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Bandsaw Brazing Fixture

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Forum topic by Arcola60 posted 11-11-2014 02:41 AM 1037 views 0 times favorited 9 replies Add to Favorites Watch
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Arcola60

93 posts in 1849 days


11-11-2014 02:41 AM

I just finished fabricating my band saw brazing fixture. It came out really nice. I am looking forward to making my band saw blades. I bought some coil stock and used the blade welder @ work. It did ok but alignment was off. No matter what I tried, it was just not right. So I did some research, and decided that brazing was the way to go, for me. I used 1 1/2”angle iron 12” long. Drilled 4- 5/16” diameter holes (in a Bridgeport mill) to ensure perfect alignment. Installed hardened roll pins in those holes. Made 4 adjustable clamps for different blade widths. Relieved the middle .875 wide X .875 deep.
I have not used it yet, I will make a fixture to grind a 20 degree scarf joint. I have 1/2” blade material, 1/4” is on order. Also shown: 56% silver solder, and flux.
I could not find any info on, if I should leave a few mils gap (.010) for the solder to flow. Or should I just butt the ends together. I am inclined to leave a gap. Any info would be very appreciated. Thanks.

Ellery Becnel


9 replies so far

View Woodmaster1's profile

Woodmaster1

737 posts in 2052 days


#1 posted 11-11-2014 03:28 AM

I used one I purchased 20 years ago. I used silver solder and the instructions had me grind a taper on each side so it would overlap. It work ok, but I have not used it since the silver solder ran out. I still have it. I will try to dig it out and take a picture.

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johnstoneb

2145 posts in 1638 days


#2 posted 11-11-2014 01:30 PM

If you leave a .010 gap you will have a weak joint. butt them together the solder will flow in and adhere to both surfaces.

-- Bruce, Boise, ID

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Loren

8311 posts in 3113 days


#3 posted 11-11-2014 02:22 PM

I scarf the joints using a grinding stone on my drill press
and a block to rest the blade end on… about 20 degrees
I think.

When I solder I apply flux to the scarfed ends and put
the blade in the fixture with a little gap for the flat solder
in between. I have tried putting the solder on the
flux and then putting the other blade end over it
and inserting the solder into the gap. Both work. I
try to get it so the bulge in the soldered joint is
minimized, which makes grinding easier. If you get
it right grinding is almost not needed.

I have not tried to do it with round solder. I have read
of people hammering round solder flat.

View 1yeldud1's profile

1yeldud1

301 posts in 2507 days


#4 posted 11-11-2014 06:16 PM

this is very similar to what Ihave built. I tried to use a blade welder at work and also a tig torch to weld my blades wuith little results. I built a similar jig. I normally USE 3/8 blades and the ocassional 1/4 blade. I do a scarf joint by hand and align the angles in my jig normally trying to have about.010 gap in the joint. i use standard silver solder (not shure with out look as to what the ratio is) I use a small hand held propane torch and have excellent results. I have even taken my jig to my place of employment and built them a few blades when they accidently run out _ one thing to be shure of is to allow a little extra blade length for the scarf joint when cuttin the bladesw to length – also clean the area to be soldered with a good cleaner to remove all oil and grease

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Loren

8311 posts in 3113 days


#5 posted 11-11-2014 06:21 PM

I use tweazers to handle the solder and avoid touching
the ground scarf with my fingers. I have a theory that
may be unfounded that finger oil can mess up the
joint.

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1yeldud1

301 posts in 2507 days


#6 posted 11-11-2014 10:12 PM

I always take a piece of scotch bright pad and lightly sand the silver solder just to remove oil and the tarnish. Clamp the blade in the fixture and have about .005 to .010 gap – take a small toothpick and put a “touch” of flux in the middle of the scarf joint then take your propane torch and lightly heat the joint until the flux starts to melt/run. Then take your silver solder and touch it to the blade while keeping the torch moving in a circular motion under the bottom 1/2 of the blade. it only takes a touch of solder as the flux will ‘pull” it right into the scarf joint. and your joint will be just fine. You might have to possibly file a small portion of the flux off of the outside of the blade – so it will not get stuck in the blade guides. As you do a few of these you will get a “feel” as to how much solder to use – Hope this helps – oh by the way if your solder flux becomes dry and stiff you can just add a very small amount of water to freshen it up – just remember not TOO much water

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Arcola60

93 posts in 1849 days


#7 posted 11-12-2014 12:55 AM

Thanks everyone for all of the helpful information. All of the comments verified what I have thought to be true.
As soon as I get set up and make some blades I will share my results with everyone.

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Arcola60

93 posts in 1849 days


#8 posted 11-24-2014 02:38 AM

Well I finished making a simple clamping fixture to grind/file a 20 degree scarf joint. Then I made a few blades. I went with .005 gap between the joint. It worked great. I made one for my friend, he has an Italian made 18” saw. This will be the test. I will update as it happens.

View waho6o9's profile

waho6o9

7174 posts in 2042 days


#9 posted 11-24-2014 04:38 AM

Excellent

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