Ernie hit the nail on the head. Wear a respirator! Buy the best damn one you can afford and use it in attics or wherever there may be dust, etc., you do not want to inhale.

We have found the Lenox Carbide Recessed Hole Saw work great in these situations. They top out at 6 7/8 diameter, but if you carry a speaker in that cutout size you're going to have a new best friend.
[Link: lenoxtools.in]

Still opportunities for cracking, but this puppy made light work in several recent jobs. Right through the plaster and wire in one job, plaster and lathe in the other.

They're not cheap, but cheaper than your time and make a nice clean hole. Don't forget the appropriate arbor and a mean old drill to go with it. And they do throw dust, so you still have to contain and clean.

I have two methods for cutting, I have a 6" hole saw and have found a few sets of speakers that will fit in it, and its by far the cleanest of the methods, second method is actually a fat max drywall knife, going slow and only cutting on the upstroke (going in) and being gentle bringing it back out. I rarely have any issues, the metal screen is pretty easy to cut through as well. We have a TON of old houses here in Ky, the last one I did dated back to 1810-1820. Seems like every other house I do (for retrofit) is a plaster and lathe, or plaster with horsehair, some with the wood strips, some with wood strips and metal, some with metal only with mortar smeared over it and plaster over it.

Good luck, just tell your customer up front that plaster is fragile and that it might chip where your cutting it. Safest bet is the hole saw.

B

You guys certainly like the tough route.

I have always traced where I wanted to cut. Then used a thin tipped screw driver and SLOWLY chiselled along the line. Little dust and I dont eat up 10 rotozip tile blades along the way.

Im my area there was typically no wire but lathe boards. Once all the plaster has been chiselled away, I cut the boards with a rotozip with a vac attachment. I can typically do one in under 10 minutes.

Cutting with a saw/rotozip/whatever will create a HUGE dust nightmare.

Also be very careful if the ceiling is in poor shape. If it has significant cracks/patches already, be certain to talk about who is responsible when it all falls off.

Using the masonry bit method that myself and a couple others mentioned doesn't create that much dust. The dust typically falls down and not out as it does with a rotozip. Without any kind of lathe boards or metal, it takes a minute or two to cut out a speaker with no cracking. I can't speak to the effectiveness of other methods really as this is the way I have always done it.

You may need some longer screws for the speakers while you're at the HD for parts :) I had a ceiling in an old antique store with 3-4 inches of misc material that didnt work out with the speaker dog ears (wouldnt flip). We got some 5"+ screws, pulled out the ears, replaced the factory screw, and voila, done.

Roto zip has a great circle cutter attachment, and a dust collector fitting for a vaccum . You will need at least two passes per hole, one for the plaster with a carbide bit, the 2nd with a HS bit for the wood. You will have to determine which bit works better on the steel lath, as I have not encoutered this challenge.

This will cut very consistent circles with reasonable dust control. Having to change bits is a pita, unless you have two of them or use a dremel for the 2nd cut.

As others have pointed out, know where your wall framing is first, but don't drlll at the center of the hole where the hole cutter guide has to locate.

Good luck.

It's been a long time since I cut plaster for speakers or wall controls. I have never had a ceiling fall but I have seen the aftermath of one falling. I have tried all of the methods listed above. No one is really any better than the other. Patience is key. We used a compass to score the plaster face and then would drill a few 1.25" holes for a reciprocating saw. Lennox makes a plaster blade. It has no teeth, only a sanding type edge. Works well and doesn't create too an enormous amount of dust. Our clean up solution was to hire a maid service for the next day. The homeowners appreciated that extra attention to detail and it cost about $100 or so. Just add it on to the labor portion of the job. I never wore a mask and we cut in a LOT of plaster homes. Most "modern" plaster will have the backer (wood lathe or expanded metal mesh, or both) with a layer of concrete like filler and then a fairly thin layer of plaster. It's the thin layer that can crack/shatter/spiderweb. The filler material usually will stay in place. I had one wall fall on me in all the years I spent installing. I had cut in a single gang retro box for a keypad. Everything went fine during the cut and rough install. When I drove the screws into the box to hold the keypad in place I over tightened just a touch and the wall just spiderwebbed on me. Then it fell. Thank goodness we had a release from the homeowner concerning plaster cracks/damage. The wall obviously had experienced some water damage at some point which probably attributed to the plaster falling. At least that's what the lady of the house decided and we agreed. The joys of a plaster home.

I said "modern" plaster and I mean plaster up until the invention of sheetrock. I have done some "new" plaster projects where the filler was 3 inches deep on top of metal mesh and then a good 3/4" of actual plaster. It was many years back that I did my last "new" plaster job. It sounded absolutely killer once we were done. The walls did not flex in the least so the bass was nice and tight with just a slight amount of loading. A real pain re-tooling the dog ears on the speakers but worth it once finished.

The hole saw method (not that POS scoring tool they sell at lowes) but a good one will do around 10-20 holes, around $60, and has little to no dust trick is to run forward toll blades start to touch, stop and go in reverse till you score or go through quite a bit.

Plenty of ways to accomplish it, just find the one that fits you.

B

You've just had dumb luck that there was never any structure on the other side of that plaster!


That's lath. A lathe turns around.


It's been so long since I did this that I forgot about the chisel method. I've avoided rotozips because of the dust.


We emphasize WHEN, not IF.

Worse yet than all of this was enlarging speaker holes in plaster under stucco... not hard if you're used to chiseling a statue a day!

Anyone use the Dremel 6800 series for holes. I am sure the bit would break if it hit a screw, but the unit has a better grip than my old dremel.

[Link: amazon.com]

+1 --- Also apply painters tape to the ceiling where the cuts will be made. Use a "Multi-Tool" to do the cutting of both the palster & metal mesh. Hope this is T&M and not a standard sheet-rock speaker install price. Good luck. Haven't had to do one of these in years and the last one was not very fun, as there was also two layers of thick plywood above the mesh, and THEN lath & plaster WTF??? (I have no idea why) --- but in a nutshell I under estimated the time & grief involved.

We installed a 5.1 system this summer in Washington DC and that plaster was the hardest thing that I ever had to cut. It chewed up every blade and saw that I tried. Ended up using a diamond blade circular saw blade designed for cutting concrete to cut the holes. You can imagine how hard it is to cut a round hole with a circular saw. It took me over six hours to cut five 6" holes and it was miserable. I swear that plaster was mixed with concrete.

Dave T.

That might not be so far from the truth. I was watching a this old house episode a few years ago and the guy that was redoing the plaster in the house actually mixed it with mortar and dumped bonding/flex agent in the mix. He said that this was to strengthen the plaster from cracking over time.....Not sure why but they did it that way though...

I've used diamond coated hole saws and jig saw blades. They are gravy expensive but work great! Same shit the granite counter guys use and masons Especially on the mortar reinforced plaster