no help.
So, when we bought the silver solder we also got a piece of brass brazing wire. It's about 0.040 inch in diameter. After having no luck with the silver solder I decided to try the brass to braze the joints on the band saw blade. I ground the same scarf joint as before, fluxed it inside and out with borax mixed with a little distilled water and hit it with the MAPP gas torch. Once the flux turned clear I held the rod on the joint and kept the flame on the joint from underneath until the rod melted. It took a while and the joint was at a bright red heat. When the rod melted it flowed into the joint just like it should. I made up 4 blades that are 152 inches long (3860 mm). We can buy wood cutting blade by the meter for 13,000 pesos per meter. That's about $3.50 a meter or $1.05 per foot. Strangely the price is the same if you buy 1 meter or the whole 30 meter roll so we just buy what we need.
Next is a sharpening jig/method to keep the blades tuned up.
Thanks for looking,
JScott