Router Cutter Diameters for a Dado in Ply

[scruffmeister]

I need to purchase a new straight router cutter to cut the dado recess to hold the back of a cabinet I am planning. I don't have any sheet material handy to check right now unfortunately, so wondering if a 6mm bit will work well for 6mm ply, or if the 6.35mm (true 1/4") sizing would give better results? Thanks.

 

[ChaiLatte]

What is easier? To make a groove/dado wider or to make a piece of plywood narrower/thinner?

 

[Hornbeam]

You need to check the thickness of your ply. Quite a lot of plywood is actually undersize so some 6mm ply is actually 5.5mm

 

[TheTiddles]

5mm cutter, two passes

 

[Phil Pascoe]

It's the back of a cabinet - does it need to be an interference fit? No. ½mm of slop will make you job easier.

 

[Hornbeam]

It might be the back but it could be structural glued all round so might need a decent fit

 

[Phil Pascoe]

Fair point.

 

[scruffmeister]

All other things being equal, a tight fit is desirable. I'll try and hold off ordering one until I have some 6mm sheet handy - only got the 18mm for the main structure currently. Thank you for the pointers.