[TheForge] Band saw (Was: Vise squad)

[Ralph Sproul]

Thanks Mike, that gives me enough info to try tig vs braze on a couple of
bad section blades I've saved for a rainy day.

When I was 10 I used to go to work with my dad and hang out at the line
shaft driven machine shop.  It was cool.

"Since I'll do any amount of work to avoid work"   ......... Sorry, but I
might have to borrow that line in the future.    :-)

Ralph


----- Original Message -----
From: "Mike Spencer" <mspencer at tallships.ca>
To: <theforge at mailman.qth.net>
Sent: Sunday, May 08, 2005 3:37 PM
Subject: [TheForge] Band saw (Was: Vise squad)


>
> Ralph quoth:
>
> > ...you've gone from a chevy cavelier friction wheel to a line shaft
> > and flat belt...
>
> Did the lineshaft years ago for the 100# Palmer hammer and later
> hooked up a 25# Jardine. Worked okay but there were numerous
> um... flaws, especially noise.
>
> In the new shop, I did it more or less right.  Motor overhead, proper
> kind of switch, no noisy transmission.  And closer (very close) to the
> recommended speed for a 25# LG.  The previous owner ran it straight
> from the 4" pulley on the motor to the hammer -- wayyy to fast --
> and it's a wonder he didn't tear the hammer to pieces.  The line shaft
> gets me the right speed.
>
> The Cavalier Revolutionary Alldays Powerplant was later and
> umm... experimental. :-)
>
> > Is your whole place run off a line shaft?
>
> No, it's just for the 25# hammer.
>
>  I always kinda wanted that, though.  I fell in love with that stuff
> when I was a kid, the first time I was in a big shop all on lineshaft.
> But I have another piece of shaft, a set of bearings, some pulleys and
> a neighbor with more pulleys.  So I may yet get more stuff hooked up.
> There's the band saw, and I have my eye on a huge pedestal grinder
> that the present owner isn't quite ready to part with.
>
> > Or was the band saw that vintage...
>
> That vintage: Big old cast iron thing, 24" wheels, Babbitt bearings,
> two flat pulleys (one drive, one clutch idler), 24"x24" tilting table.
> Weighs maybe 800#.
>
> > ...so you were test firing her for blade testing?
>
> I finally wanted to actually *saw* something.  Our house has a
> (so-called) breakneck stair in the front hall built about 1880.  Nice
> turned newel post but the handrail and balusters have been missing
> since forever.  I finally decided I wanted to make a replacement
> handrail from the 8' piece of red oak I saved out of the woodpile 4
> years ago.  Since I'll do any amount of work to avoid work, I'm
> setting up the band saw to saw that piece of oak instead of setting up
> to do it with chainsaw and adze.
>
> > My question to you on the brazed blade repairs is the slight bevel
> > your mentioning is square to the blade? or did you bevel them like
> > you'd weld a truck frame and angle that slight bevel with the length
> > of the blade to get more surface area for the braze?
>
> The former.
>
>    Cut the blade with a Beverley.
>
>    Got a good smooth or 2nd cut file.
>
>    Filed the end square to the length to the blade.
>
>    Filed the cut end to almost but not quite a chisel edge. That
>    "almost" allows you to see that the bevel is even.  It also means
>    there's not an edge so thin that it'll burn up during brazing.
>
>     ----------------   --------------------
>                     \  \                        Edge view
>     -----------------   -------------------
>
>
>
>     ----------------+  +----------------------
>                     |  |
>                     |  |
>                     |  |                           Flat view
>                     |  |
>                     |  |
>                     |  |
>      | /| /| /| /| /   | /| /| /| /| /| /| /| /|
>      |/ |/ |/ |/ |/    |/ |/ |/ |/ |/ |/ |/ |/ |
>
>
> This is a fairly coarse, ca. 1-1/4" or 1-1/2" wood cutting blade that
> I think was new old-stock from a bargain bin.  Right width but way too
> long so I had to cut it down.
>
> > The jig I'm guessing is just a way to hold the blade flat and
> > straight while brazing? are you leaving the center open for flow?
>
> Exactly.  Just a cutaway in one side of a piece of 1-1/2 x 1-1/2 x 1/8
> angle.  The inside corner of the angle iron is radiused as it comes
> from the mill.  Aligning the blade against the radiused corner is
> unreliable, so there are shims to raise the blade enough so that its
> back edge aligns on the inner face of the angle iron and not on the
> radiused inner corner.  Very crude.  If my braze lasts long enough to
> do some real work, I'll refine the jig a bit.
>
> > ...there are five "repairable" blades for when I'm real bored and
> > want to try my hand at electric annealing - or Mike gives me the true
> > secret to success in brazing blades.  :-)
>
> It's an awful thing for a guy with a background in physical science to
> say, but:
>
>        "I got back as soon as I could", says Coyote.  "I was busy
>        being a hero."
>
>        "That's unlikely," I says.
>
>        "No, no," says Coyote.  "It's the truth."
>
>        "There are no truths, Coyote," I says.  "Only stories."  [1]
>
> So here's a story: I haven't seen an electric blade welder in
> operation.  But I *have* seen and used a butt welder for ca. 6mm wire
> at a Michelin wire mill.  You ground the ends nice and square first.
> Then the gadget clamped the two pieces co-axial and with only a little
> stock unsupported between the clamps.
>
> The clamps are attached to the power cables and one is on a slider.  A
> spring presses it toward the other clamp but it's held back by a latch
> while you set up for a weld.
>
> Now release the latch and the spring presses the two butt ends
> firmly together.  When you hit the power switch, the joint glowed dull
> red, then bright red and the two ends mushroomed a bit under the force
> of the spring.  The small amount of movement in the clamp (that
> occurred when the mushrooming happened) tripped a microswitch and
> turned off the current.
>
> The you ground the joint smooth and it was strong enough to go through
> a rolling mill train without snapping.
>
> I forget now whether you could adjust the spring tension, the current
> or both.  But obviously, getting those two variables just right for the
> size and composition of the wire would be the trick.
>
> I don't know if that would work with something as thin as a saw blade
> or not.  Be interesting to try.  Or maybe only worth it if you had a
> dozen blades to do every day.  (I have a Foley Saw Filer that is just a
> whiz.  You can file a hand saw perfectly in maybe 5 minutes.  But it
> takes so long to set up for a particular pitch, rake etc. that it's
> easier to just file a saw by hand in a vise.)
>
>
> Also, you're talking about bi-metal metal-cutting blades (right?).
> That might be a whole 'nother story.
>
> - Mike
>
>
> [1] Thomas King, "Green Grass, Running Water".
>
> --
> Michael Spencer                  Nova Scotia, Canada       .~.
>                                                            /V\
> mspencer at tallships.ca                                     /( )\
> http://home.tallships.ca/mspencer/                        ^^-^^
>
> --
>
>
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