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Black anodised steel????

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Chris TickTock11/11/2019 22:23:18
222 forum posts
8 photos

Looking at a 10mm motor spindle adapter on Ebay I see they describe it as made of steel and black anodised. Now this product comes from Hong Kong.

My question is I am led to believe anodising carbon steel is a bad thing as it promotes rust whilst on aluminium it is a good thing. So if the metal is steel would it be a safe bet the metal is a mild steel or possibly not steel at all??

Chris

Jeff Dayman11/11/2019 22:51:11
1656 forum posts
42 photos

It is possible to apply a black coating on steel by several methods, but it is not anodizing. You will find anodizing on aluminum.

duncan webster11/11/2019 23:03:15
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Parkerising is one method of bluing and applying rust resistance

**LINK**

If anyone has a recipe for the gloop you heat the component in I'd be interested. I've got one for bluing which sounds distinctly dodgy, boiling solutions at well above 100C

Edited By duncan webster on 11/11/2019 23:03:45

pgk pgk12/11/2019 04:50:42
1486 forum posts
285 photos

I suspect the black coating being called anodising in the original question was just "translator's license"

Brian H12/11/2019 07:27:11
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I believe that the process in sometimes called 'Blackodising' which may explain the confusion.

Brian

Clive Hartland12/11/2019 08:09:11
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While working on large gun recuperators the internal parts were given a Black Chrome finish, they were first copper plated then immersed in a hot bath that had the chemical mix in it. After a time the items came out and the copper was brushed off leaving a lovely shiny black finish, supposedly rust resistant.

I have tead that Browning shotguns had black chrome bores to stop rusting.

Clive Hartland12/11/2019 08:12:02
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2481 forum posts
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Sheradising is another dark.black finish you see on twist drills, this done with steam at 500c.

Edited By Clive Hartland on 12/11/2019 08:12:22

SillyOldDuffer12/11/2019 10:59:21
4843 forum posts
1018 photos
Posted by Chris TickTock on 11/11/2019 22:23:18:

...

My question is I am led to believe anodising carbon steel is a bad thing as it promotes rust whilst on aluminium it is a good thing. So if the metal is steel would it be a safe bet the metal is a mild steel or possibly not steel at all??

Chris

Apologies if I've misunderstood but two things may be mixed up here:

  1. Does blackening steel promote rust?
  2. Is the motor spindle adaptor made of a suitable metal?

The information provided in the advert isn't enough to answer either question.

  1. Steel or any other metal can be coloured by any of several processes, ranging from a dab of paint up to the elaborate industrial process described by Clive. Colouring may be purely decorative or intended to resist corrosion. The best protections are achieved with hot nasty chemicals. Home workshop methods are less effective because we don't have the ways and means. Plenty of commercial blackening is thin and temporary. The purpose of blackening matters too: home blued steel would be risky on a closely inspected decorative item like a delicate clock where even minor blemishes matter, but perfectly acceptable on rough functional items. In practice an adaptor would have to get very rusty before it mattered!
  2. What the Hong Kong item is made of is unknown. As steel is cheap and strong, it's almost certainly steel. Mild-steel would be 'good-enough' for hobby use, but more likely the maker would use a tougher engineering steel because they aren't much more expensive than mild-steel. It might be a very tough alloy steel or a stainless. But who knows? The only way to find out would be to contact the maker or have the item tested.

Always worth asking is 'does it matter'? There are two bad mistakes in engineering. One is thoughtlessly buying only on cost and convenience, the other is to insist on only the best. The first is bad because it risks wasting time and money on tools and materials that aren't fit for purpose. The second sin is more serious because best is the enemy of good. Over-engineering pointlessly wastes time, talent and money on a grand-scale. It's a black-hole.

Only individuals can decide what their goals are! In your place I'd buy the adaptor and try it because my priority would be getting the tool working irrespective of look or long-life. It will probably be OK. If not, understanding why the adaptor is unfit for purpose is useful learning.  Others enjoy good tools for their own sake, or like to get things right first time.  Whatever floats your boat, but it pays to understand why you want it!

Dave

 

Edited By SillyOldDuffer on 12/11/2019 11:04:26

Chris TickTock12/11/2019 12:21:19
222 forum posts
8 photos

Thanks for all the posts. The reason I need to know is trying to evaluate whether I could machine the adapter if necessary to alter it.

Chris

Phil P12/11/2019 12:54:13
528 forum posts
143 photos

Could you not make your own spindle adapter, then you know for sure what it is made from ?

Phil

Neil Wyatt12/11/2019 13:28:40
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The real answer to your question is that he listing is dodgy.

Whether or not this may reflect on the quality and accuracy of the component is your call... the quality of such goods ranges from the perfectly OK, through rejects with cosmetic flaws, to chocolate teapot standard.

Neil

Chris TickTock12/11/2019 13:31:21
222 forum posts
8 photos

Probably will end up doing so but bare in mind the adapter is cheep and if easily machinable and it fits well on the spindle altering the other end may be the easiest option for me having as yet not done any precision boring. What I mean precisely is lets say the motor spindle is 10mm then to make a good fitting spindle adapter questions arise:

1. What bore should I make the adapter?

2. Do I pilot drill to say 8mm then use a boring tool to achieve the final diameter?

3. Is mild steel adequate for this purpose?

4. Is using 2 grub screws to fix the adapter to the spindle adequate?

Chris

JasonB12/11/2019 13:43:40
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Posted by Chris TickTock on 12/11/2019 13:31:21:

1. What bore should I make the adapter?

Forget about numbers, tolerences and trying to measure them, make the bore to fit the motor shaft, it should need light hand pressure to push it on and if right you will feel a cushioned piston effect due to trapped air in the hole. Picking up the motor shaft downwards and the adaptor should not fall off

2. Do I pilot drill to say 8mm then use a boring tool to achieve the final diameter?

Yes

3. Is mild steel adequate for this purpose?

Yes

4. Is using 2 grub screws to fix the adapter to the spindle adequate?

Unlike the ones on e-bay put the two screws at 90degrees to each other and file some flats on teh shaft for them to bear against

Chris

Chris TickTock12/11/2019 13:59:30
222 forum posts
8 photos
Posted by JasonB on 12/11/2019 13:43:40:
Posted by Chris TickTock on 12/11/2019 13:31:21:

1. What bore should I make the adapter?

Forget about numbers, tolerences and trying to measure them, make the bore to fit the motor shaft, it should need light hand pressure to push it on and if right you will feel a cushioned piston effect due to trapped air in the hole. Picking up the motor shaft downwards and the adaptor should not fall off

2. Do I pilot drill to say 8mm then use a boring tool to achieve the final diameter?

Yes

3. Is mild steel adequate for this purpose?

Yes

4. Is using 2 grub screws to fix the adapter to the spindle adequate?

Unlike the ones on e-bay put the two screws at 90degrees to each other and file some flats on teh shaft for them to bear against

Chris

Thanks Jason, I have now thanks to your post something to work from.

Chris

Howard Lewis12/11/2019 19:41:54
2440 forum posts
2 photos

At the risk of being called a pedant.

As already said, Anodising is only applicable to Aluminium. Chromic acid is one of the constituents of the electrolyte bath. As the name implies, the Aluminium is the Anode.

Sheradizing is heating steel in a Zinc powder, and is form of low er temperature Galvanising. (Galvanising is dipping the ferrous component into a bath of molten Zinc ). Strange calling it that, since no galvanic (electrolytic action by an external source is involved, just ion exchange between the two metals )

Physically akin to, but not the same as, Carburising, which combines Carbon with steel, so that it can be heat treated to harden it.

The Zinc becomes, effectively, a sacrificial anode, in preference to the ferrouis material.

Parkerising (Parcolubrising) is less of an anti corrosion coating and more of a self lubricating finish. It is applied by immersing the steel or ferrous item in a vat filled with hot / boiling fluid. I suspect that phosphoric acid will be a major constituent.

Dipping in oil after Parkerising will greatly enhance protection against corrosion.

Purely a comment:

I would advise MOST strongly against using this, but Conentrated Nitric acid is such a violent oxidising agent that it will produce a protective film of oxide on Aluminium or Iron, if they are dipped in it. A dangerous process!.

As Blue Peter used to say "DON'T try this at home".

Howard

John Olsen13/11/2019 00:53:53
991 forum posts
86 photos
1 articles

The reason galvanising is called that is because the Galvanic action takes place when the protected metal is exposed to wet corrosive surroundings. When this happens, the action is such that the zinc is consumed and the steel is protected. So if galvanised metal is used in salt water, the zinc will eventually be consumed.

John

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