Cutting notches

[Rick Hughes]

I have a reasonable number of notches to be cut into 100 x 47 timbers

Want to cut cross slots 30mm deep so timbers will slot over some 200 x

47 beams, good enough for glue joints.

Want to do the job neatly, and I have 28 of them to do.

I notice that whenever they need to do this sort of thing on any of the US shows (New Yankee Workshop for example) the use a Dado blade in a bench saw. I'm pretty sure you can't fit a Dado blade to most domestic saw benches (I have a JCB model) only the large commercial machines.

What is the neatest & consistent way of doing these ........ I know I could mark out, use saw table to make shoulder cuts and chisel out the rest ... but this will be slow and probably not end up as neat as I want.

I do have a Router table with a Trend T7 ... but not sure if there is an easy way to use that. Certainly don't have a 47mm wide bit, so it would require moving wood and bit several times - possibly end up inaccurate.

Any tips & hints ?

[The Natural Philosopher]

you can jig rout this easily if you want accuracy.

just needs a bnig square hole for the jig and off you go

But really, for lumber? two saw cuts with a hand saw and knock out the middle.

[Dave Liquorice]

That was my thought as well, why do you need a power tool at all? Sharp crosscut handsaw just inside the line to a couple of mm above the required depth. Knock out the block or take it out with thick chisel cuts and then chisel the base and bottom corners neatly.

Does require the skills to use a handsaw, mallet and chisel accurately though...

[Matty F]

I'd use a Skilsaw for the two cuts and knock out the middle. I have become expert at running the Skilsaw sideways to make the bottom extremely neat.

[John Rumm]

I find you can do a similar technique on a table saw for cutting very neat tenons using a normal blade. Making an accurate shoulder cut and then a series of cove cut style passed obliquely across the blade.

[John Rumm]

Watch this from about 1:50 on...

[harryagain]

This is a poor method of jointing and not to be be recommended for strucural work as it significantly weakens the whole job.

If this is for house construction the usual method is to use metal joints/connectors which are nailed and far far stronger.

[The Medway Handyman]

Bollox. Utter bollox.

[The Medway Handyman]

Dado blades aren't allowed in the UK because of Effin Softy.

I do this all the time, notching newel posts for decking.

Circular saw set to the depth you want. Use a rafter square, home made jig or one of these;

to ensure a square cut. Cut each side accurately, then make a series of free hand cuts a few mm apart (working right to left, so the base of the saw is supported).

Knock out the waste & trim with a sharp chisel.

Fast & accurate.

[stuart noble]

+1 but Harry may have a point

[Dave Liquorice]

Only because any monkey can wield a hammer but it takes time and a bit of skill to cut, accurate, tight fitting notches. I'd be inclined to notch both bits of timber half the required depth than notch just one the full depth though.

[dom]

Yes and no. In the OP's application he may be looking to raise a floor level, and structural strength of the new timbers is not important.

However timbers with a strength rating (C16, C24) can't be be cut down and the rating automatically maintained.

E.g. If you cut a 50*200mm C16 rated beam, you can't get 2 beams of 50*100mm rated at C16.

You *may* do, or it may be that the structural strength was concentrated in one side and the other has a significant defect within the timber.

(there's also a formula for de-rating for notches)

[Huge]

You're kidding, right? A google search yields dozens of UK sources.

[Rick Hughes]

Appreciate that, and that is the way I have done it in past It's a finished joint on show .. and a lot of them

[Rick Hughes]

The only problem is ,,, in practise if grain is running at angle, you can end up with notch breaking out, and ends up less than square ... but don't dispute this is the trad way.

Just asked Q as on all the DIY programmes they show Dado saws being used for this

[Rick Hughes]

Thanks for link ... don't think I would hit out with hammer though

[Rick Hughes]

This is not for house construction, and it is decorative so having any steel ties is not an option.

Your points on construction are correct.

[Rick Hughes]

Good link ... just treated myself to one of those .... Thnx

[Rick Hughes]

I did a lot of searching on w/end on this .... Dado blades are not something that can be attached to your average DIY saw table ... as arbor length is not long enough. Several DIY tables specifically state that a you must NOT fit a Dado blade.

They are available for Commercial (Wadkin etc.) table saws, but elfen safely does come into this .... in a Commercial use, there is a required maximum duration for blade to come to a stop after stop is pressed, and fitting a Dado blade will normally cause saw to exceed this.

The way around is that they then have to fit a DC brake to ensure it stops within required time.

[GB]

You have to love the speed nail-hammering at 3.16. :)