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Ready for Anodizing!
#1
Took over 30 hours to get things exactly the way I wanted. Two 50# bags of medium density soda for rough clean-up getting all the remaining powder coat from the belly pan nooks, crannies, web reinforcements, screw stand-offs and relieved logo casting and orbital sanding and filing marks out of the belly pan. Then another full 50# bag of 'fine' density for finish patina on everything, inside & out. Then once that was done I put everything together and taped the rear cover on from underneath and did it again as a fully assembled unit. That way there will be no difference between blast pattern textures and directions once parts are anodized where those patterns would be patently obvious if pieces were done separately, anodized then assembled. Sadly tho I cannot show anything to you. The aluminum velour-like surface is now so soft I could alter it with a firm thumb print. Even plastic or cardboard could now scratch or burnish the surface finish. That means I got it thru a rinse to remove all soda residue and let it air dry on multiple layers of beach towels then immediately wrapped each piece individually in 100% cotton terry towels with a minimum of 6 layers surrounding each side of each part then taped closed. Overkill yes, absolutely as its a whole nother 50# of soda and another 8-10 hours if a single blemish were to occur before anodizing.

A bit more about the anodizing. I'll be using a hard grade of Type II anodizing but steering clear of Type III which is uber hard anodizing or often referred to as 'hard coat.' Type 3 wreaks havoc with small threads of which there are 20 or so threaded bosses I need to keep intact in the underside of the Devialet top. In fact I have to use aluminum sacrificial screws during anodizing to thread into those so I retain the necessary "ground" connection via all but one PCB mounting screw and 18mm PCB stand-offs. And no anodizing shop will allow anything 'steel' near an anodizing tank... contaminates the entire tank on contact!! I'm sure I'll even have to prove my screws are aluminum rather than steel before they'll accept the parts. Since anodizing is NOT conductive, up to 1,000V I'm better served here by an "ounce of prevention beats a pound of cure." Far easier to mask those grounds with aluminum screws threaded into the bosses than to try and scrape the anodizing off them later. The anodizing layer itself is hard, Hard, HARD!! At/near Rockwell 58, harder than hard chrome, tool steel and about the same hardness as drill bits! Can't chip, crack, blister or peel. You could throw a handful of coins on the top once done and rub them around hard as you like but it won't scaratch! But sandpaper will scratch it because a lot of sandpaper is the same thing the anodizing layer is... aluminum oxide. Surface anodizing aluminum is a lot like a sapphire crystal over firm mud. You could still easily dent the Devialet top slightly with even a small wood mallet strike but it wouldn't scratch!

The scarey side of this is we get one shot at it. You cannot re-anodize an anodized part! If something/anything goes south I have to start over. This time with a high alkalinity based dip to remove the anodizing... the opposite of acid used for the nickel/chrome plating removal. Then re-soda blast et al. A scarey thought to me only 5 weeks out from RMAF!

Next pictures you see of my 200 should be the first totally black satin anodized, non-magnetic/non-conductive Devialet Expert on the planet!! Exciting stuff for me!
Statements in my posts are opinion only, not to be construed as fact. Any projects I engage in are at my own risk! Their outcome cannot be assured and may result in success, small/no change or catastrophic failure. I encourage no one rely on anything I say or do as gospel and to realize your mileage may vary!
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#2
Exciting stuff!! May I ask a silly question, you mentioned the top and bottom is very soft. Is aluminium that soft or is it because after the soda the aluminium got softened?
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#3
The hardness/softness of aluminum remains identical before/after blasting. The softness is actually the result of both soda, sand or media blasting and the series of peaks and valleys blasting imparts to the surface. The peaks separated by valleys will be softer without support around them a solid surface offers when surrounding them. You could use any of those blast medias on a number of soft metals with the same result, ie; copper, lead, gold, silver etc. Yet harder metals and glass wouldn't have the same risk issues related to marring or burnishing at typical fingerprint influencing levels. Surfaces like glass, steel, stainless steel etc would remain unaffected by fingerprints. Under a microscope a blasted surface of any material would appear to be a series of millions of tiny peaks and valleys per sq inch. Because the 'peaks' are so tiny/soft they can be burnished with something soft as a fingerprint. That is to say those peaks can be rolled over sideways or made flatter by a fingerprint under pressure than the surrounding area whereas other substrates like glass, steel etc are left unmarred by things like fingerprints on a blasted surface due to hardness. But for thermal heat dissipation the coarse blasted surface is to be much preferred as it simply has far more surface area per sq inch to shed its heat compared to a flat or polished surface. In 2 dimensions imagine a straight line and an erratic frequency going across a 3" screen width. The frequency line will be MUCH longer if stretched out, have MUCH more surface area on its top. Due to the surface hardness of anodizing and aluminum oxide the relatively soft blasted surface fragility disappears afterwards same as if a coat of epoxy were sprayed on it only many, many times harder than epoxy. But unlike a hard coating that flows over the peaks and settles into the valleys between them and forming a thick insulative layer the anodized surface allows the enhanced cooling effect of increased peak & valley surface area to be retained with its associated enhanced cooling benefit. Only now the previously soft peaks are more like glass/steel than aluminum in hardness with no accompanying insulative layer. A good analogy might be imagine a heat sink filled with epoxy to overflowing between all its fins & pins and left to cure alongside a normal heat sink with good airflow between its fins/pins and how each of them might work and compare to each other as an effective/efficient heat sink.
Statements in my posts are opinion only, not to be construed as fact. Any projects I engage in are at my own risk! Their outcome cannot be assured and may result in success, small/no change or catastrophic failure. I encourage no one rely on anything I say or do as gospel and to realize your mileage may vary!
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#4
I like the sound of the hard anodized surface. The plated shiny finish does tend to pick up scratches.

Will you need to run a tap afterwards through those screwholes do you think?
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#5
I would always 'chase' the threads after a project like this. Avoids surprises on reassembly. Even tho I plan on running aluminum screws in EVERY threaded boss in the case during anodizing to prevent losing my chassis ground due to non-conductive properties of anodizing. But I'll have to take lots of documentary evidence with me concerning those screw specifications as they'll be highly suspicious when they see those screws. As I mentioned earlier one steel screw could contaminate the whole tank and compromise ALL other parts in that tank being anodized besides mine. Depending on tank capacity and other parts in with mine that could cost them a few hundred to tens of thousands of dollars and I can't fault them for being careful. 6 ruined Aerospace parts from Boeing or Lockheed Martin in the tank with mine simultaneously could seriously ruin several people's day! And its still possible they could deny me the use of screws just out of overly-cautious concern.. If so then I'll have to invest in a solid carbide M3X.5mm bottoming tap to chase all the threads as due to hardness a regular HSS tap won't cut it post-anodizing. But a chassis ground cannot be compromised! This is unchartered territory for me with the screws tho hopefully with documentation, a magnet and an explanation as to "why" I need to maintain a chassis ground via those threaded bosses they'll understand.
Statements in my posts are opinion only, not to be construed as fact. Any projects I engage in are at my own risk! Their outcome cannot be assured and may result in success, small/no change or catastrophic failure. I encourage no one rely on anything I say or do as gospel and to realize your mileage may vary!
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#6
Thanks for the explanation. Am excited for your project!
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#7
Maybe I should've titled this thread "Ready for Anodizing... in about a week." My anodizer does twice per year anodizing tank maintenance & rejuvenation. Once over the Christmas/New Years Holidays and again in July. This year they were so busy they put July's rejuvenation off 2 separate times, till this week. Essentially they're closed all week to any anodizing! Just my luck! And its first come/first served next week as there will certainly be a huge back log. I have one other aerospace certified shop about 25 miles away which I may try if I start to fidget or squirm awaiting next week. Frustrating because I can't 'touch' the case due to fear of marring it in some way and I can't do much with the PCB's without access to the case... typical Catch-22. I'll look around, see what I can do towards this project with pieces I have access to and can do. Beyond that this week's pretty much a punt unless I go out on a limb of risk at another shop tho honestly the risks are equal either place but I've dealt with mine before and there's comfort in that. CRAP I hate having to make big boy decisions!!
Statements in my posts are opinion only, not to be construed as fact. Any projects I engage in are at my own risk! Their outcome cannot be assured and may result in success, small/no change or catastrophic failure. I encourage no one rely on anything I say or do as gospel and to realize your mileage may vary!
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