Air Compressor Questions

[alex123]

Hi Everyone - This is my first post as a member of this forum. I am in the market looking for a air compressor. I will be doing automotive work at home, so I need something that can run 1/2" impact gun (up to 1000 ft. lbs.), pneumatic ratchets, cut off tools, air chisel, etc.
Also important is noise level. I live in a town home and am sandwiched in between two units. I do have a garage, but would prefer something as quiet as possible. I have looked at California Air Tools and those compressors seem to be a little on the expensive end. I'm looking for ~30 gallon tank. Since the highest consumption tool I intend on running would be the 1/2 impact, I thought I would share the compressor, and air impact I had in mind. I'm not fully set on moving forward with these, hence this post. I would greatly appreciate feedback on the harbor freight 1/2" impact wrench (6 cfm @ 90 psi), and harbor freight 29 gallon 150 air compressor (5.9cfm @ 90)

I looked at the air tools I'm interested in buying and almost all of them are 4 to 4.5 CFM consumption @90 PSI. The only air hog is the impact wrench I'm interested in. The compressor yields 5.9 cfm @ 90 psi. The impact wrench I want is also rated at ~6 cfm at 90 psi. Will that be a problem? Will I get the FULL power out of this impact wrench with this air compressor?


Thanks in advance,
Alex

 

[Citation]

For what it's worth, the impact is actually about the lowest consumption tool you have on your list. I know that might sound odd and it's definitely the one that will drain your tank the fastest if you hold the trigger down. However, impacts are typically used in short bursts with pauses that allow the compressor to catch up. I never had issues with enough air even when I was feeding my 1/2 impact off a 4 gallon, 4 CFM compressor. However my cutoff wheel exceeds what my larger 20 gallon, 5.5 CFM compressor can deliver when you need to make a large cut. I suspect the ratchet will have a heavy load since that would be more like a continuous run tool. Not as sure about the air chisel.

In terms of really "quiet" compressors, without spending big money the CAT and similar are about as good as you can get.

These Kobalts seem like a good CAT alternative. Same pump design and less money. As best I can tell CAT is really a marketing/resale company and the engineering is done by others. Near identical compressors are/have been sold by GMC (not the truck brand), Quipall, Husky and others.

The HF 29 gallon is probably a good value in a belt drive compressor. No idea how noisy it is. Keep in mind that you can often improve things with changes to the intakes (look up DIY air compressor mufflers on Youtube). I wouldn't be surprised if the HF flow number is a bit inflated.

This Kobalt (Campbell Hausfeld) would be worth a look. It has a bit more air reserve thanks to the higher pressure tank. It has a 2 stage pump. Slightly lower claimed flow rate but in use these are probably very similar units.

What kind of power options do you have in the garage? 120V, 240V? 1 circuit, more than 1 circuit?

 

[454ragtop]

Probably should look at this thread https://www.garagejournal.com/forum/showthread.php?t=374376
No experience with it myself, I have an industrial compressor, which it sounds like you don't have room for.

 

[sberry]

The impact needs 25cfm, it needs it for short time. Those are industrial avg numbers, not actual consumption.

 

[alex123]

For what it's worth, the impact is actually about the lowest consumption tool you have on your list. I know that might sound odd and it's definitely the one that will drain your tank the fastest if you hold the trigger down. However, impacts are typically used in short bursts with pauses that allow the compressor to catch up. I never had issues with enough air even when I was feeding my 1/2 impact off a 4 gallon, 4 CFM compressor. However my cutoff wheel exceeds what my larger 20 gallon, 5.5 CFM compressor can deliver when you need to make a large cut. I suspect the ratchet will have a heavy load since that would be more like a continuous run tool. Not as sure about the air chisel.

In terms of really "quiet" compressors, without spending big money the CAT and similar are about as good as you can get.

These Kobalts seem like a good CAT alternative. Same pump design and less money. As best I can tell CAT is really a marketing/resale company and the engineering is done by others. Near identical compressors are/have been sold by GMC (not the truck brand), Quipall, Husky and others.

The HF 29 gallon is probably a good value in a belt drive compressor. No idea how noisy it is. Keep in mind that you can often improve things with changes to the intakes (look up DIY air compressor mufflers on Youtube). I wouldn't be surprised if the HF flow number is a bit inflated.

This Kobalt (Campbell Hausfeld) would be worth a look. It has a bit more air reserve thanks to the higher pressure tank. It has a 2 stage pump. Slightly lower claimed flow rate but in use these are probably very similar units.

What kind of power options do you have in the garage? 120V, 240V? 1 circuit, more than 1 circuit?

Thanks for the great info. To answer your question, I only have access to 120V at this time.... I rent so I don't have the option to modify the electrical unfortunately.
The Kobalt looks like a nice unit. You mentioned that the HF is belt driven. What is the difference between belt driven, and the Kobalt one? You'll have to excuse my lack of knowledge on compressors.... this is all new to me.

As for the CFM, the HF one use to be rated at 6.4... then after a while they changed it to 5.9 @ 90. The HF unit is rated to 150 psi. Kobalt is rated at 5.3 CFM @ 90, but is capable of 175 PSI, and can yield 51. CFM at 175 psi. I really don't know which one is the better unit. For me, the number one concern, is getting enough power to make sure I don't get stuck in the middle of a repair. I'll be using the unit for automotive repair only.
Your thoughts are welcome

Edit: By Automotive repair, I am referring to impact wrench, air hammer, ratchet, cut off tool, die grinder, etc...

 

[alex123]

Probably should look at this thread
No experience with it myself, I have an industrial compressor, which it sounds like you don't have room for.

Thank you for sharing this information. Unfortunately, I don't have access to 220V

 

[alex123]

The impact needs 25cfm, it needs it for short time. Those are industrial avg numbers, not actual consumption.

Good to know. Thanks for the info!

 

[FA7X]

I bought the Kobalt 30gal a few months ago and I love it. It is quiet, has no problems on 120v/15A, and runs all of my tools. I should have pulled the trigger years ago.


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[alex123]

I bought the Kobalt 30gal a few months ago and I love it. It is quiet, has no problems on 120v/15A, and runs all of my tools. I should have pulled the trigger years ago.


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Are you ever left in a situation where you're sitting and waiting for the compressor to catch up? I'm just on the fence about this whole thing. Here's where I'm a little confused. My current situation won't allow me to go with a large (60+ gallon) compressor, otherwise I would have just purchased one and been on my way. I'm limited to the 30 gallon compressors, and am concerned that I won't get enough run time, and will be constantly waiting.

If I go with cordless tools, then I'm stuck with upgrading everything when the manufacturers decide to change their power lineup ; Say for example, Milwaukee decides to discontinue the 20V and go to 24V.

A third possible option is buying corded tools, for the die grinder, cut off tool, and reciprocating saw, and then just buying a cordless (battery operated) impact wrench and ratchet. This way, I'm not stuck with the up front costs of buying a compressor, hoses, fittings, etc. As well, I get 1000 ft. lbs. on a cordless impact right off the bat, without requiring a huge compressor. That way, if they ever do change the batteries, I'm only buying a new impact wrench, and ratchet, and not a whole line up of tools every few years.

Thoughts?

 

[Citation]

How long are you going to be in this situation? I was in a similar situation for a while (kind of still am with my current house).

First you need to decide if quiet is a requirement. If it is then you need to get something like a CAT 10020 or that Kobalt quiet compressor. I think Quipall had something in this range as well. Unlike the "1hp" CAT models these are around 4 cfm @90 and would be at least in the same ball park as the belt drive models you want.

If not then a belt drive 20-30 gallon compressor like the 175 psi Kobalt or the 29 gal HF is as good as you can get.

However, a smaller compressor may be sufficient for your short term needs. I started with my 4 gallon, 4 CFM roofing compressor and found it to be fine for my impact wrench. It could do about 4 lug nuts before cycling. In about 15 seconds it was back to full pressure so it never really slowed me down.

Something like the HF, 8 gallon hotdog compressor is cheep and had just enough tank and pump to operate a grinder, cutoff wheel etc for short cuts. It will have no trouble with an impact. It costs just a bit over $100. That leaves $300 in your pocket for a bigger compressor in a few years. The HF isn't quiet but the flow rate is similar to the better "quiet" compressors.

Finally, you could build a quiet box for the compressor. They can work well but are a lot of effort.

 

[alex123]

How long are you going to be in this situation? I was in a similar situation for a while (kind of still am with my current house).

First you need to decide if quiet is a requirement. If it is then you need to get something like a CAT 10020 or that Kobalt quiet compressor. I think Quipall had something in this range as well. Unlike the "1hp" CAT models these are around 4 cfm @90 and would be at least in the same ball park as the belt drive models you want.

If not then a belt drive 20-30 gallon compressor like the 175 psi Kobalt or the 29 gal HF is as good as you can get.

However, a smaller compressor may be sufficient for your short term needs. I started with my 4 gallon, 4 CFM roofing compressor and found it to be fine for my impact wrench. It could do about 4 lug nuts before cycling. In about 15 seconds it was back to full pressure so it never really slowed me down.

Something like the HF, 8 gallon hotdog compressor is cheep and had just enough tank and pump to operate a grinder, cutoff wheel etc for short cuts. It will have no trouble with an impact. It costs just a bit over $100. That leaves $300 in your pocket for a bigger compressor in a few years. The HF isn't quiet but the flow rate is similar to the better "quiet" compressors.

Finally, you could build a quiet box for the compressor. They can work well but are a lot of effort.

Because I move for work every couple of years, a larger compressor is not an option (unfortunately). Based on what you've described, I think the Kobalt and HF are the front runners. The CAT is a great little compressor, but the CFM is pretty low. This might sound silly, but I just don't want to be in a position where I have to upgrade the compressor in a year or two. I just want to use the compressor until it's no longer running.

With that said, I will for sure need to figure out a noise reduce (muffler) system for either the HF or Kobalt. If you were in my position, which of the two would you select, and why?

 

[Citation]

If I were in your shoes I would look for used in the area. This is the one I have, my old employer bought it from Grainger. I got it when we upgraded
https://www.ebay.com/itm/Westward-Air-Compressor-20-Gallon/223269268974

It's just the typical Campbell Hausfeld type from a decade back. I've seen 30 gallon versions go for $150 and under.

That Kobalt appears to be as good as it gets in this range but it's also big and heavy. If I expected to move all the time I might get something smaller/lighter. DeWalt has a 15 gallon 200psi model with 5+ cfm of flow. I might consider it as well. It's in the $300s. Not sure about noise levels. Thanks to the high pressure it's tank capacity is about the same as a 30 gallon with lower pressure.

BTW, when thinking about tank size I like to think about psi over 100. Once my tank pressure drops to 100 I'm going to see a loss in performance of things like impact wrenches or cutoff wheels. So a rough way to think about reserve air is PSI over 100 * gallons. So a 10 gallon, 125 psi compressor has 25*10=250 gallon-psi of air. A 6 gallon, 150 has 300. The 29 gallon, 150 psi HF compressor has 1450 while that DeWalt has 1500 psi-gal. Remember, that is a rough estimate and used as a roll of thumb comparison. The Kobalt is 2250.

 

[alex123]

If I were in your shoes I would look for used in the area. This is the one I have, my old employer bought it from Grainger. I got it when we upgraded
https://www.ebay.com/itm/Westward-Air-Compressor-20-Gallon/223269268974

It's just the typical Campbell Hausfeld type from a decade back. I've seen 30 gallon versions go for $150 and under.

That Kobalt appears to be as good as it gets in this range but it's also big and heavy. If I expected to move all the time I might get something smaller/lighter. DeWalt has a 15 gallon 200psi model with 5+ cfm of flow. I might consider it as well. It's in the $300s. Not sure about noise levels. Thanks to the high pressure it's tank capacity is about the same as a 30 gallon with lower pressure.

BTW, when thinking about tank size I like to think about psi over 100. Once my tank pressure drops to 100 I'm going to see a loss in performance of things like impact wrenches or cutoff wheels. So a rough way to think about reserve air is PSI over 100 * gallons. So a 10 gallon, 125 psi compressor has 25*10=250 gallon-psi of air. A 6 gallon, 150 has 300. The 29 gallon, 150 psi HF compressor has 1450 while that DeWalt has 1500 psi-gal. Remember, that is a rough estimate and used as a roll of thumb comparison. The Kobalt is 2250.

Oh wow! That's a big plus for the Kobalt. Thank you for sharing that formula. Tbh, I had never heard of it. I just used that formula on one of the CAT 10 Gallon air compressors and it was only 250 gallon-psi of air. So that leads me to my next question. What is gallon-psi of air exactly? In other words, what does that number mean?

Edit: Forgot to ask... If I do go with the Kobalt compressor, will I be able to get the full 1000 ft. lbs of torque from the Kobalt impact wrench which is rated at 6 CFM @ 90 psi?

 

[FA7X]

Edit: Forgot to ask... If I do go with the Kobalt compressor, will I be able to get the full 1000 ft. lbs of torque from the Kobalt impact wrench which is rated at 6 CFM @ 90 psi?

Yes, because the impact doesn’t run continuously for the 5 minutes it would take to drain the tank far enough for the motor to start.

The continuous cfm is with the compressor running, and keeping the pressure above 90 without draining the tank. I wasn’t clear about cfm when I bought it, but I get it now. It runs my 6cfm Aircat like it was nothing.



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[51willys]

I went with the north star. Northern brand. It has a 4 year warranty when most compressors are generally two. You can usually find a discount code too if you look around.

My 60 gallon single stage is 11.3cfm@90. I enjoy it. I haven’t needed more air yet. I use it for personal automotive projects

 

[Citation]

Oh wow! That's a big plus for the Kobalt. Thank you for sharing that formula. Tbh, I had never heard of it. I just used that formula on one of the CAT 10 Gallon air compressors and it was only 250 gallon-psi of air. So that leads me to my next question. What is gallon-psi of air exactly? In other words, what does that number mean?

Edit: Forgot to ask... If I do go with the Kobalt compressor, will I be able to get the full 1000 ft. lbs of torque from the Kobalt impact wrench which is rated at 6 CFM @ 90 psi?

Do keep in mind that rule of thumb is far from perfect. In the real world, when thermodynamics are considered, you have more actually stored energy in a 1000 gallon tank at 101 psi vs a 1 gallon tank at 1100 psi.

Also, at some point it's the pump vs the tank that matters. Recently I was excited to have a chance to use my compressor again. I just got the wiring in my garage fixed so I trusted it with a 15A load and I got the compressor back from a friend who had been holding it as I was moving. I had tried to run my cutoff wheel with my 4 gallon compressor. No go. The 4 gallon tank was exhausted almost by the time I was starting my cut. An 8 gallon compressor (just under 4 CFM @90) was just enough to make some progress before I had to wait for the pump to refill the tank. So my compressor did much better. However, it's still limited. Recently I was cutting up an old child's bed frame so I could put it in the regular trash. This was basically 1" per side L bracket, a bit over 1/16" thick. My tank would be about 600 using my metric. Cutting a single leg was enough to use up my air reserve. After that the pump wasn't able to keep up. The compressors you are looking at have more tank but no more pump. In my case I would have made it through another leg before I had to wait for the pump but in the end they all would be waiting for the pump.

What's the point? Well you are probably going to be in the same boat I'm typically in. Most of the time I have more than enough tank or I have to rely on the pump. I don't think there are many times when a 30 gallon at 150 psi meant no interruption while 20 gallons at 130 forced me to slow down.

One plus for a smaller tank with higher pressure is you get up to operating pressure faster. I like that my 4 gallon compressor went from empty to full in less than a minute and a half. That 15 gallon Dewalt will get to a useful 90 psi twice as fast as a 30 gallon compressor with a similar flow rate. Of course if you don't have leaks this isn't an issue.

This is the Dewalt I was thinking of
https://www.amazon.com/dp/B000HZI6F4/?tag=atomicindus08-20

Anyway, I think that Kobalt is probably still as good as it gets other than noise, size and cost. But I figured it was worth pontificating just in case.

 

[alex123]

Yes, because the impact doesn’t run continuously for the 5 minutes it would take to drain the tank far enough for the motor to start.

The continuous cfm is with the compressor running, and keeping the pressure above 90 without draining the tank. I wasn’t clear about cfm when I bought it, but I get it now. It runs my 6cfm Aircat like it was nothing.



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Thank you for the info. Can you please tell me how you got the 5 minutes you mentioned in your answer? Is there a formula/calculation to determine that kind of thing?

Thank you in advance.

 

[alex123]

I went with the north star. Northern brand. It has a 4 year warranty when most compressors are generally two. You can usually find a discount code too if you look around.

My 60 gallon single stage is 11.3cfm@90. I enjoy it. I haven’t needed more air yet. I use it for personal automotive projects

I wish 60 gallon was an option for me. It's really the 220V that's become a hurdle. Plus, it would be a major pain to move it around every time I move to a new place, which I do frequently.

 

[alex123]

Do keep in mind that rule of thumb is far from perfect. In the real world, when thermodynamics are considered, you have more actually stored energy in a 1000 gallon tank at 101 psi vs a 1 gallon tank at 1100 psi.

Also, at some point it's the pump vs the tank that matters. Recently I was excited to have a chance to use my compressor again. I just got the wiring in my garage fixed so I trusted it with a 15A load and I got the compressor back from a friend who had been holding it as I was moving. I had tried to run my cutoff wheel with my 4 gallon compressor. No go. The 4 gallon tank was exhausted almost by the time I was starting my cut. An 8 gallon compressor (just under 4 CFM @90) was just enough to make some progress before I had to wait for the pump to refill the tank. So my compressor did much better. However, it's still limited. Recently I was cutting up an old child's bed frame so I could put it in the regular trash. This was basically 1" per side L bracket, a bit over 1/16" thick. My tank would be about 600 using my metric. Cutting a single leg was enough to use up my air reserve. After that the pump wasn't able to keep up. The compressors you are looking at have more tank but no more pump. In my case I would have made it through another leg before I had to wait for the pump but in the end they all would be waiting for the pump.

What's the point? Well you are probably going to be in the same boat I'm typically in. Most of the time I have more than enough tank or I have to rely on the pump. I don't think there are many times when a 30 gallon at 150 psi meant no interruption while 20 gallons at 130 forced me to slow down.

One plus for a smaller tank with higher pressure is you get up to operating pressure faster. I like that my 4 gallon compressor went from empty to full in less than a minute and a half. That 15 gallon Dewalt will get to a useful 90 psi twice as fast as a 30 gallon compressor with a similar flow rate. Of course if you don't have leaks this isn't an issue.

This is the Dewalt I was thinking of
https://www.amazon.com/dp/B000HZI6F4/?tag=atomicindus08-20

Anyway, I think that Kobalt is probably still as good as it gets other than noise, size and cost. But I figured it was worth pontificating just in case.

I want to make sure I've correctly understood what you've said. Basically your 8 gallon compressor did the job because it has more stored air right? So in other words, if I get the 30 Gallon Kobalt, I should be able to get longer run times for the tools (compared to a smaller tank) before the pump kicks in?? If this is the case, I'm assuming the only drawback would be longer wait times for that pump to fill as compared to a smaller one?

Please feel free to correct me if I've missed the train on this one.

 

[Citation]

I want to make sure I've correctly understood what you've said. Basically your 8 gallon compressor did the job because it has more stored air right? So in other words, if I get the 30 Gallon Kobalt, I should be able to get longer run times for the tools (compared to a smaller tank) before the pump kicks in?? If this is the case, I'm assuming the only drawback would be longer wait times for that pump to fill as compared to a smaller one?

Please feel free to correct me if I've missed the train on this one.

Different jobs. In one case (4 vs 8 gallon) I was trying to cut through a thin walled 1/2 conduit. I couldn't even complete a single cut without waiting for the compressor to refill. That run time included holding the wheel near the cut (I can't start with the wheel actually in the cut) aligning then proceeding to cut. With my 4 gallon compressor I used most of the available air before I could make any headway on the actual cut. With the 8 gallon I had just enough to make some headway before the compressor ran low.

So that was a case where the difference in tank capacity was critical to being able to make a cut.

With my bigger compressor things are a bit different. The 1/2 conduit would be well within what the larger compressor could do given more than double the tank and a pump that can at least come close to keeping up. But it still can't keep up. The job were I was cutting be bed frame was just a lot more cutting (and my cutting disc was worn to the point that the smaller diameter was making the cuts slower). Anyway, in that case even if I had a 60 or 80 gallon tank I would have likely run the tank down.

Think of it this way, in my case I needed to use some air to start the wheel and move into my previous cut all before I was doing any productive work. With the 4 gallon tank I didn't have enough air to effectively do this and thus it was really difficult to cut the tubes. I had (based on vague recall) perhaps 8 seconds of useful run time before the pressure was too low and I had to wait for the pump. I would spend about 6 seconds getting back into the cut so I got perhaps 2 seconds of cutting for each 20 seconds of pump refreshing. With the 8 gallon I had double the run time but it still took only 6 seconds to restart and thus I got 10 seconds of actual cutting before I had to wait twice as long to refill. Well, 10 seconds is 5x as much useful cutting. were wasted just getting ready to restart the cut). It was still frustrating to have only 10 seconds before the compressor needed to refill but that was enough to make the work practical.

When I was cutting the bed frame I had over 5 times the useful tank reserve as with my 4 gallon. So even if it took the same 6 seconds to get things lined up I had 40 seconds of run time before I ran out of air. So I would have had no issues with the 1/2 conduit. But with the bed frame I was cutting the frame as well as many of the springs. It just made for quite a bit more cutting (but with far less precision). Thus I far exceeded tank reserve. I think I stopped three or more times to let the tank fully refill. The Kobalt probably would have required only one recycle vs the ~3 I did. However, it thanks to the higher pressure, larger tank and slightly lower flow rate I would expect that refill to take ~2-3 minutes (not sure what the cut in pressure is) vs ~1.

BTW, if you haven't already left... here is another you might consider.
https://www.homedepot.com/p/Husky-3...table-Electric-Air-Compressor-C303H/206532808
At $300 it's a good bit cheaper. At 78db it claims to be quieter than the Kobalt (87). The rest of the performance specs seem to be the same (flow rate, tank size/pressure). It uses a universal motor and an oil free pump so probably would wear out faster but faster might be 20 years and replacement parts are available.
https://www.ereplacementparts.com/h...-compressor-parts-c-508437_508442_508790.html

Sorry about the book, other than having to move it, I still think the Kobalt is generally the best (and the most expensive).

 

[alex123]

Different jobs. In one case (4 vs 8 gallon) I was trying to cut through a thin walled 1/2 conduit. I couldn't even complete a single cut without waiting for the compressor to refill. That run time included holding the wheel near the cut (I can't start with the wheel actually in the cut) aligning then proceeding to cut. With my 4 gallon compressor I used most of the available air before I could make any headway on the actual cut. With the 8 gallon I had just enough to make some headway before the compressor ran low.

So that was a case where the difference in tank capacity was critical to being able to make a cut.

With my bigger compressor things are a bit different. The 1/2 conduit would be well within what the larger compressor could do given more than double the tank and a pump that can at least come close to keeping up. But it still can't keep up. The job were I was cutting be bed frame was just a lot more cutting (and my cutting disc was worn to the point that the smaller diameter was making the cuts slower). Anyway, in that case even if I had a 60 or 80 gallon tank I would have likely run the tank down.

Think of it this way, in my case I needed to use some air to start the wheel and move into my previous cut all before I was doing any productive work. With the 4 gallon tank I didn't have enough air to effectively do this and thus it was really difficult to cut the tubes. I had (based on vague recall) perhaps 8 seconds of useful run time before the pressure was too low and I had to wait for the pump. I would spend about 6 seconds getting back into the cut so I got perhaps 2 seconds of cutting for each 20 seconds of pump refreshing. With the 8 gallon I had double the run time but it still took only 6 seconds to restart and thus I got 10 seconds of actual cutting before I had to wait twice as long to refill. Well, 10 seconds is 5x as much useful cutting. were wasted just getting ready to restart the cut). It was still frustrating to have only 10 seconds before the compressor needed to refill but that was enough to make the work practical.

When I was cutting the bed frame I had over 5 times the useful tank reserve as with my 4 gallon. So even if it took the same 6 seconds to get things lined up I had 40 seconds of run time before I ran out of air. So I would have had no issues with the 1/2 conduit. But with the bed frame I was cutting the frame as well as many of the springs. It just made for quite a bit more cutting (but with far less precision). Thus I far exceeded tank reserve. I think I stopped three or more times to let the tank fully refill. The Kobalt probably would have required only one recycle vs the ~3 I did. However, it thanks to the higher pressure, larger tank and slightly lower flow rate I would expect that refill to take ~2-3 minutes (not sure what the cut in pressure is) vs ~1.

BTW, if you haven't already left... here is another you might consider.
https://www.homedepot.com/p/Husky-3...table-Electric-Air-Compressor-C303H/206532808
At $300 it's a good bit cheaper. At 78db it claims to be quieter than the Kobalt (87). The rest of the performance specs seem to be the same (flow rate, tank size/pressure). It uses a universal motor and an oil free pump so probably would wear out faster but faster might be 20 years and replacement parts are available.
https://www.ereplacementparts.com/h...-compressor-parts-c-508437_508442_508790.html

Sorry about the book, other than having to move it, I still think the Kobalt is generally the best (and the most expensive).

On the 8 gallon tank you were getting 10 seconds of run time for the cutoff tool? How long of a run time do you think the Kobalt will yield?
I want to be able to run my tools for at least a few minutes at a time without worrying about the compressor kicking in. Have I completely misunderstood the capabilities of a 30 gallon compressor? Maybe I need to go to corded tools?

 

[theoldwizard1]

Are you ever left in a situation where you're sitting and waiting for the compressor to catch up? I'm just on the fence about this whole thing. Here's where I'm a little confused. My current situation won't allow me to go with a large (60+ gallon) compressor ...

Tanks size has very little to do with volume or pressure, except for pneumatic tools that consume air in bursts (impact, hammer/chisel/riveter).

With only 120V, you really will NOT be able to run any "continuous" tools (sanders, die grinders, blasters, cut off wheel) except in bursts. Even my 2hp, 2 piston, oil lubed, 240V compressor can not keep up with my die grinder for more than about 3 minutes. Higher max pressure (150 psi vs 120 psi) and a larger tank, for the same size motor and pump just delay the time before you run out of air. And you have a longer recovery time.

Best alternative is a 2 hp (1 hp continuous) CAT compressor to start with. It will run most impacts and hammers. Add a (used) 60 gallon tank and you can get some usable run time on a die grinder (with a wait). Someday, you can put a 5hp, twin cylinder, oil lubed compressor on top.

Battery operated tools are great, if you buy good ones. Many to choose from, but I still have not seen a battery operated air hammer replacement.

 

[Dogbone]

good info here!

 

[Citation]

On the 8 gallon tank you were getting 10 seconds of run time for the cutoff tool? How long of a run time do you think the Kobalt will yield?
I want to be able to run my tools for at least a few minutes at a time without worrying about the compressor kicking in. Have I completely misunderstood the capabilities of a 30 gallon compressor? Maybe I need to go to corded tools?

If I have time I'll try to see how long it takes my cheap cutoff wheel to run my 4 gallon compressor from about 125 psi to 90 (tank pressure).

Also, remember what i was saying about run time. I was assuming about 8 seconds of total run time from a 4 gallon tank but I was using perhaps 6 seconds between pulling the trigger and actually continuing my cut (I had to put the blade back into the unfinished cut without cutting the rest of the tube).

 

[Citation]

Ok, my memory was kind of wrong. I was right to recall only 2 seconds of cutting time before the pump kicked in with the 4 gallon compressor... but that was after just 1 second to start the cut. The 4 gallon compressor have me only 3 seconds before the pump started. The 20 gallon gave me more like 12 before the pump turned on (note the cut in/out pressures aren't there same and neither are the flow restrictions. But this gives you an idea just how fast a cutoff wheel can **** down air.

 

[md21722]

Impacts typically are used in burst so you can get away with a smaller tank for something like buzzing off wheels where its only run for a few seconds at a time. If you are really working it on a rusted fastener you are going to wait or need a bigger compressor/ tank. A 1/2" impact will use about 25 CFM (7.5 HP compressor) in continuous operation. On a 30 gallon tank you can probably get 2 wheels off before it kicks on.

Air hammers typically use about 10-15 CFM continuously. But again, if you are just knocking something loose for a couple seconds, a smaller compressor will work. If you need to run it for any length of time, you need a bigger compressor/ tank or you will wait.

Die grinders are typically air pigs and will run anywhere from 12-25 CFM, with higher being more normal. Since they are typically used or longer periods of time, this should be considered the biggest user of air in the shop. Budget a full 5-7.5 HP compressor with a 80 gallon tank to use one without hating life.

Most people who use air seriously on this forum stop around 7.5 HP and 80 gallon tank.

Pancake or hotdog compressors are for people using nailers. A 1.5-2 HP 30 gallon is OK for a home guy who is mostly using an impact for tires.

As an example, I borrowed my neighbors pancake compressor& impact to pull carrier bearings. This requires a LOT of air because the impact runs a long time. It took 20 minutes with my neighbors compressor/impact. When I got my own, 2HP 26 gallon tank, it took about 2 minutes. Now I have 7.5HP on 240 gallons and I do it in seconds...

 

[alex123]

Tanks size has very little to do with volume or pressure, except for pneumatic tools that consume air in bursts (impact, hammer/chisel/riveter).

With only 120V, you really will NOT be able to run any "continuous" tools (sanders, die grinders, blasters, cut off wheel) except in bursts. Even my 2hp, 2 piston, oil lubed, 240V compressor can not keep up with my die grinder for more than about 3 minutes. Higher max pressure (150 psi vs 120 psi) and a larger tank, for the same size motor and pump just delay the time before you run out of air. And you have a longer recovery time.

Best alternative is a 2 hp (1 hp continuous) CAT compressor to start with. It will run most impacts and hammers. Add a (used) 60 gallon tank and you can get some usable run time on a die grinder (with a wait). Someday, you can put a 5hp, twin cylinder, oil lubed compressor on top.

Battery operated tools are great, if you buy good ones. Many to choose from, but I still have not seen a battery operated air hammer replacement.

Thanks for the great info! So to summarize, higher PSI and larger tank = longer run time AND longer recovery time?

So if I won't be able to continuously run any of my tools, why would I want to go with a 30 Gallon compressor? I mean... for automotive work would I be able to get away with using the CAT 10020C? It's a 10 gallon compressor. What difference will I notice by going with a 10 gallon vs 30 gallon? The only tools I plan on using are the following: impact wrench, air ratchet, air saw, air hammer, cut off tool, and air scraper.

Edit: Looking at the 15020C... not the 10020C (ie: 15 gallon, not 10 gallon)

 

[alex123]

good info here!

agreed!

 

[alex123]

Ok, my memory was kind of wrong. I was right to recall only 2 seconds of cutting time before the pump kicked in with the 4 gallon compressor... but that was after just 1 second to start the cut. The 4 gallon compressor have me only 3 seconds before the pump started. The 20 gallon gave me more like 12 before the pump turned on (note the cut in/out pressures aren't there same and neither are the flow restrictions. But this gives you an idea just how fast a cutoff wheel can **** down air.

When the pumped kicked on, were you able to still continue your cutting? Or was it a waiting game at that point? In other words, were you cutting 12 seconds.... waiting... cutting 12 seconds.... waiting..etc... ?

Also, can you please provide me your input on the CAT 10020C. How does this compare to the Kobalt (besides the obvious that it's much quieter). How will this work with air impacts, ratchets, cut off tool, and air hammers?

Edit: Looking at the 15020C... not the 10020C (ie: 15 gallon, not 10 gallon)

 

[alex123]

Impacts typically are used in burst so you can get away with a smaller tank for something like buzzing off wheels where its only run for a few seconds at a time. If you are really working it on a rusted fastener you are going to wait or need a bigger compressor/ tank. A 1/2" impact will use about 25 CFM (7.5 HP compressor) in continuous operation. On a 30 gallon tank you can probably get 2 wheels off before it kicks on.

Air hammers typically use about 10-15 CFM continuously. But again, if you are just knocking something loose for a couple seconds, a smaller compressor will work. If you need to run it for any length of time, you need a bigger compressor/ tank or you will wait.

Die grinders are typically air pigs and will run anywhere from 12-25 CFM, with higher being more normal. Since they are typically used or longer periods of time, this should be considered the biggest user of air in the shop. Budget a full 5-7.5 HP compressor with a 80 gallon tank to use one without hating life.

Most people who use air seriously on this forum stop around 7.5 HP and 80 gallon tank.

Pancake or hotdog compressors are for people using nailers. A 1.5-2 HP 30 gallon is OK for a home guy who is mostly using an impact for tires.

As an example, I borrowed my neighbors pancake compressor& impact to pull carrier bearings. This requires a LOT of air because the impact runs a long time. It took 20 minutes with my neighbors compressor/impact. When I got my own, 2HP 26 gallon tank, it took about 2 minutes. Now I have 7.5HP on 240 gallons and I do it in seconds...

Wow! From 20 minutes down to seconds! That's seriously impressive. My use of air tools will be solely for automotive work. In order of most use, I would be using impact wrench, air ratchet, air saw, cut off tool, and air hammer.

If the cut off tool is that much of a air hog, that's fine... I can just by a cordless or corded for that... but what about the rest of the tools I mentioned... would a 10 gallon work? I'm considering the CAT 10020C.

Edit: Looking at the 15020C... not the 10020C (ie: 15 gallon, not 10 gallon)

 

[wildbill23c]

I have a 30+ year old Montgomery Wards 11 gallon 1HP belt driven air compressor, still works but the tank has a hole in it so I quit using it a few years ago and bought the 2HP 29 Gallon Harbor Freight belt driven air compressor. Its still somewhat loud, but not nearly as loud as those oil-less/direct drive compressors.

My belt driven air compressor will start up when its cold, typically those direct drive and oil-less models will not, so if the compressor isn't kept warm a direct drive or oil-less model wouldn't work, and you'll quickly hate the noise from them.

There are extremely quiet air compressors out there which I think are called screw drive compressors, they're extremely expensive and quite heavy, typically a 220V connection is required as well since they're more suited for commercial duty applications than for at your house.

I have no complaints about my HF compressor, I don't use it all day every day either. It takes about 8 minutes to fill the tank from empty, but it will cycle in 2-3 minute intervals after it has filled up, but that will depend on demand as well...if you are using a high CFM tool, the compressor can/will run continuously and often times won't provide the proper CFM. I haven't had this issue as I don't run my air tools continuously anyhow, usually in short burts. Now if you are trying to run grinders, sanders, and those types of continual duty tools you'll certainly need a larger compressor but the HF 29 gallon unit seems to handle all my stuff just fine from airing up tires, to doing some occasional automotive repairs with air impacts and air ratchets. I also have a 3 gallon HF air compressor, that thing works fine for air tools like finish nailers and brad nailers but don't expect something like that to work for high demand tools like the impact guns and ratchets LOL.

The pump on the belt drive HF compressor is cast iron, and it is oil lubed so if you take care of them they'll last a long long time. I change oil in mine once a year, and I always drain the air out of the tank when I am done using it. The only minor complaint I have is the location of the oil drain hole leaves you cleaning up a mess as it drains right down the side of the tank...I need to see if I can figure out a way to thread a piece of pipe into the drain hole and extend that out for easier oil changes.

 

[DGersic]

Thanks for the great info! So to summarize, higher PSI and larger tank = longer run time AND longer recovery time?

So if I won't be able to continuously run any of my tools, why would I want to go with a 30 Gallon compressor? I mean... for automotive work would I be able to get away with using the CAT 10020C? It's a 10 gallon compressor. What difference will I notice by going with a 10 gallon vs 30 gallon? The only tools I plan on using are the following: impact wrench, air ratchet, air saw, air hammer, cut off tool, and air scraper.

Edit: Looking at the 15020C... not the 10020C (ie: 15 gallon, not 10 gallon)

Have you used any of these tools before?

With smaller air capacity, restricted by your tank size and power (110V), you can run any of these tools, but you will sometimes have to back off while the compressor does it’s thing. But unless you’re making a 200’ cut with that cutoff tool, you’re going to be stopping to change positions, move the work, or put a new disk on.

You’re not running a shop, so a little bit of time saved by having a monster compressor isn’t that big a deal. Your priorities are size, and quiet operation. Then again, have you run these tools? Impacts and cutoffs aren’t quiet tools.





Sent from my iPad using The Garage Journal mobile app

 

[alex123]

I have a 30+ year old Montgomery Wards 11 gallon 1HP belt driven air compressor, still works but the tank has a hole in it so I quit using it a few years ago and bought the 2HP 29 Gallon Harbor Freight belt driven air compressor. Its still somewhat loud, but not nearly as loud as those oil-less/direct drive compressors.

My belt driven air compressor will start up when its cold, typically those direct drive and oil-less models will not, so if the compressor isn't kept warm a direct drive or oil-less model wouldn't work, and you'll quickly hate the noise from them.

There are extremely quiet air compressors out there which I think are called screw drive compressors, they're extremely expensive and quite heavy, typically a 220V connection is required as well since they're more suited for commercial duty applications than for at your house.

I have no complaints about my HF compressor, I don't use it all day every day either. It takes about 8 minutes to fill the tank from empty, but it will cycle in 2-3 minute intervals after it has filled up, but that will depend on demand as well...if you are using a high CFM tool, the compressor can/will run continuously and often times won't provide the proper CFM. I haven't had this issue as I don't run my air tools continuously anyhow, usually in short burts. Now if you are trying to run grinders, sanders, and those types of continual duty tools you'll certainly need a larger compressor but the HF 29 gallon unit seems to handle all my stuff just fine from airing up tires, to doing some occasional automotive repairs with air impacts and air ratchets. I also have a 3 gallon HF air compressor, that thing works fine for air tools like finish nailers and brad nailers but don't expect something like that to work for high demand tools like the impact guns and ratchets LOL.

The pump on the belt drive HF compressor is cast iron, and it is oil lubed so if you take care of them they'll last a long long time. I change oil in mine once a year, and I always drain the air out of the tank when I am done using it. The only minor complaint I have is the location of the oil drain hole leaves you cleaning up a mess as it drains right down the side of the tank...I need to see if I can figure out a way to thread a piece of pipe into the drain hole and extend that out for easier oil changes.

Thank you for sharing that your experience with the HF 30 Gallon. Yes, those things are notorious for their oil drain plug location. I've heard that they are pretty good little units. @5.9 CFM , it's not bad at just shy of $387. That unit was actually what I wanted to go with, but have since come to realize that the noise level may be an issue given my current situation. Still though, great price for a 30 gallon compressor if you ask me.

 

[alex123]

Have you used any of these tools before?

With smaller air capacity, restricted by your tank size and power (110V), you can run any of these tools, but you will sometimes have to back off while the compressor does it’s thing. But unless you’re making a 200’ cut with that cutoff tool, you’re going to be stopping to change positions, move the work, or put a new disk on.

You’re not running a shop, so a little bit of time saved by having a monster compressor isn’t that big a deal. Your priorities are size, and quiet operation. Then again, have you run these tools? Impacts and cutoffs aren’t quiet tools.





Sent from my iPad using The Garage Journal mobile app

Yes, I have used these tools. Running a cutoff tool for a minute, or a impact wrench in bursts is not really an issue. What is an issue, however, is that some of these 30 gallon compressors can take 8-9 minutes to fill up with air (so I've heard), and then add the refill times on top of that.... That's where my neighbors will cause a stink about it.. unfortunately.
So you're saying I shouldn't have issues with those tools with say a 15 gallon compressor?

 

[bsaint]

All you need is a 1.5hp (make sure its like 17 amps at 115v) 60 gallon compressor. Best home owner setup for someone who uses tools. And a solberg inlet filter housing. Look for a Jenny.

 

[Citation]

When the pumped kicked on, were you able to still continue your cutting? Or was it a waiting game at that point? In other words, were you cutting 12 seconds.... waiting... cutting 12 seconds.... waiting..etc... ?

Also, can you please provide me your input on the CAT 10020C. How does this compare to the Kobalt (besides the obvious that it's much quieter). How will this work with air impacts, ratchets, cut off tool, and air hammers?

Edit: Looking at the 15020C... not the 10020C (ie: 15 gallon, not 10 gallon)

So I did that test by connecting the cutoff tool right to the compressor. It was cold in the garage and I didn't feel like pulling out a 50ft hose to do the test.

The 4 gallon compressor, per it's gauge said it was starting at just under 120psi (I should check that since it should fill to a bit higher) then kicked in at just under 90. I'm sure I could keep cutting at less than 90 but consider it was dropping about 10 psi/second. It wasn't going to run much longer. The big compressor fills to 135 on the gauge and kicks in at around 100 so the PSI drop is similar to the smaller one. At 100 psi the tank pressure is still higher than the tool's operating pressure thus no loss in performance.

I can't offer any insight into the CAT 15020 (or the Kobalt low noise 26 gallon that might be a better deal) or the Kobalt 2 stage beyond playing specs games. No doubt the 30 gallon Kobalt gives you a lot more tank and about 25% more pump. That's not insignificant on paper. I'm not sure how much it will come into real world play. Basically never for an impact. It could matter if you use a blow gun a lot.

OK, when I was helping my dad and brother out with some rebuilt compressors I created an Excel table to calculate fill times just to make sure the compressors were ball park hitting their specs. So as part of this discussion I found the video below.

The spreadsheet predicted 9:22 to fill from empty. He said it took 9:18. I had a private moment of pride

OK, so I used the same calculation to guess how much air my cutoff wheel used and how fast it would drain a compressor. An estimate of 25CFM seems right give how long it took to drain my small and large compressor. So ignoring the pump turning on, it would take about 20 seconds for the cutoff wheel to take my 20 gallon compressor from 135 psi to 90. The same calculation says the big Kobalt would take 56 second from 175psi to 90. Well, that would give you some pretty reasonable cutting time and honestly, since the pump would kick in at, probably 135 psi) you would probably get just over a minute of run time. It would then take about 4:30 to refill the tank to 175 psi. So yeah, that is a useful increase in run time before waiting vs my 20 gallon compressor. Of course, my 20 gallon with a lower peak pressure will refresh in 1:30. BTW, that semi-quiet Husky would, based on specs, match the two stake Kobalt.

So let's run that same calculation with the 15 gallon CAT and 26 gallon silent Kobalt.
CAT 1520: 150psi down to 90, 15 gallon tank, 25 cfm cutoff tool: 20 seconds, refill: 1:31, $410 (all but matches my 20 gallon compressor)
Kobalt 26gal quiet: 150psi down to 90, 26 gallon tank, 25 cfm cutoff tool: 34 seconds, refill: 3:10 $300

and the others:
Kobalt 30 gal 2 stage: 175psi down to 90, 30 gallon tank, 25 cfm cutoff tool: 56 seconds, refill: 4:33 $470
Husky 30 gal semi-quiet: 175psi down to 90, 30 gallon tank, 25 cfm cutoff tool: 56 seconds, refill: 4:33 $310
Dewalt 15gal:225 to 90, 15 gal, 25cfm tool: 44 sec, 3:30 refill, $410

Well, as much as I would like to have more shop projects these days I don't. I'm not going to wear out my compressor that fast so the universal motors (Husky and DeWalt) and oil free pumps (all but the 2 stage Kobalt) aren't drawbacks to me. Also, for the over $100 savings if I went with the 26gal or Husky would be more than enough to pay for a set of brushes and pump rebuild. If I were moving a lot the smaller size/weight of those designs would matter.

Of the lot I would probably pick the Husky because it's not too loud and noise isn't critical to me. If noise was critical I would probably pick the 26 gal because the performance hit isn't too bad vs the CAT and the cost savings is big.

Sorry, yet another long, rambling post.

 

[Citation]

I have a 30+ year old Montgomery Wards 11 gallon 1HP belt driven air compressor, still works but the tank has a hole in it so I quit using it a few years ago and bought the 2HP 29 Gallon Harbor Freight belt driven air compressor. Its still somewhat loud, but not nearly as loud as those oil-less/direct drive compressors.

My belt driven air compressor will start up when its cold, typically those direct drive and oil-less models will not, so if the compressor isn't kept warm a direct drive or oil-less model wouldn't work, and you'll quickly hate the noise from them.

Personal experience:
Oil free don't care about cold.
Oil-direct drive: Emglo 4 gallon doesn't like cold starts and will trip it's breaker when starting cold. Not all direct drive oil compressors are as touchy.
My belt drive compressor seems to not mind starting in the cold.

Older oil free compressors were louder than the belt drive oiled compressors. It doesn't seem like this holds as true with newer models. For example in my above post the belt drive Kobalt was (pre specs) louder than the oil free Husky (which is internally a belt drive). The CAT, a direct drive (but low RPM) oil free was the quietest of the bunch.

 

[DGersic]

Yes, I have used these tools. Running a cutoff tool for a minute, or a impact wrench in bursts is not really an issue. What is an issue, however, is that some of these 30 gallon compressors can take 8-9 minutes to fill up with air (so I've heard), and then add the refill times on top of that.... That's where my neighbors will cause a stink about it.. unfortunately.

So you're saying I shouldn't have issues with those tools with say a 15 gallon compressor?

Remember that fill from empty time is a lot longer than recovery from 100 psi to 120 psi because you hit the impact gun trigger a few times.

I’d say go for as big as you can, but realize that they’re all noisy, as are the tools. If noise is a problem, 15, 30, 60 gallon won’t matter that much.




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[alex123]

All you need is a 1.5hp (make sure its like 17 amps at 115v) 60 gallon compressor. Best home owner setup for someone who uses tools. And a solberg inlet filter housing. Look for a Jenny.

Won't that setup take forever to fill the tank?

 

[alex123]

Remember that fill from empty time is a lot longer than recovery from 100 psi to 120 psi because you hit the impact gun trigger a few times.

I’d say go for as big as you can, but realize that they’re all noisy, as are the tools. If noise is a problem, 15, 30, 60 gallon won’t matter that much.




Sent from my iPad using The Garage Journal mobile app

Good point!