Question about Metal cutting blades in angle grinders

joebiplane

joebiplane

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I am doing a project for the company I do contract work for. they are doing a remodel at a bank and there was a Half height wall that had to be removed. seems that origionaly there were two 4" Square pipes built into the wall by cutting into the concrete floor and inserting the pipes and cemented them in and filled the inside of the pipes with about 12" of concrete.... They certainly do stabilize the half walls.... i have to remove them to below the tile floor since new tile is foing in wher this wall was.
my first thought was a cutting torch but that be a bit of overkill and the pipe id filled with concrete and it is a working bank lobby and could get messy. so i'm now thinking that I could cut them out with angle grinder and many steel cutting blades.. The pipe seems to me to be sched 80 with sidewalls about 1/4" thick. I'm am not experienced with using cut-off wheels and thickness like this...
Is it readily do-able or am i biting off more than i can chew ( cut)
thanks
 
In general, cutting torches and concrete don't mix well, but it could be done. The cutoff wheel in a grinder will stink, make lots of airborne particulate and be slow. And noisy. Are you able to get in there after hours? If so, check into a radiac type wheel for you grinder and get with it. Cover everything within 25 feet with drop cloths, and watch your sparks.

I did a fab job in a bank under construction over the summer that involved lots of cutting, grinding and welding. It was new construction, but we had to watch the already installed glass for pitting from grinder swarf, and of course, all carpet hat to be protected with plywood.

If you go the torch route, keep a fire extinguisher at hand, and someone besides yourself watching for fires. Same rules.....cover carpet, guard glass. And when the concrete pops out, be sure you have a face shield, or you will get a face full of grit.....some under the skin.
 
Thanks Tony,

You have confirmed my "tinkerer's intuition" about torchres and concrete..( Air bubles in the mix,I guess).

my first choice , which I tried yesterday wasa trip to home depot where we rented a large Makita electric " Pavement breaker" I felt we could jack-hammer around the pipe intil the STUMP :huh: came out. The jack hammer was run by my boss as I was cutting cores out of the floor in another area to install my own 4" square pipes for a " Customer Que "type of counter leading to the cashiers Line.

He gave up on it after an hour but that still seems to be the best answer. filling the resultant holes is not a problem as we have a week before the tile floor gets changed. of course the bank is a 2.5 hour drive making the logistics a bit difficult.

we can only work at the bank when it is closed so that helps the " Mess factor " while we are working

i still think the jack hammer is the best solution... maybe the unit we rented was a dog.

I will return the " CORE CUTTER" tomorrow to our local Rental country and see what they
reccomend .
 
Thanks Tom,

how much mess did the grinder make & what kind of blade did uou use in the grinder as Tony mentioned a " radiant" blade...what-ever that might be.
sorry for all the questions... I don't normally do demolition work so I'm pullimg ideas from "you know where":thinking:
I was thinking i would use my horror freight Angle grinders with a box of blades but that would probably be too light duty to be effective. I would like to get both pipes out and thefloor repaired for tile and necessary clean-up done in 4-6 hours...or less
 
"Radiac" is a brand name that's caught on well (Coke, Kleenex, etc.) Simply a thin abrasive cutoff blade made for metal. Tom's idea will work, as long as there is no rebar in the mix.

Reason for the torch vs concrete is the aggregate (rocks) expand and the cement binder "pops" out violently. Kind of hard on the eyeballs.

This doesn't sound like a HF grinder job. Use a better quality and you can use it again after this job.
 
Hi, If I understood your situation correctly, you have 2 verticle metal tubes which are about half wall height and have 12" of concrete poured into the bottom, if that is the situation and you have access all around them, the way I would tackle it would be to get a 5" angle grinder with a thin 1.2 to 1.6mm metal cut off blade and go around and just cut the tube lightly till you you reach the concrete inside, once the metal tube has been "ringbarked so to speak" a few hits with a big sledge hammer at the top should see the concrete crack and it should just fall off. The sparks can be stopped by a couple of plywood boards covered with some wet flannel bed sheeting stapled to them, which you would move around to catch the sparks as the direction changed. If you need to remove the tubes slightly below the floor level than use a big rotary drill with an impact function ($40-80) with a concrete spade or point on it to make a small recess around the tubes and then use the cut off wheel as above and go as low as possible. Just my 2 cents worth.

Oops.. I noticed that after I posted that Tom Reed also made the same sugestion a few posts above earlier to mine.
Sorry about repeating the same sort of advice.

Cheers

Ed.
 
i love it whenpeople think like I do !
i have several horror freight 4 or4 1/2" angle grinders, but i think it would be easier & faster with a 7-9 inch unit... so Iwill look into renting one locally. i would have litttlw use for such a heavy duty unit or I would go and buy it

A Hitachi 7" at lowes it'$ 159.99 at horror freight It's about 99.00 but i don't want to chance the HF burning out on me before I'm done with the job ( experience talking ) since I will have $300.00 invested in just mileage and travel time.... :nono: it Would not be a good deal for the company that is paying me...to go there ,to do it, and get it done... properly .
 
do you have access to an air compressor and plasma cutter, or a plasma cutter with built in compressor?
 
I'm with the Grinder guys.

I'd either go with a 1.2mm disc on a 5" or a 2.5mm on a 7". Personal preference would see me with my 7".

A 9" would be nice if there was no awkward positions to put yourself into but cutting at floor level horizontally means you have limited control of the grinder and may put yourself or others at risk in the event of a kickback/bite. This is my reasoning for the 7".


Flame cutting will still need cleanup and in the event of a concrete explosion can be very painful. think hot rocks under the skin as pointed out by Tony.

Whatever route you take is going to be messy and tedious. I hope they're paying well!
 
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