Over the last 10 yrs or so, I’ve media blasted many things using my pressure pot blaster, and always felt it took me a long time to do so. My compressor can keep up, and aside from blockages that are time consuming, it always feels that it takes me too long. I’ve used several different types of media depending on the material/ amount of rust, and have settled with crushed gl***. Last year I got a HF blast cabinet, and same thing. Last night I did the rear calipers (small single piston) on one of my daughters daily drivers, and I think it took over an hour using 20-30 grit crushed gl***. Rust wasn’t really bad at all. Does this make any sense?
Amount of paint and rust changes the strip time. An hour is excessive. My blast cabinet would probably take about 5 minutes per caliper. I run mine at about 90-100 psi.
I usually run about 60 psi. If you crank the pressure up too high, all the media shatters into dust and you use a lot more media. Nozzle size definitely affects blast time. I strain all my media with an old tea strainer to get the clumps out. It's a pain but, in the end, it saves time and keeps you blasting, especially with the pressure pot.
I had the same problem for years,until i got a gas powered compressor,its a 4 cyl chev motor with a screw compressor,made by Sullaire.Best investment i ever made,that thing will blow 120 psi all day long no mtter the size of the nozzle.Any normal shop compressor just cant keep up with sandblasting,after a couple of minutes it starts to show.
Not sure, but it measures 0.190” dia on the HF gun. At the moment I have it at around 85-90 psi. Compressor is an IR 6 hp (220V) dual stage rated at 14 CFM @ 90 psi with a 60 gal tank. Pic of nozzle and media I used on the caliper. Wish I would have taken before and after pics of caliper.
Make sore that the air from your compressor is dry. Any water in there will make the media clump and clog.
Just blasted an exhaust manifold yesterday using princess auto unit. Took a long time to get air and sand valves set properly to avoid clogs etc. but once set, blasting only took a few minutes. Haven’t used it in years so forgot how to get it set up for proper mix of air and sand.
Probably a bit of moisture going through. I have one moisture trap, and a super tiny desiccant container hooked up to the cabinet. Haven't really had an issue with moisture clogging but have clogging issues with just debris clogging nozzle. I've had moisture issues for sure when using my pressure pot outside. At first yesterday I couldn't get any media through, and after many attempts, I finally noticed a piece of debris wedged inside the gun between the inlet nozzle opening before the output opening portion. My initial guess is that the nozzle that came with the HF gun is just too big at 0.190". Thoughts?
You’ve got to have material moving. I just did some engine parts and brackets In my cabinet. But before that I had them soaking in a tub with heated (really hot) Harbor freight degreaser. 24 hrs. They came out with 1/2 the paint gone and the other 1/2 was blistering. Hit the rusty spots with sand, then change the sand out back to gl*** beads. Oil pan, timing cover, balancer, 3 pulleys, 5 brackets all with spots of rust. That took about 1-1/2 hrs.
We had a Davis sand blast cabinet in the high school auto shop I taught in and the shop had a 3 phase 5 hp compressor with an 80 gallon tank and even when things were set up right I wouldn't say it was fast. The gun on that blaster had a nozzle the same ID as a flathead Dodge six valve stem as there was a draw full of those valve guides in a cabinet in the store room that I figured out I could cut down the od of one end in the lathe and use for nozzles. That one would run the compressor tank out of air all too often. The volume of air flowing is just as important as air pressure. The blast cabinet guns work on the venturi principle in that air flow past the end of the tube coming up from the media supply draws the media into the air stream.
The siphon tube can be a big hindrance to sandblast cabinets. The ones that come with a HF cabinet are junk. I made my own based on drawings I saw online. Not too difficult to do, and makes a world of difference. This link will show how to fabricate it. https://www.mojotiretools.com/Stuff_Workshop_Sandblaster_2.htm
Use two moister filters when blasting, you will be surprised how much water the second filter removes.
15 cfm and 1/8" nozzle size seem to work together pretty well....at least for pressure blasting. The cabinet is a siphon blaster, isn't it?
You can't have too many CFM... I've always used 80 grit aluminum oxide 'sand'. It's been a good compromise as far as aggressiveness vs final finish and doesn't seem to 'wear out' as quickly. Rusty, pitted cast iron is the slowest to clean.
The bigger the object the longer it takes. Bridge girders take longer than parts you can hold in your hand
I had a pressure pot and a 25hp rotary compressor. I could do a '32 frame in less than an hour and a '60 impala convert in about 10 hrs. Then I watch the guys on tv with the trailer mounted soda blaster do a car in 2 hrs.
That is really interesting. Quite the intricate setup, but does it really help? I agree the pure suction approach is not optimal based on what I have seen with my pressure pot unit. Gun is a suction type. Agree. My recollection is that what local garages take to get the job done.
The main thing is moving the blasting material. if the materials jamming up and not coming out of the nozzle you aren’t gonna do anything. Unlimited CFM with four grains of sand a second does nothing quick.
It absolutely helps. Like others have said though, if your media gets damp from moisture in the lines, or clogs due to debris in the media, then nothing will help except curing the problem. But if none of those things are happening, then this will help a lot. It certainly did with mine.
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