# Concrete grinders



## CO762 (Feb 22, 2010)

We've always used a plane jane grinder (4.5-7) with a diamond wheel on it. Turns out there are real things out there manufactured to do the same thing, but at about 2x the cost. Anyone know why the difference? Shroud can't be that much and I doubt they use ultra high end diamond wheels.


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## PrecisionFloors (Jan 24, 2006)

Because they are specialty tools and have a very small market by comparison to a grinder. Why do you think jambsaws are so much more than a grinder....only floor guys need them.


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## angus242 (Oct 20, 2007)

I would suspect there are differences, maybe even subtle.

For one, the ergonomics are designed so they can remain flat during grinding.

I would think sealing would be different??? I'm sure a tool that's designed to grind concrete would be better protected against all that fine dust.

Better dust containment????

More powerful motor???

My disclaimer is I'm assuming. I have no actual data on what, if any, differences there are. I do own a Bosch concrete grinder and I like it.

I did NOT like paying for it :furious:


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## Elyrain (Dec 17, 2007)

I have a good friend who grinds for a living and have helped him on and off. He just buys 4" and 7" 90deg "sanders", they are like a grinder with a 5/8" arbor but u can adjust the speed, very handy. The shrouds are the difference, a 7" shroud is around 100$.


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## CO762 (Feb 22, 2010)

PrecisionFloors said:


> Because they are specialty tools and have a very small market by comparison to a grinder.


like this?

http://www.toolking.com/flex-lrp1503vra-all-around-polishing-pipe-sander-kit

as a guy, I'd love to have it, but as a person, I have no idea what I would do with it.

angus, should be some sort of specialization, but other than OEM parts like the dust collector not a lot others. A guy was trying to tell me how great makita diamond blades are and I kept trying to tell him they don't make diamond blades, someone else does. Other than the dust collector, I'm with Elyrain's friend on this one and split the difference on the low side and go with a metabo 7". that way, after a tool purchase, a person would have enough money left over for beer, which IMO is a guidestick to the value of the tool.


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## PrecisionFloors (Jan 24, 2006)

Yeah probably just like that....mos of these specialty tools are nothing more than a grinder with a clever attachment. They take a $35 grinder, attach $8 worth of aluminum and plastic, and then retail it for $800. I'm in the wrong damned business :laughing:


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## CO762 (Feb 22, 2010)

PrecisionFloors said:


> I'm in the wrong damned business :laughing:


I mumble that every morning when I try to get out of bed.

Fishing lures is another one. I read an article about a guy that ties flies and he sells them for $500/each....and most of those are works of art, wall hangers so to speak. Now that'd be a gig if it didn't drive ya nuts.

But yeah, something to think about. IMO niche is the way to go if you aren't financing the job and running crews.


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## CO762 (Feb 22, 2010)

For those with a metabo 7", they now have a dust shroud for it.


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## Bill_Vincent (Apr 6, 2005)

I dunno-- back when my family had a union company down in New Haven, Ct, we also dod terrazzo, and more times than I can count, my father would loan me out to a GC to grind down a slab that was poorly poured-- 220 volt 3 phase machine that just the diamond plates alone for it were 1000.00 a pair. The machine itself was about $10K.


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## charimon (Nov 24, 2008)

Okey, 
I have owned the Flex, Bosch, and now run Hilti dustless concrete girinders.

The Flex has great dust collection however its main issues were you could only get to 1" from the edge. It ran about $400
The Bosch was less comfortable than the Flex and i Sold it to a budy.
The Hilti uses their DCG500s and an attachment so it is a dual purpose grinder.

These are all German engineered and built tools, Mainly the reason is Europe tends to use alot of concrete ,masonry, instead of wood and so these companies already had the tools there, and just exported them here, where as china and Japan dont have the same internal needs and the nitch market is already full.

What separates them from reg grinders.

1 these are "small frame" grinders that run from 10-12 amps (until recently 8 amps was max in this size)

2 have thermal safeties This means you can run them HARD and they will kickout before damage. (I killed the Flex after 5 yrs when i burned up the electronic control.) 

3 They also have "smart power management. this means that they will add amperage to keep the disc at speed under load.

4The dustless hoods are VERY effective as long as the collector is working (not clogged) Diamond abrasives had Metabo make a self vacing grinder (Metabo also makes the Ridgid cement board saw) that dumps into a bag that the operator wears. 

5 Their electronic's are designed to deal with the abrasive dust.


In 06 we installed 45,000 sf of laminate flooring in an old Hotel remodel, my cup grinders ran about 3hours a day to knock down high spots and ridges that were in the old wall lines. The Hilti ended up being the best It is also the Cheapest around $210 for the grinder and $130 for the hood.

Hope this helps Craig


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## CO762 (Feb 22, 2010)

Bill_Vincent said:


> the diamond plates alone for it were 1000.00 a pair.


It'd be useless, but interesting to know how the industrial diamond market has changed since then.


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## CO762 (Feb 22, 2010)

charimon said:


> Hope this helps Craig


Was a good read Craig. I never thought about the size component of it.
I guess this is why metabo as 875,691 different grinders/sanders. 

This is my math:
7" metabo, $250
7" diamond wheel, $150
Dust shroud (metabo, metal), $150:
=$550

For "spot use" it seems like it would be right on. For more production work of larger areas, Bill's setup would be more in line--obviously, I know.

What I could never figure out is the GC's using their "hiltis" to bush hammer things down instead of grinding them. My thinking is they already have a hilti, so it's just one of their attachments vs. getting another setup. But in costing the man hour difference, i'd bet it'd be better to get a grinder and keep it for such use.


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## charimon (Nov 24, 2008)

CO762

I would look at a 5" unit rather than a 7" I also have a 7" with a Dustcontrol hood.... the larger unit is harder to control by hand, the larger the job the more taxing it is. (this is counter intuitive, the larger being slower, but it turns out that way) It is my recomendation that you will be happier with a 5" or go with mounted 7" like the Hum B










Craig


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## CO762 (Feb 22, 2010)

charimon said:


> It is my recomendation that you will be happier with a 5" or go with mounted 7" like the Hum B


dang Craig, now that looks slick. I'll check into that.

Gratzi.


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## jeffbudding (Jul 26, 2012)

*Metabo*

I like the german metabo grinders. Cost a bit more but they really are tough.


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