Here's a drawing and materials list for a very simple power hacksaw. The original was published in March 1936 Popular Mechanics magazine. Without shaft bearings, it's clearly meant to be run at low speeds, and oil applied occasionally. If you have a number of cuts to do, and no grinder, here's an alternative.

I would (from my experience with build version 1.0) suggest not using a cheap vice with an "iffy" swivel base. As tempting as the idea of making angle cuts may be, if the swivel comes loose while the saw is running, bad things happen.

When cutting, occasionally applying a few drops of ordinary motor oil on the blade/cut point makes it run much more easily.

Always wear eye or face protection. This is a lightweight tool for occasional use. Run it at a sensible speed - hand hacksaw blades are not made for high speeds. Gear down the drive if necessary (I found a gearbox from a junked cordless drill and married it to the motor from an extinct blender, then added a 5:1 reduction on the drive belt and pulleys.

I don't have pictures at the moment - I took mine apart to rearrange it after things came adrift when the cheap vice swivel didn't hold square, and parts went in several directions. Next time I'll use a fixed vice.

I used steel flat bar I had on hand - not necessarily the dimensions given, but hefty enough. My driveshaft is 5/8" steel round bar, left over from the TimberWolf axle (luckily, I had a pully that fit, but a wooden pulley could be made up with 3 plywood discs easily enough). My hacksaw frame was also a spare on hand - 12" rather than 8". The "traveller" could be made up with steel sides and hardwood blocks, or even pieces of teflon or delrin - or rollers. I used steel on steel and greased the slide.

Photos (I hope) when v.1.1 is complete.

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I had thought of doing something similar with an angle grinder, but the realization of what might happen if a cutting wheel grabbed and broke dissuaded me from that idea. I hope this may be of use to someone else. The original article is just a short squib with the drawing above, but you can Google it in PM for March 1936.