Hole saw

[Democritus]

Hi Guys,
What’s the best option for cutting holes through MDF.?
I have a cheapo set of bi-metal hole saws, but they are struggling to cut through a 3/4 inch sheet of MDF. Is it the tools, or is it the MDF.? If it’s the MDF, what should I use to do the job ( 8 x 35mm holes)
D.

 

[Spectric]

You have answered why they are struggling, cheapo holesaws are best avoided. Also these type of hole saws will struggle to remove the waste from the cut and so clog then burn. What you need is a decent forstener bit, but I would ensure rear support to prevent breakout.

 

[peter-harrison]

Holesaws are designed to cut metal and they don't do wood etc very well. They don't clear the sawdust at all after they have cut the first 6-10mm. You can greatly improve this by drilling a hole or holes just inside the outer radius of the holesaw. This will allow the sawdust to fall through and stop the kerf getting clogged.

 

[recipio]

Hole saws demand a lot of power and MDF is a beggar for clogging up the teeth. I would make a template with a 35 mm hole and use a router to make the holes. I actually burnt out a Ryobi motor in a pillar drill by drilling about 20 x35 mm holes in ply. An expensive lesson learnt.

 

[Democritus]

Thanks, guys.
I’ll forget the holesaw route (although it says on the tin ‘for use with metal, wood...), and try something else. I have a 35mm Famag Forstner bit, but I‘m a bit reluctant to use it for this job, (just a stand for wood lathe tool rests), in case it gets knackered. I might try drilling holes on the perimeters and then knock the MDF out.
Any other ideas gratefully received.
D.

 

[Distinterior]

Drill halfway through, then flip the bit of MDF over and drill through from the other side.......If its only 18mm thick, this will reduce the clogging and be a lot easier to cut out the holes.
Also, make sure you set the speed of your drill at an appropriate RPM....If your speed is too fast, there is a greater likelihood of clogging the holesaw bit.

 

[deema]

It’s not the quality of the holesaw, it’s the method. All holesaws will only drill a certain depth before the teeth become clogged with cut material. There is nowhere for the cut material to go other than within the cut. The key is to cut a little and then remove the cut material, rinse and repeat. Metal / wood holesaws have shall gullets compared to wood only holesaws and can cut a shallower depth before swarf removal becomes necessary.

 

[Democritus]

Hi Guys,
Used the drill round the perimeter method. Not the cleanest finish in the world, but will do for my purpose.
Thanks for all your help.
D