Bead-blast questions
Postby blaat! » Sun Jan 08, 2:13 pm
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Just about to bead-blast my engine and I have some questions. Luckily I have access to a nice blast cabinet and the rental fee is beer. My engine is completely apart and cleaned of oil and crud. I'm planning to temporarily assemble the cases, cylinder, and head (with no internal parts) and then bead-blast it. I'm thinking this will protect the internal and gasket surfaces while blasting all the visible areas. Then I will clean all the parts thoroughly, install the bearings, and begin final assembly.
Is it unnecessary to protect the internal and gasket surfaces?
Will the bead-blast clean them up without damaging them?
Will bead-blasting them individually allow me to do a more thorough job?
I'm afraid particles will end up in the bearings and inside the engine if I don't do a good post-blast cleaning, but water based cleaners seem to dull uncoated aluminum and solvent based would require lots of volume to do a thorough cleaning. I don't have a parts cleaner.
How do I thoroughly clean all the abrasive off without adding surface staining or patina back on the exterior surfaces?
Should I buy several aerosol cans of carburetor or brake parts cleaner?
Thanks!
-Jim
Re: Bead-blast questions
Postby Rick » Sun Jan 08, 4:48 pm
The easiest way to start an argument is to talk about glass beads, politics and religion- in about that order. Lots of people clean engine parts with glass beads and say they've never had a problem, but I don't do it.
Glass beads aren't sharp, so they work by exploding into shrapnel that is sharp and scrubs the part clean. The problem is with soft materials, like aluminum, and especially cast aluminum that is porous- little shards of glass can get embedded in the casting, or get stuck in a small cavity, and cause disaster if they come out when the engine is assembled and running. I've never had a problem with glass bead blasted parts because I just don't do it.
I do have a cabinet and do lots of blasting- usually use fine aluminum oxide- great for wheel parts, steel etc.
I have blasted aluminum engine parts with aluminum shot, from here:
http://www.transmet.com/products/aluminum-shot
It's really fine and does a nice job, but after I ran some aluminum oxide in my cabinet I'm concerned that some of the hard media is lurking in the corners of the cabinet, so I just don't blast aluminum engine parts anymore. Walnut shells won't remove the discoloring and oxidation, but will clean.
Other opinions will vary, and again, I've never had a bad experience with glass beads, but I don't use them.
Rick
Re: Bead-blast questions
Postby Rick » Sun Jan 08, 5:34 pm
This is a head I cleaned last summer- no abrasive blasting. I soak in degreaser, power wash, soak, powerwash, etc a few times, and clean discolored areas with mag wheel cleaner that contains hydrofluoric acid.
But- a friend who read the contents of the can just about choked when he saw it contained hydrofluoric acid- told me to look it up on the web before ever using it again, and it's really toxic stuff- passes right through skin and 'decalcifys' bone, basically turns your bones to jelly. I called a chemist at the university to ask about it, and he said in his opinion no consumer product should contain hydrofluoric acid- it's just too toxic.
So, be careful.
clean1.jpg
clean2.jpg
I use it outside, with skin and eye protection and a hose ready to rinse, but it appears that even momentary contact is dangerous. I have a small fiberglass tub with a top, and use it only for scrubbing with this cleaner- don't know how to dispose, so I just keep it covered.
Rick
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Re: Bead-blast questions
Postby Jordan » Sun Jan 08, 10:43 pm
Soda blasting could be a safer alternative? I've never tried it, but read some good reports when used on aluminium.
With stuff like glass beads, I'd plug all oilways and drillings before treatment. You can't see in them, so it's hard to be certain it has been all cleaned out aferwards.
I looked up hydrofluoric acid in Wiki - gulp!
Jordan
Re: Bead-blast questions
Postby JimF » Mon Jan 09, 4:55 am
What about walnut shells? I must admit I know little of the advantages/disadvantages of the common blasting medias available, but either soda or walnut shells or perhaps steel shot would leave no dangerous residue.
It seems to me that I saw an article on this subject within the last year or two either in the UK magazine "Classic Bike" or "The Classic Motorcycle."
I tried to find a link where I could search for articles in back issues - if I knew what issue it was in I might be able to find it. But I couldn't post it here without violating copyright laws either.
Jim
Related (pre-existing) Thread
Postby DewCatTea-Bob » Wed Jan 11, 1:56 am
____ Here's a link to the very-first thread that was started on this subject-topic.....
viewtopic.php?f=3&t=32
____ Probably the most important warning considering such work, is to be sure to prevent grit-dust from getting into the threaded-holes !
____ Also, (currently from page-17), here's a past/existing related-thread concerning soda-blasting.....
viewtopic.php?f=3&t=11
Dukaddy-DUKEs,
-Bob
PLEASE NOTE... If this-post is not-yet signed-off with '-Bob', then I'm still in the process of completing it,, and if not also included with 'DCT' near bottom as well, then I may edit this post's wording at a later time. - Dct.Bob
Re: Bead-blast questions
Postby miken » Sun Feb 12, 6:13 am
my only recommendation is to keep clean hands.. as once you are done blasting oil etc shows up fairly quickly. I cannot find an old link I have but there is a sealer application that you can use that helps big time. You will also come out with a better texture if you can find someone that uses wet bead blasting.
love the results myself..have used soda blasting with the same equipment and the results turn out great just not as matte
on my old indian motor (glass)
save yourself time and tape the bearing surface areas and avoild the gasket areas as well.
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Re: Bead-blast questions
Postby ecurbruce » Tue Feb 14, 12:01 am
This is sort of on subject, regarding sealer for aluminum...
Eastwood restoration products offers a clear finish for bare metals called "Diamond Clear", product number- z satin finish.
It goes straight on bare aluminum just after cleaned bead blasting. The satin finish looks just like bare
bead blasted aluminum.
It claims to be resistant to 300 degrees, is good right onto engine parts, that's where I've used it. Also available in gloss finish, but I've not used that.
Bruce
Re: Bead-blast questions
Postby blaat! » Fri May 11, 5:15 pm
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Finally blasted it. I used Ballotini extra fine bead. The stuff was just like talcum powder when I opened the 5 gallon bucket and I was concerned that it would not be abrasive enough. It took a couple hours just to do the exterior of the engine, and it did not alter surface details in any perceptible way. I may go more abrasive by a grade or two next time just to reduce the time involved and to remove the really minor scuffs and scratches... the extra fine actually seemed to reveal surface imperfections rather than remove them. I guess it is better to be more conservative when abrasive blasting.
before-bead-blast.jpg
after-bead-blast.jpg
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Sand cuts the metal. As in takes it off. A sandblasted finish will hurt your knuckles. A beadblasted finish is similar to a really fast little guy with a ball pen hammer .
The sandblasted finish will mar easily. Little sharp edges, The beadblasted is more lasting. If you beadblast and spray lightly with a clear coat it will become darker.
The sandblasted metal will be difficult to clean.
I would not sand blast.
Glass bead peens the surface of the metal, closing up the pore structure. Aluminum oxide etches the pores open. The etched surface can retain dirt and discoloration more readily but also provides "tooth" for a surface protectant or paint/ clear coating to adhere to. The surface will appear slightly darker than a bead-blasted finish.
If you intend to use aluminum oxide, 180 grit is what I used universally to prep all metal parts for the aerospace coatings that I applied.
I have a question. I do like the look of the matte finish that Nate shows. What does that do to the writing on the guns? Specifically, I got a reasonably good deal on a couple of Taurus Gauchos, and I would love to get rid of the large TAURUS on them. In addition to the look, would that do it? If not, IS there a way?
Blasting won't remove lettering unless it's really coarse blasting media and shallow letters. If those are stainless guns the lettering will need to be buffed off.
How does the finished product look if done by someone who knows what they are doing (NOT someone like me)? Would blasting after help or harm the final look? What is the cost of the two procedures? Feel free to PM me, I tried to PM you, but it says you can't receive new messages.
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