Need 9" Hole Saw

[inertiacoupling]

I have a house that has hand plastered walls that use a light metal mesh under the plaster.

I'm having central air put in, and my HVAC man says I can help make his job easier if I put in the 9" holes for the ducts and returns in the ceiling.

Does anybody know where I can get a 9" hole saw, or of an efficient way to make these holes?
Thanks for any advice

[FloridaOrange]

I could do it with a dremmel and something like this: http://www.rotozip.com/Shop/Category...tm?IID=2?HID=6
With the mesh you might have to get a good bit or a bunch of so-so bits.

I don't know that a 9" hole saw is made or at least readily available.

[jadnashua]

The metal lath will be a killer...sharp and nasty stuff. I've used a Rotozip to cut large round holes. None of the bits available for it would last long going through the lath. But, if you set the depth to cut through the plaster, it would give you a nice template to cut the lath, maybe with a metal cutting blad on a jigsaw or a good pair of tinsnips or aviation cutters.

This might work. I might also catch and make a mess! http://www.holepro.com/powerseries.html#X The biggest traditional hole saw I found was 6".

[jimbo]

Plaster tears up the teeth on any saw blade you use. Buy several!

[geno54]

I'm having central air put in, and my HVAC man says I can help make his job easier if I put in the 9" holes for the ducts and returns in the ceiling.

Does anybody know where I can get a 9" hole saw, or of an efficient way to make these holes?

The reason he said that is because cutting plaster with either wood lathe or metal grid is that is tedious and time consuming to perform. Chips are common and ceilings sometimes have to be repatched and or painted afterwards if not done carefully. No 9 inch hole saws I know of.

[brownizs]

Actually, there is a tool that is used with a Rotozip to cut a hole up to 12-14". It sits in a hole that you drill, then from there, the Roto sits on the outside edge. You do need to use a Carbide tip cutter.