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Looking for the best way to cut in holes for boxes in plaster and lath with out busting up the plaster . Tried a roto zip the plaster dulls the bits quick and seems to over heat in the lath
 

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sounds more like cement plastered walls
same in my home.
i had to use grit-edge blades in a recip saw or sabersaw (at low speeds) to get clean cuts
 

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Last time I tried to do it cleanly on old lath & plaster the Plaster guy came behind me and used his hammer to open the wall up.
He showed me how the plaster had lifted from the lath as I was being careful.
The old guy told me that had he just fixed my nice run it would have started cracking with in weeks all around the patch.

Now I just use a hammer.
 

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If you are going to use a Rotozip, you need to use a tile bit for the plaster and a wood bit for the wood lath. But that is not the best way anymore.

Use an oscillating tool with a grit blade for the plaster, and the same tool with a wood blade for the wood lath. This is the absolute best way I found to cut plaster, and that pretty much all that I have in my area.

A grit blade in a recip saw or sabersaw does too much damage to the plaster. Use the oscillating tool.
 

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Before I go busting up the plaster I use a short piece of steel snake and probe behind the wall. I'll drill a 1/4" hole to do this. Once I know it's clear to cut and then make another 1/4" hole in one of the corners until I've determined where the lathe starts and ends. Then I'll find the next piece of wooden lathe and cut out between those two pieces so I can fit a standard old work metal gem box. That's the way I've always done them but nowadays if I can find the stud I'll always use a smart box, especially if the outlet's going to be used often.
 

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1) make center mark for box.
2) use 1/8" screwdriver and linemans, tap screwdriver handle with lineman's and make a 1"x1" hole where rough center is to find lathe layout for room.
3) center box (3x2 switch/gem box) on center of piece of lathe and trace with pencil.
4) chip plaster outline with 1/8" screwdriver, overlapping each puncture.
5) cut lathe with multi-tool.
6) fish wire
7) set box level with plaster ears on plaster, drill 1/16 holes through ears
, screw in #4x3/4 screws.
8) wire device and plate.

90% of the time no patching necessary. I've set 100s of boxes this way and it just flat works. With wire fishing usually takes me about 20-30 min per box.
 

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cordless 4" grinder with a diamond blade for plaster with metal lath. hammer and sawzall for wood lath.
 
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1) make center mark for box.
2) use 1/8" screwdriver and linemans, tap screwdriver handle with lineman's and make a 1"x1" hole where rough center is to find lathe layout for room.
3) center box (3x2 switch/gem box) on center of piece of lathe and trace with pencil.
4) chip plaster outline with 1/8" screwdriver, overlapping each puncture.
5) cut lathe with multi-tool.
6) fish wire
7) set box level with plaster ears on plaster, drill 1/16 holes through ears
, screw in #4x3/4 screws.
8) wire device and plate.

90% of the time no patching necessary. I've set 100s of boxes this way and it just flat works. With wire fishing usually takes me about 20-30 min per box.
If you are using a multitool (I assume the same as an oscillating tool?) to cut the lath, then I am curious why you don't use it for the plaster too? It cuts like butter and doesn't cause any cracking or separating of the plaster from the lath.
 

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If you are going to use a Rotozip, you need to use a tile bit for the plaster and a wood bit for the wood lath. But that is not the best way anymore.

Use an oscillating tool with a grit blade for the plaster, and the same tool with a wood blade for the wood lath. This is the absolute best way I found to cut plaster, and that pretty much all that I have in my area.

A grit blade in a recip saw or sabersaw does too much damage to the plaster. Use the oscillating tool.
Same as I use. Haven't had any blow out issues
 

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DIYer4Life said:
If you are using a multitool (I assume the same as an oscillating tool?) to cut the lath, then I am curious why you don't use it for the plaster too? It cuts like butter and doesn't cause any cracking or separating of the plaster from the lath.
I have had problems with blowing out plaster and it seems to smoke the blades in record time. I have the least problems using the method I described.
 

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I have had problems with blowing out plaster and it seems to smoke the blades in record time. I have the least problems using the method I described.
Gotcha.

I'm not trying to change your mind or anything, but if you're up for trying it again, those blades I linked to above work really well and last a long time. A lot of the houses around here have that plaster that's just about concrete and they cut right thru it.

I've always worried about banging on a plaster wall with a hammer. It probably takes more finesse to do it right than I have.
 

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If you are going to use a Rotozip, you need to use a tile bit for the plaster and a wood bit for the wood lath. But that is not the best way anymore.

Use an oscillating tool with a grit blade for the plaster, and the same tool with a wood blade for the wood lath. This is the absolute best way I found to cut plaster, and that pretty much all that I have in my area.

A grit blade in a recip saw or sabersaw does too much damage to the plaster. Use the oscillating tool.
This. And always cut the end of the lath furthest from the wall stud first.
 

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aftershockews said:
This. And always cut the end of the lath furthest from the wall stud first.
The trick is to not cut through all the way first pass. Cut a 1/3 through on one side, the hop to the other and vice versa. When you get to the last pass, leave a 1/4" or so of lathe left on the bottom, then break the piece off with your linemans. Keeps the lathe nice and strong, and doesn't make it vibrate, which keeps the plaster tight to the lathe, thus no bulges or patching needed.
 

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I have only ever encountered horse-hair plaster but I was told by an old timer that they used asbestos in some of it. So he told me to wet with a spray bottle of water as I go to knock down the dust so I don't breathe it in. I only have done this a handful of times but was curious have any of you heard of this?
 
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