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Dado blades - "do YOU dado?"

Discussion in 'Wood / Woodwork / Carpentry' started by theSouth, 12 Jan 2015.

  1. theSouth

    theSouth

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    I'm new to a (decent) table saw and the question of dado blades has arisen since I'm starting to make some cabinets, book shelves, etc - so I need to cut plenty of rabbits/dado cuts.

    I'm also building the screw advance box jig http://woodgears.ca/box_joint/jig.html from the wonderful Mr (Matthias) Wandel - and I rather like sizing of 1/4" cuts. The box jig helps (obviously) but it would be better if I could cut each 1/4" in one go.

    When I bought the saw I had a dado-ready arbor fitted, but from my googling I can see, yet again, there appears to be some debate each side of the Atlantic ocean with regards to the use of dado blades.

    There's lots of chatter and I can't make any sense of it!

    The disc braking systems used in "Europe!" seem to mean that dado blades should never be used, but others disagree.

    I've made several dado cuts just by moving the fence and to be honest it's not been too much of a pain, but obviously as I make more and more it will be. I don't want to go back to routing these as I don't have a decent router table (though I have a Festool guide rails + router + TS55)

    So - are you in Europe and "do you dado" or "do you NOT dado" ?

    Thanks in advance!!
     
  2. JobAndKnock

    JobAndKnock

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    Disc brakes are on cars, not saws! (in the main) All new table saws supplied in Europe, together with secondhand ones supplied by a dealer, are required to come to a halt within 10 seconds of the power being turned off. When using a table saw this rule only applies to trade shops and work sites where it is an finable offence not to comply , if caught. When you load-up the arbor of a table saw with a stacked dado head or a trenching head then MOST are incapable of doing the 10 second stop because of the near impossibility of setting-up a braking mechanism which works for both a thin saw and a heavy dado set. BTW the reason that the 10 second rule was brought in was to reduce the number of "run-on" injuries (often amputations) where operators touched spinning cutters which were still winding-down after a power-off - on large saws and machines like single-end tenoners without brakes the cutters could and did run for up to 20 minutes in some cases, almost silently. My understanding is that since the law was changed about 15 years ago, including retro-active braking requirements we had to deal with, is that there has been a considerable reduction in the number of these accidents (about 80% from the local HSE inspector). If you use a heavy head on a saw it will probably be necessary to double-nut the block to prevent the cutter loosening when the saw slows down under braking

    There's little point in reading US sites when it comes to saw safety (and much chatter seems to have at least some of its origins there) - they've only legislated riving knives in the last few years, their rip fence designs are stupidly inadequate in the main and US sites are full of kickback stories (why? It's a minor sub-topic here), but then the first things they seem to do when they buy a saw is throw away the guard.......... On safety topics the USA is generally way behind us here, unless you consider that technical dead-end, the Saw Stop :rolleyes: to be an advance. I don't - sticking plaster technology if ever I've seen it

    I don't do many rebated corners or full through housings - they look a bit tacky IMHO and were always regarded as low grade work when I came through my time (a stopped housing or a butted side to top, or better still a mitred joint, looks far neater and more professional). If I need to cut through housings (rare these days) I tend to use a radial arm saw with the appropriate head on it because they can be more easily guarded and I find them far easier to use - easier to pull a head across a piece of timber than slide a 6ft long bookcase side across a saw, I find. Stopped housings I've always worked with the router. Rebates I almost always cut with the spinde moulder (faster, better quality rebate, safer), although for smaller ones or out on site I'll use a router. As a rule I find trenching/dado heads time consuming and fiddly to adjust, so only worth using for a biggish batch

    On the subject of a router table - all a router table is is a piece of plywood (or similar) with a hole drilled through it and a router screwed to the underside. It can be supported on a couple of trestles an a pair of 3 x 2s. An adjustable fence is simply a piece of 2 x 2in PAR softwood secured and pivoted on a coach screw at one end and with the loose-end clamped in place with a G-clamp. I know you can spend (waste) loads of money on router tables, but TBH I'd rather just get the job done than getting hung-up on how expensive a bought-in one is

    I think you've come here looking for someone to justify your decision for you. Trenching/dado heads are more dangerous than standard saw blades - in the main because people just don't guard them properly. Take a look at the HSE WIS16 page I referred you to previously and there is some advice about how to guard dado heads on the table saw. It's worthing remembering that a saw bench is not like a sander - get it wrong and it can bite! And unlike lizards we humans can't regrow fingers
     
  3. theSouth

    theSouth

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    hi (again)

    quite a few assumptions in there :) mostly wrong I'm afraid.

    especially this:

    "I think you've come here looking for someone to justify your decision for you."

    I'm afraid that's just not true, quite the reverse actually

    I posted to see what various views were on dados. to be honest I'm not that keen on getting one, it was a free option to get the longer arbor when I bought the saw.

    I really just wanted to make sure I wasn't 'missing a trick'. hence I'm in the process of building Matthias' invention.

    and, I don't JUST look at American sites. there are some great UK ones I like to watch now and again. but there are many more American ones, that's just a fact.

    thanks for replying anyway
     
  4. JobAndKnock

    JobAndKnock

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    Not as far as the technical stuff goes, there wasn't! :p I do this for a living, so I have a real need to know what legislation applies and to whom. You, as an amateur, are in a much easier position. I was also trained in a workshop where we had a variety saw - a type of table saw specifically engineered to accommodate dado heads........
     
  5. Dave54

    Dave54

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    Never used a dado head myself. Always used router for housings or a spindle for rebates. Can't really see the point in having to faff about changing the blade etc to do different things. I want my saw to be a saw, it's too useful in itself, even in my one man workshop. I don't like the idea of having the extra potential for workpiece rejection either, although you can take measures to protect against that.
    I'd echo the need for proper guarding, and the need for pressure pads. All of which means more changover time. No way I'd use one without. Or for that matter a saw without proper guard and riving knife. Which means more time changing back. . .
    I would suggest that you read the H & S sheet that JobAndKnock linked to. As he pointed out. You only get one set of fingers!
     
  6. GrinAndBearIt

    GrinAndBearIt

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    My oh my ... that screw box jig thing ... what a work of art!
     
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  7. JobAndKnock

    JobAndKnock

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    What's a screw box jig thing? :?:
     
  8. 481

    481

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    :eek:

    You should talk to someone about these urges...
     
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  10. JobAndKnock

    JobAndKnock

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    He's either talking 'Murican - or he's the mad bunny butcher.......... :eek:

    Anyway I always thought that dados were chair rails.........
     
  11. Norcon

    Norcon

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    I'm fitting a new arbour to my saw that will allow the change over between dado and sawing.
    Have the dado cutter ordered also.

    Looks as if I'll have to trim a section off the dust shute off to make it fit. :(
     
  12. Dave54

    Dave54

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    It's a box jig thing with a screw. :)
    Seriously, beautifully made though it is, there are easier ways to make to make box /comb / finger joints with a router.
    My own shop made jigs are 'orrible looking things in raw ply, bolted together with allthread. They work, and my effort goes into making the actual job.
    Mostly I ended up using dovetails, and cutting them by hand because they look better, and it's quick for one off work when you're used to doing it.
     
  13. JobAndKnock

    JobAndKnock

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    I'm with you there, Dave, although I prefer to use dovetails on strength grounds, too

    Back in the day saws designed for the purpose came with pull-out sliding table sections and proper overhead guards........ (Wadkin PK, etc)
     
  14. JobAndKnock

    JobAndKnock

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    BTW have you ever seen the box joint cutters that wooden box makers used to use? Ten or more thick cutters mounted on an arbor with spacers - on the right machine (something like a vertical hauncher) they could cut 12in width of fingers at a pass
     
  15. Norcon

    Norcon

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    What saw do you have?
     
  16. Norcon

    Norcon

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    Wadkin have a very poor line up of new machines today as regards choice.
    I'd expect they cannot compete with the europeans.

    And the chinese ones are even cheaper.
     
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