If you’re cutting metal in the workshop, you’re likely using a table-mounted cutoff saw, or perhaps a bandsaw for finer work. The power hacksaw is an unwieldy contraption that looks and feels very old fashioned in its operation. Despite the drawbacks inherent in the design, [Emiel] decided to build one that operates under drill power, and it came out a treat.
The build uses a basic battery powered drill as its power source. This is connected to a shaft which rotates a linkage not dissimilar to that seen on steam locomotives, but in reverse. The linkage in this case is turning the rotational motion of the drill into linear motion of the hacksaw, which moves along a metal rail, guided by a 3D printed bearing.
With a body of plywood and plastic moving parts, this might not be your tool of choice for high-volume, fast paced work. However, as [Emiel] notes, it’s faster than doing it by hand, and it was a fun build that by and large, used what was already lying around the workshop. It’s not the first time we’ve seen a powered hacksaw use 3D printed parts, either. Video after the break.
And if you have a loaf of bread and a bologna you can make sandwiches!
Nice old lathe he has there. Not one on The Best Web Site In The World, though the marque is covered: http://www.lathes.co.uk/fleck/
Lots of power hacksaws there too. They do the trick, the cuts are straight and the blades are fairly cheap. I suspect that bandsaw blades have come down massively in price, which accounts for the decline in popularity of the power hacksaw.
Bandsaw blades (good ones… garbage has become a lot cheaper…) haven’t really come down much over the last 40 years (I can’t speak before then). The big issues in industry are speed (primary), maintenance/setup, and skill.
Power hacksaws require more skill to use with good results than a drop bandsaw, for a number of reasons, including proper blade speed and cut rate control. You go through a lot of blades fast with unskilled workers. They also require a lot more regular maintenance than a band saw, or the precision goes away. There is a lot of exposed sliding surface and any machines have the bushings side loaded by the crank pull during the cut, all of which require routine gib adjustment and in service lubrication. Think the ways on a lathe, but without modern automatic lubricators. In addition, poor technique is much more likely to destroy the blade on the first cut than on a bandsaw. (used to work with a guy that pretty much treated hack blades as one blade-one cut. He couldn’t be bothered to understand the relation between feed rate control and tooth size, and that the powerhack will strip the teeth on the first stroke if the setup is wrong… No holding back and gentle feed start it)
Band saws are much more forgiving on these measures. Many require nothing more than a little periodic, other than blade changes. With a hydraulic rate control, they can pretty much be set up by someone competent and do a decent job on most any material (though not optimal for but one) being operated by relatively unskilled workers. They are also several times faster since they are pulling teeth at the appropriate speed 100% of the time (rather than about 1/3 of the time), though the cuts are usually (not always) a little lower in quality due to the band being less stiff than a powerhack blade, and the needed play in the band guides, rather than the more rigid pin mount for the powerhack.
The shop finally got rid of the last Racine about two years ago and replaced it with a bandsaw. Blade costs went down to near nothing (comparatively), and cuts on 2″boiler tube and 3″X3/8 angle stopped being measured in cigarettes. 8″X3/4 box tube, on the other hand….
At a guess, that market has gone to good metal-cutting blades held in a jigsaw or reciprocating saw depending on the project.
interesting build but it needs a few tweaks. the saw ‘bearing’ doesnt seem like it’d last long and I noticed the saw looked like it was cutting into the vise when it hit bottom.
I thought the same when watching the video, also to me the choice of using wood and not steel for the frame seems strange since he is able to weld. The wood seems to wiggle around while sawing, which is no surprise. But in the end a nice build and if it does the job for him there is nothing to complain, or upgrades may follow
But sloooooooow!
Change the Youtube replay speed to X2, I promise you it cuts fast enough from your armchair!
Unfortunately real life doesn’t have a FFW.
I worked in a shop with a power hacksaw and there’s a huge speed penalty. Nothing happens fast :(
Yeah, or you could start with one of these for drill driven rotary > linear:
Multifunction Reciprocating Saw Adapter Set Change Electric Drill Into Reciprocating Saw Jig Saw Metal File Cutter Drill Attachment for Wood Metal Cutting $48.58 [N.B. FAR cheaper on Banggood or Aliexpress, but sometimes hard to find on the Web. However the Banggood Email Spam I get every day touts these really cheap all the time.]
Take a look…
https://www.amazon.com/Multifunction-Reciprocating-Adapter-Electric-Attachment/dp/B07N74P6CB
Yup it’s a recip-saw not a hack-saw. But that shouldn’t matter for most use-cases. There are more options available when it comes to recip blades compared with hack-saw blades. Plus, the recip can do what the hack-saw does for most light-duty jobs provided you setup the rig to take its time (let the tool do the work slowly – the outcome will always be better).
I have been thinking about building something similar, but more advanced and simpler at the same time.
I will not put in a linear guide, but connect the saw with a few bearings directly to the eccentric.
This will not only create a reciprocating motion but will give the saw also a wobble, which reduces the contact area between the saw and the material to be cut.
The perfect goal is to have 3 to 5 tooth of the saw in contact with your material, so adding a bit of wobble is advantageous for solid materials.
I also have a pretty specific need for my own saw. I have a bunch of left overs of 75mm solid round stock of St51, which is quite a bit harder than the regular soft construction steel. I don’t really care if the saw takes 1 or 3 hours to cut a disc of, as long as I don’t have to stand next to it to mother it is’t OK with me.
I think you’re overengineering it with a wobble function. The blade teeth have a kerf so that should not be necessary, and you’re going to clamp the job in a machine vise anyway. A return lifter, cutting fluid suds pump and a dropout switch which opens and cuts the motor when the job is finished would be better considerations. Also the ability to add and remove weights (eg. gym weights) to the arm, for different job materials (ie more weight for steel, less for aluminium). These are all functions my old commercially-made power hacksaw had.
Popular mechanics, March 1936, P475 almost identical build https://books.google.com/books?id=ztsDAAAAMBAJ&pg=PA463&source=gbs_toc_r&cad=2#v=onepage&q&f=false
I would wager that inspection of the blade will show it stamped “30 strokes per minute” to avoid heat damage. They last for ages at the right speeds.
Years ago I had a power hacksaw, I think it was taiwanese, darn heavy to drag around the shop floor (even on wheels) but it did a magnificent job when given a pieice of solid steel bar stock.. It had a small hydraulic lifter piston to lift the blade for the return stroke so the teeth weren’t dragged backwards on the job. As others have surmised, the availability of cheap ‘golden dragon’ bandsaws, cold saws and dropsaws have overtaken them in cost and use in the home workshop.
Nice simple build though. I reckon a cheap ballbearing metal drawer slide from any hardware store might be more durable than the printed slide, and a flywheel to smooth the strokes out a bit could be some minor improvements.
Having read a couple of posts, this one made me comment to appreciate your creative tricks. The practical engineer does it again. I think it’s pretty creative and having seen how it works and makes cutting much quicker and easier, at least it seems so. But kudos to you all the way for doing excellent work!
outstanding