And now the continuing story of a quack, that’s gone to the dogs first part in a series discussing tools, and their upkeep… (full points to those who get the reference)
Blades:
Let’s start out simple, and then I’ll go into some detail in the extended entry, to save you nice folks who have no interest in this from having to scroll past everything… Blades are the business end of many wood and metal working tools… They’re the sharp end of the stick if you will… Most people in the shops I’ve worked in over the years have taken this for granted… Most of them have been wrong… Some dangerously so… What it comes down to is keep the damn things sharp, and know what each type is made for… Today will be a bit about when to change them due to dullness… Next time, I’ll ramble about types… I’m sure you’re all asleep by now already, but for those insomniacs…
The worst thing in the world is a dull tool… (well perhaps not the worst, paper cuts and lemon juice… nuclear detonations… paying taxes… they’re worse… but just work with me here…) When the blade on the tool you are using gets dull, you are going to have to push harder in general… You have stopped cutting with the blade, and now you are grinding through the work… The material may be pinching in on the blade too since there will be less clearance around the blade… You are creating more heat which can warp the blade at worst, or just blow the temper at best… If you are working with a power tool, you should not have to push hard, let the blade do the work at its own pace… The sawdust should be as coarse as possible, indicating a slice of wood, rather than powder like you get from a sander… The two worst cases I run across are table saws, and band saws…
People will use a table saw blade for months in some places… By the time anyone thinks to change it, you could use the saw dust as talcum powder… They’ll let it go so long some times that it will start smoking as it cuts… Don’t feel bad if you don’t know this, these people are supposed to be professional woodworkers and they don’t seem to get it… Easy ways to tell the blade is dull… 1) fine sawdust. 2) burn marks along the cut edge of the wood. 3) the saw bogs down as you are cutting. 4) you can’t remember the last time you changed the blade. 5) the cut seems to want to bend on way (caused by one side of the blade losing the edge of the teeth, usually from hitting a screw or nail in a old board) 6) you are straining to push the wood through the saw
Yea, those seem pretty obvious don’t they… So why don’t people change the blades?... The world may never know…
Band saws are a slightly different breed… In most theatrical shops, they get used for a number of strange materials that tend to gum them up, so what you think might be a blade problem could be something else… The same basic indications work for the band saw as the table saw… Finer sawdust, having to push hard, burning/smoke they’re all indicators… Band saw blades are particularly susceptible to getting their set ruined… The set is how much each alternate tooth on the blade is bent outward… It makes the blade cut a little wider than the actual blade is, so the material doesn’t bind on the blade, and you can make turns in your cut more easily… Usually, most shops will run a band saw blade until it breaks… There isn’t a lot of danger in that, but it will scare the hell out of you every time you go through it… If you can’t maintain a straight cut, you’ve got a bad blade… (If you change the blade, and it still won’t cut straight, you’ll need to wait until I get to tweaking the setup on these tools, further along in the series) Smoke and burning cuts may just be that you are pushing too hard through very thick material, try backing off a bit, and see how things go… You may also just have the wrong blade, check out the next entry for more on that…
Most of the other tools use either a circular blade, which follows the table saw rules, or straight blades, which follow the band saw guides… The real secret is, that if you think it might be dull, change the bloody thing… Odds are, you’re right since nobody else ever thinks to change blades…
Next time, Blades: Part 2…