perhaps it is just me but i feel using a metal bearing is a poor idea and seems to defeat the whole point of the exercise, each to their own of course
ATB
When you're teaching bow drill a lot it makes life a lot easier in as much as you are not always replacing the bearing block and believe me you do get attached to certain parts of a kit. It's the same principle as putting a limpet shell in the top or using a pebble with a convenient hole in it. It's also the same as using a chainsaw or lawnmower cord or climbing accessory cord. If we all did it properly we'd be using nettle or leather as our cordage and we'd probably also be doing more on egyptian bow drill than we do.
It sounds strange, but the bow and the bearing block become very personal pieces of kit. You get used to the size, weight and feel of them. If you had to do bowdrill on a daily basis it wouldn't be long before you thought about "customising" your bearing block and bow.
With bowdrill it's very easy to get stuck in a rut, you have a set that you know that it works (when I started it was an all Ivy set) and you tend to figure why try and fix what's not broken. I try to get as many combinations as I can now. My current hearth is a piece of alder and I use a hazel drill. There are though loads of combinations and quite a few will use the same wood for the whole set as I did with my first ivy set.
Someone once even gifted me a hearth made from elder, three instructors had a go at getting a coal out of it and I was the ony one that managed it, the coal was probably more made from the fibres from the sycamore drill than it was of the elder hearth though, I have done the same with a sycamore drill and ash hearth, a lot of the time it's just plain patience and perseverence even if the combination is round the wrong way it can be made to work.
I was teaching bow drill last Thursday, I was under a chute, but the weather was atrocious and I was using all the kits at my disposal. All of the students managed to get a coal, but the first student to get a coal was using a hazel drill and a lime hearth. That combination wasn't however the most consistent of the day, a complete hazel set was. It always took longer and it forced people to go from scratch (burn in, cut the notch, place down the ember pan and then steadily bow for the coal giving it maximum effort for the last ten seconds), but the coals that it yielded were some of the best that I've seen and although it took them longer to get promising signs they were normally the first people to actually get a coal.
Don't get me wrong, I teach to go from scratch, but people are generally lazy and will think that I am not watching and use an existing hole and notch.
When we teach group bow drill we tend to use palette wood and broom handle, not really a natural combination, but it works well enough. moduser was actually using a piece of palette wood and a hazel drill for bow drill on the first coal that he took to flame. It was there and it was available.
Each to thier own, yes I agree, but I also say that the situation dictates that you use what's available.