Cutting thin slots in hard wood

I am using fuzzy hinges on my Mig.3 rudder. But the rudder post on the fin is made of hard ply and I cannot get a scalpel blade through it. I have tried using a thin dremel wheel on ply but it cuts a slot wider than 0.5mm whereas the fuzzy hinge is 0.25mm thick. Anyone got any clever ideas?

1. Use Robart hinge points instead and simply drill through your fin post
2. Drill a, say, 1/8 hole above and below where you want the hinge and remove the ply between the holes using a fine saw or file. Replace with balsa.
3. Find a multitool (Google multitool) that has fine blades. I got a cheap multitool before Christmas and it's amazing how easily it cuts through wood and aluminium. If you can find a hobby version with finer blades please share.

I've never tied them John, but often thought they might be handy:

www.shesto.co.uk/hand-tools/saws-and-saw...with-scalpel-handle/

0.24mm

I would go for Mike's first suggestion, Robarts are better for large models and easier to install

Trouble is I have already slotted the rudder. My logic is that the rudder post and rudder leading edge do not mate very well and fitting strain-free robarts would be a tough call (otherwise I totally agreee that they are the easy option). So I love the sound of the shelsto micro saws and will post with results when they arrive.

Also not enough 'meat' on the fin post to support robarts. The fin strength is in the composite skin..., Note the warped post which makes for gaps between the fin and the rudder... And there's a pull-pull elevator mechanism to still fit in the void which may clash with robarts or extra thickness to the post