Dean_Fuller

http://toronto.en.craigslist.ca/tor/tls/3197215088.html


http://toronto.en.craigslist.ca/tor/bar/3190972060.html


http://ontario.kijiji.ca/c-buy-and-s...AdIdZ405341334


Something like these..anything smaller than 40 gallon and you will spend more time waiting than working.

depami

Pneumatic equipment will normally specify CFM @ PSI. Typical media blaster will usually require 10-20 CFM at 80 PSI. Various manufacturers will play games with those numbers to make their equipment appear better than it really is. McMaster Carr is a good resource of information when doing such research, especially if you have a printed catalog.

17prospective buyer

I was interested in that old "60-80 gallon" one in Woodstock, which is only half an hour away from London. I could get my buddy to drive there with me to pick it up. Maybe i will see about that one.

Will report back on this thread about my successes with blasting with my existing setup and a larger setup if i buy one. Maybe this thread could be of use for anyone else restoring a 928 that wants to do the stripping/blasting him/her self?

dr bob

If you plan on lots of future work that will benefit from a big compressor, like painting, pneumatic bodywork tools, or blasting, there's no substitute for having the right stuff. If this is a once in a long while need, you can a) rent a larger compressor, or b) farm out the blasting work. Places that do it all the time have the compressors, filters, media, technique, etc to do it without so much experimentation. They hang on to the mess, the noise, and the electric bill too.

Real production shops are moving to screw compressors rather than reciprocating units. There are some smaller ones that might do the trick for you. Or find a used recip unit that was replaced by a rotary screw unit.

Dean_Fuller

I should have asked before...what KIND of parts are you wanting to blast?

Body parts? ( thin aluminum is VERY hard to blast. I would not do it. Heat damage is a real possibility.)

Steel parts? ( fine but stay away from machined surfaces. )

You may be better off just paying someone to do the parts for you unless, like Dr Bob said...you plan to expand your horizons.

Also..I if blasting in the open at home I would recommend using a bio-degradable media. Your folks are not going to want aluminum oxide all over their yard. Sand, walnut shells, soda....

17prospective buyer

I am aware of how media blasting works. I want to blast aluminum and steel engine parts and other parts Eg. water bridge, engine block, motor mount heat shields, undercarriage, wood (furniture), concrete, steel tractor parts, general stain removal from wood/concrete.

I know not to blast machined surfaces, they only need to be cleaned of sealing material and nothing else.

Soda is the obvious choice for blasting on a house, furniture, and anything else that is thin or delicate in some other way. It can also be used on assembled engine blocks AFAIK since it can just be wiped off with a damp rag, or hosed off if everything is sealed up well.

I want to try to avoid sand for the reason that it causes silicosis unless NIOSH approved breathing apparatuses are used.

James Bailey

This is the VW flat 4 very clever design with a custom camshaft running the two front cylinders as a 4 cycle gaslone engine BUT the rear two as two cycle compressors !
Dunn-Right Incorporated Home of the


www.dunnrightinc.com/


All you need is a dual port type I or type III VW Engine! DR3 CAV COMPRESSOR COMPLETE UNIT. DR3D Deluxe Conversion Kit. DR3D Deluxe Conversion Kit ...

10" x 28" 44" in Height LIGHT ...

Dean_Fuller

I did not mean to offend.

17prospective buyer

You didn't. Thanks for sharing your knowledge. Major respect for your project too Dean. I couldn't do that.

17prospective buyer

Well guys, i have tried blasting with the slag i bought and it went quite well for an amateur setup. It stripped paint well but not rust. This was at 90 PSI, the compressor pressure switch closes at a 120PSI tank pressure which turns off the compressor. I guess it is pretty much the same as an air brake system on a truck, just without a governor/compressor unloader circuit.

I could only blast for about a minute before flow became too low to get anything done. The gun did not clog up that much, just required some shaking once in a while to get a good media flow into the air stream.

The only thing i had on there to dry incoming air was a small dessicant dryer inline between the gun and the quick connect hose. It collected moisture quickly.

Revelations/research tells me that the best drying setup for a large duty cycle compressor such as ours is now, is having a 25-50FT coil of hose functioning as a condenser for the water vapor, with both a separator for condensed water vapor, AND a dessicant dryer to get rid of all the remaining water vapor. It is unwise to put a separator right after the compressor primary tanks, because the air right after a compressor is hot. As we all know hot air has a much larger capacity to hold water vapor than cold air. Therefore you need to cool the air through a coil of hose/heatsink to allow it to condense before it hits the water separator. However, a gravity feed gun seems to have large enough orifices that can function fine on less dry air. I imagine a siphon feed unit would really benefit from having the dryest possible air.

In conclusion, i think i will need to get another coil of hose to serve as a condensor, and a water separator right after that coil of hose, to adequately dry the air properly. I will also need higher air volume capacity. So, i am looking at getting an old 60 gallon unit with an electric motor-belt driven piston style air pump. I am using my fathers compressor right now and don't want to burn it out on a duty cycle it was never designed for. The higher duty cycle also forms much more water vapor due to the excessive heat.

I hope this thread can be dedicated to DIY/home media blasting information purposes. Can a mod maybe change the thread title to something that would suit that?

I will try food grade soda too and report my findings on that as well.

depami

It's good to hear results of your efforts.

You will likely experience more problems from moisture with soda than with slag.

You should be able to change the title yourself. Go to your first post, click edit, go advanced and change title.

Good luck with your endeavors and keep us updated.

17prospective buyer

Update: Did some blasting today and my findings...

Gun Principles: -the gun seems to operate on the principle of the weight of the media, force of gravity, and the venturi principle to shoot a stream of air with media in it

Potential Problems with Gun: -the gun does create a low pressure and therefore a siphon effect because of it's tapered nozzle (high velocity=low pressure, atmospheric pressure acts to push the media into a low pressure area)
-the hopper for media must be able to breath since quite a significant vacuum is created, i improved this and drilled a hole equivalent in diameter to the orifice at the bottom of the hopper feeding the nozzle
-the hopper delivers consistent and sufficient media flow into the air stream until the hopper gets to about 1/4 full, i think this is because the weight of the media above the orifice becomes less, at this point shaking is needed to keep a consistent flow of media, a possible solution to this will be fixing a barbed swivel fitting to the cap of the hopper and have a tube from the fitting to a large (40lb plus) container of blast media so that you always have the force of gravity delivering media to the gun, this will make the gun less portable however
-the orifice that delivers media into the air stream will only deliver fine abrasives such as sand or soda, coal slag stripped parts much faster than sand but clogged constantly

Air Supply: -the air supply i used was a small single piston oiled compressor with two existing tanks for a total of about 5 gallons of capacity, however, using an old air pig tank, i was able to add another 8 gallons of air capacity to the system

Blast Settings: -because of the small diameter of the nozzle, the gun does not consume much air, and seems to operate fantastically well on lower PSI settings
-regulating the pressure to the gun seems to be dependent on blast media, the ratio of media to air cannot be regulated at the gun, but lower PSI will deliver more media and actually do a better job, to a point
-PSI settings seem to generate a bell curve, lowest PSI will not do a good job since the velocity of the media will not be high enough to clean, but using max PSI (120-130) seems to lower performance (i assume not enough media is forced into the air stream at this PSI)

Conclusion: The gun did as good a job as any ones i have seen, the blast radius from the nozzle is sufficient. A dryer seemed to make no difference, even as the compressor started heating the air up alot. As media, sand seems to be the most consistent. Currently i am using mortar/cement sand from Home Depot. It is about $4.50/bag and does not need to be screened for use in this gravity feed gun. It did a fantastic job stripping paint (and yes, the cadmium plating on every steel 928 part), it prepped up my front engine hoisting hook, dipstick tube, and ignition coil brackets. It created a surface that is grey and ready for paint, although i would be more careful if using this on aluminum parts. Very happy with the results and with a couple modifications, this will be very useful for my 928, and my family in general.