Cutting Cornice Mitres

[AlexJ66]

Greetings, I have come to a temporary hold on bedroom renovations while I attempt to get my cornice mitre cutting correct before actually attempting to cut the actual cornice lengths. I have them about 85% right, just want to get them as perfect as I can without having to plug up too many gaps.

We have this profile http://www.tradeconnect.com.au/csr-gyprock-concerto-cornice-4800mm-p-3716.html, and I have this motre box http://www.tradeconnect.com.au/mitre-box-5575-and-90mm-cornice-p-3963.html.

I suppose the main, and perhaps stupid question, is can I extend the slots down in my mitre box, as they aren't deep enough to cut through the whole cornice (holding breath hoping this really does not sound too stupid). Is there something better I should be using? Rod, what do you professionals use?


Thanks in advance,

Kev

[Honorary Bloke]

G'day AlexJ66,

I note that so far there have been 23 views of your question and no posts.:rolleyes: Hmmm . . . . But being a Yank, I'm too far away for you to get your hands on my throat.:D

First off, if you have them 85% right using that mitre box, you are way ahead of the game. Of course you can extend the slits down the box, that is expected. Just find a bit of wood that is thick enough to reach above the existing slots and cut it on down. The bit of wood will keep the slots straight as you go.

That said, cutting compound mitres by hand will be challenging. I'm no pro, but even hobbyists generally use an electric mitre saw.

The inside corners should be joined by coping the profile of the cornice on one end. The outside corners will require a compound mitre cut. The techniques are a bit extensive for a short answer, so you may want to take a look at this link for a more detailed explanation.

http://www.royalmouldings.com/HowToFiles/How%20To%20Install%20Interior%20Mouldings.pdf

Good luck!:)

[rod@plasterbrok]

Hi we have an excellent page on cutting decorative cornice on our web site.

We also have a page showing you how to calculate the dimension to cut the mitre.

Yes cut the mitre box down, the only reason its not done at the factory is for packing and transport, so they dont break!!

Explaining in detail takes too long to write out in one post. Here are a couple of quick tips on cutting cornice.

Always cut the cornice with the upper member furthest away from you.
The upper member when you cut is the wall member. ie. cut it upside down.
when you mark a line on the wall member, after cutting the side that has the line on it is an EXTERNAL Mitre.
The side without the line is an INTERNAL mitre.
The cornice has to sit square in the mitre box or held square.
You must keep your saw straight up and down.




Let me know if you have trouble following it and I will assist.

Cheers
Rod Dyson

[AlexJ66]

Thanks very much for the responses Bob and Rod, I actually thought I had deleted the topic :(


Yes cut the mitre box down, the only reason its not done at the factory is for packing and transport, so they dont break!!


I suspected this was the case Rod and that my question was indeed a stupid one, but the damn cheap old thing started to fall apart when I was cutting it, so I dashed out and bought another plastic mitre box with the cuts all the way down. This worked perfectly, well as close as I can get without spending the rest of my life on it ;) The ceilings are 12 foot high, so some jointing compound or excess cornice cement wil hide those gaps anyway :D

Thanks again,

Kev

[durwood]

I think you are set to go, doesn't matter how good your mitre cutting might be you will probably find the room doesn't have 90 degree corners.