Enlarging a hole in concrete wall

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Old 08-24-15, 10:15 AM
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Question Enlarging a hole in concrete wall

Hi! I need to increase a diameter of a 3" hole in a concrete wall that's about 8" thick. The new diameter should be 4 1/2" so a 4" ABS pipe can be inserted.
The curve ball is that the cabin does not have any electrical sources and no generators allowed. I can only use battery operated tools that are brushless (no sparks).

What are my options? I could not find a concrete rated hole saw that's 4 1/2".
Are there any tools that would allow me to work from the inside of the existing hole?

Any ideas/suggestions/links are greatly appreciated in advance.
 
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Old 08-24-15, 10:22 AM
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Why all the restrictions?
There's going to be sparks anyway you try and do it from the bit hitting the stones in the concrete mix.
 
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Old 08-24-15, 10:40 AM
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Welcome to the forums Sam!

While I have an assortment of wood and bi-metal hole saws, I've never had or used a masonry one [not that I have many occasions] so what I've always done when I needed a hole like that in masonry is to drill a series of small holes along the perimeter of the hole and then take a hammer to it.
 
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Old 08-24-15, 10:59 AM
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Restrictions are in place due to extreme fire hazard on the BLM land where the cabin is located. Is there anything I can use to work from the inside of the hole ?
 
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Old 08-24-15, 11:04 AM
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Is there anything I can use to work from the inside of the hole ?
Sure.... a hammer and chisel.

I've done it before. Put on your safety glasses and use a long, sharp masonry chisel and a small sledgehammer.
 
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Old 08-24-15, 11:14 AM
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Hi Sam, is this a poured concrete wall or concrete blocks? The latter would be much easier.

It would be easier if you work from both inside and outside. Without electric, even battery powered tools will be a challenge. You could charge them off of some arrangement powered from your car. Then, with several long masonry drill bite you do somewhat as Marks suggested. The difference I would suggest is not trying to go straight through. If you start with an 8" diameter hole and allow your chisel work to taper in from both sides the chisel work will be much easier. Once the pipe is in place, patching around that pipe is very easy.

Another thought would be a battery powered Reciprocating Saw with a diamond blade. But I have never used one.

Bud
 
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Old 08-24-15, 02:48 PM
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Google star drill. Nice to have without power. They are about a foot long and you hit then turn using a 3 or 4 pound hammer. I would outline as stated.
 
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Old 08-24-15, 03:26 PM
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I have one Awhile back I had to add to my son's concrete step and I guess my masonry drill bit was dull because I just couldn't make any headway but I had also brought my star drill along and was able to finish the hole for rebar with it and a 4lb hammer
 
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Old 08-24-15, 04:06 PM
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marksr, a set was govt. issue in my field a long time ago. Got me thinking and couldn't dig them up. Were for contingencies only but come in handy.
 
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