I know more about this than I want to, though on a smaller scale than the
system you're describing. The big bags are the air separator units to take
the silica and other junk out of the air. All you really have to pay
attention to is the pick up line and the gun. Usually the problem is that
the media has gotten damp and won't drop when the suction line takes it up.
You get a void around the suction end and no media being delivered. Blasting
cabinets and guns are dirt simple. You can also take apart the media uptake
line and the gun to make sure the line isn't clogged or the venturi isn't
abraded away. There's usually a ceramic nozzle that the air gets sprayed
through that creates the vacuum that picks up the media.
Big systems often have a knocker that agitates the media feed funnel. If
that isn't working you'd also get voids.
Try changing the media out--it doesn't require much moisture to make it
clump.
Other stuff to worry about:
Sandblasting distorts sheet metal--you generally want to use something less
aggressive, like plastic media. Much slower, but your parts won't get bent
by weird skin stresses.
Stuff gets everywhere. If you use silica or silicon carbide you can't afford
a spec of it in your engine. Use caps and lots of tape. Glass beads are not
quite so bad, but harder to remove.
Five hundred bucks for a hundred pieces doesn't sound bad to me--and I have
my own blast cabinet. Blasting takes a lot of time and cleanup. It's got to
be 20 minutes per piece on the average. That's 2000 minutes or 33 hours. For
the amount of time involved I think you'd have a pretty aggressive
competitor there for any conceivable business. I'm spoiled I suppose, but I
figure that works out to less than ten bucks an hour if you include space,
utilities, equipment and materials and ignore the capital cost of the
equipment. I wouldn't test mattresses for that. I have my own cabinet for
convenience, and because I don't charge myself anything for my time. I sure
wouldn't do it as a business though.
-----Original Message-----
From: owner-fot@autox.team.net [mailto:owner-fot@autox.team.net] On Behalf
Of elliottd
Sent: Monday, February 16, 2004 11:20 AM
To: Friends of Triumph
Subject: Clogging Sand Blast Cabinet
I just paid $500 to a sandblast shop to have about 100 parts for the TR3A
stripped of all the paint and rust. I found the price rather steep.
I have a friend who has offered me free use of his huge blast cabinet which
is big enough to accept up to a TR6 fender or hood. The problem is it seems
to be getting clogged somewhere and the gun only shoots air. Neither he nor
I know what the problem is or how to get it to run so that the blast media
comes out the gun with the compressed air. I assume that something is
getting clogged but may be wrong. The gun is fed by a huge air compressor
(almost brand new) that has a duty cycle of about 20% when sand blasting or
glass peening. In the back of the blast cabinet is a vertically mounted
cylindrical tank measuring about 18 inch diameter and 3 feet long with a fan
in it and beside that is a steel cabinet which measures 2 ft by 2 ft and is
about 9 feet high. This latter cabinet is connected at the top with a 8"
flex duct from the cylindrical fan/tank unit. The front of this opens as a
door and inside are about 36long canvas tubular bags or sleeves, each about
8 feet long hanging there very neatly. At the bottom is a slide drawer
where sand has to be emptied periodically with a shovel.
Can anyone help so I can get this going and keep it going. I could save
myself and the guy who owns the TR that I'm doing for him a lot af money.
Maybe I could start up a small sideline business doing blasting. Anyone
suggest a good web site with cross-sectional diagrams which might help
explain its operation and the maintenance required.
Any other ideas ?
Don Elliott, 1958 TR3A, Montreal, Canada
|