Decorative Cornice and Mitre box

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Hi all,
I am installing some new decorative cornice.

The cornice size is larger than normal with one side being 165mm and the other 55mm or close to it.

I will need to cut inside angles only for the cornice as I am joining it up to existing cornice.I only neeed to cut four angles.

Can I buy a mitre box to suit this size cornice and where I join the new too the existing cornice would I just butt it up? use tape on the join? Or just apply gap filler as I butt them up to each other.

I have pretty much worked out how to join the patterns and read up about the angles in regards to pattern join,just the above has got me.

Thank you

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[rod@plasterbrok]

You can buy a large mitre box or you can easily make your own.

You just butt the two together, apply cornice adhesive to the join before fitting the cornice, this help form the bond.

There is no perfect way. But if I were to recomend one thats close, it would be to use a scrim made up of sizal dipped in cornice adhesive and place it behind the join so each piece is embeded into it.

Now I didnt even go to that trouble in my own home. Although I did do this with raw plaster without the scrim. I still have the odd crack here and there.

Dont use gap filler to fill the joins you can never get it smooth. If you get a hairline crack later then gap filler is ok to do the repair.

Cheers Rod

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Thanks Rod,
Cornice rocked up today,I noticed a few hairline cracks in it in the centre of two lengths, after looking at them further they r more than cracks they run right through the cornice in the centre,still my fault I should have told driver to take them back,no wonder he was super carefull carrying them from truck.

Rod is there a link to where I would be able to find a plan to make a mitre box to suit my cornice size?

I am in two minds to wear the cost of this cornice $75.00 and pull the existing cornice off and replace it all with 90mm cornice,the 90mm will cover the gap between the ceiling plaster board and the walls and I can use my mitre box instead making or buying another.

Also when I use my laser level it shows me that on one wall the cornice is set about 10mm lower down than the other cornice on the other wall,very old house here,thankfully the existing cornice has only nails holding it in place.

Thanks

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[rod@plasterbrok]

I would get them to replace it if it is cracked through the center!

A Mitre box is not hard to make. I presume the cornice you have comes down the wall 165mm and out on the ceiling 55mm, if it is the cornice I am thinking of.

You will need to get the exact dimensions by holding it in place against a wall and mark each member and measure it out. See http://www.how2plaster.com/msdc.html diagram A.

Best to make the box out of some solid wood 20mm ply is good. the box will be, say 55mm wide (inside measurement) and say 180mm high (inside measurement) . The most important measurement is the 55mm one. The box should be about 300 - 350mm long.

See the pics on this site to see how to do the cuts on the box. http://www.ceilingspeakermounts.com/...nts/index.html

Dont ask me LOL it was the best pic I could find!

The most important thing with the cuts is to make sure they are perfectly 45 deg. across the box and perfectly plumb up. Use a square to make a line to work to and cut slowly. Or get the cuts done by a cabinet maker (buy him a beer).

Hope this helps.

Cheers Rod

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Thanks Rod for reply,
The mob i got the cornice from said they will replace it for me,but prob two week wait for it,so they r going to give me lengths of 90mm,plus refund of balance.

The 165mm actually sat on the ceiling and after removing the remainder of cornice I can see why the larger side was on the ceiling,the plaster is a bit short,so I am filling it in with strips of plaster board to allow the 90mm to fit.

Cheers

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