Subject: [Shop-talk] HF rotary hammer vs. demolition hammer?

From: Brian Kemp <[email-masked]>
Date: Thu, 30 Oct 2014 22:13:19 -0700

I want more power, but will $160 plus tax and bits make a big difference?

Can anyone compare a Harbor Freight rotary hammer such as this one:

http://www.harborfreight.com/10-amp-3-in-1-1-18-in-variable-speed-sds-rotary-hammer-69274.html

to their demolition hammer like this one:

http://www.harborfreight.com/10-amp-120-volt-demolition-hammer-68148-8068.html

I have a four year old version of the first, model 97743 (about $70 well 
spent), and have been using it with 3/4" chisel from this set:
http://www.harborfreight.com/2-piece-sds-masonry-flat-chisel-set-42651.html

My project is demolition of a bathroom.  The rotary hammer in chisel 
mode has been fair breaking the wall tile, which is metal lath with 1/2" 
of cement, 1" of cement, then tile.  I used a diamond blade in an angle 
grinder to cut the vertical grout joints to make the tiles pop easier, 
but I'm at 2.5 days and still have more to go.  The tile guy did quality 
work back in the 1960-70 range.  Unfortunately, the galvanized water 
pipe behind the tile is plugged and cold water barely flows, requiring 
near full demolition.  There are also problems with the drain pipe, so 
while I'm at it...

I want more breaking power, especially since the next step will be to 
cut a trench in the slab to get at the drain pipe.  For the trench, I'll 
probably drill a series of holes then connect the dots with the pointed 
chisel, starting at an edge and making small breaks.

My question is will I get more breaking power with the demolition 
hammer?  They are both 10 amps and about 3000 beats per minute.  The 
demolition hammer has an impact energy 9 ft. lbs. but that means little 
to me in comparison and there is no impact specification for the rotary 
hammer.

My other option is to just have the plumber break the trench.  I'm 
getting tired of demolition, but I like electrical and framing.  I will 
hire out the plumbing since there are two bathrooms and the other one is 
used by my wife and daughters, so time is very important once that work 
starts.

By the way, if anyone needs to drill a 1" hole through a 10" poured 
concrete foundation, a rotary hammer like one of these is the way to 
go.  I now only use my 1/2" hammer drill for tiny things like Tapcon 
screw holes.

Shop content - this bathroom is an apartment under the garage (hill side 
home, garage at street level at the top).  As part of this project, I'm 
also installing a sub-panel, so I can get real power in the garage and 
run my 15A compressor without unplugging the living room entertainment 
center and pulsing the compressor on/off a few times to get it started 
without tripping the breaker.

Thanks,

Brian
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Archive: http://www.team.net/archive

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From: Jeff Scarbrough <[email-masked]>
Date: Fri, 31 Oct 2014 08:56:57 -0400

On Fri, Oct 31, 2014 at 1:13 AM, Brian Kemp <[email-masked]> wrote:

> My question is will I get more breaking power with the demolition hammer?
> They are both 10 amps and about 3000 beats per minute.  The demolition
> hammer has an impact energy 9 ft. lbs. but that means little to me in
> comparison and there is no impact specification for the rotary hammer.

>From the comments, it seems that the demolition hammer is a one-use tool.
Several of the lowest ratings refer to the fact that replacement bits are
hard to come by.  That would be worth looking into before you buy one...

Jeff Scarbrough
Corrosion Acres,Gga

[email-masked]