Cutting a 150mm hole in a wooden garden office wall

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Im fitting an AC vent to a garden office. Its double skinned with insulation between the two. Should I just bite the bullet and get a 155 mm hole saw, or is it easy enough to drill and stitch multiple holes?

Feels like a hole saw for a one-off job is a bit much, but dont want to end up cursing myself half way through the stitching...
 
Mark it out, drill a small hole right through to get your centre point on the other side, start it off with a hole just inside the circumference and use a jigsaw, repeat on the other side.
 
150mm is a pretty big hole - are you sure that your drill is up to it? This is the sort of job where you can all too easily burn out a combi drill by overheating the motor or cooking the battery. So, if you have a cordless drill it will ideally need to be top of the range (i.e. one with a metal chuck, metal gearbox housing and metal gears inside) and you will need to have an extra long side handle fitted because when (probably not if) the holesaw digs in and stalls it will kick back like a mule, potentially wrenching the tool out of your hands. I think almost everyone I know (tradesmen) has had this happen to them more than a few times over the years. For a corded tool doing the same job you'll need a heavy drill with a side handle. In both cases you need to keep the speed down to no more than 150rpm, ideally a lot less (more to reduce injury risk too yourself). One problem is that some insulation, e.g. mineral wool types, have a tendency to wrap themselves around the teeth of the hole saw, clog it and stall the tool. Similarly with some msterials like MDF and damp wood you will need to removecthe saw from the cut regularly to clean the (clogged) teeth

TBH stitch drilling, whilst not as neat, is a heck of a lot safer with these big diameter holes
 
I too would use a jigsaw with a suitable length of blade. If too long it will bounce off the outer wall.

A hole saw is gonna be about £70 excluding the arbour.

If you chain drill, you will still need to cut through the timber between the drilled holes.
 
opps said:
Fair play

I was looking at the bosch ones

Bi-Metal Holesaw, Hole Saws, Power Tool Accessories at D & M Tools

Bi-Metal Holesaw, Hole Saws, Power Tool Accessories from D&M Tools
www.dm-tools.co.uk www.dm-tools.co.uk
Click to expand...
I was slightly out - Toolstop is currently selling them at £39 with the arbor a further £10.15, however there was a guy on eBay selling them for about the £35 to £40 mark late last year including an arbor. Even so, still cheaper than Bosch or Starrett and cut as well (I have 5 or 6 Morse holesaws, some Starretts, some Makitas and some Bosches, all for doing plywood and timber floors - Morse is a long established American manufacturer, although not seen so often in the UK)
 
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