Cutting Holes in Old Rock Hard Plaster

They make small handsaws for wallboard to cut rectangular (or whatever shape) holes like that. No electricity needed, just hand muscles.

If you are only doing a few I would not worry about dulling the blade. The saws are pretty cheap and if you kill it doing this job it is not a big financial deal.

The round holes can be drilled using a masonry bit of the correct size. Higher drill speed will make a smoother hole.

You can buy or use a power tool to cut the large holes, but I find the dust abrasive and it gets into the tools. Over time it causes wear. I like the manual handsaws, but there is a new class of power tool called an []oscillating tool.

It looks like a slightly larger Dremel too where the blade oscillates at high speed and it is a multi-function type of saw. Blades are not cheap, but you can quickly do things that were almost impossible with any other tool.

If I am thinking about the same wallboard saw then I agree that they are very handy with drywall. This 50 year old rock plaster is probably too hard for me to try to cut through by hand. So far the saber saw and a hand full of blades is at the top of my list. I suspect I'll be pretty grumpy once I get started. It will be slow going, very noisy and make quite a mess.

don't use the course blades use the ones with the most small teeth, use the ones for metal cutting, you'll get a cleaner line

You might consider using a rotary saw with a masonry or ceramic cutting bit.

http://www.amazon.com/DEWALT-DW660-Cut-Out-Rotary-Collets/dp/B000051WQX/ref=sr_1_4?s=hi&ie=UTF8&qid=1431009555&sr=1-4&keywords=rotary+saw

You need to step from the past into the future with adhesive picture hangers...I use these everywhere, they work great with no failures to date....even works for heavy tapestries....and are removable leaving no damage to wall, requires no tools....I didn't think these would work but decided to try them some years ago, amazing....

http://www.apartmenttherapy.com/command-adhesiv-17825

I was amazed at how well they work but I still don't think I want to trust them for anything very heavy or expensive.

Those will work in general, but the OP's current project involves hanging CABINETS. I think that's going to require a stronger bonding to the wall than Command Adhesive provides, even if you bought enough strips to cover the back of the cabinet.

As I understand the OP, he just needs holes to reroute wiring. He didn't mention cabinet mounting. For that, all he needs is some good screws(I usually use #10 deck screws with torx heads). I put in a pilot hole with a masonry bit, but sometimes, I'm lazy and just let the deck screw force it's way in. My 1920s house has very hard pine studs that holds screws well. If I'm still concerned about weight, I have added a strip of wood screwed to the wall that the cabinets rest on. But then, sometimes I tend to overkill.

That should help. I never thought about saber saw blades for tile. It would seem to me that the saber saw would be too violent up and down to prevent breaking tile. Since I'm not cutting tile I don't have to worry about that . Thank you.

Just feed it slowly to minimize the chatter, but I suspect the plaster will cut like butter. Here's another style that you can use with a smaller pilot hole.

How big a rectangular hole, would a pattress cutter do? Maybe an oscillating saw?

I just use a hammer, and tin snips to cut the wire....patch back up when complete....

You can try the saber saw with carbide blade, but I'd go with the multi-tool. Since they oscillate, they don't throw the dust like a rotary saw. I bought one for one job - replacing some ceramic floor tile on concrete slab - and have used it for several other jobs.
Do you have a Harbor Freight store nearby? If so, get: Oscillating Multi-Tool #68861 $20 ( or they have a $38 variable speed version if you want to throw some money away)3-1/2" Diamond Grit Multi-Tool blade #61829 $13 (maybe 2 if you don't live close to the store)

I suggest a sawszall (reciprocating saw) with a set of the cheapest bimetal demolition blades you can find, about 8 tpi is perfect. Unless your plaster really is cement they should handle it OK; I've used the carbide edged blades in the past and they are SLOW.

I recently cut a 3 x 4 ft hole in my wall. (Building a spice rack into the wall) The house was built in 1927 with what they called "lathe and plaster". But it is really cement plastered over thin lathe boards nailed to the studs. (Tampa, Fl "Bungalow")

It isn't plaster, but cement and is indeed hard as a rock, and about one inch thick including the quarter inch wood strips. I used a reciprocating saw with cheap wood blades. The cement completely wore off the teeth of three blades, but I finished the cut. Blades are cheap. Or I could have used carbide blades. The main problem was putting a spacer under the saw foot to hold the saw up high enough so the blade didn't hit the wall on the other side. I just taped a 1 x 3 board onto the saw.

A drunk man was dragging a chain down the middle of the road, when the police asked him why dragging a chain down the middle of the road in the middle of the night, The drunk fellow responded "Well Occifer, have you [burp] ever tried to push one?"

OK maybe it wasn't that good of a joke but he did ask for one:

Any suggestions (or good jokes I can remember while struggling with this)?

Thanks,
Bruce

And I get an 'off topic' for trying to help him out, sheesh! LOL.

I did ask for a joke and by the end of this weekend I'm sure I'll need one or two. I got your "OT" wiped out.

A guy was having terrible headaches and nothing seemed to help, so he finally went to the doctor. After a series of tests and scans, the doctor diagnosed the problem. "Your testicles are pressing against your spinal cord. This pressure is causing your severe headaches. I consulted numerous specialists about this rare problem. They all said the same thing... The only way you can get relief is to have your testicles surgically removed." The guy wasn't very happy about this diagnosis and went home to think about it. Finally, he couldn't tolerate the headaches any longer and had the surgery. After the surgery, his headaches were gone, and he was elated. He decided to buy some new clothes to celebrate. The tailor was able to guess his sportcoat size, his shirt size, his shoe size and his pants size immediately without even measuring. Everything fit perfectly. The guy said that he also needed some new underwear. The tailor said, You need size 38." The guy said that he was amazingly accurate on everything except his underwear size. He said he had been wearing size 34 for many years. The tailor said, "No, you can't wear size 34... they will push your testicles against your spinal cord and you will get a terrible headache!"

Hey Bruce: When one of my clients calls and wants to put a swamp cooler through a lathe and stucco wall, I use two tools, 1. Hi speed rotary saw fitted with a 5" diamond blade ( cuts through like butter) 2. A 1/2" drive rotary/hammer drill. Use the drill, fitted with a masonry bit to drill holes at the corners of the rectangles & Use the rotary saw to cut the straight lines, 4"/5"/6" diamond blades are very common. Most of my tools are De Walt, Porter Cable or Makita, good quality tools will give you a quality job. Wear hearing, dust and eye protection.

Using diamond blades dry?

I have used diamond blades wet to cut floor tile. I have a diamond coated hole saw that I also use wet for floor tile. I was always told that the diamonds would get very hot and cause the bonding agent to fail if you used them dry.

Bruce, Yes, you can cut concrete with a dry diamond blade saw, its all in the technique.

If you force the cut, then the blade will get hot, but if you allow the blade to slowly cut the material, then you should have no problem.

Remember, that when using a wet saw to cut brick or tile, the blade is in constant contact with the substrate, thus, it needs a lubricant to carry away the heat and filings(water).

In some applications when using a diamond blade saw, the advantage of a lubricant are not possible, such as a wall or ceiling, so in these cases, numerous light passes with the saw and ample time for the blade to cool are necessary, take your time and you can accomplish the job without damaging the saw or the blade.

Tony

What? I can't see what I'm not hearing!

Bruce, If you want the best tool for the job, get one of these: http://www.homedepot.com/p/Ryobi-4-in-Tile-Saw-TC401/205654302

This tool is great for cutting wall tile and lath and plaster. We have a rental (built in the mid 60's) that has the new style lath and plaster (drywall board with a layer of plaster on top). It's actually very nicely constructed and only expensive custom homes use this type of wall today.

The tool pumps water to the surface you're cutting, so no dust. Since your wall is made of plaster, getting it wet shouldn't damage it.

Good luck with the job and let us know how you cut the wall.

An abrasive cutoff disk in an angle grinder could get you close to the corners, finishing off with a saber saw as previously noted. Disks are available for steel, other metals, and masonry.

Home Depot 5 kW laser cutters and 10,000 psi water-jet cutters haven't arrived yet, but some entrepreneur could work on that.

An Irish Priest is transferred to Iola, TX. He rose from his bed one morning. It was a fine spring day in his new West Texas mission parish. He walked to his bedroom window to get a deep breath of the beautiful day outside.

He then noticed there was a jackass lying dead in the middle of his front lawn.

He promptly called the local police station. The conversation went like this: "Good Morning this is Sergeant Murphy, how might I help you?"

"And the best of the day to yourself. This Father O'Malley at St Ann's Catholic Church. There's a jackass lying dead in me front lawn and would ye be so kind as to send a couple o' yer lads to take care of the matter." Sergeant Murphy, considering himself to be quite a wit and recognizing the accent, thought he would have a little fun with the good Father, replied, " Well now Father, it was always my impression that you people took care of the Last Rites!" There was dead silence for a long moment, then Father O'Malley replied, "Aye, 'tis certainly true; but we are also obliged to notify the next of kin first, which is the reason for me call".

Before the final match, the Norwegian wrestling coach came to Ole and said, "Now, don't forget all the research we've done on this Russian.
He's never lost a match because of this 'pretzel' hold he has".
Whatever you do, do not let him get you in that hold! If he does, you're finished'. Ole nodded in acknowledgment.
As the match started, Ole and the Russian circled each other several times, looking for an opening. All of a sudden, the Russian lunged forward, grabbing Ole and wrapping him up in the dreaded pretzel hold. A sigh of disappointment arose from the crowd and the coach buried his face in his hands, for he knew all was lost. He couldn't watch the inevitable happen.
Suddenly, there was a scream, then a cheer from the crowd and the coach raised his eyes just in time to watch the Russian go flying up in the air.. His back hit the mat with a thud and Ole collapsed on top of him making the pin and winning the match.
The crowd went crazy. The coach was astounded.
When he finally got his wrestler alone, he asked, "How did you ever get out of that hold? No one has ever done it before!"
Ole answered, "Vell, I vas ready to give up ven he got me in dat hold, but at da last moment, I opened my eyes and saw dis pair of testicles right in front of my face...I had nuttin' to lose so wid my last ounce of strength I stretched out my neck and bit dose babies just as hard as I could."
So the trainer exclaimed, "That's what finished him off!"
"Vel not really. You'd be amazed how strong you get ven you bite your own nuts!

That one has been around for a while. I first heard it from a South African guest in 1974.

If you think that cutting plaster is tough going try chasing rendered brick walls....

One considers the real need for any renovations or alterations very carefully before starting.

Dust and noise and pain...

Cut then air chisel to chase.

Drill corners,8mm, of chased route to depth +2mm, saw blade set to the same depth, note the white plastic depth guides strapped to grinder body.

I'm surprised at how little dust can be seen in this photo...it was not that "clear" when I was standing there taking that photo.

That's my nephew, showed him one cut and he went for it.