Bead-blast questions

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blaat!
Posts: 149
Joined: Thu Aug 25, 2011 4:31 pm
Location: Massachusetts

Bead-blast questions

Postby blaat! » Sun Jan 08, 2012 2:13 pm

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

Rick
Posts: 331
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Location: Northern Plains, USA

Re: Bead-blast questions

Postby Rick » Sun Jan 08, 2012 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

Rick
Posts: 331
Joined: Thu Nov 11, 2010 1:12 am
Location: Northern Plains, USA

Re: Bead-blast questions

Postby Rick » Sun Jan 08, 2012 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

Jordan
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Re: Bead-blast questions

Postby Jordan » Sun Jan 08, 2012 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

JimF
Site Admin
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Re: Bead-blast questions

Postby JimF » Mon Jan 09, 2012 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

10531
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Location: Surrey, Canada/Atyrau, Kazakhstan

Re: Bead-blast questions

Postby 10531 » Mon Jan 09, 2012 5:32 am

For what it is worth, I'll jump in here :)
I have a lot of time using Plastic Media, Prunis (ground walnut shells) and Glass Bead. Used them when I used to overhaul helicopter transmissions.
Prunis was great for taking bits of paint off that the chem stripper wouldn't budge, but it won't remove stains very well and leaves a lot of dust. does work nice and slow though.
Plastic media is a bit better than Prunis, without so much of the dust. Good for paint stripping alloy parts before crack testing as it doesn't alter the surface structure too much, but again, doesn't remove stains that well.
Glass bead will remove everything including chemical surface treatments like alodine (aluminium) or Dow 1/19 (magnesium) and alter the surface of the metal. You will have to mask any surfaces that you don't want altered close to where you are blasting. There is blasting tape available for this.
I used to heat the part in an oven just to warm it and remove any moisture before blasting, then blow with DRY!! compressed air after blasting to remove any residue.
Didn't have any issues with contamination. Our transmissions were test run on a test rig at full load/rpm to make sure everything was good, and we never had one returned before it's next overhaul was due.
You must be CLEAN though.
I'll be trying out CO2 blasting soon, as I am going to paint strip the engine on my Alazzurra with it in the next month or so hopefully. I'll report back with results.
Don't have any experience with Soda Blasting, but it looks pretty good. Would be interested to see what the dust levels are like.
Cheers
Graham

DewCatTea-Bob
Posts: 2897
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Location: Near SE side of Lake Michigan

Related (pre-existing) Thread

Postby DewCatTea-Bob » Wed Jan 11, 2012 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

miken5678
Posts: 113
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Location: Jax

Re: Bead-blast questions

Postby miken5678 » Sun Feb 12, 2012 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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ecurbruce
Posts: 286
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Location: Lakeland fl

Re: Bead-blast questions

Postby ecurbruce » Tue Feb 14, 2012 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- 10300z 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

blaat!
Posts: 149
Joined: Thu Aug 25, 2011 4:31 pm
Location: Massachusetts

Re: Bead-blast questions

Postby blaat! » Fri May 11, 2012 5:15 pm

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
Before


after-bead-blast.jpg
After


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