Pump Drill


Never Alone In The Bush
Staff member
Jun 16, 2011
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Melbourne, Victoria
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I started with a piece of eucalypt as a fly-wheel. Its a dense, relatively heavy wood. I also found a straight branch to use as the spindle:
I found a fallen tree and cut one end off a branch to give a working surface.
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I marked the center as best I could judge it, then used the auger to cut a decent diameter hole into it
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The wood was still attached, so it was firmly held in place while I drilled. Once the hole was deep enough, I cut a section of the branch off; so I had a fly wheel with a center hole.

Next I found a dry wattle and split out a "plank" for the cross bar:
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Here are the bits and the tools I have:
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Next steps were really just assembly and tuning.
I went through several "rounds" of making adjustments to get it running smoothly
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I was very please and somewhat surprised how easy the overall project was !
The drill worked really well for what it was, although it still needs more tuning.

One major issue was the spindle was not really straight enough and that was a limiting factor. I probably need to throw it out and get a new one, but I wasn't able to do that.
I also found that having a longer string allows the cross bar to sit lower which is more stable, and gives more spin per "pump" and is therefore better.
In fact I think I'd recommend a much longer spindle than the one I used, although you may wish to consider storage and transport options.

Removing as much mass from the cross bar as possible was a good move, a heavier cross bar acts as a fly wheel itself and destabilizes the motion.

I could see that the fly wheel itself needed tuning, but without a straight spindle, that seemed a bit pointless

I made a "chuck" with a cross cut in the base of the spindle so I could insert bits for drilling. I made some wooden bits just to test with, but bone, stone or metal could be used.
You can wrap twine around the cuts in the spindle to tighten it, but I had a snug fit and didn't need to, although with use it may loosen a bit and may need it.

I made the chuck cuts a bit skew which lead to s somewhat wonky action - I wasn't paying enough attention; so that's another reason to replace the spindle.

As well as using the pump drill to make holes, a suitable "drill" cold be fitted to allow friction fire.