A Forstner Mystery

I’m sure we all do it. Tidy up the workshop, find something that doesn’t have a home and put it somewhere that makes sense…..at the time.

Until you need to find it.

I have 2 sets of forstner bits, apparently. A basic set, and one quite a bit more comprehensive. So it was with a somewhat decreasing level of amusement that I searched, and searched for either set for a small job.

The forstner gremlins have them (or is that forstner gnomes?). Either way, they’ve hidden them well. Buggers.

The Chainsaw Blade

Dropped into ACE Saw Service on the way home, with my Husky in tow to see if I could get a blade more suitable for slabbing, such as a ripping blade.

After sorting out the most suitable blade that is available, I got taken into the workshop to see what they actually have out back, and was surprised just how much machinery they have, and the range of services they provide.  Despite the large, Paul Bunyan sized chainsaw out front of the store, the range of Stihl saws in the showroom, and the extensive chainsaw museum upstairs, they also do knife, blade and chainsaw sharpenings (as well as servicing)

One thing that caught my eye was some very large circular saw blades they were working on – 600mm+ that are apparently from the firewood industry.  I was surprised – thought that oversized method for cutting up firewood would have been killed off by the overly ambitious OHS industry and regs.

Outside was a very large blade – over 1 metre diameter.  Apparently even when the blades reach end-of-life, the steel gets used in other items.  Shame – I’d love to get a couple of these large blades to mount on either side of the shed door!

The chain that came with my saw looks something like this one

Every link between those that has the teeth have a riser to try to minimise the likelihood of a kickback, particularly a bar-tip kickback.  This sort of chain is not used by professionals, and it increases the amount of load on the chainsaw, and given the ones used by homeowners are already likely to be underpowered this just exasperates the situation (for the sake of safety).

The more traditional chain looks like this

and this is what I picked up.  There isn’t a dedicated ripping blade that will fit my chainsaw.  A ripping blade has an additional spacer, and the tooth angle is decreased from 20-30 degrees down to 5 degrees.  As the blade needs sharpening, I will work it towards this optimum cutting angle.  One other thing I learned from ACE is just how much of the tooth can be used up in sharpening before the blade needs replacing.  You can be left with only around 2-3mm of tooth before the blade is used up!

Oregon is one of the main producers of chainsaw blades, and are responsible for the modern tooth design.  The original profile was quite different, and not very effective.  The founder of Oregon was doing a lot of investigating, and found a wood-boring larva that was very effective at getting through the timber.

By duplicating the C shaped ‘jaws’ of the larva, the start of the modern chainsaw blade was born.

I wonder how many of these larva have since met their demise at the hands of the very tooth profile they inspired?

%d bloggers like this: