# tool for fine cuts for plaster ceiling



## Islander (Jul 11, 2016)

So, I've got the 4" holes cut for the octagon boxes. However, some of them have the retainer tabs.









What would you recommend for doing the fine cuts so that the tabs will clear? I don't want to be hammering away at the ceiling - it's a bit crumbly in place.

Something cheap, preferably - I'm on a shoestring budget.


----------



## MikeFL (Apr 16, 2016)

If it's wooden batts & plaster the standard sheetrock knife works well. Take your time and don't use a lot of pressure and you'll end up with a real nice job. Cost around $3.


----------



## macmikeman (Jan 23, 2007)

ROTO ZIP. If the plaster is the extremely hard kind, then put a tile bit in that tool .


----------



## HackWork (Oct 2, 2009)

I used to use a Rotozip like Mike recommends. However, I now use an oscillating tool. It works very well on plaster. You can buy one at Harbor Frieght for real cheap if you don't want to commit to a brand name one right now. 

I use good quality grit blades from a company called Imperial, but you can use pretty much any blade for your purpose, it will just dull quickly.

To make the hole for the boxes themselves, I use a grit holesaw.


----------



## MechanicalDVR (Dec 29, 2007)

Wally World has an oscillating tool for @$18


----------



## canbug (Dec 31, 2015)

MechanicalDVR said:


> Wally World has an oscillating tool for @$18


Not in Canada.

Tim


----------



## Southeast Power (Jan 18, 2009)

Islander said:


> So, I've got the 4" holes cut for the octagon boxes. However, some of them have the retainer tabs.
> 
> 
> 
> ...


I would mark the hole for the box and the ears, then use a grit hole saw on an angle to cut the ear notches, then use a bigger 4" or what ever mm that is holesaw for the main hole.


----------



## splatz (May 23, 2015)

What you want here is the smallest teeth possible, the coarser the saw, the more likely it is to snag and pull the wood and crack the plastic, or break a chunk off the plaster. 

The smallest teeth of all is a grit or abrasive blade. The oscillating tool is by far the most trouble free way to go. About $30 USD for tool and a grit blade, from the bottom of the barrel brands, which won't last, but will work. 

If you can't swing $30, or you're just in a bind, a fine rasp or coarse file will take this out with a little patience. It's such a small amount of material to remove it won't take long enough to matter much. I wouldn't want to do 100 this way but four is yawn.


----------



## trentonmakes (Mar 21, 2017)

Add my vote to oscilliating tool

ANSWERE THE QUESTION STEVIE!


----------



## Chris1971 (Dec 27, 2010)

Hole saw.


----------



## MechanicalDVR (Dec 29, 2007)

canbug said:


> Not in Canada.
> 
> Tim


That stinks you guys don't get the same prices, the Wally's here have like a mini circular saw, the oscillating tool, and I think it was a drill for $18 each.


----------



## Going_Commando (Oct 1, 2011)

Plasterboard, wooden lathe and plaster, or metal lathe and plaster? I would use different approaches with all 3, but they all would involve a 4 1/8" hole saw run in reverse. The rest is where it depends. 

The oscillating multi tool and a carbide blade are a tit combo, but tough for making roundish holes. I've done it, but prefer the hole saw running backwards.


----------



## telsa (May 22, 2015)

Islander said:


> So, I've got the 4" holes cut for the octagon boxes. However, some of them have the retainer tabs.
> 
> 
> 
> ...


You realize that the 'wings' swing mightly -- and largely conform to the box exterior -- during insertion ?

That is, the photo is of the wings as deployed -- not as inserted ?


----------



## Going_Commando (Oct 1, 2011)

telsa said:


> You realize that the 'wings' swing mightly -- and largely conform to the box exterior -- during insertion ?
> 
> That is, the photo is of the wings as deployed -- not as inserted ?


No ****, sherlock. :laughing:


----------



## trentonmakes (Mar 21, 2017)

Chris1971 said:


> Hole saw.


I took it as he already had a 4in hole cut out

ANSWERE THE QUESTION STEVIE!


----------



## Chris1971 (Dec 27, 2010)

[/FONT]


trentonmakes said:


> I took it as he already had a 4in hole cut out
> 
> ANSWERE THE QUESTION STEVIE!


Who is Stephanie?:blink:


----------



## nrp3 (Jan 24, 2009)

When I have done work in fragile plaster and lathe, I have used the rotozip simply because it puts the least pressure on both materials. Yes you have to have control of it or it can catch and ruin what you are doing. Plaster bits for the plaster and a new wood bid for the lathe will usually result in a clean cut. The newer hard plaster, sometimes with metal lathe in is another animal entirely. That I might tackle with the vibratory saw. If you are going to be in the old work game, you need good bits, regardless of tool type. The cordless vibratory saws aren't half bad. Tried out my buddies cordless Milwaukee and it worked pretty well. I have a used Ebay Fein.


----------



## splatz (May 23, 2015)

If it's plaster on separated metal lath - the diamond shaped stuff - you have to have a carbide grit hole saw for the big hole, but you could get the notches with no special tool. (Never try a regular bimetal hole saw, it will grab and make a disastrous mess!) 

You can just drill a bunch of holes and chip out the plaster with a screwdriver, then carefully cut out the mesh with *****. 

The rotozip is good in that it doesn't push and pull on the material at all but it's usually so much more power than needed, it can get away from you. Old lath is usually really brittle and it's barely more than popsicle sticks. 

I am going to try one of these on some plaster next time I have a chance, see how this thing works - they are occasionally pretty handy -


----------



## HackWork (Oct 2, 2009)

splatz said:


> If it's plaster on separated metal lath - the diamond shaped stuff - you have to have a carbide grit hole saw for the big hole, but you could get the notches with no special tool. (Never try a regular bimetal hole saw, it will grab and make a disastrous mess!)
> 
> You can just drill a bunch of holes and chip out the plaster with a screwdriver, then carefully cut out the mesh with *****.
> 
> ...


That looks dinky. Why not just chuck a Rotozip tile/plaster bit in your drill? 


But I would still stick with the oscillating tool and a grit blade. I've got all different generations of plaster in my area and the oscillating tool with these blades work excellent on all of it. I've sold off my Rotozip, which I used a lot before getting the oscillating tool.


----------



## nrp3 (Jan 24, 2009)

Will the grit blade go through the metal lathe and survive?


----------



## HackWork (Oct 2, 2009)

nrp3 said:


> Will the grit blade go through the metal lathe and survive?


Yes. Grit will go thru anything. It also always keeps cutting unless abused. I have maybe 6 of those grit blades, but I still have my first one because it will still cut (just not as fast as the newer ones).

A lot of the ceilings here have metal lath in them and the grit hole saws go right thru it like butter, so I would always recommend using a holesaw first. The oscillating tool is good for notches and rectangular boxes.


----------



## telsa (May 22, 2015)

HackWork said:


> That looks dinky. Why not just chuck a Rotozip tile/plaster bit in your drill?
> 
> 
> But I would still stick with the oscillating tool and a grit blade. I've got all different generations of plaster in my area and the oscillating tool with these blades work excellent on all of it. I've sold off my Rotozip, which I used a lot before getting the oscillating tool.



Those drills were originally marketed as "Beaver Bits."

I have some forty-year old examples -- still.

They are more _brittle_ than you might imagine.

I would NOT recommend them for this application.

I'd go with Hax's tool set.

You want a _grit_ bit -- T.C. being the standard.

You must fear that any conventional tooth will dig in and pull the old work to shreds.

Hence, the usual approach of reverse rotation.

Plan B is to use a ruined// worn out holesaw -- that approaches TC grit for toothiness -- as in being toothless.

I must say, that I'd lean towards using the classic bar-type box support in old lath and plaster work -- you know -- the extendable bars used for fan-rated boxes. All of that effort to stay away from any dependency upon the lath and plaster. For me, the wings are totally insufficient box support in dodgy old work. I'd want studs.


----------



## nrp3 (Jan 24, 2009)

I'll have to look into those grit bits and the hole saws too. I know they have some grit bits for the vibratory saw at HD and Lowes, but can't remember whether they have hole saws. Have to check that out on the next trip over.


----------



## HackWork (Oct 2, 2009)

nrp3 said:


> I'll have to look into those grit bits and the hole saws too. I know they have some grit bits for the vibratory saw at HD and Lowes, but can't remember whether they have hole saws. Have to check that out on the next trip over.


All you have to do is ask Uncle Hax. Actually, you would probably be the uncle cause all you guys are old farts.

For the oscillating tool, I would order the grit blade from the link I posted, or check out the same brand on Amazon, that's where I got them last. 

For the holesaw, this is a really good deal: 
http://www.homedepot.com/p/Milwaukee-4-in-Recessed-Light-Installation-Kit-49-56-0300/202327774
It's 4 3/8" which you may find a little larger. It has always worked for me. 

I have also used this one for 6" recessed lights:
http://www.homedepot.com/p/Milwaukee-6-3-8-in-Recessed-Light-Hole-Saw-49-56-0305/202327775


----------



## MechanicalDVR (Dec 29, 2007)

splatz said:


> If it's plaster on separated metal lath - the diamond shaped stuff - you have to have a carbide grit hole saw for the big hole, but you could get the notches with no special tool. (Never try a regular bimetal hole saw, it will grab and make a disastrous mess!)
> 
> You can just drill a bunch of holes and chip out the plaster with a screwdriver, then carefully cut out the mesh with *****.
> 
> ...


I've had good luck with one of these bits in a small cordless router that you can get two hand control of. 

In a drill they are too out of control.


----------



## Islander (Jul 11, 2016)

telsa said:


> You realize that the 'wings' swing mightly -- and largely conform to the box exterior -- during insertion ?
> 
> That is, the photo is of the wings as deployed -- not as inserted ?


Yep, I realize that. But thank you for asking.


----------



## Islander (Jul 11, 2016)

Going_Commando said:


> Plasterboard, wooden lathe and plaster, or metal lathe and plaster? I would use different approaches with all 3, but they all would involve a 4 1/8" hole saw run in reverse. The rest is where it depends.
> 
> The oscillating multi tool and a carbide blade are a tit combo, but tough for making roundish holes. I've done it, but prefer the hole saw running backwards.


In this case, it is wooden lathe and plaster. The circular holes were already cut (but I'll have to try that reverse the hole saw trick next time).


----------



## Islander (Jul 11, 2016)

*follow up to this*

I decided to spend a bit more coin and get an oscillating tool. I know I will need it again in the future, so I might as well invest in something decent. Got one that matches my other power tools, so that they can use the same charger.

Anyways, that blade was like a hot knife through butter on that plaster and the wood lathe. Definitely worth the money spent on it.

Thanks everyone for your advice.


----------



## trentonmakes (Mar 21, 2017)

Islander said:


> I decided to spend a bit more coin and get an oscillating tool. I know I will need it again in the future, so I might as well invest in something decent. Got one that matches my other power tools, so that they can use the same charger.
> 
> Anyways, that blade was like a hot knife through butter on that plaster and the wood lathe. Definitely worth the money spent on it.
> 
> Thanks everyone for your advice.



Smart move!

ANSWERE THE QUESTION STEVIE!


----------



## MechanicalDVR (Dec 29, 2007)

Islander said:


> I decided to spend a bit more coin and get an oscillating tool. I know I will need it again in the future, so I might as well invest in something decent. Got one that matches my other power tools, so that they can use the same charger.
> 
> Anyways, that blade was like a hot knife through butter on that plaster and the wood lathe. Definitely worth the money spent on it.
> 
> Thanks everyone for your advice.


What brand did you go with?


----------



## Islander (Jul 11, 2016)

MechanicalDVR said:


> What brand did you go with?


PowerFist!

Just kidding - I went with Milwaukee.


----------



## MechanicalDVR (Dec 29, 2007)

Islander said:


> PowerFist!
> 
> Just kidding - I went with Milwaukee.


I just picked up the M12, I'm loving it cutting mostly sheetrock and plywood sheathing.


----------



## HackWork (Oct 2, 2009)

I wanted the M12 due to size but a lot of people said it had no ass to it and the battery dies very quick. So I got the M18.

I like it, but it is big and heavy. It's good for when I need to make huge holes in hard plaster for panels. But overkill for one or two single gang openings.


----------



## Islander (Jul 11, 2016)

HackWork said:


> I wanted the M12 due to size but a lot of people said it had no ass to it and the battery dies very quick. So I got the M18.
> 
> I like it, but it is big and heavy. It's good for when I need to make huge holes in hard plaster for panels. But overkill for one or two single gang openings.


Agreed on the M12 battery life. I just bought a small battery for it, and after trimming two or three openings so that the box tabs would clear, it used up half the juice. Still, it is an invaluable tool, and I am glad I put the money into it.


----------



## MechanicalDVR (Dec 29, 2007)

HackWork said:


> I wanted the M12 due to size but a lot of people said it had no ass to it and the battery dies very quick. So I got the M18.
> 
> I like it, but it is big and heavy. It's good for when I need to make huge holes in hard plaster for panels. But overkill for one or two single gang openings.


I looked at them both and rather have the lighter weight of the M12 for what I do most often.

It lasts with the large battery just fine.

I did a 14"x38" cutout for a panel in 1" plywood under 5/8" sheetrock last month and that was a chore with my Dremel brand and I had to switch to the corded model to finish.


----------



## JBrzoz00 (Nov 17, 2013)

Bosch makes a ton a different size diamond grit hole saws. Well worth the $.


----------

