Stupid, stupid mistake...

[Nightjar]

I have a 16mm dia 1/2" shank bit for making lock rebates that will cut up to 75mm deep. It is surprising how many other jobs it is also useful for.

Colin Bignell

[John Rumm]

They have their uses. Not a finesse tool in any sense, but quite handy for rough cutting in awkward places. The blades are cheap and bendy enough to work round corners, cut flush to stuff etc. A bit like a slower safer alternative to a circular saw in some cases. Handy for demolition etc.

For a cheap own brand one, Axminster's "White" version is ok. A good one with pendulum action and tool less blade change would probably be nicer. Although there is a reasonably jump in price to the Makita range of tool.

Other thoughts:

> ...a few plunge cuts with an oscillating tool...

Ah, the universal DIY get out of jail free tool!

> ...good quality jigsaw and long blade...

For a couple of short cuts like that, probably. They romp through batteries fairly quickly though and have limited depth of cut.

You could always practice a plunge cut on some scrap with your mains saw before trying it for real.

[DDS]

Did it work, the idea using the router?

[Bert Coules]

John, thanks for all that. A reciprocating saw with a decent length blade sounds like a handy thing to have: I'll investigate. The oscillating tool likewise, though prices appear considerably higher even at the budget end.

Bert

[Bert Coules]

It did, though it wasn't as neat a job as I'd have liked: I'd forgotten that my seldom-used router needs considerable pressure to plunge the bit home (is that normal, by the way?) and so using it against a vertical surface wasn't the easiest thing in the world, especially at and just above head height. But the occasional uneveness of depth and other inaccuracies don't affect the job and will all be hidden, so I'm not too annoyed.

I wanted to get the window in and sealed by yesterday but it didn't happen; and today I've got torrential and seemingly continuous rain so I'm hoping that my rather Heath Robinsonish weatherproofing of the large gap where the garage wall used to be will hold up against the elements.

Many thanks to everyone who contributed thoughts and ideas. Much appreciated.

[John Rumm]

I find its a tool that comes in handy every now and then - cheap disposable blades that are fairly tough and can get into awkward places.

The Bosch one can usually be had for about £60. Blades are fragile so need a little care when using. Also can be expensive if bought singly, although not too bad if bought in bulk from ebay etc.

It would be a fairly slow way of chopping out your frame, however their unique cutting style does make them invaluable for getting things cut in otherwise very difficult circumstances.

[John Rumm]

They ought to not need much pressure - but obviously the spring tension is det to carry the weight of the machine plus s bit of push, so will need more when not upright.

In the circumstances you could just plunge it a bit, lock it off, and route each pass - save fighting it as you cut.

(cheap routers often have poor plunge locks mind you).

[Bert Coules]

Never occurred to me! But I'll be prepared, if there's a next time...

Thanks.

Bert

[John Rumm]

Just imaging you are an American with their fascination for fixed based routers ;-)

[Dave Liquorice]

forgotten

Don't have a router and never used one but wouldn't the design of the cutter tip have considerable effect on how well it will plunge? No cutting tip and it's bound to be hard work.

As John says set up the router to the correct depth then swing the cutter into the work, thus using the cutting edge on the side of the cutter, by pivoting on the front edge of the sole plate? Like plunge cutting with a circular saw.

Note my first eight words...

[John Rumm]

Yup definitely... most straight fluted cutters also have bottom cutting sections, and hence will plunge. However there are some rebating cutters that are not designed to plunge.

(does not stop you plunging beside the actual cut position and then moving into the work laterally of course)

One advantage of plunging into the work is that you don't have to start at the edge. i.e. you can route away most of the material leaving an edge in place to help support the router using the full width of the stock, taking that off in the final pass.