Cutting a door out of an MDF sheet

[Why Not Indeed]

It may well flex like a wobble board in use.

The OP says they're making a softwood frame around the door.
If I were the OP, I would extend the vertical element of the frame to the full length of the sheet.

 

[foxhole]

Assume you are using 18mm MDF?

 

[big-all]

as an asside
you can use piano hinges in the end grain in 12mm successfully with care and they are very strong[ask for process iff required] but iff you want knuckles retracted below the surfaces at all the hinge plate will protrude at the back perhaps up to 2mm

 

[Deluks]

Thanks for all comments so far.

Using 18mm MDF.

The sheet being used isn't full width, so I still have the full length offcut to use as a straight edge, with clamps.

Haven't quite worked out door size yet, almost to the ceiling, but doesn't need to come down to the floor though as the bottom part is a boxed in stairwell which will be obscured behind the bottom part of the panel.
So the door needs cutting out on all 4 sides, there will be plenty of 'meat' left in the frame, all the way round.

Softwood frame (2x1 & 2x2) is affixed to walls, floor and ceiling, plenty rigid.

I can unlock the depth adjustment in the saw and static plunge to get the hole started.

I haven't used router for a couple of years, I forgot about the multiple pass technique. Sounds too messy though, and all my worst mistakes in the past have been with a router!

Out of interest, has anyone ever used the Kreg hinge cutting jig? £35ish, looks useful.
I have a homemade one I made years ago, but was a bit keen and went through a door that I'd spent ages working on!

 

[opps]

Out of interest, has anyone ever used the Kreg hinge cutting jig? £35ish, looks useful.

I just use a combi square and a Makita 35mm hinge cutter.

Makita Forstner Bit Concealed Hinge Cutter 35mm

Shop Makita Forstner Bit Concealed Hinge Cutter 35mm online or visit us in-store at Leyland SDM. Next day delivery available.

leylandsdm.co.uk

I pre-drill a 0.5mm hole for the cutter to drop in to.

I have used about 5 different hinge cutter bits in the past, The Makita one is the best I have used. Way faster than the other ones that I have tried, cleaner edges as well.

I haven't used the Kreg- however it will be £35 plus the cost of suitable clamps.

An advantage of the Kreg is that it will set the depth of cut- with the Makita bit I drill until the main part of the cutter is about 4mm under the surface.

From reviews I have read elsewhere, the two holes in the template to screw the cup down don't always line up correctly.