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WARNING - ONLY READ THIS REPLY IF YOU HAVE NOTHING BETTER TO DO,
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Hmmmm -
"exactly" the same?
Firstly let's clarify we are talking ALLOY here (see the PS at the end of this post).
When I restore a bike I am after the best result with the least amount of hassle.
That is
exactly why I bought the vapour blaster (which cost a bomb) and have so many customers who are far happier with the 'off the gun' finish than with dry bead. With my bigger cabinet (dry) I too can achieve a damn fine finish but it takes far longer, relies on bag fresh beads, reduced operating pressures (equating to more time on the job) and requires more post blast cleaning (which is a critical part of the blasting process). Generally to get the heavily oxidised castings back to that shown with the Cagiva cases (in my previous post) it would take a longer time with the dry process, whereas with wet blasting an excellent off the gun finish is relatively quick resulting in a lower billing time to the customer.
I have restored many early Ducati's using my old school dry cabinet using a two step process and been very happy with the results prior to rebuilding the engines but after using a vapour blaster I would never bother using the dry blasting cabinet for that work again.
I have done both wet and dry blasting and vapour blasting has few pitfalls whereas the dry process does. Dry bead blasting can cause impregnation by shattered abrasive media embedding in the castings (which is scary if inside the engines and gearboxes), compaction of abrasive and greater contamination of oil galleries should abrasive media find it's way into them (it should NOT if you know what you are doing) plus contaminated recesses etc. Vapour blasting does none of the above and is also far cleaner for the shop environment too with NO dust or abrasive residue at all when you open the cabinet or bring out the finished job.
When you look at the surface of the work with an engineers mono-scope like the one I use the surface is also smoother and with few open areas which means longer surface life with less maintenance, and greasy marks do not penetrate anywhere near as easily and are easily wiped off with a turps soaked rag.
With dry blasting at normal blasting pressures the bead degrades more quickly, often with smashed bead with sharp edges hitting the job, whereas when blasting using the wet process the water cushions the beads from each other and the work face meaning pressures can be higher and therefore the job is usually finished more quickly relative to the fantastic finish you get. Vapour blasting also has the added benefit of non foaming detergent additives and inhibitors also added for better cleaning action where required which you simply cannot do with the old school dry cabinets which is why mine is being generally used with either angular abrasive (garnet and aluminium oxide) or the old beads from the vapour blaster as a pre blast on very severely corroded parts often for prep for TIG welding etc.
In the end it all boils down to time on the job versus finish achieved and, given that I can do both wet or dry, vapour wins hands down on both counts with the added bonus of superfine finishes on delicate work if required including carburettors etc where you cannot afford to have ANY impregnation or contamination by abrasive media.
If you like using the old dry blasting that's great but everyone whose work I have done (and there are a number of them on this forum) using the vapour / aqua / wet blasting have been much happier with the excellent result for their dollars.
In closing I will point out that before I went to the expense of buying the new machine I had the use of another wet cabinet and knew what I was happier with given time on the job and the excellent finish achieved.
Cheers
Dave Mac
PS - For
FERROUS ie steel items, particularly those that are going to be painted, I recommend using a dry process with ANGULAR (grit) abrasive or glass bead if you prefer but never use grit on alloy unless you want to bugger it!
