Gallery, Projects and General > How to's
Anodising Aluminium - my setup that seems to have worked.
andyf:
Dave, I've only just read your post. So good that I've printed it out for future reference. Concise, too - OK, there was a lot in there, but every word counted. Thanks very much. :thumbup: :thumbup: :thumbup:
Andy
Jonny:
Havent done any anodising for 4 or 5 years, it was rather hit and miss, even done hard anodising a few times at 13.8v.
What put the dampener on things was my son breaking the 4ft fish tank, gallons of 20% sulphuric flowing out.
I used to get electrical breakdown especially when using wire. Only success was filing up a taper and wedging in a hole.
Tried as many different inks as i could, name it must have tried it some at best with little success, but in the end opted for what the pros use.
Initial current draw on this 4 1/2" dia exceeds 8 amps but drops to around 2 1/2 amps after 10 mins.
http://pic20.picturetrail.com/VOL15/728921/1243489/98753075.jpg
Around 4 amps initial on this dropping to 1 amp.
http://pic20.picturetrail.com/VOL15/728921/1243581/27203664.jpg
DMIOM:
hi Jonny,
agree - connections can be a challenge!
Given that the metals in the tank can normally only be aluminium, lead or titanium; the obvious starting point for many is to keep it all-aluminium.
Some folk try using aluminium bolts and straps, racking etc. but its never that easy/reliable - firstly the mounting hardware has to be stripped (alkaline etch) between runs; secondly aluminium nuts&bolts aren't that great either. If there is a suitable tapped hole on the workpiece, a threaded rod could be used; or a heavy-gauge aluminium wire doubled-up and 'self-tapped' into the threaded hole. The problem with the latter is (a) getting a good enough contact (needs pounds if not tens of pounds force to get reliable connection) and (b) as the wire doesn't fully fill the hole, its a real trap to carry over process chemicals from one tank to the the next - those chemicals may not be enough to poison the next tank, but if they leak or leach out they can cause visible blemishes on the finished article.
The next step which works well in many cases is to use titanium wire/rod. If there are any holes or bores in the workpiece (needn't be tapped) then a good springy Ti rod can be perfect to make connection and suspend the item - but it does need to be well-sprung (typically a J shape) - 1/16" rod is too compliant in most cases, but 1/8" rod can work well. The great benefit of Ti is that it has both the mechanical springiness and that it doesn't need stripping between runs - you run it once to pickle or blue it, thereafter (unlike aluminium racking) it has no significant effect on the anodising current load either.
The 'ultimate' is to use Ti clips - and they have the advantage of presenting a sharp edge to help maintain the electrical connection - two sketches below show round wire and angular clips in use in a bore
After using Ti rods for a while I invested in some racking, clips & hardware from ServiSure, and it was well worth importing them. We did buy various spines and racks, but for many of the items, we use a spider made of their clips and hung from the tank bar by a 1/8" Ti rod.
Using the full spine etc. for a large item (14" tray)
The clips are available in big sizes as well
Here, a long cylinder (about 9" if I remember correctly) is held using two large clips each suspended from a 1/8" Ti rod to Ti angle
And our most frequently-used combination - a spider of small step-clips on a 1/8" Ti suspension rod
Dave (no connection with ServiSure, just a satisified user)
Jonny:
Nice one there Dmiom did have a couple of Ti to try but never got round to it.
Every pro anodiser i have been in uses Ti spring clips and have a Ti machining job to do shortly.
Run out of dye and need to replenish.
I used lead to fully line the rear on both tanks protruding out of the sulphuric level and attaching a meaty croc clip. Aluminium foil rips and tears easilly and starts to float or lift off bottom and sides.
Incidently fitted a fair few of those in your bucket plus made some at work.
cozy:
Here's a few pics from when I've done some...
Rear caliper bracket I made for the bike...
Did some other bits as well...
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version