Compressor Questions

Doug Bernhardt · Post by **Doug Bernhardt** » Sat Mar 04, 2006 5:47 pm

Okay....this is what I need it to do. Some light sandblast duty, not of the woodsign level but for some glass sand carving and need it to be able to run a sander. It's a small shop so this would be a single use not for two or three ppl at the same time. It also would be required as a nailer and if it could run an HVLP spray gun that also would be of help. I'm confused by the requirements and ratings on the compressors I've seen. Any help is appreciated.

Patrick Mackle · Post by **Patrick Mackle** » Sat Mar 04, 2006 10:00 pm

Doug,
The sander will require the most air, as it generally is used continueously.
The HVLP can also use alot on large surfaces. If you are only spraying a few square feet with pauses inbetween you can get by with a smaller compressor.
The nailer should not be a problem unless you are roofing with a big gun.
A smaller compressor with a larger tank generally will give you longer intervals between the pumping cycles, depending on the air demand you could run it too hard.
If you don't want to feel dissatisfied with your purchase down the road, keep in mind that what really counts is the size of the motor and pump. The tank is really secondary and really depends on the space it will require. In my shop I have a 1hp, 5hp, and 25hp. The 1hp is on wheels and good for air wrenches, small spray paint jobs, and barely good enough for small on-site frosted glass jobs-no sandcarving. The 5hp will handle medium glass carving jobs with an occasional pause. The 25hp is nearly a monster and powers my sandblast room. Grrrr...ouhh-auhh!!
I think you would be happy with a 2-3hp compressor with about a 40-80 gallon tank. Be wary of some cheaper compressors. They boast high CFM
ratings, but they rev their pumps at a higher RPM which shortens the life.
Check the RPM's on the motor and the diameter of the pump pulley to get an idea of the pump speed. When these pumps begin to wear they load the air with oil vapor and you will also see it in the condesation water when you drain the air tank. You may get what you pay for.
It's always best to have a little more power than you need, and in compressors they last longer if they aren't overtaxed.
Merci-boo-coo on sharing your shots of France.
Pat

Roderick Treece · Post by **Roderick Treece** » Mon Mar 06, 2006 8:11 pm

Doug,
I have a 5hp 220v 100gal. works great for most thing.Could be a liitle bigger for sparying auto type bigger finishes.I'm not sure but I think any bigger and you go up to 3 phase which I don't have.
Good luck

Roderick

Patrick Mackle · Post by **Patrick Mackle** » Mon Mar 06, 2006 10:44 pm

There are 7hp 220v single phase motors but they are less common and more expensive. At that point you may as well consider moving up to a 3 phase motor if you currently have 3 phase service. Probably more efficient and a little cheaper to run.
You could employ a "motor generator" with which you run your single phase motor to power a 3 phase motor which inturn generates 3 phase power. My friends run 220v 3 phase mills and lathes in their residential garages that way.
Pat

Doug Bernhardt · Post by **Doug Bernhardt** » Tue Mar 07, 2006 9:05 pm

Good advice...the purchase is a couple of weeks away and am just trying to get up to speed. Am not into adding anything electrically to "this" shop as I'm likely here for just another year and at the same time do the tasks required at present and future. Will post things as they happen and with any more advice requirements...thanx

vance galliher · Post by **vance galliher** » Wed Mar 08, 2006 11:03 am

Hi Doug, the only thing I would add to the requirements is make sure its a two-stage. I'm mainly doing glass work now and no longer have to wait for the compressor to catch up with me. It has brought the fun back into blasting........

Doug Bernhardt · Post by **Doug Bernhardt** » Wed Mar 08, 2006 7:07 pm

Vance...now thats a word I've been wondering about "2stage" what exactly is that and how does it affect to cfm etc?

Patrick Mackle · Post by **Patrick Mackle** » Wed Mar 08, 2006 7:24 pm

Two stage compressor pumps have two or three cylinders. Single stages can also have two cylinders. The difference is that on the 2 stage, air is drawn into the first cylinder, compressed and sent to the second cylinder which is a smaller cylinder which therefore compresses that same volume of air to a higher pressure.
Pat

vance galliher · Post by **vance galliher** » Wed Mar 08, 2006 8:51 pm

Doug, no we both know what the real difference is !......thanks Pat,...... great explanation.

Doug Bernhardt · Post by **Doug Bernhardt** » Wed Mar 08, 2006 9:12 pm

Good and thanx again...Looks like what I need is a 2stage (220v) 60 or more gal(lon) gal? Will check the local spots end of this week and see what is what. ....and will keep you all posted. The sander is important and will also check the spec sheets to see if the thing can drive one of those..as it seems from the mail as well as postings here that that will be the single largest consumer.

vance galliher · Post by **vance galliher** » Wed Mar 08, 2006 9:33 pm

expect to pay about $2,000 for a good one.....have fun

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