On 5 Oct, 15:09, "TMC" wrote:
Not sure that thin blades are an option

as the blade has to be thinner than the width of the teeth otherwise the
blade will bind I think that if you made the teeth narrower than say about 3
mm the blade wound become too thin to be stable

That sounds reasonable, but I thought I remembered thin blades being
available to cut vertically through T&G.

Even on a thin cut at 45 the material removed will cause the hatch to sit
lower than the surrounding floor

Yes, I had wondered about that. Oh well, on to plan B:

much better to make a vertical cut and batten around for support

It is much easier to get the depth right and there is no way to make a
cut with the blade 45 degrees the other way.

Or better still use a router and those circular plastic inserts that fit
flush and take the routed out piece

I do have one of these and they are very good in some circumstances,
but a) the hole is circular and b) it's quite small. I want to cut a
hatch about 2' x 3'.

Thanks,
BraileTrail