pneumatic versus electric tools (Modified by scarab@---------)

[scarab@zzzzzzzzz]

Hello Norman & other friends,

In part because my hands don't like the vibration of air hammers, I am 
primarily a slash-and-burn carver, i.e., my preferred method is to 
first cut chunks off with a diamond blade on an angle grinder, then 
grind the remainder. My preferences for pneumatic tools over electric 
have been discussed before, but I will repeat a few points here, most 
in agreement with other posts, some in disagreement.

• As far as economy, in long-term use, because of repairs and 
replacements, pneumatic is probably cheaper. This is one reason why you 
see all most heavy industrial workers using pneumatic tools instead of 
electric (safety and ergonomics being other reasons). However, you have 
higher electric costs and the initial setup costs are dramatically 
higher for air tools. I am speaking here of the highest quality 
grinders, not the Northern or Central Pneumatic. (The best names are 
Chicago Pneumatic/nowGeorges Renault, Dotco/Buckeye, Diabrade, Suhner, 
and ARO/Ingersoll Rand; higher and lower quality sub-lines exist in 
most of these brands.) A good grinder is a lifetime investment. Someday 
you might need to replace the bearings or possibly even the air motor, 
but the expense of this is not comparable to having to replace an 
entire electric tool every few years of heavy use. But to give you an 
idea of what I mean by high-quality, my 7" 8000rpm grinder cost close 
to $1000 (a 9" 6000 rpm grinder would be the same), and my 5" 12,000 
rpm grinder cost over $600. A high-quality 12,000 or 24,000 rpm die 
grinder will cost over $300. (Then there is the cost of needing larger 
compressor capacity; I will comment on this under a separate thread.) 
Obviously, this is out of the reach of most people. I chose to go this 
route only because I knew the alternative for me was to simply not 
carve, as I had found the electric tool experience to be so 
distasteful, exhausting, and dangerous. However, for cheaper tools, 
many of the points I mention below will still apply. Cheaper tools will 
tend to have less power, more vibration, more noise, and wear out 
faster, in approximate proportion to how much less you spend.
• Ergonomically, for the safety of your hands, (high quality) air tools 
win hands down. Vibration is substantially lower, and in the case of a 
4-1/2 or 5-inch grinder, astonishingly lower. It is a totally pleasant 
experience to use such a small grinder all day long with a diamond 
wheel--quiet, smooth, light, precise. Cheap air grinders, however, may 
not offer as much of this advantage, though I have two cheap Taiwanese 
7" sanders I use for grinding or cutting with 4-1/2" blades which are 
very smooth, though slow and not very powerful.
• Air angle grinders are smaller and weigh approximately 40% less than 
comparably sized electric grinders. This makes a big difference after 
an 8-hour day of cutting. But if you are a big, beefy man or woman, you 
might enjoy that 9-11 pound electric body grinder. In center water feed 
polishers, the weight difference is closer to 60% lighter for air. When 
you have a lot to polish with 6 or 8 diamond grits, it really adds up 
fast to be less user fatigue and sore wrists.
• Air grinders in the 4-1/2" size generally have a much smaller grip 
than electric, because you don't need to wrap your hand around an 
electric motor. This is essential if you have small hands, as I do, but 
perhaps men with very large hands would perfer the electric tools.
• Air tools are significantly quieter than electric tools, especially 
if you use ones with available mufflers.
• Air tools run cool or cold, electric tools run warm or hot. Take your 
pick. I have never found the coolness to be a problem, perhaps because 
my grinders have rubber/plastic grips, which help insulate, and I wear 
gloves.
• Air angle grinders are less powerful than comparably sized electric 
tools, so you will need the best one you can get. Air tools will stop 
if the blade binds in a hole. This can be hard on the blade, but 
eventually you will learn to cut without binding. Electric tools have 
sort of a reserve of power, whereby when they start to bind they pull 
extra current and just keep on going. The problem with this, I have 
found, is that if you are running a big 9" body grinder and the blade 
wants to bind, the grinder will just about pull your whole body over 
the top of the stone. Very unpleasant, dangerous, and hard on the 
wrists.
• Getting oil on the work should not be a problem if you buy a quality 
tool and be sure to get ones with rear exhausts. A sound-muffling hose 
goes over the air hose and directs the exhaust and any blow-by oil onto 
the floor, where it is absorbed by the wet grit.
• With either electric or air, you wind up having some sort of 
umbillical cord to drag around, although the air hose is more 
cumbersome than an electric line.
• I doubt that anyone would prefer an electric die grinder to an air 
grinder; air grinders are so much smaller, lighter, and smoother, even 
the cheapest ones.
• I now do all my work wet (having built small, inexpensive water feeds 
on all my tools) and would never consider going back to dry cutting. 
The advantage of air tools here is I don't have to worry about trusting 
my life to a cheap GFI and I can slosh as much water around as I want 
without concern, including hosing off the tool.

In sum, I would say go air if you are into carving for life or for a 
living and if you have the money and the place to put one or more large 
compressors. For those on a normal person's budget, or for occasional 
use, or if you feel you need the maximum power of a 9" electric body 
grinder, you will get by with electric. If you have ergonomic concerns 
as I do, find a way to go pneumatic. If you are primarily a chisel 
carver, you will need an air compressor anyway, and will at least want 
an air die grinder. Consider upsizing your compressor for later use of 
larger air tools. If you are building a studio, make provision for air 
even if you don't go to air tools now; you may later. In any case, keep 
carving!

Randy Jorgen
Moab, UT
beetle@---------