Removing sharp perforation edges on stators with ferric chloride - Page 3 - diyAudio
Go Back   Home > Forums > Loudspeakers > Planars & Exotics

Planars & Exotics ESL's, planars, and alternative technologies

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 7th July 2007, 03:29 AM   #21
diyAudio Member
 
Join Date: Feb 2006
Location: Malaysia
Hi,

Is this the electro polishing we are talkng about now??

http://www3.telus.net/public/aschoep...lyticrust.html

Cheers
__________________
Audio_Idiot
  Reply With Quote
Old 7th July 2007, 11:30 PM   #22
expert in tautology
diyAudio Member
 
bear's Avatar
 
Join Date: Apr 2002
Location: New York State USA
Default Re: Perforated Al ESL stator prep

Quote:
Originally posted by glorocks

The panel should be first wet sanded with 4-600 grit "wet or dry" emory paper. Use a soft rubber sanding block. This may be enough to knock down the ridges.
<edit>

That would not be emory paper.
Either SiC, silicon carbide, or else aluminum oxide if it is wet or dry.

_-_-bear
__________________
_-_-bear
http://www.bearlabs.com -- Btw, I don't actually know anything, FYI -- [...2SJ74 Toshiba bogus asian parts - beware! ]
  Reply With Quote
Old 8th July 2007, 04:02 AM   #23
diyAudio Member
 
Join Date: Jul 2007
Bear, you're right. Back in my day, we called wet sanding SiC abrasive papers "emory" paper. I'll be more careful in the future.
  Reply With Quote
Old 8th July 2007, 04:02 AM   #24
diyAudio Member
 
Join Date: Jul 2007
Regardless of what we call the abrasive, the important point is to use liberal amounts of water to keep the abrasive from clogging up. A soft backing for the abrasive system, such as a heavy sponge or a soft grout float will allow you to break down the edges without the use of chemicals.
  Reply With Quote
Old 8th July 2007, 12:07 PM   #25
diyAudio Member
 
auplater's Avatar
 
Join Date: Apr 2005
Location: KyOhWVa tristate
Default Electropolishing AL

Using NaOH (lye) will usually leave a grey or black smut on the aluminum... it will etch but not polish the edges... maybe not the effect you want...

Commercial epolish uses decidedly unfriendly acids and high current density for the desired effect... typically Sulfuric/HF solutions ... or phosphoric-chromic-sulfuric-nitric mixes at 100 - 200 asf... not gonna post any formulas as someone will get hurt...

Brite dipping would also work... but again... find an anodizer and let them deal with the hazards...

Lye won't form an oxide, it'll keep etching till all the OH is exhausted and will leave the aforementioned smut.

Best to either find a commercial plating/finishing shop and see if they'll do it... or live with a crappy half-baked NaOH etch and then sand the results... <- would not be my choice.

Why not pour lye down the drain? That's what Drano is... and most other drain cleaners (excepting the sulfuric acid or enzyme types)... won't hurt pvc or copper plumbing... and it'll clean out all the hair and organic crud from years of mis-use...

btw... emery IS aluminum oxide.... http://en.wikipedia.org/wiki/Emery_(mineral)

Emory is a university in Atlanta Ga.

I'd leave the chemistry to chemists..

John L
__________________
"...His brain is squirming like a toad..." Jim Morrison
  Reply With Quote
Old 8th July 2007, 01:08 PM   #26
bigwill is offline bigwill  United Kingdom
diyAudio Member
 
Join Date: Dec 2004
Location: UK
Yeah, I'm now thinking of just countersinking every hole and sanding it with very fine whatever-paper.

However, I performed an experiment in which I dipped an aluminium candle holder in lye. The black smut readily washes off and the resulting surface does not look corroded.. In fact it looks pretty good.
  Reply With Quote
Old 8th July 2007, 01:55 PM   #27
diyAudio Member
 
auplater's Avatar
 
Join Date: Apr 2005
Location: KyOhWVa tristate
Default etching

If it works, and gives you what you want.. go for it...

The smut problem depends on the alloy... low alloy Al (6061, 2000 series) aren't too big of a problem, especially if you can wipe the smut off and no further finishing is required. You can also polish up the surface afterwards with Softscrub (w/o the bleach) or even Ajax or Comet.. (or a pumice slurry)

John L.
__________________
"...His brain is squirming like a toad..." Jim Morrison
  Reply With Quote
Old 8th July 2007, 04:02 PM   #28
bigwill is offline bigwill  United Kingdom
diyAudio Member
 
Join Date: Dec 2004
Location: UK
Isn't Al just Al? What is it alloyed with?
  Reply With Quote
Old 8th July 2007, 11:12 PM   #29
diyAudio Member
 
auplater's Avatar
 
Join Date: Apr 2005
Location: KyOhWVa tristate
Quote:
Originally posted by bigwill
Isn't Al just Al? What is it alloyed with?

Not at all... pure aluminum is almost never found... most is 6061, alloyed with copper, silicon, and magnesium to make it heat treatable...

http://www.suppliersonline.com/prope.../6061.asp#Spec

other alloys include 202x copper-magnesium series, 7xxx series, etc... pure Al is extremely soft and of limited use... I believe spec'd 1199... 1000 series is the purest

http://mdmetric.com/tech/alumcomp.htm

All these alloys behave very differentluy and have dramatic differences in tensile stregth, heat treatability, surface properties, etc.

most of the black smut left is copper, iron, silicon and other insoluble crud... it plays havoc in the metal finishing industry w/o the proper post treatments (hence the nitric, HF, etc. ) post-etch rinses

FWIW

John L.
__________________
"...His brain is squirming like a toad..." Jim Morrison
  Reply With Quote
Old 9th July 2007, 08:49 PM   #30
expert in tautology
diyAudio Member
 
bear's Avatar
 
Join Date: Apr 2002
Location: New York State USA
Auplater knows his stuff in this department.

Although I have never seen a "smut" build up on aluminum, that doesn't mean that it wouldn't happen.

As far as pouring lye down the drain, it could simply etch right through copper or brass sink traps. Probably wouldn't, and just leave it bright and shiny?

Guess it depends somewhat on the amount and concentration...

Ok, flush liberally with water when ur done...



_-_-bear
__________________
_-_-bear
http://www.bearlabs.com -- Btw, I don't actually know anything, FYI -- [...2SJ74 Toshiba bogus asian parts - beware! ]
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Alu stators, holes/perforation aligned? bentl Planars & Exotics 2 22nd April 2009 08:00 PM
MDF edges and screws rinx Multi-Way 32 16th August 2008 03:36 PM
Help: ferrous chloride/water ratio theAnonymous1 Everything Else 41 30th March 2007 08:50 AM
ferric chloride hacknet Parts 27 19th December 2002 07:41 PM


New To Site? Need Help?

All times are GMT. The time now is 03:13 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2