How to cut neat holes in ply?

[LittleSister]

How can I cut a neat hole in ply?

I want to mount some switches in an existing ply bulkhead, requiring circular holes about 2" diameter. The edges of the holes will remain visible.

I imagine that if I cut the holes using a conventional hole cutter, I'll end up with a ragged mess. If I cut something smaller and try to widen it out, it's most unlikely to remain circular.

 

[ShinyShoe]

Can you get to both sides of the ply with a drill and bit or can you only go one way?

Can you put backing material on both sides or again is it too enclosed a space

 

[neil_s]

I have always found those hole cutters with a pilot drill bit and a cylindrical saw blade leave a very neat finish. Just be careful to apply the cutter perpendicular to the job, so that it starts cutting all around the circle.

 

[russ]

Can you drill from both sides? If so then try using a hole saw from each side to stop splintering. Could also try drill through with centre bit and then reverse the rotation when hole saw touches ply to score the grain before cutting.

 

[JumbleDuck]

I suggest cutting slightly undersize with a hole saw (28mm for 30mm, say) and then enlarging to the final size with a flap wheel and drill.

 

[bedouin]

If you are careful how you start the hole then a conventional hole cutter should be fine at least in the surface where you start. I find it harder to get a clean exit but you are probably not so concerned about that side.

 

[Refueler]

Apply tape to the ply to cover area to cut.

Use a fine tooth solid hole cutter with central drill bit, designed for Cabinet Makers .... not the universal hole cutter type where cutter is a sprung steel ring.

Have a good speed to the drill but advance very very slowly so that at first its just grazing the surface and slowly cutting ... once through a touch - you can then advance at reasonable pace.

I would suggest getting a scrap bit of ply first and practice.

There is a trick with unpainted, raw ply ... Thin CA (superglue) applied to the circle to be cut ... it soaks in and hardens the wood fibres .....

 

[LittleSister]

Access to the front isn't too bad - plenty of width, but floor just inches below and a shallow projecting ledge a few inches above.

Access to the rear is poor - have to lean over and look backwards under deeper projecting ledge, and constraints to side as well - but I'm less concerned about appearance here, so long as it doesn't show from front.

The ply is thinly varnished. (Actually probably some sort of sprayed lacquer, 40 years old.)

 

[Daverw]

Use a sheet of ply taped using double side tape to the front face, drill thorough both slowly with new sharp good quality hole saw

 

[Refueler]

Access to the front isn't too bad - plenty of width, but floor just inches below and a shallow projecting ledge a few inches above.

Access to the rear is poor - have to lean over and look backwards under deeper projecting ledge, and constraints to side as well - but I'm less concerned about appearance here, so long as it doesn't show from front.

The ply is thinly varnished. (Actually probably some sort of sprayed lacquer, 40 years old.)

Old ply tends to splinter more than new .... so tape and VERY VERY slow with fine tooth hole cutter ...

Avoid those cheap universal hole cutter sets .... they are OK for holes that get hidden - but not for visible ones.

You can of course cut the hole and then add a cosmetic ring to clean it up ?

 

[Graham376]

Use a Forstner bit for very clean cut.

 

[LittleSister]

You can of course cut the hole and then add a cosmetic ring to clean it up ?

I wondered about that, but haven't yet gone searching for a ring of appropriate size. It would need the internal return (within the hole), and not be so wide as to foul the screws around the hole required to mount the switches. The switches just poke through the hole.)

 

[Hacker]

Using backing pieces clamped either side is the usual method of reducing breakout splintering

 

[Refueler]

I wondered about that, but haven't yet gone searching for a ring of appropriate size. It would need the internal return (within the hole), and not be so wide as to foul the screws around the hole required to mount the switches. The switches just poke through the hole.)

Vent rings ... plumbing rings .... check out caravan shops ..... doesn't have to be 'marine inflated price item' .....

My 5m daysailor lost its mushroom cowl top to its cabin vent .... temporary replacement was the top of a CD disc 'box' ... fits perfect. One day I might fir proper cowl ... or improve the CD box lid !!

 

[Fr J Hackett]

Using tape is an old wives tale, it doesn't work you will still get some splintering. A router using a piece of MDF or ply with a hole in it as a template is the best way. You could use a bearing guided cutter with a template of the same size hole or a larger hole and a guide bush. After that the next option is to make a ring.

 

[lw395]

Some ply is quite prone to splintering.
If it really matters, you could draw the circle with a pencil and compasses, then cut through the top veneer with a scalpel.
Cutting undersize and opening out with a flap wheel is good on thin panels, including GRP. Might be slow and costly with a thick bulkhead?

 

[Stemar]

A router would be ideal, but with the limited access. I agree with using a decent hole cutter. Would one of these help to get in there? Erbauer Angled Keyless Chuck 10mm

 

[Graham_Wright]

Circular based router (mine is a Zen) inside a ring of the correct, calculated diameter securely fixed to the ply.

You need to do the sums. Required diameter, less radius of router plus radius of the bit (I think!) equals ring diameter.

Of course, you hen have to find the ring!

 

[Norman_E]

Use a Forstner bit for very clean cut.

That will work very well provided you can start the cut with the drill square to the surface. On breakthrough it will splinter the back of the plywood, though that may not matter.
I use a thing like this KWB Drill Stand/Guide 778400 (for Drills and Cordless Drill, 43 mm Euro Collar): Amazon.co.uk: DIY & Tools mounted on a piece of plywood to ensure square cutting with a holesaw. A good method is to drill the pilot hole in the panel you are cutting, then mount the stand on a piece of 9mm ply and use the holesaw to put the pilot hole in that. You can then push the stand firmly against your panel with the pilot drill through both holes and put the holesaw through both the 9mm ply and your panel in one cut.

 

[Fr J Hackett]

Circular based router (mine is a Zen) inside a ring of the correct, calculated diameter securely fixed to the ply.

You need to do the sums. Required diameter, less radius of router plus radius of the bit (I think!) equals ring diameter.

Of course, you hen have to find the ring!

Much easier to make a template using a hole saw then use a bearing guided cutter or a guide bush. But perhaps the easiest is going to be a forstner bit but get it square on to the surface as Norman says.