Powered Hacksaw

Hi Chaps.

My fist post here. I'm Roy (from England).

I'm no master craftsman but I do have a small garden workshop where I like to spend my spare time with a few small machines that are either old and restored, or cheap, or 90% self built. I've been looking for ideas and inspiration for something I've been wanting to build for a long time.... a powered hacksaw. My old arms do ache after cutting metal the old way so it's time for something to do the donkey work for me.
I did actually acquire a donkey saw about 12 yrs ago but it was a massive beast that took 3 people to move it. And it was wrecked. Broken castings in all the wrong places. Needless to say I should have salvaged at least some of the parts for a future build but alas that didn't happen.

So... my build. I have started it. Only purchases so far have been a pneumatic cylinder (which I hope to run as a hydraulic cylinder using baby oil) for £17 from ebay, a pack of blades (£7) and a cheap Chinese DC motor speed controller (£2.50). Everything else has come from my accumulation of scrap, including the slide and motor. The motor is the wire feed from an old massive mig welder so already wormed and 24V. Power is a 19V 6A laptop power supply.

The drive is a combination of a Whitworth Link and a Scotch Yoke. I reckoned this would give me a nicer action than a con-rod.

The hydraulics will hopefully give me a controlled descent and hopefully a cam will give a lift on the return stroke. Working on this at the moment.

The whole thing will be a benchtop piece rather than floor standing and as compact as possible.

If you guys are interested then I'll post my progress and welcome some constructive criticism.

Thanks for reading.

Hi Roy welcome aboard, I am with you on your profile name. I think most of us would be very interested in your project.

I was intending to clear up a little and grab some pics tonight but in my haste to finish the cam (for the return lift) after work tonight I made a total balls up and forgot to add the 25mm shaft to the overall diameter. Obviously it turned out a little on the small side!

Managed to salvage the cam but now need to fit a new larger bearing for it to run against. Will be a better design in the long run.... I hope!

I'm in the final stages of my build and have done a 1st cut. It's very evident that I have a few issues to sort out.

The main one is far too much weight on the blade. Most of the builds I've seen involve adding weight to get some more bite from the blade but I need the opposite. Anybody know if there id an ideal downward weight for a hacksaw?

And, I'm cutting on the push stroke and think I would be better to cut on the return stroke. This is simply a case of reversing the motor but also the main coupling is on a RH thread and will undo if I reverse the drive so a bit of welding will be required.

Apart from that an a few small mods and tweaks it should be completed soon.....ish.

Welcome Roy! Looking forward to seeing your hacksaw!