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Not so common Double Bladed Hack Saw

rivett608

Diamond
Joined
Oct 25, 2002
Location
Kansas City, Mo.
I have wanted one of these for a while and now have a nice one. It is a late 19th or early 20th century Double bladed Hack Saw....... you could put a fine blade in one side and course in the other or different thickness blades for screw slotting? This one was shop made by a Mr. Otis...... I think the only company that produced these for sale was L.L. Davis in Springfield, Mass back in the 1880-90's.......

The saw is about 15" long total...... anybody have one?

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Mr. Otis was a rather talented tool maker!

The tension adjustment is nicely made and self explanitory....but does the handle crosspiece have any play at all? I'm wondering how both blades would be kept at proper tension if there was any slight difference in their length.
 
Rivett608:

Needless to say, this is a beautiful piece and on belhalf of everyone, I thank you for posting it.

George,

I think the mathematical concept that "Three Points Define a Plane" is in play here. The design does guarantee that both blades are tight provided that there is some "play" in the adjustment mechanism. It does not require much play if the blades are close to the same length.

Your question was very thought-provoking - exactly the kind of thing that makes PM so interesting.

Until I saw your question, I had this WILD FANTASY involving the now-discontinued Starrett screw-slotting hacksaw blade set. That was a four-piece set. I had a brief vision of a "cruciform" verson of this saw with four blades, they being the four blades from the Starrett screw-slotting set. After reading your question, I realized that you can get two blades tight at one time, but not more than two, with a single adjuster. My four-blade fantasy is impossible except in a very complex two-adjuster version.

John Ruth
 
Rivett,

It is a neat item. But, I think its use is clear - Jail Break! Note the two hacksaw blades are perfectly spaced to allow the cutting of one cell bar on each blade with one sawing motion. That is, two bars in one sawing motion!!!! Just enough space to squeeze through.

I suppose the unanswered technical question is does one orient both blades in the same cutting direction or in a push-pull cutting orientation?

Oh, and I have heard on the street that the under bidder's wife is having 'associates' look for you, but I'll never let on your in KC, MO.

And, at least it is not as ugly as that ugly lathe you posted!!!

:cheers:
 
Actually, I think a "triangle" version blade holder would work. Three points/blades describe a plane, of course.

Just the kind of thing that engineers fantasize about, of course.

Joe
 
Mac... I think the blades in opposite direction would make for the fastest and most even sound to get through the bars...... I guess one's needs a bigger cake to get it into the jail?

John & Joe I like that idea of a 3 or 4 bladed saw...... I see how the 3 would be easy..... on the 4 I wonder if.... lets say you have a cross and the 9 and 3 o'clock tighten from the top and the 6 and 12 o'clock tighten from the bottom???????

On this one there is a little play and the top is keyed so it does not turn.
 
Well, now South Bend's remark got MY mental processes going. In order to have a four bladed "cross" hacksaw you'd need four separate tension adjustments........but they could be quite attractive with four matched old style wingnuts.

Might be hard to use in close quarters though..........:)
 
Neat saw, thanks for the pics.
Being a Davis level guy myself, I do have a couple of the Davis hacksaws, but they are single blade. Never saw a double blade Davis saw, or any reference to one.

Mel :typing:
 
4 blades would not be a problem if you had a hemispherical washer pair or other convex/concave bearing between the hex nut and the "+" shaped blade holder.

If you want to get fancy- put an autoindexing mechanism in the handle. After every X srokes it rotates to the next blade...

In all seriousness though- it is a nice bit of work.
 
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Thanks for posting - a really interesting device. I find myself wondering what it would be like to use. Have you tried it? That knob doesn't look as though it would be comfortable to hold for long, and there's no obvious place to grab the forward end of the frame as there is on a normal hacksaw. Could this be why it never caught on?

George
 
Found another one in my shop!

For all those wanting to make one.... here is a easier way...... just send me $ 20 + shipping and I'll send you this one! I found it in a drawer in the shop... I bought it years ago...... it is not nearly as nice as the one above but then it is about 1/5 the price. It takes a blade about 9", the handle is some sort of plastic, it is mounted a little off center (this was not made by as fine of a craftsman as the one above)... has some surface rust on it and a few paint splatters.... 1st one to email me (and pay) gets it... email at wmrrob - at - gmail -dot - com

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