best way to cut 175mm hole in mahogany

Cutting a hole

Are there no other answers? I have never seen a hole cutting saw that big although it might be worth inquiries. A so called fly cutter with one adjustable arm and a cutting tooth might go that big and would be at least a good way to mark the hole out.
A jig saw with a wood cutting blade might do it. The only other option might be to drill a series of holes joining them up with a file or saw blade.
Sorry I feel i am saying the obvious with no real help. good luck olewill
 
Router?

Either:

Fix a batten across the back of the piece (with DS sticky tape, etc.) making sure it's fixed to both the middle and outside of the hole. Set up a tramel(sp?) rod on the router, fix it to the centre of the hole, and keep routing a deeper and deeper slot until you've cut through. Remove the batten + cut disc.

Or:

Use similar method to cut a bigger hole in thin ply - fit the collar to your router and use it to trace around the inside of the ply template whilst it is fixed to your workpiece (DS tape, screws, clamps, etc.). You need to calculate the right sized template hole to take account of the difference in diameter between the router collar and cutter diameter.

If you've got a router table you can make circular templates very easily.

If you're not too fussed about keeping it round, you can use a jigsaw.

Andy
 
sjclewes said:
hi there all woodies what’s the best way to cut a 175mm hole in 1 inch mahogany any ideas greatly appreacheated
Click to expand...

You don't say if the cut out section is to be kept and used, or how much room you've got to work with. Is this piece of mahogany part of the boat/fixed, or a board that can be bench work. You can get hole saws that size, but they cost a mint and are more suited to a drill in a jig than working freehand. The torque on something that size will be enormous when it bites.

If you've got a good quality jigsaw, a Bosh or similar, cutting a hole in 25mm timber is easy enough. Especially with a radius that large. Bosh 101B blades give a good fine/clean cut. Just take it steady, not to higher speed.

Let us know what facilities/gear you've got available and what the job actually is. If you've got a small piece of timber that's not easily clamped it will restrict your options somewhat.
 
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cant remember the brand name.. rotordrill or rotorcutter... Its like a router,but uses what looks like a drill bit, but the length of the drill bit itself is also a blade.
Or a router. where you use an "arm" secured into the middle of the circle, and then swing it around. I wouldnt try free hand.
 
Very cheap and very slow

Two nails, separated by the radius of the hole, through a wooden batten. Sharpen the cutting nail frequently.
 
Routing will be most accurate, if you have a good router and working space. Otherwise, if super accuracy isn't called for, I would consider roughing out a slightly undersized hole by either chain drilling or jigsaw, or both. The hole can then be finished to the marked size with an abrasive flap-wheel held in an electric drill. With care, this can be quite accurate.
 
If I was doing it it would be with a jig saw, because I have a jig saw but none of the other things mentioned.

I have cut smaller holes than that with a jig saw through GRP sandwich decks with no problems.

Where is Seanick when you need him?
 
A 177mm Starrett holesaw will be an eye-watering price, although there might be "economy" makes available. Also, operating such a size in a hand held drill would be a bit fraught I should think, it'll take considerable power.
 
If the hole is hidden (by a speaker or similar) then a jigsaw, if it has got to be super accurate then finish with a router and circular template, using this method I would still make the initial hole cut with a jigsaw say 8 -10 mm inside finish diameter and then finish with the router, dont try to plunge cut and finish in one pass its not kind on your router and makes it a lot harder than it needs to be
 
NDH hints at the best way, a method often used by kitchen fitters for making clean accurate cuts. Use a template and a router to make the first cut, around 1mm deep with, say, a 6mm bit. Then use a jigsaw to cut the waste out, following the cut made by the router bit, but leaving a little for subsequent cleaning up with the router. If you leave around 0.5mm to clean up and the router bit is sharp you should be able to do the last cut in one pass.
This assumes you have a router and a jigsaw. If you haven't then you can clean up a jig-saw cut with a rotary sanding bobbin in an electric drill and with a little care you'll get a good finish.
 
well everybody i didnt expect so many great replys i shall go and try on a bit of waste wood i shall let you all know how it turns out by the way i did think of laser cutting but i dont know whether they can cut 1inch mahogony
 
Cutting holes

Suspect you have more than enough advice to get the job done. So just to pick up on your point about laser cutting should you ever consider going down that route, an alternative would be water jet cutting. It uses a high pressure, very fine jet of water entrained with abrasive to cut only slightly less accurately than a laser. The thickness shouldn't be a problem and there would be no danger of heat damage. Good luck what ever method you choose.
 
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