Cutting circular holes without central drill bit.

[harrymonkfish]

Hi All

I have an idea and don't know whether it will work. My first feeling is it won't.

I need to cut out circular shapes in 3mm birch plywood. These are for decorative purposes. They cannot be painted and no holes can be filled. The circles will be approx 140mm diameter.

I'm thinking if i used a 140mm saw hole cutter with the drill bit removed and used a drill press and clamped the wood firmly to the drill would I be able to cut a nice round circle?

Thanks for looking
Paul

 

[Burnerman]

Yes, with care....use a solid hole saw though, not one of those split types!
Your problem will be with the hole spacing - so much easier with a pilot drill to measure from.
John

 

[harrymonkfish]

Thanks John.

The hole saw I am looking at is a solid one

http://www.toolstation.com/shop/Pow.../Holesaws/sd1530/PUNK+BiMetal+Holesaw+/p28270

What do you mean by hole spacing problem?

Thanks
paul

 

[Deleted member 174758]

I'm thinking if i used a 140mm saw hole cutter with the drill bit removed and used a drill press and clamped the wood firmly to the drill would I be able to cut a nice round circle?

More likely you'll find it being thrown across the workshop even if clamped down. You can do that sort of thing with a low tooth count holesaw, but it needs minimal number of teeth and a lot of clamping. Something like a 3- or 4-tooth TCT holesaw in the appropriate arbor should work if run slow enough (say 50 to 80rpm), although you may need to look at Starrett to find the dead size you require (and I'm not sure that anyone does 140mm hole saws - 127mm and 152mm outside no problems - these probably equate to 122 and 146mm respectively on the inside). Edge finish on holesaws isn't always so brilliant so be prepared to clear up a bit

 

[Burnerman]

Thanks John.

The hole saw I am looking at is a solid one

http://www.toolstation.com/shop/Pow.../Holesaws/sd1530/PUNK+BiMetal+Holesaw+/p28270

What do you mean by hole spacing problem?

Thanks
paul

Without a pilot drill, Paul, its pretty awkward to get the hole in the exact position you want to be......presumably you wish to create some sort of geometric pattern.
Anyway, I dont think you'll have any great problems, but I would recommend fairly high speed, and very gentle pressure on the drill as the hole saw starts to cut.
The hole saw needs to be fitted into an arbor, make sure that is tight.
Have a few practice runs - nothing ventured, nothing gained!
(I used to create loads of wheels / cams using this method during my teaching career....although its not the best method, it can work).
John

 

[harrymonkfish]

The circles will be printed on and turned in plaques with quotes on that i sell.

So really this needs to be a reliable method otherwise it wont be worth it. i sell about 50 a week at the moment.

Do you think there will be much damage to the edges of the wood? Something that a quick sand cannot fix?

Thanks

 

[Burnerman]

I needed to cut timber discs for the kids I taught....they had to investigate the lift that a cam would give when the pivotting axle position was variable.
The material I used was 10mm ply or pine, and the diameter was between 50 and 70mm.
There was the occasional raggy edge, which was quickly put right with a second or two on a belt linisher.
John

 

[harrymonkfish]

That's good enough for me John. I'll go with it. I will let you know how I get on.

Thanks for advice.

 

[Norcon]

An Armeg Adjustable hole cutter might do the job.
Available from Axminster...
http://www.axminster.co.uk/armeg-adjustable-hole-cutter-40-to-200mm

Once in the pillar drill it might be stable enough without the center drill.
There's a plunge action through the polycarbonate dust shield and it might be possible to clamp it down.

A sacrificial ply on top might help prevent tear out.

Another option is laser cutting.

 

[Lower]

I would drill a hole in another piece of wood using a conventional hole saw in a conventional manner and then clamp that piece of wood on top of whatever you want to cut.

It'll act as a drill bush and stop the hole saw wandering when you start the cut.

 

[foxhole]

Thru 3mm ply you could punch out the holes, grind off the blade on your hole saw and sharpen edge, then you can use a large mallet to punch out the holes.

 

[Dave54]

If I had 50 of these a week to do, and the possibility of needing more (I'd assume?) I would have to at least get some quotes for laser cutting as Norcon suggests. It may not be economical for you at present, but at least you'd know what the costs are. Also, thinking laterally slightly, do any of the laser companies produce blanks the size you want as waste? Couldn't hurt to ask.
The thing is that as a business you have to ask yourself whether your time is better spent making the blanks, with the probable need to sand etc. or doing something else. For me at least there is nothing as boring as batch producing parts, particularly once the initial novelty wears off.

 

[Deleted member 174758]

In the right volume 3mm plywood can be cut using a forme knife on a cylinder press which is how they cut out cardboard packaging and some leather shoe parts (or at least how they did when we still had a shoe industry)