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SurfLung
Master Diver
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Joined: Sat Jan 01, 2011 2:03 pm
First Name: Eben
Location: Alexandria, MN
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Easy Tank Tumbler

Fri Aug 10, 2018 11:30 am

Tank Tumbling Made Easy... Eventually!
- I acquired a few USN surplus scuba tanks awhile back and when I got the valves off a couple of them needed tumbling to remove surface rust. I'd been meaning to try a reloading tumbler called the Frankford Arsenal Tumbler. Here's a video I made when I was just getting it set up:


- I got started on this tumbling thing and immediately began to wonder what kind of mess I got myself into. I temporarily broke my tank vise so I couldn't get the big valve bushings off and had to work thru the 1/2" valve opening... That and the flat face of the bushing on the inside made it hard to get the tumbling media out... Quite a lot of physical work shaking the tank, checking it, and re-filling it, etc. And, I was using a strange media made up of stainless steel needles about 1/4" long. Not very aggressive, difficult to get in and out of the tank, and messy.

BUT, I'm happy to say the learning curve took a steep turn upward over the weekend. I fixed the tank vise and the bushing came out pretty easy. Then, I remembered we have some nice ceramic tumbling media over at work and I borrowed some of it. I also added water which had the effect of washing both the tank and the media. This made it so I actually emptied and refilled the water without dumping the media and I could tell the tumbling was done because the water began to come out almost clean.

The final step to all of this was making a high pressure air wand... From plumbing at the hardware store. This is what Luis Heros told me to use to instantly dry the interior of the tank and avoid flash rust. After finally emptying the water and media from the tank, I turned it upside down with the edge resting on my bench, inserted the wand up until it touched the end of the tank... And turned on the high pressure.

I have a mini-Maglite on a string that I use for tank inspections. And, holy cow that tank is clean, dry, and smooth as a baby's butt! :)
SurfLung
The Freedom and Simplicity of Vintage Equipment and
Vintage Diving Technique are Why I Got Back Into Diving.

User avatar
SurfLung
Master Diver
Posts: 1280
Joined: Sat Jan 01, 2011 2:03 pm
First Name: Eben
Location: Alexandria, MN
Contact: Website

Re: Easy Tank Tumbler

Fri Aug 10, 2018 11:40 am

Update - I made that video awhile back and posted it to PhotoBucket. This morning, I downloaded it from there and re-posted it to YouTube. I actually used this tumbler on just those two tanks... I may have another tank or two that could use a tumble but so far only those first two surplus tanks needed it. They had already been converted to Scuba and must have got a few wet fills because both were badly rusted.

After tumbling them both, I thought they looked nice and clean but one DID have discolored blotches where the rust had been. When I took them up the Brainerd for Hydrotesting, the one with the discolored blotches was failed on the visual inspection. They didn't try a Hydro test on that one. The other one passed both visual and hydro just fine and I have been using it as my go-to lake diving rig. Gives me up to 40 minutes at the 12-20 ft depths the lake offers.

Tank Drying Tip - After blasting as much water out as I could with high pressure air, there still was some moisture. I set the tanks near the heat register with valve opening down to let it drain... And the darned things never got dry. The trick is to set them near the heat register with the valve opening UP... That lets the water vapor escape and the tank becomes totally dry.
SurfLung
The Freedom and Simplicity of Vintage Equipment and
Vintage Diving Technique are Why I Got Back Into Diving.

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antique diver
Master Diver
Posts: 1693
Joined: Sun Dec 10, 2006 12:50 pm
First Name: Bill
Location: North-Central Texas

Re: Easy Tank Tumbler

Fri Aug 10, 2018 12:38 pm

SurfLung wrote:
Fri Aug 10, 2018 11:40 am
Update - I made that video awhile back and posted it to PhotoBucket. This morning, I downloaded it from there and re-posted it to YouTube. I actually used this tumbler on just those two tanks... I may have another tank or two that could use a tumble but so far only those first two surplus tanks needed it. They had already been converted to Scuba and must have got a few wet fills because both were badly rusted.

After tumbling them both, I thought they looked nice and clean but one DID have discolored blotches where the rust had been. When I took them up the Brainerd for Hydrotesting, the one with the discolored blotches was failed on the visual inspection. They didn't try a Hydro test on that one. The other one passed both visual and hydro just fine and I have been using it as my go-to lake diving rig. Gives me up to 40 minutes at the 12-20 ft depths the lake offers.

Tank Drying Tip - After blasting as much water out as I could with high pressure air, there still was some moisture. I set the tanks near the heat register with valve opening down to let it drain... And the darned things never got dry. The trick is to set them near the heat register with the valve opening UP... That lets the water vapor escape and the tank becomes totally dry.

May I suggest an additional step to speed up the drying process.
Make the last rinse with very hot water. Let it set in the tank long enough to heat it up to point you need gloves to handle it, then turn it up to drain. The visible water will disappear quickly, then I use a heat gun and iron pipe fixture to turn the tank upside down for the final drying with hot air.
"I get plenty of excercise just pushing my luck!"

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antique diver
Master Diver
Posts: 1693
Joined: Sun Dec 10, 2006 12:50 pm
First Name: Bill
Location: North-Central Texas

Re: Easy Tank Tumbler

Fri Aug 10, 2018 12:41 pm

Nice Tank Tumbler!
"I get plenty of excercise just pushing my luck!"

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