thinwater
Well-Known Member
If you have a drill press, a fly cutter is on of my favorite methods. But don't even try it otherwise.
Cutting a hole
- Thread starter Little Dorrit
- Start date
Seashoreman
Well-Known Member
Have made a few speaker cabinets in the past. No elaborate workshop at the time, just in the garden shed.Methinks your Jigsaw skills are better the mine
As someone said practice first and take your time.
prv
Well-Known Member
Depends whether the edge of the hole is going to be visible, or covered by a flange on whatever’s being installed in it.
For a visible edge, I would take the time to set up a jig for a router, after roughly cutting out the bulk with a jigsaw. Not many of us can cut a perfect circle by hand, and the inevitable wobble will look very home-made.
At 20cm, though, I suspect this is for an inspection hatch with a flange, in which case I would just use the jigsaw, more carefully than in the former case. Any slight imperfections will be covered by the fitting.
Pete
For a visible edge, I would take the time to set up a jig for a router, after roughly cutting out the bulk with a jigsaw. Not many of us can cut a perfect circle by hand, and the inevitable wobble will look very home-made.
At 20cm, though, I suspect this is for an inspection hatch with a flange, in which case I would just use the jigsaw, more carefully than in the former case. Any slight imperfections will be covered by the fitting.
Pete
Little Dorrit
Well-Known Member
It doesn't need to be that tidy - I think I'll go at it with a jigsaw.
TLouth7
Well-Known Member
A router trammel is your friend here.
Just a scrap piece of thin ply, screwed to the bottom of your router, with a hole around the bit. Then put a woodscrew through the scrap the right distance from the outside edge of the bit (some trial and error may be required. Drive the screw through the centre of the intended hole (pencil lines on both the workpiece and the trammel will help with lining up), plunge the bit into the 10mm ply and push it round in a circle. You may want to do a couple of passes at increasing depths.
The same idea works with a jig saw, but at 10mm thickness and only 200mm diameter I would be worried about the blade bending.
I have used this up to 16 foot diameter, takes a while to do a full circle.
Just a scrap piece of thin ply, screwed to the bottom of your router, with a hole around the bit. Then put a woodscrew through the scrap the right distance from the outside edge of the bit (some trial and error may be required. Drive the screw through the centre of the intended hole (pencil lines on both the workpiece and the trammel will help with lining up), plunge the bit into the 10mm ply and push it round in a circle. You may want to do a couple of passes at increasing depths.
The same idea works with a jig saw, but at 10mm thickness and only 200mm diameter I would be worried about the blade bending.
I have used this up to 16 foot diameter, takes a while to do a full circle.
penberth3
Well-Known Member
Use a brand new blade. Even better if you can find a narrow blade which is better for cutting a small radius.
savageseadog
Well-Known Member
If the OP is drilling or into something fitted in a boat it's a good idea to make sure of what's on the other side. Fuel tank? Electrics, Hoses? Sea?
Richard10002
Well-Known Member
Nor had I
https://www.ebay.co.uk/itm/40mm-200...-Saw-Drill-Bit-for-Woodworking-/222730999478?
Trammel?
http://www.powertool-supplies.co.uk...AItLw_KYzn6YpYe87HEqUW4mDHDjXx9xoCse8QAvD_BwE
No idea how this works, but it looks like a neat solution is possible.
Last edited:
Little Dorrit
Well-Known Member
I'm making something to secure gas bottles in a gas locker.
VicS
Well-Known Member
Just just glued 4 little chocks to the floor of the locker that fit inside the cylinder's bottom ring.
Saved all this high precision carpentry!
rogerthebodger
Well-Known Member
I did something similar in my gas locker for bigger gas cylinders.
Mine were half way up the cylinder to stop it shifting and banging on the inside of the locker
macd
Well-Known Member
Remember when snooker referees had an unweildy partial sphere to mark the position of a ball for cleaning etc? It took decades before someone realized that two points was enough to define a ball's position on a plane. Three points would secure it on that plane.
VicS
Well-Known Member
There may only be three ........ but no I don't remember when snooker referees had unwieldy partial spheres.
macd
Well-Known Member
I might better have described them as partial spherical holes: the ball was the sphere inserted into them. But, in my roundabout way, I was agreeing with you.
PowerSlapper
Well-Known Member
Little Dorrit
Well-Known Member
Without wanting to start a new thread does anyone know where I can buy blades for an old Bosch P10 Jigsaw, T18's I think?
John the kiwi
Well-Known Member
A few years ago i treated myself to a decent jigsaw with variable speed and also variable blade orbit. Not sure of the right term, but the blade draws back from the cut on the down stroke.
Compared to the cheap and nasty fixed speed lightweight unit i had previously it was a revelation! Get a decent jigsaw - that's half the battle won.
Then get good blades - 90% of the way.
My new jigsaw has facility for a adjustable cutting fence just like a skilsaw.
I made a flat bar that would go through the normal fence slot but is totally flat and with a wider section at one end. in the wider section I drilled a 3 mm hole which is exactly in line with the front edge of the teeth on the blade. To cut a circle i drill a largish diameter hole say 20 mm which touches the larger circle then sit the jigsaw in place, put the radius arm in place and drive a 3 mm screw through and into the circle centre leaving it just a little loose. you can guess the rest.
Works well.!
Compared to the cheap and nasty fixed speed lightweight unit i had previously it was a revelation! Get a decent jigsaw - that's half the battle won.
Then get good blades - 90% of the way.
My new jigsaw has facility for a adjustable cutting fence just like a skilsaw.
I made a flat bar that would go through the normal fence slot but is totally flat and with a wider section at one end. in the wider section I drilled a 3 mm hole which is exactly in line with the front edge of the teeth on the blade. To cut a circle i drill a largish diameter hole say 20 mm which touches the larger circle then sit the jigsaw in place, put the radius arm in place and drive a 3 mm screw through and into the circle centre leaving it just a little loose. you can guess the rest.
Works well.!
Slocumotion
Well-Known Member
How do you prevent your jig saw/Trammell/disc combination from becoming a freehand circle- wrecking device as you complete the cut?
As for downward cutting blades - the work of the devil! Especially when manufacturers of decorative faced ply sponsor the secretion of one in a mixed set of blades supplied with a new jigsaw - ,
"Job's nearly done, blades getting a bit blunt now though, pity to spoil the work by bashing on through, I'll just use that other wood-cutting blade for the last bit.... then ......LIFT SLAM LIFT SLAM LIFT SLAM - What the......!!!
Or am I the only one?
As for downward cutting blades - the work of the devil! Especially when manufacturers of decorative faced ply sponsor the secretion of one in a mixed set of blades supplied with a new jigsaw - ,
"Job's nearly done, blades getting a bit blunt now though, pity to spoil the work by bashing on through, I'll just use that other wood-cutting blade for the last bit.... then ......LIFT SLAM LIFT SLAM LIFT SLAM - What the......!!!
Or am I the only one?
Little Dorrit
Well-Known Member
There are a few things to prevent splintering on the edges. 1) If your blade cuts on the 'up stroke' turn the piece over 2) Use masking tape on the cutting line 3) Score the cutting line deeply before cutting 4) Take it easy! 5) Always ensure the piece to be cut is totally fixed as close as possible to the cutting line. Having said this I totally agree that some inferior wood saw blades don't help!! ...so perhaps 6) Buy good quality blades?
Last edited:
