How do I cut a 140mm circular hole through 5mm ply, without a jigsaw?

[prv]

This is one I saw on E bay and is of good quality. It will give you a good result.

http://www.ebay.co.uk/itm/Starrett-...Home_Garden_PowerTools_SM&hash=item51bd3dd3c8

I usually buy mine from this listing: http://www.ebay.co.uk/itm/HOLE-SAW-...Garden_PowerTools_SM&var=&hash=item3a841398b1

Range of sizes, usually the best price, and I have no complaints over quality.

£17.35 delivered for 140mm. I guess that's a little more than I was expecting, but it is quite a big saw. You may get a Performance Poo or similar cheapo jigsaw for that.

Pete

 

[Cloven]

I usually buy mine from this listing: http://www.ebay.co.uk/itm/HOLE-SAW-...Garden_PowerTools_SM&var=&hash=item3a841398b1

Range of sizes, usually the best price, and I have no complaints over quality.

£17.35 delivered for 140mm. I guess that's a little more than I was expecting, but it is quite a big saw. You may get a Performance Poo or similar cheapo jigsaw for that.

Pete

See post #5 - same supplier

 

[itchenseadog]

Use a 140mm hole saw with caution. If you're not use to using them in a battery or mains drill, they can grab and do damage to your hand/wrist/knuckles. I have seen many injuries from large hole saw use from the inexperienced including a broken wrist during my time in the industry

 

[Lakesailor]

£17.35 delivered for 140mm. I guess that's a little more than I was expecting, but it is quite a big saw. You may get a Performance Poo or similar cheapo jigsaw for that.

Pete

And guess what? A jigsaw will cut other size holes, square holes, irregular holes, straight lines, wavy lines. Just buy one.
I've had a cheap B&D one for years and keep promising myself I'll get one with a roller behind the blade. But the bugger won't die and keeps cutting everything I try to cut.

 

[chuzzlewit]

The cheapest : a wooden strip and two nails , the smaller one only just protruding and sharpened with a file. Should cut 5mm ply and give you some healthy exercise.

 

[Greenheart]

Wow! So many replies to such a little question, thanks to all. There are pieces of hardware described here, which I might have gone to my grave without knowing existed.

I've owned cheap jigsaws in the past, and wasn't thrilled by their ability or endurance. But that's not the reason I'm not considering one...

...in order to be sustainedly useful, I'd need it to be cordless. The boat doesn't fit in my garage and she's very far from any sockets at the club. I guess I could run a small jigsaw off a car battery, through an inverter? A tad more cost and bother than I was hoping was necessary though. I was temporarily tempted by the Tesco cordless jigsaw at under £40, until a review warned that acquiring the battery doubles the price! And of course, the cordless Makita jigsaw cost more than my boat...

So...hole-saws. Very appealing, I've used smaller ones, long ago. But my issue with these is a combination of the price for a 140mm, limited usefulness and the fact that my drill isn't powered either - a funny old hand-powered thing. I like its dependability away from charging points as much as I dislike the blisters that develop on my palms & thumbs.

The adjustable hole-cutter looks great - cheap, versatile and would make SWMBO wince repeatedly as I use it. Not sure if its use is restricted to electric drills? I daresay that's a question no member of B&Q staff will be old enough to answer.

Chuzzlewit, that's a nice Dickensian idea, using a bit of wood & sharpened nail as a cutting edge. I might call my boat Mudlark and cook fish over a fire on the beach as I work.

Being a real cheapskate, at the moment it's looking like I'll stick to 'stitch' drilling with the old hand-drill. No cost at all, good exercise and not much chance of it going wrong...

...but it's been very entertaining reading your contributions, thanks again. :encouragement:

 

[prv]

If you insist on using nothing but an eggbeater drill, then I agree that drilling a line of holes will be your best bet. You won't turn a 140mm holesaw with that, and I can't imagine the medieval torture instrument working all that well either (to be honest it doesn't look great even in a power drill).

At least an inspection hatch will cover up the inevitable ragged edge.

B&Q staff? Most of them are OAPs, the company having realised that they can employ them on part-time shifts for the same money as young folk, and many of them are much more knowledgeable.

Pete

 

[Greenheart]

B&Q staff? Most of them are OAPs, the company having realised they can employ them on part-time shifts for the same money as young folk, and many of them are much more knowledgeable.

I beg their pardon. I must have been unlucky when I visited my local B&Q - several clueless student-age girls. Cute, but useless.

When I've drilled my rings of holes, I'll photo them and post the pics for the forum's amusement.

 

[rogerthebodger]

Without the use of power tools I would mark the circle and use a sharp wood chisel and mallet to cut round just inside the like then use a wood rasp to get the exact round shape. The ply would need to be supported quite well to resist the cutting hits of the mallet but it the ply cannot be supported on a bench or floor a stout piece of wood could be clamped or propped behind the side of the work piece.

 

[prv]

The ply would need to be supported quite well to resist the cutting hits of the mallet but it the ply cannot be supported on a bench or floor a stout piece of wood could be clamped or propped behind the side of the work piece.

I believe he's cutting into a buoyancy tank, so no way of supporting it from behind.

Pete

 

[Greenheart]

Nice idea. Fascinating to consider the perfectly effective, if slower, ways of traditional carpentry. I might just use that method, too. The bulkhead in question is at home at present, yet to be cut to fit its location on board. I'm reluctant to cut the holes before positioning the ply, lest I find some irregularity of the rear-deck's construction, which prevents easy insertion of the ply, and puts the holes off-centre.

 

[prv]

Here you go Dan - detailed step-by-step instructions for adding an inspection hatch to a buoyancy tank with an old eggbeater drill: http://www.pettigrews.org.uk/lm/page031a.htm

Pete

 

[rogerthebodger]

Having been playing with wood for over 50 years since school in the UK in the early 1960's I do find the traditional way some times much better and get frustrated when some one I employed to work on my boat first goes for the power tools. Don't get me wrong power tools do have their place.

Just last week I was cutting a 100mm hole for an access hatch in a cover panel to allow access to a sea cock. Boat in Durban me 600 km away so I cut the hole under size for it to be trimmed on site is the hold is not in the right place.

OK I do have mains power on my boat but mainly use power tools for the stainless work I do.

 

[Greenheart]

Here you go Dan - detailed step-by-step instructions for adding an inspection hatch to a buoyancy tank with an old eggbeater drill:

Thanks Pete, that's an amazingly similar bit of work! Although I doubt I'll do as painstakingly neat a job as that gent. Some very helpful hints there, though.

Nice to see that such a thorough job included placing plastic bottles in the cavity, as built-in buoyancy!

Actually I'm putting in inspection hatches as sealable access-holes for stuff I'll want to keep secure and dry. I have it in mind to bolt fairly small cages to the inner side of the bulkhead, so that items placed inside won't rattle around loose amongst forty or fifty empty lemonade bottles. The Osprey's rear deck is 36" long and 48" wide, and at present the cavity beneath is gaping...

View attachment 42461

...I'll put in a central iroko post, about 1.5" square, and rely on that to stiffen the deck above and also to add rigidity to the new 5mm ply bulkhead.

I've seen other GRP Mk.2 Ospreys which either had no holes/hatches/drains in their rear bulkhead, others with removable panels...Seajet has spoken of storing beer in his.

The job of inserting the bulkhead panel won't be made easier by it having to be significantly bigger than the hole, for enough epoxy to cover the contact-areas...

...plus those big polystyrene blocks will get in the way. And...in case you thought I was making it easy on myself, I'll be running two sections of 65mm square drainpipe, from either side of the central iroko post, to those horrible clumsily-cut transom holes...then it'll all want filling, fairing and painting. Great fun. Ought to be ready to launch, by mid-October.

 

[zzyyxx]

http://www.machinemart.co.uk/shop/product/details/185mm-mini-dovetail-pull-saw

 

[prv]

Ought to be ready to launch, by mid-October.

I'm worried that might prove too close to the truth. You want to get out there! I'm already checking the tides for our main summer cruise to the Channel Islands and Cornwall in a couple of weeks. It's time for sailing now, not drilling holes and painting.

Pete

 

[prv]

That blade's too wide to cut a 6" circle.

Pete

 

[rogerthebodger]

This is what I use if I cannot remove the panel

http://www.ebay.co.uk/itm/Stanley-K...591?pt=LH_DefaultDomain_0&hash=item2a2e5792d7

All kinds of keyhole or pad saws suitable for the job.

Also like this

http://www.ebay.co.uk/itm/Vintage-P...lectable_ToolsHasdware_RL&hash=item27e37b9d46

 

[David2452]

Use a 140mm hole saw with caution. If you're not use to using them in a battery or mains drill, they can grab and do damage to your hand/wrist/knuckles. I have seen many injuries from large hole saw use from the inexperienced including a broken wrist during my time in the industry

Indeed, I don't recall ever doing 140mm but I have done a lot of 127mm and a few 150mm holes with a holesaw and care (and a good side handle on the drill) is needed

 

[Greenheart]

I'm worried that might prove too close to the truth. You want to get out there! It's time for sailing now, not drilling holes and painting.

Thankfully, this dismal weather hasn't made the lateness of my preparations too painful. But even in late July last year, things were wrong on the boat which were seriously diminishing the pleasure of sailing her, and I'm going to put them right before I launch again.