3D printed power hacksaw

[CaptainObvious]

Here's something I did some time ago and haven't had time to use or work on since then until this week when I pulled it out of the drawer for testing.



It's a fully printed power hacksaw, well, except motor, blade and screws... but you get the idea.
In the video it's cutting a 1/4 inch thick by 2" wide aluminium angle extrusion, that is a bit of a torture test for the tool; it takes a very long time to go through it but it does the job.
A more powerful, faster motor should be better, this turns at 60RPM, 120 would be much better.

It's still a work in progress, there are some things I would change in the design, specially find a good clamping system and add ball bearings in some of the hinges. There's already a provision for a switch to turn off the motor when the saw finishes cutting, it's installed but not wired at the moment.

[soofle616]

Interesting concept. You could probably improve cutting efficiency if you were to match the lengths of the pivot links better making the whole system closer to a parallelogram. As is there is a noticeable upswing in the cutting action so you're only utilizing a very small portion of the blade at any given time. Making the saw move in a more linear fashion would keep more of the blade in contact with the work yielding more cut per stroke (though that could result in excess torque requirements).

[CaptainObvious]

Interesting concept. You could probably improve cutting efficiency if you were to match the lengths of the pivot links better making the whole system closer to a parallelogram. As is there is a noticeable upswing in the cutting action so you're only utilizing a very small portion of the blade at any given time. Making the saw move in a more linear fashion would keep more of the blade in contact with the work yielding more cut per stroke (though that could result in excess torque requirements).

Actually that would be a bad thing, since you need a certain amount of pressure on the cutting surface for the saw teeth to dig in and remove material, if you make the cutting surface longer the pressure is distributed over a larger area so cutting efficiency drops.
On the second half of the video you can see it cutting along the length of the aluminium extrusion, that doesn't work well at all, I need to find a way to mount the work piece at an angle. When the extrusion was mounted at an angle (as in the beginning of the video) it cut it at a reasonable speed.
Alternatively I could mount the stock material higher, that would force the blade to pitch up and down as it moves back and forth, thus creating a very effective cutting motion.

[curious aardvark]

Very clever :-)

[CaptainObvious]

Very clever :-)

Not so much... it's more a case of being a day late and a dollar short; I did this because a couple years ago gave myself a permanent Repetitive Stress Injury to the joints of my right ring and pinky finger by cutting similar stuff with a manual hacksaw.

I'll work on the design a bit more and then upload the STL files to Thingiverse.

[Roxy]

I don't want to take anything away from this. But what would have been really good to get me on board would be a mechanism where once it saws through the part you put in the holder, it just benignly goes back and forth and doesn't wear anything until you get around to taking the part out.

[jimc]

not the most productive tool on earth but cool none the less.

[CaptainObvious]

I don't want to take anything away from this. But what would have been really good to get me on board would be a mechanism where once it saws through the part you put in the holder, it just benignly goes back and forth and doesn't wear anything until you get around to taking the part out.

Actually there's a limit switch mounted on the base, you can see it at the beginning of the video below the screw that holds the blade in place. It's not wired yet but the idea will be to connect it to a relay so that when the saw cuts through the material and drops on the switch it will disconnect the motor.

[CaptainObvious]

Could it cut a 2.5 by 1 inch solid bar of aluminium? A bit to my surprise the answer is yes.
Veeeeeeery slow, specially because I'm running it at half speed, but getting it done!

IMG_1216.jpg

[araripe]

Hurry, hurry please. Great project. I really need it. Thank.