3D Printed Linkage Produces Automatic Hacksaw!

The more tools you have the better. Unfortunately, not everyone has the space, or the money for full-size equipment. Looking to expand his maker capabilities, [Bruno] had the clever idea to turn a hand-tool, into a power tool. One we’ve never even seen before — a powered hacksaw.

Using his 3D printer he designed a linkage system, not unlike a steam locomotive drive to turn rotary motion from a geared motor into linear motion. Not only that, it also angles the hacksaw as it goes. 3D printed brackets hold the hacksaw in place, and weight can be added to the top to adjust the cutting speed. He even 3D printed a guide for his vice to line up the material to where the blade will cut.

It’s a bit slow, but it’s fantastic at making cuts!

And if you want to make your own, he’s provided all the source files too.

And the ultimate test — will it cut steel?

Wanna take the project to the next level? Why not go all out and build a full-size bandsaw?

35 thoughts on “3D Printed Linkage Produces Automatic Hacksaw!

  1. You have never seen a powered hacksaw? its a entire commercial genre of machine tools.
    Sorry but my jaw is dropping at that line written by a editor.
    I have two commercial ones (one is a beast weighing in at 3/4 a ton, and the second is portable and on little wheels), and they are slow but they are also automated so you can leave them to cut.
    In the UK they’re known as manchester saws occasionally, or donkey saws, but powered hacksaw will produce millions of results on google. The only reason they are not more prevalent is a bandsaw will be quicker but the hacksaws are cheap to run long term and can be left to chomp through large pieces while you walk off and do other jobs.
    This is my small portable one, its the classic layout, guides and hangs the frame from them.

    And the monstrosity :-

    Myford boy has made his own too.

    Kudos for 3d printing one, be interesting to see how long lived it is in comparison to a homemade one using steel/aluminium as the materals and built the traditional way.

    1. How weird. My friend has something that I believe performs a similar task except it’s more of a horizontal band saw with a hinge at one end. It also has weights so you can adjust how the saw bears down on the object being cut. Wouldn’t the hacksaw design wear the blade out faster?

      1. Not sure on the one in the article but a pack of power hacksaw blades will last large amounts of time because they are stiffer and taller and more rigid and are all hard composition because theyre not designed to be held by a wobby handed apprentice in use and live in ideal conditions. I’ve been running the little saw for 7 years now and I’m only on the third blade because I just leave the same tpi blade in all the time. In the same period I rebushed all the linkages and put new bearings in the motor because I got tired of listening to the thumping of the sloppy linkages for longer periods when they got worse due to the amount being stuck in it, so it was working away.

        The big saw, I’m still sourcing blades for as it takes 0.5m blades. I don’t expect I’ll need more than a handful to accomodate the different tpi’s I want to cover. As it has suds and hydraulic load control, in my hobbyist workshop they will probably outlast me.

        I have a doall vertical bandsaw, and I’m probably replacing the band in that a couple of times a year because it tends to shed teeth if it snags. I’ve never owned or ran a horizontal automatic bandsaw to be able to compare blade life to a donkey saw though. I’d imagine because they cut faster, more heat is generated as a result and they wear more. If one ever follows me home for scrap money I’ll give it a go and see.

    2. Tech Journalists have a variety of actual experience and knowledge levels…. Everyone constantly learns new things though – despite a decade in and out of machine shops, R&D labs, and so on – I still learn the names of new basic hand tools on a semi-regular basis, not to mention more specialized devices, processes, materials, etc.

    3. That a Hackaday contributor was previously unaware of power hacksaws is a jaw dropping event, itself is a draw dropping for me. Why would anyone who was unaware of power hacksaw, think of doing a go web search for them? I have a metal cutting band saw. I’m able to start it on a cut on it and leave it to finish the cut just like did with the machine shop grade power hacksaw I had.

  2. Adding a weight to the end should help. I have seen these, but they usually move back and fourth along a slide so the motion is completely linear. I even a dangerously fun prototype of a high speed version! This looks nice and polished, and perfect when you just want to walk away and leave something cutting.

    1. If you search myfordboy’s video’s on youtube you can find ones with his homemade power hacksaw on them, and his runs scary fast (to my eye), but, it works just fine for him and reduces cut time.

  3. Hi

    I am a electrician. Ive been using hacksaws for over 25 years, and just to let you know that you should reverse the blade on your hacksaw for your cutter.
    If you look at the saw you will see that it is designed to do the main cutting as you push the handle.
    Great job…

    1. For some people this topic seems to be a religion. We had a discussion with a few people about this. One was trying to convince the others that the push-cut configuration is the correct one, even though the pull-cut one makes it a lot easier and more precise. He didn’t want to accept this argument.

      1. It depends on how the cam arrangement geometry for the driving link is done, some are set up to cut on pull and some on push. The saw will stroke faster in one direction than the other because of this geometry and its the slower stroke you want the teeth facing forward on as the stroke will have more power.
        On the little saw I posted a broken link to above, the geometry lifts the blade on the forward stroke and pulls the blade into to the workpiece on the slower return hence needs the blade backwards. The monster is a different beast entirely and I’m still at the measuring and working out geometry as it doesn’t have a sliding rail system but a giant adjustable throw linkage which moves the entire casting as one unit with no external guides.
        I have a friend and his saw’s cranked linkage is above the centreline of the saw and cuts on the forward stroke as a result.

      2. In my personal experience (which is only in my garage) the push method seems to cut faster on softer materials, while the pull method worked better on hard materials.

        The first cut I also found more precise with the push method.

        So… I switch around the blade quite often. Call me crazy.

        1. not crazy, above I mentioned the linkage geometry and its effect on pulling in the blade to the workpiece or pushing it off for the return, plus theres sometimes a cam inside the rear arm pivot that holds the blade helping this too. If you put the blade the “wrong” way around in soft material it will try to cut when the pressure is lower because of this. In a soft material this can help as otherwise the blade can jam and the drive belts slip if they dig in too much on a cut. Same for cutting thinwall tube. Its functionally equivalent of removing some of the nose weight from the front of the saw to lighten cutting force.

  4. Sure, looks cool, but I’ve been watching that video for over an hour and it doesn’t look like it’s making much progress through that cut! Is that a live feed??

  5. Not only is the power hacksaw not in the slightest bit new, it’s an old enough category of machine that as far as most modern commercial shop work goes is actually obsolete in favor of cold cut saws, abrasive cut off saws and horizontal band saws.
    The overly simple linkage there is also not providing proper lift to the blade, merely angling it while still letting it ride on the material. This will wear the blade out faster.

    1. He made an affordable alternative to metal cutting band saws. Saws like this where getting the job done before shops decided they needed the speed of the band saw. While the snobby rich kids may turn their nose up at this, this this is a good fit for the personal lower budget shops most have.

  6. I made one like this a few years back. There is a design I think from Popular Mechanics from the 1950’s that used two piston rods from a car as part of the linkage. I used a variable frequency drive and ac motor so that I could vary the speed that it sawed.

  7. It needs a mechanism to keep the pressure of the teeth on the return strike otherwise it will not last long. The teeth get rounded over and then it does not cut worth a damn.

    1. While it’s good practice to lift the file on the backstroke, it seems to be unnecessary on hacksaw blades. in hand or power saws I never notice what you describe occurring on the blades because the blade wasn’t lifted on the back stroke.

  8. For cutting wood and probably plastics, you could make one that used a bow saw blade. They cut in both directions. I have also seen 12″ bow saw blades for use in a hacksaw frame.

Leave a Reply

Please be kind and respectful to help make the comments section excellent. (Comment Policy)

This site uses Akismet to reduce spam. Learn how your comment data is processed.