Shoebox 1st Run

Hello all,

After lurking for a bit, I finally got my account set up, mostly to share my excitement and pleasure with my new Shoebox.

Like many of you, the pain of getting tanks filled at the scuba shop 40 miles away was a real burden. Then by a complete stroke of luck a friendly fellow by the name of Zasadny moved within 5 miles of me. He was happy to fill me up whenever I needed air, and that always meant a great conversation about topics wide and varied while we waited for the bottle to fill.

But it was too good to last, and he left me, and took his compressor with him...dang! He moved away without any thought at all of my air needs ;^)

The idea of going back to the scuba shop was really unappealing, and then turned out to be impossible when they went out of business.

So to keep shooting I was going to have to make an investment in a compressor. After considering all of the alternatives I opted for the Shoebox Max, which arrived earlier this week.

After doing all of the set up, tonight was the first run, and I have to say I am very pleased.

Topping off my Drager 88cf bottle from 4050 to 4500 took a surprisingly short 1hr and 5 minutes. The pressure on the fill rig and the bottles valve gauge matched, so I am fairly certain about the accuracy of the numbers. The auto shut off occurred at 4200, I made a quick adjustment to the spring and turned it back on, and it ran to 4500 without shutting off, but I was monitoring it for just that possibility. I made another adjustment to the spring somewhere between the two settings and now it shutdown immediately with the bottle at 4500, so it should be set at a safe level. Of course, now having it stop short of 4500 is not a big deal like a full fill from the scuba shop was - I can top off any ol' time I please now ;^)

My input pressure was 87psi. I monitored the temperature of the cylinders with an infrared thermometer, the hottest reading I could find anywhere on them throughout the entire fill was 78F - the fan does a great job keeping things cool.

As mentioned I was surprised at the short time to produce 450psi into the large bottle. Based on the performance info on the Shoebox page I was expecting it to be over twice that long. Hour long run times should mean low maintenance and a nice long life for this unit.

I am very pleased tonight, and I hope you don't mind me sharing my excitement.

Thanks for reading.

Rod
 
Congrats. I'm different, I used my Shoebox a grand total of 2 times. I got a nitrogen setup to back-up when the paintball shop couldn't fill my tanks. The Shoebox sat in a box for 2 years before I gave a shooting buddy a great deal recently. A couple of months ago I got a smoking deal on a Supercharger and didn't have it long before I saw another deal on a Shelden Kidde compressor. So that's what I have now.
 
"rnabholz"Thanks BlackDiesel

Lots of ways to skin the cat, and people's access to services and facilities varys widely. Add in available time and expense and other variables and the answer to the complicated equation is different for everyone.

Glad you found your answer, and happy I seem to have found mine.

Rod
I have to admit that getting air was never a problem. The paintball shop near me usually have enough pressure to fill to 4500 psi and only charges $1.50 per 1000 psi. So I usually topped up from 3k to 4.5k and it was really cheap. But I wanted to be free from depending on anyone for air.
 
I got a MAXX about 2 weeks ago. Love it! Takes about 15 to 20 min to top off my small Air Venturi 4500 tank from 3000 to 4500. I like the idea of thumb screws on the cover. I did add a carry handle. Makes it a lot easier to move it when not in use. Sure do go through a lot more lead than when hand pumping! The only bad thing I see is that I am no longer loosing weight. In 3 months of hand pumping, I lost 10 pounds and 2 new belt holes. 
 
Thanks Quad,

I have never used a hand pump, not that the exercise wouldn't do me good....

You mentioning your small tank is interesting as since I have the compressor now, I have given the first serious consideration to getting something smaller than the 88cf. In the past it was all about filling the biggest thing I could find at the air source. Now with my own compressor, I can see the convenience of the smaller and lighter bottles......Always something else I "need"....... ;^)

Thanks

Rod
 
Second run is in the books.

It made 300psi into the 88cf tank in 43 minutes, shutting off at 4300.

I could probably tweak that shut off pressure a bit, but there's really no need, and it is at a nice safe level, so I'll just leave it be for now.

Over the two runs it seems to be making about 400psi/hour into the big tank. Well pleased with that for my needs.

Ran very cool as well, with the infrared thermometer showing low to mid 70sF throughout the run.

All is good!
 
I have had a couple of requests for a live version of the spreadsheet. I I have uploaded a blank copy to my website. You can get it here:

http://www.homebuiltastronomy.com/shoeboxlog.xlsx

Couple of notes. Enter start and end times in 24 hour format (1:30pm would be 13:30). You will also have to manually enter the total minutes, I added a quick calculator for that in the upper left.

Let me know if you have any questions

Rod
 
The value of keeping the compressor log was affirmed last week. On the 5th, I did a short run to top off my 44CF bottle from 3900, and I noticed that things seemed to be moving slower than normal.

I stopped the run at 4300psi and entered the run's data into the spreadsheet.

https://docs.google.com/spreadsheets/d/1oygaCsqJRjNGGTpXGPIYnAU1ZkyqWbBh5Tz7ODzHb24/edit?usp=sharing

It showed that the performance of the system was definitely down, as it was making just 282psi/hour into the bottle, where in the past the norm had been around 400.

It caused me to take a look at the system, and starting with the newest component in the system, a new fill rig, I found a leak at the pressure gauge, nothing a quick turn of a wrench couldn't fix, but it was definitely causing an issue, a 25% decrease in production.

On the 10th I topped off from 3600 to 4500, and the system made 394psi/hour - that was consistent with what I had come to expect from past performance. 

Having the records in the log made it easy to see the change in performance without relying solely on memory, and saved me wondering if I was imagining things.....;^)

Definitely worth the couple of minutes each fill to make the entries.

Rod