cutting holes in Plaster with thick mess??

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27hillcrest

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I have to cut 60 holes into an old school. The walls are metal mess covered in plaster about 3/4" to 1" thick. I am thinking of using a grinder with a diamond blade to cut the holes. Has any body done this before? Is there a better way?
 
A grinder is going to make an awful lot of dust.
A sawzall or jigsaw (I'd use a jigsaw if given the choice) may do damage to the surface area you need.
Holes saws will dull quickly on the plaster.

My recommendation:
Roto-zip with carbide bits and a vaccuum system ~ which amounts to a $14 collar and a vaccuum.

RZVAC1_RZ_pd.jpg
~ Roto-zip RZVAC1
DC500_1.gif
~ Dewalt DC500 (battery/corded operation)

Any shop vac with a 1 1/4 hose will work with the RZVAC1.


I use this set-up quite frequently...tried it out for the first time in my own home, I didn't want to remove all the furniture to install a couple of recessed cans...clean-up was a breeze as there was nothing to do but empty the vac.
 
JohnJ0906 said:
Celtic, I am definately going to give that one a try! You use that in drywall too?
Click to expand...

I use it on just about everything...sheetrock, tile, plywood...whatever's in the way is history.

Don't get me wrong, a sawzall has it's place - I'll use that for large scale demo where the goal is to get something out of my way...like an entire rack or conduits. My jigsaw is for for more delicate work where the end result must be perfect. The rotozip is just quick and clean with a little margin for error.
 
celtic said:
My recommendation: Roto-zip with carbide bits and a vaccuum system ~ which amounts to a $14 collar and a vaccuum.
Click to expand...

The rotozip blades can get red hot when cutting plaster, and they'll also throw off a lot of sparks inside the wall, especially when hitting the mesh. Also, with 3/4 plaster you'll be smoking those carbide bits like crazy and probably breaking off several of them in the wall. I'm not a big fan of using them in old buildings with hard plaster and well-seasoned studs for those reasons. One errant spark or an incendiary broken bit in the studbay could cause a problem you just don't want to have to deal with.

http://www.milwaukeeconnect.com/web...uct_27_40027_-1_283019_189562_189319_127418_Y

Good luck. 60 holes in 3/4 plaster will not be fun. :O
 
27hillcrest said:
I have to cut 60 holes into an old school. The walls are metal mess covered in plaster about 3/4" to 1" thick. I am thinking of using a grinder with a diamond blade to cut the holes. Has any body done this before? Is there a better way?
Click to expand...
Round holes?...

Perhaps a Core Bore? M-4 Drill Rig, if available, as a handheld unit. The hardest part in using it, IMO, is maintaining the position of the core drill. To do so, cut some hole-saw cores out of plywood, osb, or such, soak 'em in water, and screw one to where you want a hole placed, as a guide. Use a hand-pump, water spray can to water cool the drill and substrate, as the built in water cooling has too crude an adjustment. Keeps dust under control, too. Yes, you'll most likely need a wet vac for "overspray" Definitely a 2-man operation. Wouldn't hurt to have a fire extinguisher nearby either, just in case the spray can happens to be empty :grin:


Might seem a bit overkill, but it'll knock out 60 holes in flash. Well, that might be a slight exaggeration. This rig will definitely zip right through plaster and mesh. I'd guesstimate 10 to 1 actual cutting time over any other method mentioned here so far. You'll essentially have a finished hole in the same time it takes to start a hole with a rotozip :wink:

PS: Some plastic sheeting and duct tape will be needed to protect finished areas.
 
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Smart $ said:
Round holes?...

I'd guesstimate 10 to 1 actual cutting time over any other method mentioned here so far.
Click to expand...
What if the holes are for devices?
What the hell are ya gonna do with 60 round holes ?
:D :D
:D
 
celtic said:
What if the holes are for devices?
What the hell are ya gonna do with 60 round holes ?
:D
Click to expand...
Hire you to make 'em fit :grin:

On the serious side, I'd use your method.
 
The problem I have found with saw zaws and plaster is that the blade pulls , and sometimes cause damage to the wall/ ceiling

they make core bits to fit on a half in. grinder -I have used on cinder block and works beautifully -wear a dust mask though -
Smart -I like your idea of using the wooden starter guide that would work with this also -thanks for the tip
wodden guide with toggle bolt or soft wall anchor here I come
 
We had good luck with a battery powered 4" circular saw and a diamond blade in ceramic block walls. I think it would would for this application too, but not if the holes have to be round.
Don
 
Has any testing been done for Asbestos in the plaster? Since this is an old school there is a good chance that it may be an issue.

Roger
 
Hey Don, Have gotton big kudos for a 12 pipe 3 in. conduit rack with each pipe having it's own hole - have to fire seal anyway through cinder block - the core really does fly through the block :wink:
 
cutting holes in plaster with thick mess??

cutting holes in plaster with thick mess??

I've had to do the same here, only through stucco that had a 'chicken wire' mesh.

Sawzall is a bad idea; the action of the saw pulls on the mesh, breaking out material outside the area.

I have not tried the roto-zip, but my expierence using ine in 3/4 MDF makes me think that it might work well.

The grinder works great - especially with a diamond blade.

Now, your dust problem is going to be huge. For the grinder, you need to tent off the area, wear a mask and goggles, AND have some means of holding the vacuum hose as close to the work as possible.

For the roto-zip, catching the dust seems easier. Just holding the hose at the tool catches a lot; or, you can set a box over the spot, and do your cuttng inside the box. Clear plastic (plexiglass) on top, vac hose inside, you've got it made.
 
27hillcrest said:
Thanks for the info all the holes are for data drops and recps.
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If that's the case, the Milwaukee plaster blades are the way to fly. The teeth are profilated in such a way that they don't "pull" the plaster loose. Rotozip carbide bits are 4 bucks a piece last I checked, and using my history as a gauge, you'd need about 7 to 9 of them to make 60 rec cutouts. You can make all 60 with one or two plaster blades in the sawzall. The diamond wheel still requires that you saw the "corners" out, as you can't grind the full depth without overcutting and risk not having your cover plate cover.
 
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