John Edwards says it's "an easy job" to clean the head and barrel. My experience is otherwise and maybe someone can enlighten me. When blasting between the fins I get very little bang for my buck. The end product looks clean but upon close inspection - I mean CLOSE, and with a flashlight - it turns out that most of the rust is still there, it's just not visible when viewing the part as a whole. I assume the reason for this is (a) the small clearance between any pair of fins, and (b) the blowback of air and abrasive from the barrel itself, which slows/weakens the abrasive that's coming out of the nozzle. So there is really no way to aim the abrasive square onto the fins where they need it most, but get only sideways glancing blows of the abrasive, which are not very effective to remove the rust. Anyone have a "cure" or tell me what I'm doing wrong?
The best way to get a barrel and head done (a job which is tedious at best!) is to take it to someone who has a rotablast and get them to wire it to the cage so it dosen't bang around and break a fin and walk away from it for ten minutes. Make sure you use a wooden plug or piece of plywood on each end of the bore with a bolt through them. The rotablast dosen't use compressed air, it uses paddles which flick the medium at the object to be blasted. They can usually be found at engine reconditioners or turbo remanufacturers (I have one in the next unit to me if thats any help)
It is "easy" enough to clean the head and barrel if a repaint is all your after... And I am not pulling a barrel just to paint it!
I am not one to look too closely between the fins...if a flashlight is required to see dirt at the base of the cooling fin, then I can live with it. A rust-bleeding top-end however, will receive my attention.
Please note that I am not attempting to prep the surface for a finish that would have been beyond what I think the factory or a refitter would have done.
I also live in a desert climate and my rust situation here is perhaps different from what is experienced elsewhere.
Hi John, know what you mean, the rust seems very hard and won't go with blasting only.
I first remove the rough dirt/rust with a drill in a Dremel, then give it a quick blast and put it a few days in a bucket with 'cleaning vinegar'. Then wash it and blast it again. The vinegar dissolves the hard rust and depending on the degree of rust you will have to repeat it. I've had very good results with it, Good luck, Regards, Michiel
Rotablasting cabinets are pretty universal you should try to find someone in New York City that has one, they tend to be used mainly by engine reconditioners/Truck service shops/ even in the aircraft industry, the one in the unit next door was built for blasting jet aircraft brake discs! The nice thing about them is there is no user input apart from putting the item in the cage and switching it on, so it tends to be quite cheap the other thing is some people use them to ball peen, which gives a lovely finish and isn't as destructive as grit
Dave: Is "the next unit" anywhere near New York City?
John: I'm not looking between the fins for aesthetic reasons, but if I don't get rid of the rust, paint won't stick which would mean more rust, etc.
I understand about the paint not sticking on rust, but the cast iron barrel and head will forever be in need of a repaint periodically...nature of the beast. So. remove the large rust chunks by whatever means are at hand, and coat with paint.... getting a good paint cost between the fins is another issue anyway!
There are commercial rust removal chemicals that are not toxic, but I have not used them yet. http://www.ecosafechemicals.com/
Spraying paint onto the barrel in particular has the same problem as the blasting..the depth of the fins and 'blowback' caused by spraying pressure will limit coverage. I always hand paint mine which leads to a heavier deposit of paint and better coverage..though it is time consuming.
I even cosidered vitrious enamelling which would be very durable and is completely heat resistant, but was unable to find anyone to do it.. ...Ian
For hand painting, I put mine on an old fork tube or broom handle clamped horizontally in the vice, then slide the barrel on, when I need to move it around I simply slide it round to the next part. I have had good results with Sperex, , sprayed lightly on trying to cover it all then wait until it is just going tacky, then spray the whole can on the barrel to a point where it is running off it and then place it quickly in front of a space heater (about 2ft away) then put the space heater on and it blows the runs off it and leave it there for about 15-20 minutes, then let it cool (it gets VERY hot) and when it cools it should be a very nice finish. I've used this method on both matt and gloss finishes, the gloss finish lasted for years on my Harley which I used to ride all year round. The matt finish by it's very nature is porous so unfortunately it dosen't last too well, but I guess that if the paints are compatable you could spray the matt over the gloss finish. You may have to wait about a month before you can spray the matt over the top of the gloss as it may react with it.