BobLang":329pisnt said:
I'm doing some research for an article on European style table saws, and am curious about the rationale for the short arbor length.
I have heard two reasons. The first is that cutting with a stack dado head in a table saw is considered too dangerous and therefor the arbor is kept short to prevent it.
Both and a bit more, Bob.
The stacked dado set is considered dangerous in the main because it is very difficult to guard adequately on most saws. The over-riding factor is that in the EU we have a slew of common (since the 1994) safety legislation which in the main applies to equipment in industrial environments, but which in turn has generated national standards such as the relevant, to us, BS (British Standard) for table saws which precludes the manufacture in the EU for local sale of any table saw capable of taking more than 5/8in or 16mm width of blade and mandates a 10 second stopping time on new machines, DIY or pro (pro machines also need to be retro-fitted with braking). Factories/employers are required to utilise the safest method of doing any process - for rebating that means a 1-1/4in or 30mm shaft spindle moulder rather than a saw bench and dado head - for through housings (dado trenches) that means either a radial arm saw with a dado head and auto return mechanism or a router and jig. In both cases it is much easier to safeguard the operator than it would be on a table saw. If you take into account the fact that we in Europe have worked predominantly in MDF, veneered MDF, chipboard and veneered chipboard for casework products since the 1980s with plywood prices having risen to unaffordable heights for many and then also note that the use of biscuit jointers and dowel borers is quite common in casework firms here it isn't really surprising that dado heads are nowhere near as widespread as they are in the USA. In fact, other than being in use on some radial arm saws, their use has all but died out since the 1970s. Another factor may be that we tend to use face frames much less here, so housing joints, if they are used at all, need to be the stopped variety - which are all but impossible to produce on any type of saw. They're a doddle with a router, however.
BobLang":329pisnt said:
The second is that the mass of the dado stack can cause the arbor nut to loosen when the brake is engaged.
Again this is a factor. Since the 1990s ALL saws sold in the EU (industrial and DIY) have been required to stop within 10 seconds when the stop button is pressed. If your low cost saw has no brake and depends on friction/belt tension to stop it then it won't stop in the required time when you load a 1.5kg dado stack on it, so the way round that is to shorten the arbour so that it can only take a standard saw blade. Your saw might be more sophisticated and have a DC injection brake, but again the stacked dado set might lead to you overrunning, or worse to the braking being so effective that it unscrews a single nut and dumps the blade set off the arbour. Again the cheapest solution is to shorten the arbour thus restricting the user to a standard blade. But also by doing this you are not encouraging anyone to run sans guards/riving knife as they would with a dado set and therefore are much less lilely to lay yourself open (as a manufacturer) to being sued for selling a dangerous product. The fact that some people are importing saw benches which will take dado heads just means that they area sailing very close to the wind, although it would take a major accident and a legal case to get a better idea of exactly where the line is actually drawn.
The introduction of braking has been a major bugbear to manufacturers of many different types of machinery and some of the solutiuons to the problem of braking have included shorter saw arbours and aluminium cutter blocks (for spindles) both approaches reducing the spinning mass to be brought to a halt to manageable levels on machines with small motors.
I hope that gives you an inkling of what's going on here, although if you want to PM me I might be able to provide you with the text of an article I've had published on the subject here in the UK
Scrit
