Fire by friction.... reversed?

[capacious]

I was exprimenting with a different woods for the bow drill today, and something rather interesting/strange happened.

I used holly for the drill, and pine for the hearthboard. I also, through lack of options, used pine for the bearing block as well.

As usual, the drill end was nearly flat , to maximise friction, whilst the other end was a point (to minimise it). On the hearth, the drill refused to become seated, and would not burn the hearth. BUT: the bearng block, with the ponted end, started to smoke. So I reversed the two, and commenced drilling. I produced an ember, with the bearing block and pointed end, and then set it to my tinder and got flames (yay!!!).

Now, call me stupid if I am, but shouldn't the end with less friction, by definition, produce less friction?

Has anyone else found that this has happened to them?

There are only two possible explanations I can think of - 1. The hearth was slighty damp, or more so than the bearing block (which was cut from the same board), which seems unlikely to me.

or 2 - Having a smaller surface area on the point increases the pressure on that point, therefore increasing friction.

Has anyone else got an explanation for this? as I'm rather curious as to why it happened.....

 

[cicelythepotter]

yes this has happened to me too.
i was using pine for all components through lack of alternatives. i think the bearing block was just drier and softer than the hearth. though curiously when i tried turning it around, and using the hearth as the bearing block and vice versa with the drill upside down, the top (flat)end started smoking. i tried several times, switching the bearing block and hearth around and reversing the drill but each time the top end was the one that started smoking!

 

[Longstrider]

It may have been due to the increased pressure caused by the thinner top on the spindle as you say. You adapted and persevered, thats the important part. At least it didn't burn right through the bearing and drill a hot-ended stick into the palm of your hand like it did to me when I risked soft pine as my bearing

 

[rich59]

The sweat from the brow falling into the hearthboard?

Lubricating the bearing with "nose oil" and ear wax usually prevents too much smoke from the top.

 

[Ed]

It may have been due to the increased pressure caused by the thinner top on the spindle as you say.

Thats exactly whats going on there ... make sure your baring block/spindle top is well lubricated to prevent smoke there. A bit of spit will do the trick, as will any waxy leaves you may find about


Ed