How to chamfer inside edge of architrave in situ

Hi

Per title, I need to bevel the inside edge of some architrave on some internal doors (long story but I need extra clearance for the door catch to swing past the architrave immediately in front of the catch plate).

I'd prefer a low dust method, architrave material is MDF. It is 25mm thick and I'd prefer not to remove to carry out the work as this may destroy it; I ordered via the internet and want to avoid having to reorder.

I don't think I am skilled enough to get a nice consistent 45 degree bevel by eyeballing it with a block plane and/or chisel. Could somebody please recommend a basic method that I could use? I have looked at chamfer planes but these are either bulky or suitable but very expensive.

Any tips gratefully received. Thank you.

Picture?

Hi

It's rectangular cross section square edged (no moulding profile) MDF architrave. 25mm x 75mm, nailed to the door frame in the usual manner.

I will take a pic when I get home from work.

Block plane is only dust free option.

Id say get a trim router, ebay have loads of makita copies that are good. And you need a 45 deg cutter with bearing.

https://www.ebay.co.uk/itm/101748-K...188793&hash=item3f7e894844:g:5wwAAOSww3tY5cHk

Use mask and vacuum up after.

Only a router will give you a consistent chamfer.

Cant you chamfer the doors?

Stanley knife? Do 2 vertical cuts then whittle out the middle bit.