Enlarging an Access Opening

Grumpy_chap

We have a small service void with access through a removable panel in the side of a cupboard.  I need to enlarge the access opening.  This needs to be done in situ.  I do not have access to a jig-saw.  How can I easily and reasonably neatly enlarge the access opening?

EssexExile

https://www.diy.com/departments/12-keyhole-compass-saw-curved-circle-cutter-hand-saw-7-tpi-300mm/5056316302319_BQ.prd

You'll be a while! How about drilling lots of holes close together then joining up the holes?

Grumpy_chap

That looks like it will be easy enough for cutting down (or up) at the sides.
Getting a straight line for cutting across could be more difficult.  Perhaps the series of drilled holes would work for that, as you suggest.

MikeJXE

Drill a 20mm hole in one corner, mark a line from that to another corner, cut along the line with a hacksaw blade, repeat 

grumbler

With a hacksaw blade it will be a hard job even if you have a special handle for it. However, most of the job can be done with a proper hacksaw with a blade fixed perpendicularly to the frame.

Grumpy_chap

I realised I was a couple of pound short of a free delivery on my Amazon basket, so I have added one of the keyhole saws for £6 which works out well.
I'm thinking to drill the holes every inch across, cut down either end into a starting hole and then saw across the line to join up the holes.  That will probably get the straightest finish that I sensibly can - I don't think I'd be skilled enough to follow a pencil line all the way across, especially not in the fixed working angle.

ThisIsWeird

I presume the saw you bought is like Essex's example, and has teeth suitable for chipboard. Don't use a hacksaw blade, for example
I'm not sure drilling a series of holes is the best solution, since that, itself, is surprisingly hard to do in a straight line - the bit will almost certainly wander a small amount as the start, so you'll end up with a slightly wiggly set of holes. To then try and match these holes with a saw cut will be hellish! You will almost certainly end up with what it was - a cut between dozens of part-remaining holes. Knobbly.
I'd personally mark out the required opening, drill a hole in each corner (you could even get away with just two holes, in diagonally opposite corners), with the outside circumf of the hole sitting within the finished corner - and saw away to the next corner. Take it slowly - if you push forward too hard, the blade will tend to bend or twist, and then you are off-line. Also, as soon as you can, lower the angle of the saw relative to the board. That way, more of the blade length will be buried in the slot you are cutting, and will be naturally kept straight by it. You might not achieve a perfectly straight line, but it'll probably as good as it gets using a saw.
Once the panel is cut out, you'll likely have wee 'horns' in each corner around the holes, so they'll need sawing away too. Or, use a rasp if you have one.
Or, easier but probably just as wobbly, check out eBay and Fb for locally available jig saws - you'll almost certainly get one for £15 or even less.
But they still wobble!

TELLIT01

A cordless/corded multitool with oscillating head would do the job but probably overkill pricewise if that's the only job you need it for.

Grumpy_chap

ThisIsWeird said:

I presume the saw you bought is like Essex's example, and has teeth suitable for chipboard. 

Yes.
The same saw but a little cheaper and I avoided a delivery charge for my basket.
Hopefully, it may arrive for the weekend.

FreeBear

TELLIT01 said:

A cordless/corded multitool with oscillating head would do the job but probably overkill pricewise if that's the only job you need it for.

Just one job is enough to justify buying toys tools. Shop around on ebay or faceache marketplace, and you'll find one at a reasonable price.

stuhse

Do you really not know anyone, friend, work collegue, relative who would be willing to lend you their jigsaw ?