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Old 06-04-2010, 11:57 PM
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Default Power hacksaw question

Couple days ago I got a power hacksaw.
Fella said that it made a mess of lighter weight metal, but did fine on heavy stuff. He said that if you held the end of the 'saw' up a bit while it cut it was OK and didnt try to wreck anything.

So, today I coerced the thing into the shop and had a good look at what I had.
Spun it all by hand ( got no 3 phase and have to swap the motor over ) and it did everything it should smoothly and in a straight line.
Did notice however that the teeth on the saw were pointing backwards. I would have put in round the other way and had the saw cut on the push stroke.

Which way is correct? Or does it not matter?

Was going to fit a finer tooth blade to see if that cured the aggro on thinner metal. Got a suspicion that the thing would cut better on the push anyway......but maybe not.
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Old 06-05-2010, 12:03 AM
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Aj, I've always seen them cut by the teeth pushing against the fixed jaw of the vise.
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Old 06-05-2010, 12:07 AM
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In this case the fixed jaw is at the back, which could explain why it is set up the way it is.

Might need to futz with it and see if one cuts better than the other on thin stock.
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Old 06-05-2010, 12:14 AM
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A power hacksaw cuts on the same stroke as you'd cut with a hand-held hacksaw, i.e. on the forward or push stroke. We've got an old Racine power hacksaw in my industrial maint. program, and the fixed side of the vise in on the right side (when looking from the front), and the saw cuts right to left. When the blade returns from it's cut stroke, it should lift out of the kerf, and not cut at all until it cycles back. I've had no problem cutting 1/4" and thicker stock with ours, but for thinner, I have to sandwich the part with some wood to add a little surface area and stiffness for the blade.
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Old 06-05-2010, 01:45 AM
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Ironman is right and that is usually also toward the hinge. If you are having trouble with light materials go to a finer blade and reduce the weight on the saw. There will be some form of weight adjustment, cylinder, sliding weight, counter weight or something to control the push down on the blade. For fine cuts you will need little on the blade.

This type of saw really shines when gang cutting or cutting bar over one inch.
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Old 06-05-2010, 06:45 AM
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Thanks guys

I always thought they lifted a little out of the cut for the return as well, but I couldnt see anything obvious when cycling it by hand.
When I get the motors swapped over I will have to see how it behaves with a bit of steel to work on.

The blade assembly is pretty heavy as it is, but does have a front handle that is just a rod so a weight could be added if need be.

If for some reason it just proves too heavy and will not deal with thinner stuff, I think I could make some sort of spring attachment that will hold some of the weight up.

The last 2 bits of steel I cut were 32mm thick and done with an angle grinder. Took about an hour for that little effort. It starts to make you look for a better way pretty fast.
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Old 06-05-2010, 09:23 AM
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I have one thing to say about your power hacksaw -- Pictures, where are the pictures??
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Old 06-05-2010, 09:39 AM
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Quote:
Originally Posted by Harvuskong View Post
I have one thing to say about your power hacksaw -- Pictures, where are the pictures??
Me too cause im lost.
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Old 06-05-2010, 02:14 PM
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Powered hacksaw video. If I did this correct.

I sure would like to have one myself.

http://www.youtube.com/watch?v=6BvhZxfMPDU

Scott
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Old 06-05-2010, 03:10 PM
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I have a 4" x 4" Keller, from about 1948, thats waiting for a new mounting base, I got it in a deal with the late FIL. They are fun to watch, but slower than death in operation. The usually set up procedure for a 3" diameter steel rod, is set it in the vice, start the machine, go in and watch the movie Gone With The Wind, about the time in the movie when Atlanta burns, the cut will be almost complete. Again fun to watch, but slow, comparing them to a modern bandsaw, is like comparing the Wright Bros flyer to a modern jet fighter, both are airplanes, but diffidently worlds apart.

In the Keller manual, they state the cut is done on the back stroke and the blades slightly lifts on the front stroke, as the blade can flex when being pushed thru the metal, but will not while being drawn thru the metal. And as such, the teeth on the blade face toward the fixed part of the vise, which is back toward the rear of the saw.


jack
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Last edited by platypus20; 06-05-2010 at 03:17 PM.
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