Chris,
(1) Ceramic nozzles simply wear longer than steel nozzles. Tungsten nozzles are the longest wearing, but are expensive. Ceramic nozzles are probably a good compromise between service life and expense.
(2) Nozzle size has only to do with the size of your compressor. Larger nozzles provide more blast media volume, making the work go faster, but they also use more air. If you don't have the compressor capacity to handle the larger media volume, you will have a low velocity at the gun.
A comment on required compressor capacity: your compressor should not run continuously while you are bead blasting...it should have enough capacity to shut down and rest occasionally. If your compressor runs continously, your don't have enough compressor capacity.
Blast cabinets are big air users; I believe my 48" Skat-Blast "Pro" cabinet uses 13 cfm @ 100 psi. I have a two-stage 6.5 HP compressor with an 80 gallon reservoir. Typically, the small Craftsman 2-3 HP lube-less compressors will run continuously, and maintain low air pressure that really drags the job out. Because they lack cylinder lubrication, these compressors will be expended pretty quickly.
(3) If you are working on steel, you will probably want to use your full air system pressure. The higher the pressure, the faster the work goes, however, the time between compressor recovery runs is shorter. On soft materials, like aluminum, you may want to reduce the pressure to avoid inadvertently damaging the part. If you don't want to be monkeying with the air system regulator, you can try holding the gun further away (stretch your holding arm out there ) or hit the piece only with the lower velocity particles at the edge of the media cone.
Here's another tip: Whenever you have a part that isn't painted, I suggest you use bead-blasting only as a last resort to cleaning the surface. Bead-blasting leaves a matte finish that is atypical of natural cast aluminum or unpainted steel. It will not look right (if you are discriminating), and you could lose judging points.
Alternately, you can try polishing out the matte finish after the part is cleaned up, but then you could probably have just polished or wire-brushed the corrosion off the piece in the first place.
Another option is to acid-clean natural parts that must have a "slick" finish; muriatic acid for steel, and phosphoric acid for aluminum (in both cases, the acid should be diluted with water). I have more success cleaning natural steel parts in muriatic acid diluted 1:3 (one part acid, three parts water). If that dilution isn't working well, try increasing the acid strength. I have had less success acid-cleaning aluminum and getting a good result.
(1) Ceramic nozzles simply wear longer than steel nozzles. Tungsten nozzles are the longest wearing, but are expensive. Ceramic nozzles are probably a good compromise between service life and expense.
(2) Nozzle size has only to do with the size of your compressor. Larger nozzles provide more blast media volume, making the work go faster, but they also use more air. If you don't have the compressor capacity to handle the larger media volume, you will have a low velocity at the gun.
A comment on required compressor capacity: your compressor should not run continuously while you are bead blasting...it should have enough capacity to shut down and rest occasionally. If your compressor runs continously, your don't have enough compressor capacity.
Blast cabinets are big air users; I believe my 48" Skat-Blast "Pro" cabinet uses 13 cfm @ 100 psi. I have a two-stage 6.5 HP compressor with an 80 gallon reservoir. Typically, the small Craftsman 2-3 HP lube-less compressors will run continuously, and maintain low air pressure that really drags the job out. Because they lack cylinder lubrication, these compressors will be expended pretty quickly.
(3) If you are working on steel, you will probably want to use your full air system pressure. The higher the pressure, the faster the work goes, however, the time between compressor recovery runs is shorter. On soft materials, like aluminum, you may want to reduce the pressure to avoid inadvertently damaging the part. If you don't want to be monkeying with the air system regulator, you can try holding the gun further away (stretch your holding arm out there ) or hit the piece only with the lower velocity particles at the edge of the media cone.
Here's another tip: Whenever you have a part that isn't painted, I suggest you use bead-blasting only as a last resort to cleaning the surface. Bead-blasting leaves a matte finish that is atypical of natural cast aluminum or unpainted steel. It will not look right (if you are discriminating), and you could lose judging points.
Alternately, you can try polishing out the matte finish after the part is cleaned up, but then you could probably have just polished or wire-brushed the corrosion off the piece in the first place.
Another option is to acid-clean natural parts that must have a "slick" finish; muriatic acid for steel, and phosphoric acid for aluminum (in both cases, the acid should be diluted with water). I have more success cleaning natural steel parts in muriatic acid diluted 1:3 (one part acid, three parts water). If that dilution isn't working well, try increasing the acid strength. I have had less success acid-cleaning aluminum and getting a good result.
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