Building a sandblaster

There is no more useful tool aboard a steel (or wrought iron) ship than a sandblaster.  I found some plans on the internet that gave me some good ideas on how to make my own unit.  I found an old acetylene tank in the scrap dumpster in the shipyard and went to work.  I filled it with water a few times before I started cutting it apart.

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So after cutting off the top and flipping it around and rewelding it to the body, you get this!  I added some wheels and a bought some cheap hydraulic hose and the air/water separator and the regulator on Ebay.  It uses ceramic nozzles that I bought through the McMaster-Carr website.  I run this off the 20hp air compressor already installed on the boat.  It is no match to the shipyard sandblaster that can blast a whole boat in one day, but it is perfect for me in that I can run it myself and do lots of small parts.

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Here is a detail picture of the filling bowl where the sandblasting grit gets put into the blaster.  The threaded rod pulls up a backing plate that has a neoprene gasket on it that makes an airtight seal.  As the pressure builds up in the tank, it also pushes the gasket up as well.  I have only had to replace the gasket once so far.  As the grit can be expensive, I pick up the used grit off the ground in the shipyard and sieve it through a screen to get out the larger bits and then reuse it.  I can also sweep up the grit I have already used on the deck and I get about three passes through the blaster with it before it just gets pulverized to dust and doesn’t work very well.  A special glass visor helmet/hood, tyvec suit, gloves and a good respirator are all required before starting any blasting.

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I turned a metal work table into a temporary blasting booth.  It is just a scrappy plywood box with a glass window on top.  Its purpose is to contain the grit and dust while working on small parts.  I mounted two halogen works lights inside as well as an input to hook up my shop vac.  The shop vac isnt pulling out the dust from the box, its actually blowing air into the box on one end, and there is a baffle air vent on the other side, creating a flow of air from one side to the other.  It gets very dusty inside when blasting, so the airflow clears the dust enough to see what you are doing.  I later installed a pair of heavy rubber gloves there the two arm holes are here.  I nailed old firehose over all the moving seams of the box, to make it as airtight as possible.  Underneath the grating seen here, there is a screen that allows me to filter the used grit and gravity feed it into a bucket for reuse.  Here are some turnbuckles and parts freshly de-rusted.

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Once I had the power to sandblast, I didn’t want to stop!  Anything that would fit in the blast cabinet was fair game!  And then I got really ambitious and started blasting the inside of the gunwhales and the main deck.  It took awhile, but it was progress every day.  After blasting to bare metal – I primed everything with the green Dimetcoat inorganic zinc primer.  Some real progress!

Rusty before:

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Primer after!

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4 Comments

  1. David P. Gill
    Posted November 19, 2009 at 2:15 pm | Permalink

    I am the skipper of a Sea Scout Ship located in Morro Bay CA. Our group is out of Visalia CA some 3 1/2 hours east of the ship. We can only spend every other weekend out at the ship. The ship is a 78 foot long ex-shrimp trawler from the east coast. Abondoned over five years ago at the dock it was donated to our group so the ex-owner aould be forgiven of the back docking fees. You have inspired me to keep up the effort to keep working on her. Although she looks like heck, after reading your story about sand blasting the rust off gives me hope to keep going. There is quite a bit of rust on the sides of the ship. We also have to contend with the tree huggers watching us like they have nothing better to do. I have gone over to Harbor Freight and picked up a inexpensive sand blaster and I am going out to the ship this weekend. I am going to spend my time working on the ship sand blasting the bow section than coating it with Ameron 236 Primer. While I am doing this I am going to have a group of young men and women down in the engine room scrubbing the bulkheads. The exhaust system has been leaking down there for some time and the old owner never repaired the leak so we are going to be locating the hole in the exhaust system and making repairs to that this weekend also.

    Again thank ypu for giving me hope.

    Very Respectfully
    David P. Gill
    Skipper Sea Scout Ship Saint Joseph SSS-20

    • Posted November 21, 2009 at 9:15 am | Permalink

      Hi Mr. Gill – Thank you so much for finding my site! Always great to meet someone fighting the same battles. In fact, one of my best resources is a local historical ship society I joined with a few like minded, privately owned, historic ship owners and lovers – The North River Historical Ship Society. I cant tell you how nice it is to have other folks to bounce your troubles off of! In regards to your sandblaster, its not the actual grit that is a environmental hazard – its the old paint that might contain lead as you probably know. The black beauty coal slag grit I use is inert and non-toxic. As my ship is in the yard here, there is blasting grit everywhere and a resourceful guy like myself can collect it off the ground, dry it out, screen it and reuse it again. The limiting factor for me at the moment is the number of cubic feet per minute my air compressor puts out. The more air, the faster the blaster will work. I have found my blaster to be invaluable right now – it is really making a big difference. You don’t know how many Ingersoll Rand model 182 needle scalers I have gone through before now! Good luck with your restoration – I would love to see some before and after pictures!

      • David P. Gill
        Posted November 22, 2009 at 9:47 pm | Permalink

        Eric

        We are out here this weekend and needle guns roaring and the sand blaster puffing we are making headway. We traded our anchor windless that did not work to another captain that has several just like it and wanted it for parts. He gave us one that works. We need to prep the deck and build a mounting foundation for it.

        I was inspired when we got underway yesterday and tied up next to a ship that looks worse than ours. Paint peeling and rust.

        We have three young men here this weekend and four adults working, Eating and living here this weekend. We were hield over because the ship we are tied up next to is leaving tomorrow and we will need to move ours so they can get out. We will return in a few weeks with a nice looking anchor windless after we take it home for an overhaul
        Have a great week. I’ll forward pictures later.

        Skipper Dave

  2. Posted March 26, 2012 at 3:20 pm | Permalink

    Please let me know how you delt with areas where material will refelect back at you and out got cleaned up after blasting the deck. I love your gravity fed blaster. How much PSI did you have ? Thanks.

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