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Die grinder powered by RS compressor for extended use

rmcphearson

Hot Rolled
Joined
Jan 12, 2008
Location
Rochester, NY
I do a lot of hand grinding with a 90 degree pneumatic die grinder outfitted with a 3" rubber pad and roloc type sanding discs. My 80 gal 7hp 10.3 scfm@90psi piston compressor doesn't even come close to giving me the air that I want for almost continuous grinding for hours at a time occasionally.

I guess a rotary screw compressor is what I need. I priced one for about $5k. Any alternatives? If not, any recommendations for a single phase 220v RS compressor?

Thanks,
Roland
 
Roland, unless you just want a rotary compressor, you might consider a more efficient die grinder for a lot less? 10 scfm should be enough to power a 3" roloc-type disc. Is your compressor optimistically rated? The die grinder with worn vanes?

Another alternative is another conventional compressor in parallel with the one you have.

A good rotary should be quieter and last longer, but $5K seems pretty pricey if running a 3" disc is your ultimate objective.
 
Air is an extremely inefficient way of powering a tool. Save money and invest in an electric die grinder.
 
I do a lot of hand grinding with a 90 degree pneumatic die grinder outfitted with a 3" rubber pad and roloc type sanding discs. My 80 gal 7hp 10.3 scfm@90psi piston compressor doesn't even come close to giving me the air that I want for almost continuous grinding for hours at a time occasionally.

I guess a rotary screw compressor is what I need. I priced one for about $5k. Any alternatives? If not, any recommendations for a single phase 220v RS compressor?

Thanks,
Roland
I think 10.3 at 90 PSI is a very small CFM rating for 7HP. I would expect at least double that if it is a two stage with a good motor. Is your compressor from HF with a single stage two cylinder pump and fake motor rating?

For instance: Ingersoll Rand 2475N7.5-FP Type 30 7.5-HP 80-Gallon Two-Stage Air Compressor 230V 1-Phase Fully Packaged 7.5 HP, 24 CFM at 175 PSI

Larry
 
It's a Nitro/Napa compressor. The specs are correct. No longer supported by Napa. Made in the land of China "where people ain't hardly got noth'n at all. No possessions, no religion too."
 
It's a Nitro/Napa compressor. The specs are correct. No longer supported by Napa. Made in the land of China "where people ain't hardly got noth'n at all. No possessions, no religion too."

Well.. their AIR is so much thicker with all the crap in it, they don't have to pay much attention to no steenkin' seals, either, yah?

JMNSHO but BOTH your compressor and grinder are below the mark. Add leaky Chinese hose and fittings if you cheaped-out on those as well.

Electric grinders? Freehand?

Make my next one with an overhead chain and counterbalance, please.

Heavy bastids will wear you out and/or run you in circles off the precession of a great deal more rotating mass than air-powered needs.
 
get an electric grinder. Your electric bill will go down and you will not be spraying oil mist over your work and into your lungs.
Bill D
 
An electric die grinder or grinder would have to be the same size and shape (90 degree) and rpm of my pneumatic one for this application. I'm willing to try it if one exists. But I'm assuming there's no such thing. If I am correct, please recommend a small RS compressor. My budget is $5k.
 
If you have done alot of work with die grinders, the electric models are much larger, generally do not work for long at low speeds. I am hoping that some of the new electric motor technology finds its way into electric grinders to make them more compact, run at slower speeds without overheating.
 
I don’t know if this will work for you but I modified my cheapo right angle electric grinder and it will run all day long and Out
65f9ff245370bf434304adb93187df98.jpg
7a6ae15f14fcc90d379d74bff1406d1a.jpg
04dc2d35d1c530a4871a150e4ccd4ab2.jpg
produce any small air grinder made total cost $16


Sent from my iPhone using Tapatalk
 
An electric die grinder or grinder would have to be the same size and shape (90 degree) and rpm of my pneumatic one for this application. I'm willing to try it if one exists. But I'm assuming there's no such thing. If I am correct, please recommend a small RS compressor. My budget is $5k.

ATTACHMENTS + OTHER TOOLS | FOREDOM should be under $500 depending on options. You would have to take the guard off to get 3" but you likely don't have one now.
 
If you have done alot of work with die grinders, the electric models are much larger, generally do not work for long at low speeds.
+1 "Self-cooling" off waste air has always been one of the biggest advantages of air-power and lack of it a shortcoming of electric, yes.

I am hoping that some of the new electric motor technology finds its way into electric grinders to make them more compact, run at slower speeds without overheating.

it may have been happening, but I doubt either of us want to be the test subject at the prices they are asking..

Metabo - who "claim" to have "invented" the original electric angle grinder (??) now list cordless models. The RPM range claimed is impressive. So is the price!

Sustained or continuous use has never been a strong point for any other cordless tools I've used- 2/3 of what I depend on - metal, wood, or even drywall - are still "corded".

Foredom was mentioned. Historically, a solid mainstay in smaller goods.

But what about the more SERIOUS electric motor-driven flex-shaft grinders?

ISTR the auto industry used to use a LOT of those? Have those vanished from the market? I found plenty of sources for new flex shafting on several supplier websites - but not the tools FOR it.
 
I don’t know if this will work for you but I modified my cheapo right angle electric grinder and it will run all day long and Out
65f9ff245370bf434304adb93187df98.jpg
7a6ae15f14fcc90d379d74bff1406d1a.jpg
04dc2d35d1c530a4871a150e4ccd4ab2.jpg
produce any small air grinder made total cost $16


Sent from my iPhone using Tapatalk

Wow! That's great info. Thanks Edwin. I would need the smallest and lightest one of those to minimize fatigue as I will be holding it with one hand for long periods of time.
 
Wow! That's great info. Thanks Edwin. I would need the smallest and lightest one of those to minimize fatigue as I will be holding it with one hand for long periods of time.

The usual challenge is.. that the "smallest and lightest" take longer to get a given job DONE. So the time one has to hold it extends, and one is worse-off.

The Old Skewl trick - I mentioned automotive, as-in body joint and seam cleanup after welding, all done by CNC "robots" nowadays - was to hang a raft of motors off the overhead, shafts carrying plenty of motive power to a handpiece that had no hot nor heavy motor "in hand".

I'm sure operation takes getting used to, but so did an air-hose.

Any "long periods of time" exercise hints that at least two differently-configured grinders might be a significant gain as well.
 
YOu don't really tell us what you are doing, but grinding for hours, man,I would find a way around that.

First, you compressor is probably not what it says, NAPA being the pinnacle of compressor tech.

Second, all of the grinding needs the reach and flexibility of the air grinder? I think like a machinist, rough and finish, rough with an electric angle grinder, finish with your air tool, lower air use.

lots of small air leaks eat air capacity

so does poor supply hose, you are dealing with effective psi at the end of hose, if you have a long skinny supply hose[with leaks] it raises the tank pressure needed to do the work you are doing.

While a heavily loaded grinder will indeed use that much SCFM, most here I think have difficulty believing your wrists last longer....
 








 
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