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  1. #31
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    Quote Originally Posted by BobL View Post
    Using silicone at the edges and around bolt holes on HDPE or Polypropylene sheet produces a very effective seal. To get a really good silicone/plastic surface adhesion, edges and holes have to be thoroughly cleaned with a solvent and then wiped/primed with raw vinegar and let dry. This is how we made fume hoods in metal free laboratories where there were some pretty aggressive chemicals in use and they lasted for more than 15 years before the silicone seals started leaking.

    Epoxy does not bond well to HDPE to begin with and is also more rigid and moves a lot less that HDPE. Over the long the HDPE swells, shrinks and flows under different temperatures and pressures (ie around bolt holes) so it can easily break away from the epoxy. We typically got 4-5 years from epoxy plastic seals.

    Thanks Bob.
    It seems pretty reasonally priced.
    https://www.ebay.com.au/itm/HDPE-SHE...G9Lq:rk:3:pf:0

    I wasn't going to use HDPE AND epoxy. I was going to paint the inside of the cabinet with epoxy paint.
    It may not be a good idea anyway....

  2. #32
    BobL is online now Member: Blue and white apron brigade
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    Quote Originally Posted by Sterob View Post
    Thanks Bob.
    It seems pretty reasonally priced.
    https://www.ebay.com.au/itm/HDPE-SHE...G9Lq:rk:3:pf:0
    You might even be able to get it cheaper if you could buy a 1200 x 2400 sheets

    I wasn't going to use HDPE AND epoxy. I was going to paint the inside of the cabinet with epoxy paint.
    It may not be a good idea anyway....
    It sounds counter intuitive but to reduce wear resulting when a highly abrasive pressure blast makes contact with a surface, you coat it with something softish so the abrasive jet bounces off it.

    One of my bros worked in the mining engineering and he one showed me around a gold ore processing site that used huge slurry pumps. When the ore/slurry jets were in pressurised contact with steel or painted steel (eg inside steel hoppers or inside pipe elbows) it always abraded it away. To slow down the abrasion they fitted wear plates made of HDPE or Teflon (Exxy!) and it last a lot longer longer than steel.

  3. #33
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    I used to do maintenance work in a place that did grip blasting plus other types of finishes, the blast room was always a problem. The grit would be sucked into the hopper, consequently wearing away the bends etc. plus the blasters boots, about 3-4 weeks and a new pair of boots would be required. I don't remember the name of the product, but it was similar to urethane, but would bubble up into a reasonable thick layer approx 6mm. My Brother was a blaster there and they coated their boots with it, boots lasted about 3 months before another coating was required. The bends had wear plates that were swapped over with the same stuff and lasted about 4 times as long.
    Kryn
    To grow old is mandatory, growing up is optional.

  4. #34
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    Guess what?...now I have a job that I need a valour blaster for and I haven't got one....grrrr.
    lol

  5. #35
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    Keep us in the loop.
    I bought a 120l white bulk container from Bunnies yeaterday, with the intention of fitting a glass viewing port in the lid, gloves into the front and a drain plug in the bottom.
    I intend to tilt it a little to the rear and to one side towards the drain. I've got a large SS drum with a pump fitted to the bottom and a swirling bypass jet to keep the content stirred. The drum also has a sort of free-wheeling stirrer in the bottom. It came from a dye mixing and batching setup. The main pump outlet is a 3/4" hose. So I intend to locate the plastic tub next to and above the drum - which will need me to stand on a platform to use it. Should work out. I'll figure out some lighting and fresh water spray onto the glass - hoping I can manage without a wiper.
    I ordered one of the suction nozzles I mentioned earlier and I already have a compressed air foot pedal. I might finally get somewhere.... if only it wasn't so damn hot here.... another 41deg. day today with little progress on any project.
    Cheers, Joe
    retired - less energy, more time to contemplate projects and more shed time....

  6. #36
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    Hi Joe,

    You could always use a magnetically driven wiper, like the ones used on boat windows.
    Best Regards:
    Baron J.

  7. #37
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    Quote Originally Posted by BaronJ View Post
    Hi Joe,

    You could always use a magnetically driven wiper, like the ones used on boat windows.
    I like the idea. I just have never seen them and can't find any references or pictures of them. Any links?
    Cheers, Joe
    retired - less energy, more time to contemplate projects and more shed time....

  8. #38
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    Hi Joe,

    I've just done a web search for "Marine Wiper Systems" and can't find any pictures of what I had in mind !
    The thing that I was thinking of moved a blade horizontally across a glass window.
    Now I'm wondering if I am mistaken, and confusing it with something like this.

    https://www.amazon.co.uk/InnovaGoods...SIN=B07CG3P5PS
    Best Regards:
    Baron J.

  9. #39
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    Quote Originally Posted by jhovel View Post
    .. if only it wasn't so damn hot here.... another 41deg. day
    Struth is that all, it got to 46degree in the shed today, and the other worker said it was too hot and went home!!!!
    Kryn
    To grow old is mandatory, growing up is optional.

  10. #40
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    Quote Originally Posted by jhovel View Post
    Keep us in the loop.
    I bought a 120l white bulk container from Bunnies yeaterday, with the intention of fitting a glass viewing port in the lid, gloves into the front and a drain plug in the bottom.
    I intend to tilt it a little to the rear and to one side towards the drain. I've got a large SS drum with a pump fitted to the bottom and a swirling bypass jet to keep the content stirred. The drum also has a sort of free-wheeling stirrer in the bottom. It came from a dye mixing and batching setup. The main pump outlet is a 3/4" hose. So I intend to locate the plastic tub next to and above the drum - which will need me to stand on a platform to use it. Should work out. I'll figure out some lighting and fresh water spray onto the glass - hoping I can manage without a wiper.
    I ordered one of the suction nozzles I mentioned earlier and I already have a compressed air foot pedal. I might finally get somewhere.... if only it wasn't so damn hot here.... another 41deg. day today with little progress on any project.
    Will do , but it will not be in the next few months....I have stuff spread 60 km apart at the moment....Will have to wait until we find new digs.

    Re: Wiper
    I dug a bit into these. Not sure it won't be too annoying without one.
    No-one is telling what they use, but I thought they must be using a Rear Wiper assembly off a car.
    They seem more compact and should make installing easier. Might be worth a look.
    They are not particularly cheap on ebay and its hard to see what your getting.

    I think it would pay to be able to wander around a wreckers yard to spot something suitable.

    I have come arcoss a linear wiper, but that was off a very old car and would be hard to find anyway ( can't remember which one now. )

  11. #41
    Join Date
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    Malvern East
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    The system they use is a rotary actuator pneumatic cylinder with a wiper arm attached and a constant water feed to the ARM to remove grit

  12. #42
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    Sep 2014
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    Elimbah Qld
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    Do a ebay search for ( Wiper Motor for Land Rover Series 1&2 ) They are a self contained unit with an on/off switch at the back $40 new

  13. #43
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    Quote Originally Posted by Aussie Bruce View Post
    The system they use is a rotary actuator pneumatic cylinder with a wiper arm attached and a constant water feed to the ARM to remove grit
    OK..I have never seen that.

  14. #44
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    Quote Originally Posted by stevejw66 View Post
    Do a ebay search for ( Wiper Motor for Land Rover Series 1&2 ) They are a self contained unit with an on/off switch at the back $40 new
    Thanks! Thats looks the goods.

  15. #45
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    I finally found some time - and a need - to connect together and try out my collection of wet blasting gear.
    For this first test, I didn't bother with the blasting cabinet. I just used the blasting gun - first without grit then with grit, finally with double the amount of grit - inside the open hopper drum.
    Let's say up front that it does work....
    Yep, there are 'buts'. My pump is a very powerful 1/2Hp and produces a good fierce 1/2Hp stream. My compressor produces about 100PSI in its 50l tank. It switches on at about 65PSI.
    Using the blaster, that tank last for about 6 or 7 seconds before the compressor restarts - and then manages to keep the pressure at about 40PSI If I stop and start often enough to look at the workpiece, as would be normal practice.
    The blasting gun came with a 1/2" connector on both air and water supply branches. I changed the water inlet to a 3/4" hose tail and connected my 3/4" water/grit hose to that. I used a 1/2" hair hose to the foot valve and plugged my 3/8" compressed air hose to the other end.

    The water/grit/air stream comes out through an 8mm hard ceramic jet nozzle - quite a sharp strong stream without air and a pretty fierce stream with air.
    However, it feels like a hard stream from a tap on your hands, you can't feel the grit at all, but it definitely comes out! I had it all over me and in my hair after I finished
    I don't know if you can feel the grit in the water in a small commercial vapour blaster - with a 2Hp pump.... where the recommended air pressure is between 30 and 80PSI.

    To the 'need' I had: I'm rebuilding a 37 year old Honda Postie bike and wanted to clean the engine cases (and other bits) thoroughly. So I washed them in degreaser and then rinsed them in petrol so they would dry quickly. That got the oil and grease and gunk off, but there were lots of stains and marks - maybe from mud - and a little bit of surface corrosion.
    In the wet blaster, the spot that showed any effect from the grit was maybe 6mm diameter and it took maybe 10 seconds of holding the gun still on that spot to make it noticeably cleaner. So a small engine case would probably take a couple of hours to clean a little bit better than degreaser and a wash.
    So after trying various distances and doubling the amount of grit in the hopper, after about an hour, I gave up. I've had cases hydroblasted commercially and they came up nice and clean and shiny, my attempt made it just clean and mat...
    Since 'mat' was all I was getting, I finished the job dry blasting just on the outside of the cases. That got most of the stains off - apart from a few I missed
    Here are a couple of pis of the setup and one of one of the cases.
    IMG_20190201_175300.jpg IMG_20190201_175325.jpg IMG_20190201_175358.jpg IMG_20190201_175456.jpg
    I think my next move is to look for a 2Hp high pressure water pump with a relatively open impellor.... and fix up my bigger 3Hp compressor, that has a decent size tank on it too...
    Cheers, Joe
    retired - less energy, more time to contemplate projects and more shed time....

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