Air die grinders, same as electric die grinders ?

[tigman47]

Besides one uses air, and one plugs in. Are they basically the same ?

[calweld]

Not really. Electric die grinders tend to vibrate more, and chatter more in the hole than air. The big advantage to air is the air motor has no momentum, when you release the trigger it stops. I have and use both, mostly it's a matter of convenience (whichever is handy, airline or electric cord), but on delicate or critical things I prefer air.
One other thing -- I've never smoked an air motor yet . . .

[precisionworks]

Are they basically the same ?
Yes, and no.

Electric motors generate heat, air motors run cool.

Electric motors have limited power, air motors are available with well over one full horsepower:
http://www.airturbinetools.com/html/straight/205XSV.html

Even the higher horsepower air tools weigh little. The tool above weighs 14 ounces. The Milwaukee 5196 also produces one horsepower but it weighs 125 ounces, almost ten times more.

Air tools have a higher initial price, but a lower total cost of ownership. Other than two bearings & four or five nylon vanes, there are no other wear parts.

If you use this tool infrequently, an electric grinder may be the better choice. If used often, the air tool will cost less, weigh less, run cool & produce more power.

[neophyte]

Deciding which to use comes down to:
The job at hand, cost to acquire, cost to operate and personal preference.

My pneumatics are small and easy to handle so I prefer to use them for blending welds on ornamental projects or light de-burring.
With them however comes the cost of the grinders, (two) a straight shaft and a 90 degree angle unit, the cost of the air compressor and the cost to run it. I have a 6.5hp 60gal compressor that barely keeps up when I am going full bore with my pneumatics.

If I am grinding in a situation that requires less finesse, fast stock removal, or just for a quick fix, I use a variable speed electric die grinder. I believe the cost to operate it is less in the long run though I do have to occasionally replace the brushes or the unit. I guess my point here is that I prefer doing that to running my compressor to the point of $$$ replacement.$$$ Maybe I should have gotten a larger compressor? In most cases I already have power to the area in which I am working and find it faster to plug in the electric rather then to roll out the air hose. If you have air at your bench this would really be a toss up.

Another consideration might be where you plan to use it. If it is cold the electric is nice. I was running two moisture traps on my air line this past winter and still had problems with occasional freeze ups. I was using Marvel tool oil but I was not using an in-line oilier. Have never owned an in-line oilier so I can't say if this would have eliminated my freeze problem or not.

If it came down to just one???...... it would be electric.

[Laiky]

seems to me that the electric grinders have more low speed torque than the air. the air grinders are lighter and smaller. Electric is very portable, air requires a LARGE compressor to run. Funny, as stated above i prefer electric tools in the winter because they give off heat, where as pneumatics are great in the summer for the cool running and breeze.

[fun4now]

i prefer my 90% air grinder over my electric mainly due to size and ease of use, its small and i have air at my welding table so its just as easy to plug in to air as it is elect. i just find the air nore conveneant. i do agree about the low speed option not being so great on the air grinder but it still remains my 1st choice 2nd would be my lil dremel then my big electric grinder. i have a husky air tank i got at homedepot, keeps up fine.(se pic) i think its a 80g but might be a 60 gal.?? i can check if you like.
just my $.02
james

[Fishy Jim]

I prefer air as well. The size of the tool and the comfort/finesse in controlling it being the deciding factors. There are days when I would love to drop my baby air compressor off a very high, very jagged cliff because it can't keep up, but when I work at other's shops with enough flow and pressure, I sure do love that little tool for porting intakes and exhausts.

I've always wondered how it would compare to a flexible shaft tool with a big motor strapped to it. You're always fighting the hose (even with a super flexible 1/4" section off the tool itself before the main 3/8" hose), so it's not like the flexshaft would be any different. We had some 1/3hp units back in the art shop in HS, but I never used them on anything but copper then (my little corded dremel was better for that).

[precisionworks]

Have never owned an in-line oilier so I can't say if this would have eliminated my freeze problem or not.


Jesse - Moisture in the line is causing the freezing. Eliminate the moisture & you'll stop the problem. It's worse in cold weather as the air+water vapor in the colder lines reaches the dew point, condenses out & freezes.

Air tool oil is needed all year long. It neither helps or hurts the freezing problem.

[fun4now]

I've always wondered how it would compare to a flexible shaft tool with a big motor strapped to it.


FWIW i have the craftsmen all in one grinding tool with the flex shaft atachment for it and i find it to be a pain, i have brok several of the flax shafts they are verry sensitive to over bending. and the on off is still at the moter so its can be a bit dangerouse if ya get it caute in somthing.:eek: all in all every thing i intended to use the flax shaft option for has turned out to be much more conveneant with a lil multy speed dremel. defenetly spend the extra $20 for the ajustable speed version, i found this out the hard way as i got the single speed first and now have 2 ajustable speed versions, a cheep one from HF ( my tester) and a good dremel multy speed (well werth the $$$$) the dremel is smaller and more comfortable in the hand and also has so many extra atachments its mind boggeling :D
so in my opinoin dont waist you $$ on the flex shaft, just get a nice dremel multy speed and skip the flex shaft. if you already have a dremel multy speed you are not missing anything, you have it coverd.;)

You're always fighting the hose (even with a super flexible 1/4" section off the tool itself before the main 3/8" hose), so it's not like the flexshaft would be any different.
the flex shaft is werse and it breaks easily.;)

[tigman47]

Well my air die grinder makes my little compressor kick on to much, so I have to get something else. And a bigger compressor is not in on my mind right now.

I should of asked if the electric die grinder would spin just as fast as my air one.

[fun4now]

not shoure about the exact speed ( i cant count that fast :p ) but they bolth get the job done.;)

[precisionworks]

I should of asked if the electric die grinder would spin just as fast as my air one.


Most electric die grinders run around 25k RPM.

Air die grinders are commonly available from 25k to 90k RPM. The higher speed tools use smaller tooling.

[neophyte]

Jesse - Moisture in the line is causing the freezing. Eliminate the moisture & you'll stop the problem. Air tool oil is needed all year long.That was my understanding as well and is why I added the second moisture trap. This helped but did not totally eliminate the problem. I have heard of people using a product called KILFROST TOOL OIL but have not tried it. A nicer solution would be to work in a heated garage all of the time.

My understanding is that the freezing is partially due to lower temps in the tool caused by the change in air pressure (high to low) in the tool as it is used. It was explained to me as being like the carburetor icing that we see take place in aircraft carburetors.

[fun4now]

FWIW; i put like 3 drops of synthetic air comp. oil in my air tools every time i atach them to the line for use.my shop gets heated by a gas space heater when im in there and is on its own when im not. also i have never liked the line oilers that you atach to the compresser as it puts oil in all your lines so painting will never be an option. i have used the inline oilers that atcah directly to the tool, with good results in AZ. on the job site other than the acational break off due to dropping they worked good. that was on nail guns though i'm not shoure how well they would work on a air grinder, i would think you would need an ajustable one or atleast a specified low flow or you would likely end up with oil spewwing out all over the place.:eek: as it adds oil as the air goes threw in a siphin methoud with the high volume of air used on a grinder it could sereously over oil unless its low flow or desined for that aplication.:rolleyes: not shoure that was much help :o stick to 3 drops at startup regardless of temp, the oil should help stop the freezups.

[Prototype3a]

Has anyone seen a shop with an air dehydrator? We have one for each of our air systems onboard and I was wondering if it was really worth it when operating tools with the air.

[fun4now]

for paint or plasma cutting i would say ya but for standerd air tool i wouldnt worry so muc like was said earlyer not too much in side there to worry about.;)

[Bulldog]

I run a air dehydrator in my home shop (mostly for the plasma cutter) I can tell ya my tools work alot better at my home shop then they do when I bring them to some other shops that I work at. I hate using them in some of the shops. The water in some shops is ridiculous. Ya may as well hook up to a water hose! After I use them at other shops I run them on my dry air to make sure there good and dry then I give them a good shot of air tool oil.
Bulldog

[Fishy Jim]

Sounds like the air at the universities metal lab. They only had a few classes on machining, primarily for their engineering students to understand how their designs come into existence, so the up-keep was a very low priority. I did some intake porting while on my work study hours and ended up soaked from the water discharging out the tool. Since they mainly run the air in the shop for cooling cutters and blowing away chips - I suppose the water is a free bonus. Not so cool when you need it for running tools.

[fun4now]

i supose it would depend on weather you service the lines, i drain my tank every day to insure i dont colect water, i supose if ya let them go it would reduce the efectiveness of the tools.:rolleyes: supose ya could get some water grinders for that school.:p

[Fishy Jim]

I graduated a few years ago. It was a pretty cool lab assistant gig for being in college though. I had full access to a couple lathes, a bridgeport, and a horizontal mill and grinder plus enough tooling to make all of them very functional. Air really wasn't used on anything for power. The professor who was responsible for maintaining the compressor didn't care and wouldn't let anyone who did do anything about it (it wasn't my boss, he was equally disgusted at the matter).

[neophyte]

It was a pretty cool lab assistant gig for being in college though. I had full access to a couple lathes, a bridgeport, and a horizontal mill and grinder plus enough tooling to make all of them very functional.

Dang, You would think that a guy in this position would just flunk out a couple a years running and hang out for awhile.:)

[fun4now]

LOL, sounds good to me too, i supose that lil thing called tuition had some thing to do with wanting to leave.now if ya could get daddy to fit the bill that would be another situation. :p