Removing old cornice.

Is it difficult to remove part of the old cornice. I have just installed a new kitchen and new bulkheads above some cupboards and of course they need to have cornices around the bulkheads. I have bought the new cornices to match the old ones which are quite fancy and deep. Now where the bulkheads meet the wall and the old cornice I need to mitre the old cornice with the new and create an internal corner. I have figured the best way for me to do this would be to cut out a small section of the old cornice, say about 300mm so I can join in a small section of new cornice with a simple but joint where the old meets the new and with the mitre cut on the other end for the angle of the internal corner against the bulkhead. I hope I have made this clear.
So what I need to know is how do I remove the old section of cornice without damaging or removing part of the ceiling or wall so the new cornice can be fitted.

Removing can be the fun part the experts may have better ideas
Like rip it off and replace the lot.

I have used a spatula like the ones used for icing cakes thin and long with enough force it can separate the bond unless its Liquid nails

Make a template prior removal John as often all doesn't go well:~

I would not cut it back 300mm, as then you have to match a mitre as well as a join. Joins are much harder to match.

Even though the cornice looks the same, often it comes out of a different mould that is slightly different. Slight differences may be apparent in a join where they are not so apparent in a mitre.

To cut the mitre you need to use a stanley knife and be patient while cutting away.

To mark where to cut measure how far from the wall the cornice projects on the ceiling, then mark this measurement on the cornice by measuring out from the corner along the ceiling edge of the cornice.

Then with a pencil draw a line directly from that mark to the bottom corner. This will give you an indicater where to cut.

With the stanley knife make a cut as deep as you can through this line, err on the side closest to the wall as you can trim easier than fill, then cut in a v along that cut from the wall side. Continue until you cut all the way through.

I normally then cut a mitre on a spare piece of cornice and hold it up to see how it matches then trim as requried untill you get a perfect match.

This takes 20 minutes or so but is wll worth the effort!

Cheers Rod

Thanks guys. So Rod you are saying to cut the mitre on the existing cornice and mitre the new cornice up to that. I will give that a go. I see your point about the joint that would have to be pretty good if I cut it back 300mm.
Okay Ray, so what do I do if they have used liquid nails? Start praying.? :)

Will catch up with you later Ray. got your messages ok.

John, cut the mitre on the existing cornice first, then trim that to match a properly cut mitre that has been cut in a mitre box on an off cut of cornice that is easy to handle. When you have it fitting nicely you cut your full length and it will also fit just as well.

When you cut a free hand cornice institu like that you will never get the cut right the first time. It is better to under cut on the first attempt then trim as required to get the right fit.

Cheers

Rod