Air compressor modification help?

I have a 5gal California air compressor that's fairly new and it's not in my budget to replace it at this time. It works great and is nice and quiet in my basement shop. Primarily use it for blowing out the build up in small hollow forms, finish nailers, etc. But I want to be able to use the small Grex random orbit 3" sander or the new random orbit offered by Woodturning wonders. Of course my compressor doesn't have the air capacity.

the compressor is rated as5.5 Gallon Steel Tank - 3.10 CFM @ 40 PSI 2.20 CFM @ 90 PS. The Grex is rated operating Pressure 90 psi and air consumption 8 SCFM

The pnuematic random orbit sander from Woodturning Wonders per their website is rated at "Minimum requirements for air is 90 PSI and 3 CFMs" Is their a simple and somewhat inexpensive way to add an auxiliary tank inline with my air compressor to increase capacity to the necessary requirement of the aid sanders? I still have the 30y/o old 4-gallon twin tank contractor compressor that the Cal Air unit replaced if that can be used (but I'm assuming I would need more than that extra 4gal capacity) Any ideas, tutorial links or video links for doing something like this? Thanks Ricc

Having a larger tank doesn't add pressure or flow capabilities. It only adds delay before the compressor tries to keep up or catch up. Air is a compressible fluid. When it 'un-compresses', pumps (compressors) go to work.

Get yourself one of these Neiko close quarter drills and forget using your compressor for this, it hasn’t got the capacity to run the sander/drill, about $40-- on eBay

Attachment 408824

Once the air in both tanks is drained and the compressor is running flat out you will have to stop and wait longer until the air is built up again in both tanks. The second tank will do little good unless you are using the sander for only a couple minutes total. If you want to use air tools you'll just have to get a compressor with a higher rating than the largest air tool you have.

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Originally Posted by Leo Van Der Loo

Get yourself one of these Neiko close quarter drills and forget using your compressor for this, it hasn’t got the capacity to run the sander/drill, about $40-- on eBay

Attachment 408824

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Thanks guys.

Leo, I have used those drills off ebay and look-a-likes from other suppliers like Amazon, etc. They never seem to last long and heavier than the air units I was hoping to be able to use.


T

Listen to Leo. The electric is not as loud, and you are not running a 2HP or larger air compressor to feed the pneumatic sander.

Ricc
What is the capacity of the 30 year old compressor. You could parallel both of the compressors and have additive airflow, but it would still be very short lived even at that. Once both compressors cycle a few times, you're going to have saturated air at the sander, which isn't a good place to be for the sander internals. I don;t think you would be happy, even with both compressors paralleled.
One other consideration is understanding how Grex arrived at 8CFM. Many manufacturers have an assumed "duty cycle" for a tool, on/off periods, and average out the CFM based on this duty cycle. I would be very shocked to see a sander consume only 8CFM continuously. I have a 17cfm 5HP compressor and it can't keep up with sanders, or die grinders, on a continuous basis. Sanders are air hogs.
I personally think you're asking too much of your compressor(s) to run a sander on anything other than a very light duty cycle. Even at that, you'll need to wait for the receiver tank to condense between cycles, or as I pointed out earlier, you'l have saturated air at the sander.
If you read through the threads here on the forum concerning sanders, and air compressors, you'll see that a good many people have moved away from air, and invested in either corded electric, or battery powered, sanders, and away from pnuematics.
I know that this isn't the answer you're looking for.

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Originally Posted by Ricc Havens

...I have used those drills off ebay and look-a-likes from other suppliers like Amazon, etc. They never seem to last long and heavier than the air units I was hoping to be able to use.

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I have the Milwaulkee close-quarters drill and quit using it for woodturning years ago (and save it for drilling -- in tight places!) I use two pneumatic random orbital sanders, the Grex with 2" or 1" disks and one from Woodturners Wonders with a 3" disk. The surface I get from the ROS is far better than the rotary drill. Both are much lighter in weight and in my experience are easier to handle and far easier to control than the electric drills.

Of course, like many things in turning a lot depends on how you work. I think one value of the rotary drill is if the turning needs a lot of sanding you can use coarse paper and take it down quickly (at the expense of a lot of dust and the other problems with coarse rotating sanding disks). The ROS can be much gentler and produces much less dust when run at low speeds. Note that I remove tool marks with hand scrapers so not much sanding is needed and can usually start with 400 grit, sometimes as coarse as 220. I do all such sanding with the piece stationary or turned by hand, usually off the lathe.

If you want to run the ROS wide open you will in fact need a more powerful compressor - an extra tank doesn't help much. However I CAN use the small random orbital sanders at much less pressure and CFM than rated if I am running at slow, gentle speeds, my normal use. On the 2" Grex I have to hold the trigger down just part way for the slower speed. The 3" palm sander has an extra valve that limits the air and speed with even a full press of the palm trigger. Sorry, I don't remember the minimum pressure and CFM. I tested the sanders once on a small pancake compressor just to see if they would work. I don't remember the specs on the compressor but I could check and try it again if that might help.

I wish you lived closer - you could try both of these and see for yourself. I like the Grex so much I got a second one so I can keep 1" disks on a long shaft on one (for the bottoms of boxes and things) and 2" disks on the other.

In my opinion the 3" palm sander is the cat's meow for things like this:

Attachment 408886

I do have a large air compressor and use it so much in and around the shop that if I didn't I'd look for a used one if a new one wasn't in the budget.

Like all air tools, the pneumatic sanders do need a few drops of oil added to stay in good working condition. I know people who use the close quarter drills a lot and they report long life as long as they blow the dust out. Seems to me filtering the air vents would help.

JKJ

I had an underpowered air compressor and it just didn't cut it. Spraying lacquer,paint, or using my impact wrench was a pain. Bought a larger unit and added a hose reel (free from my son in law who's shop foreman at the Ford Dealer) and I'm spoiled at all I can do with it. Been trying to use my Makita random orbit sander, but it just spins with the lathe. I see a lot of YouTube turners use various drill mounted sanding pads, balls, etc. That might be the way to go.

Making some rolling pins I took some 80 grit sticky back sandpaper stuck to a flat board to make them straight.

The 55 degree angle drill from Woodturners Wonders is a better choice than the Neiko. It will last a lot longer as it is well made.

thanks guys for all the input. I was trying to get away from the heavier angle drills since they don't seem to last long and the weight sucks with my arthritis. Plus a bigger compressor isn't in my limited disability budget. But, looks like I don't have much choice but to stick with the drills.

Ricc I have the Milwaukee, it is exactly the same as the Neiko, and it did exactly the same thing these other makes do, the rear bearing rotated in the housing because of the saw dust that got into that bearing.

I took it apart and used epoxy to fix the housing, and then installed a sealed bearing, as the one that was in it was just a shielded bearing, I still have and use the drill and it works fine after all this time.

If I needed to get another Milwaukee or Neiko drill I would change that bearing first, the problem of these drills when used as sanders will then not happen, and it will last many years, as these are well made drills.

Like I said they are identical and made to be drills, not sanders, so that is where the problem lays, and it can be dealt with.

This is outside of my expertise, but given my interest in air compressors lately I'm under the impression that you can run two compressors at the same time (getting you the CFM you need) by putting check valves (one way valves) in the lines of each compressor.

A lot of the 'quiet' compressors run multiple small heads, sometimes as many as six and I believe this is one of the ways in which they accomplish that. I have a twin head compressor but mines uses a bleeder valve on a timer to get both compressors up and running without pressure in their lines (and probably a one way valve as well)

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Originally Posted by Brian Holcombe

This is outside of my expertise, but given my interest in air compressors lately I'm under the impression that you can run two compressors at the same time (getting you the CFM you need) by putting check valves (one way valves) in the lines of each compressor.

A lot of the 'quiet' compressors run multiple small heads, sometimes as many as six and I believe this is one of the ways in which they accomplish that. I have a twin head compressor but mines uses a bleeder valve on a timer to get both compressors up and running without pressure in their lines (and probably a one way valve as well)

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You mean something like this type ??, considering that the OP doesn’t have a budget for a larger compressor, one of these would be even more expensive than a larger regular compressor.

And yes you can use 2 or more compressors feeding into one tank to get more CFM, normal compressors do have valves to prevent the air to feed back through the compressor and also to take the pressure off of them for restarting without a load on it.

Attachment 408935

One other option to consider, if you really want a ROS action, you can get an electric ROS. Metabo makes the only one I am aware of that is small enough, 3 inch diam. It weighs about the same as the angle drills.

Also, if weight is a problem, try a regular electric drill. The shape is more amenable to using both hands to hold it. I had a Neiko angle drill that stopped working after about a year, and I decided to use my regular craftsman drill as I looked for replacement for the Neiko. Five years later, the craftsman is still running strong. And I can't remember a time when the drill couldn't reach a spot on the inside of a bowl.