Some background. I've always liked airguns having owned a few Crosman pumpers when I was a kid and upon adulthood I discovered the high powered spring guns. I quickly discover 3 things I didn't like about springers. 1, they are loud. 2, they move a lot when being fired. And 3, they weren't very accurate at distance, at least the ones I owned weren't. Then one day 8 or so years ago I discovered a type of air gun that I was unaware of until that point in time, the PCP.
I got into this PCP air-gunning sport perhaps like many of you, on the cheap. I ordered a Benjamin Discovery package which included a hand pump and began my long and expensive journey into the PCP world. I quickly discovered using a hand pump is a lot of work even when you're only pumping the gun to 2000 psi. After acquiring 2 Hatsan PCPs that required 2900 psi I decided the hand pumping thing wasn't for me. In hindsight maybe I should have stay with the hand pump and incorporated my shooting into a workout scheduled thereby enjoying the sport as well as losing some weight. Anyway, it was at that time, maybe 5-6 years ago, that I decided that getting my own high pressure air compressor made sense.
Back then I don't remember there being all that many options regarding affordable 4500 psi high pressure compressors, China hadn't yet started to make them back then. There were dive compressors that cost $3000+, and there was the Shoebox compressor. Once again wanting to get my own compressor, on the cheap, I decided to go with a Shoebox Max. I bought the deluxe model with hardened tool steel pistons, belt instead of chain drive, and a small built in fan. I want to say the small compressor cost me with shipping somewhere in the $700.00 range. I bought a small oil-less shop compressor to act as the first stage, so at somewhere in the $800.00 range I was ready to start making my own high pressure air. Now that I had the means to make H/P air I needed somewhere to store it. I ordered a Great White carbon fiber tank from Airtanksforsale.com and finally had a means to charge all my PCP air guns at will.
For many years the Shoebox served me well and I never had any problems with it reliably making up to 5000 psi air. As far as maintenance goes, I had to only replaced the orings in the cylinders one time, which cost $0.00 as the Shoebox came with an extra set of orings. Anyone who owns one of the old Shoebox compressors knows the big disadvantage compared to other H/P compressors is the amount of time needed to fill a tank, about 4 hours to fill a Great White tank from 3000 to 4500 psi. This is because the rods that act as the pistons are very small. The 3rd stage piston/rod is only 1/8th of an inch in diameter. Also a Shoebox needs attention every so often while it's working as the rods that act as the pistons need to be lubricated with white lithium grease.
Shortly after I started using the Shoebox I disabled the auto shut off switch because the banging noise it made while the compressor was working drove me crazy. I would just set an alarm to remind me to check the Shoebox every so often to lubricate the rods, and check what pressure had built up in the tank. The nice thing about a Shoebox is spare parts are cheap and available and if you need to talk with someone at the company, which is here in the USA, about any problems you're having they are more than happy to help. The bad thing about the Shoebox setup as it comes from the factory, there is no water separator or H/P filter to remove any moisture. But I eventually bought a Alpha filter from Airtanksforsale.com and that problem was solved.
In May of this year I bought an Alpha-Carette compressor from Airtanksforsale.com. I really didn't need a new compressor as the Shoebox Max met all my compressed air needs, but I thought it would be nice to have a more self contained compressor. I liked the fact that I would no longer need an additional shop compressor to get H/P air and the Alpha-Carette was basically a set it and forget compressor. Upon getting the new compressor and firing it up I was a bit disappointed as it soon stopped running. I contacted Joe B. at Airtanksforsale.com and he said he would need to contacted the manufacturer in China to see what the problem might be. Luckily I have some mechanical/electrical skills and was able to find the problem on my own, a $1.00 thermal switch. Once the switch was replaced the Alpha-Carette fired up and I had no other issues. This compressor is truly a set it and forget it compressor. I would select what I wanted the shut off pressure to be, select how often and for how long I wanted the automatic condensation drain to open, plug the compressor into a 110 outlet and then press start. I could then go do whatever you wanted while the nice quiet compressor chugs along at a non-frantic pace, filling my great white tank from 3000 psi to 4500 psi in about 35 minutes, at which point everything turned itself off. Very impressive.
The only real problem with the Alpha-Carette compressor is, it's longevity is unknown and when parts are needed it is unknown if they will be available. I've got a feeling that the original design, what the compressor was originally designed to do, was a normal 2 cylinder low pressure air compressor. It appears the manufacturer took the original design, modified the second cylinder, added water cooled heads and a water cooled H/P cylinder, and added the electronics needed for the auto drain valve and auto shutoff. Turning the original low pressure design into a H/P compressor. My guess is the bottom end, crank and connecting rods are unmodified from the original design, but I've never stripped the compressor down to see. Time will tell how durable the compressor will be after owners begin piling the hours on. If they last 500 hours it will be money well spent. But if they stop making H/P air after 150 hours then that's another matter.
Shortly after acquiring the Alpha-Carette I spotted a good deal on eBay for a nearly new Coltri MCH-6SH gas powered compressor so I bought it. I sold both my Shoebox and Alpha-Carette the compressor and have been using the Coltri compressor to supply all my H/P air needs.
About the Coltri, which by the way is the same compressor that Daystate uses. Unlike the Alpha-Carette the Colti was designed from the beginning as a H/P compressor with 4 stages. There are 3 large ball bearings on the crankshaft and each connecting rod has it's own needle bearing. The Coltri puts out 3.5 cfm so filling the great white tank from 3000 psi to 4500 psi takes about 5-6 minutes and because the Coltri has not only a water separator but also a H/P cartridge filter, the air going into the tank is dry and clean. Everything is self contained and there is no need even for electricity, just a little bit of gas. The Coltri does not have the auto condensation drain the Alpha-Carette does but it fills so fast there is no need to open the drain valves until after the compressor has filled the tank.
If ever I need parts for the Coltri they a readily available, if not cheap. If you ever want to see how to take apart the compressor, the manufacturer has made some very nice videos available on Youtube and a very nice parts schematic is available online listing every single part and part number, something unavailable for the Alpha-Carette. Because the Coltri fills so quickly I doubt I will ever need to do any maintenance on it but for changing the oil. After 100 hours you're supposed to replace the valves, costing $200.00 in parts, but I doubt that I would get 100 hours use on the Coltri in 10 years.
If like me you've decided the hand pump thing isn't for you, then this is my advice regarding these 3 compressors and which one might be right for you. If low cost and easy, inexpensive maintenance is what's important to you, and you don't use too much air, and you don't mind it taking hours to fill your tank, then the Shoebox is for you. If you want a set it and forget it compressor and you're willing to take a chance on unknown reliability, and you don't want to spend $3000+ on a dive compressor, then the Alpha-Carette is for you. If you use a lot of air and can afford $3000+, and want a compressor that was designed to make H/P air quickly and will probably be the last compressor you will ever own, then the Coltri/Daystate compressor is you.
I got into this PCP air-gunning sport perhaps like many of you, on the cheap. I ordered a Benjamin Discovery package which included a hand pump and began my long and expensive journey into the PCP world. I quickly discovered using a hand pump is a lot of work even when you're only pumping the gun to 2000 psi. After acquiring 2 Hatsan PCPs that required 2900 psi I decided the hand pumping thing wasn't for me. In hindsight maybe I should have stay with the hand pump and incorporated my shooting into a workout scheduled thereby enjoying the sport as well as losing some weight. Anyway, it was at that time, maybe 5-6 years ago, that I decided that getting my own high pressure air compressor made sense.
Back then I don't remember there being all that many options regarding affordable 4500 psi high pressure compressors, China hadn't yet started to make them back then. There were dive compressors that cost $3000+, and there was the Shoebox compressor. Once again wanting to get my own compressor, on the cheap, I decided to go with a Shoebox Max. I bought the deluxe model with hardened tool steel pistons, belt instead of chain drive, and a small built in fan. I want to say the small compressor cost me with shipping somewhere in the $700.00 range. I bought a small oil-less shop compressor to act as the first stage, so at somewhere in the $800.00 range I was ready to start making my own high pressure air. Now that I had the means to make H/P air I needed somewhere to store it. I ordered a Great White carbon fiber tank from Airtanksforsale.com and finally had a means to charge all my PCP air guns at will.
For many years the Shoebox served me well and I never had any problems with it reliably making up to 5000 psi air. As far as maintenance goes, I had to only replaced the orings in the cylinders one time, which cost $0.00 as the Shoebox came with an extra set of orings. Anyone who owns one of the old Shoebox compressors knows the big disadvantage compared to other H/P compressors is the amount of time needed to fill a tank, about 4 hours to fill a Great White tank from 3000 to 4500 psi. This is because the rods that act as the pistons are very small. The 3rd stage piston/rod is only 1/8th of an inch in diameter. Also a Shoebox needs attention every so often while it's working as the rods that act as the pistons need to be lubricated with white lithium grease.
Shortly after I started using the Shoebox I disabled the auto shut off switch because the banging noise it made while the compressor was working drove me crazy. I would just set an alarm to remind me to check the Shoebox every so often to lubricate the rods, and check what pressure had built up in the tank. The nice thing about a Shoebox is spare parts are cheap and available and if you need to talk with someone at the company, which is here in the USA, about any problems you're having they are more than happy to help. The bad thing about the Shoebox setup as it comes from the factory, there is no water separator or H/P filter to remove any moisture. But I eventually bought a Alpha filter from Airtanksforsale.com and that problem was solved.
In May of this year I bought an Alpha-Carette compressor from Airtanksforsale.com. I really didn't need a new compressor as the Shoebox Max met all my compressed air needs, but I thought it would be nice to have a more self contained compressor. I liked the fact that I would no longer need an additional shop compressor to get H/P air and the Alpha-Carette was basically a set it and forget compressor. Upon getting the new compressor and firing it up I was a bit disappointed as it soon stopped running. I contacted Joe B. at Airtanksforsale.com and he said he would need to contacted the manufacturer in China to see what the problem might be. Luckily I have some mechanical/electrical skills and was able to find the problem on my own, a $1.00 thermal switch. Once the switch was replaced the Alpha-Carette fired up and I had no other issues. This compressor is truly a set it and forget it compressor. I would select what I wanted the shut off pressure to be, select how often and for how long I wanted the automatic condensation drain to open, plug the compressor into a 110 outlet and then press start. I could then go do whatever you wanted while the nice quiet compressor chugs along at a non-frantic pace, filling my great white tank from 3000 psi to 4500 psi in about 35 minutes, at which point everything turned itself off. Very impressive.
The only real problem with the Alpha-Carette compressor is, it's longevity is unknown and when parts are needed it is unknown if they will be available. I've got a feeling that the original design, what the compressor was originally designed to do, was a normal 2 cylinder low pressure air compressor. It appears the manufacturer took the original design, modified the second cylinder, added water cooled heads and a water cooled H/P cylinder, and added the electronics needed for the auto drain valve and auto shutoff. Turning the original low pressure design into a H/P compressor. My guess is the bottom end, crank and connecting rods are unmodified from the original design, but I've never stripped the compressor down to see. Time will tell how durable the compressor will be after owners begin piling the hours on. If they last 500 hours it will be money well spent. But if they stop making H/P air after 150 hours then that's another matter.
Shortly after acquiring the Alpha-Carette I spotted a good deal on eBay for a nearly new Coltri MCH-6SH gas powered compressor so I bought it. I sold both my Shoebox and Alpha-Carette the compressor and have been using the Coltri compressor to supply all my H/P air needs.
About the Coltri, which by the way is the same compressor that Daystate uses. Unlike the Alpha-Carette the Colti was designed from the beginning as a H/P compressor with 4 stages. There are 3 large ball bearings on the crankshaft and each connecting rod has it's own needle bearing. The Coltri puts out 3.5 cfm so filling the great white tank from 3000 psi to 4500 psi takes about 5-6 minutes and because the Coltri has not only a water separator but also a H/P cartridge filter, the air going into the tank is dry and clean. Everything is self contained and there is no need even for electricity, just a little bit of gas. The Coltri does not have the auto condensation drain the Alpha-Carette does but it fills so fast there is no need to open the drain valves until after the compressor has filled the tank.
If ever I need parts for the Coltri they a readily available, if not cheap. If you ever want to see how to take apart the compressor, the manufacturer has made some very nice videos available on Youtube and a very nice parts schematic is available online listing every single part and part number, something unavailable for the Alpha-Carette. Because the Coltri fills so quickly I doubt I will ever need to do any maintenance on it but for changing the oil. After 100 hours you're supposed to replace the valves, costing $200.00 in parts, but I doubt that I would get 100 hours use on the Coltri in 10 years.
If like me you've decided the hand pump thing isn't for you, then this is my advice regarding these 3 compressors and which one might be right for you. If low cost and easy, inexpensive maintenance is what's important to you, and you don't use too much air, and you don't mind it taking hours to fill your tank, then the Shoebox is for you. If you want a set it and forget it compressor and you're willing to take a chance on unknown reliability, and you don't want to spend $3000+ on a dive compressor, then the Alpha-Carette is for you. If you use a lot of air and can afford $3000+, and want a compressor that was designed to make H/P air quickly and will probably be the last compressor you will ever own, then the Coltri/Daystate compressor is you.
