Drilling Through Lathe and Plaster

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  #1  
Old 11-30-11, 11:24 AM
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Drilling Through Lathe and Plaster

I'm getting ready to install a video projector in an old church that has lathe and plaster for walls and ceiling.

The installation calls for a 1 1/2" threaded pipe to penetrate the ceiling to attach to the mount in the attack space above.

My question is this: if I try to drill a 1 1/2" dia. hole through lathe and plaster I'm concerned that when the hole saw hits the metal lathe that it runs the risk of grabbing it and making a massive mess of the plaster- cracking and chipping it.
Does anyone have a suggestion on how best to achieve this hole? I thought of using an abrasive type tile hole saw to make the cut- sort of grinding my way through.

I look forward to hearing any suggestions.

Thanks,
Joe
 
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Old 11-30-11, 11:39 AM
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Yes, and abrasive hole saw should go through both the plaster and lath. Are you sure it's metal lath?. If the building is old enough it might have wood lath. If you have wood lath it still might be a good idea to use an abrasive hole saw to get through the plaster. If you use a regular hole saw the plaster will dull the teeth so much that it will not cut the wood lath very well and if you get vibration you could loosen the plaster around the hole. Now once you are through the plaster then go to a regular saw to finish the hole through the lath.

If you can put something around the hole to contain the dust. Cut a cheap ball in half, poke a hole in the center install your saw and bit on the inside then chuck it into the drill. Hold the ball tight to the work and it will catch most of the dust..
 
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Old 11-30-11, 11:47 AM
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On the dust catching thing...I've also used a clear plastic chip dip container or a deli container...you can sort of see through it as you start.
 
  #4  
Old 12-01-11, 04:16 PM
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Thank you gentlemen. Great ideas on catching the soup that falls.
In my mind I was imagining a hole saw with a continuous gritted rim (tile style), but when I went to search for a "gritted hole saw", I kept running into saws such as this: M.K.Morse Carbide Grit and Recessed Lighting Hole Saws
Let me know if you think this will do.

Also... good question on the lath. I really don't know if there is metal for sure-- I'm just planning for the worst case scenario.

Thanks again,
Joe
 
  #5  
Old 12-01-11, 04:45 PM
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I think that should do the job. One thing: if it is metal lath be careful to have a good hold on the drill and make sure the ladder is well placed and that you are balanced. The saw could grab the lath and take you or your wrist with it.
 
  #6  
Old 12-02-11, 09:14 AM
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That is exactly my concern: that the saw will catch the metal lath (if present). If it does, holy cow, who knows what damage might occur to the surrounding plaster. My thoughts were to use a continuous rim abrasive bit and "grind" through it. That way, there's nothing to catch on the metal. I think maybe I've convinced myself-- haha.
I appreciate the input though. At least it confirms that I'm barking up the right tree.

Joe
 
  #7  
Old 12-02-11, 05:44 PM
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I am curious about one thing. You expect to mount the projector from something in the attic. So from the attic you should be able to tell what you have for lath. It could be metal lath, either diamond mesh or rib lath; it could be wood lath; or it could be gypsum lath. Let us know what you run into and how it goes. We like to know if our advice was good advice.

How old is the church house and what in part of the country are you?

The advice you get here is always worth at least what it costs you.
 
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