# A36 Plate Scale Removal



## Iceman (Aug 29, 2016)

Any tips.

HSS tool in a fly cutter is obviously not going to work. The A36 actually altered the tool profile essentially upon contact. So wrapped around this soft machinable steel is some sort of mithril/adamantium/unobtanium. 

I'm guessing this is carbon scale from the hot rolling process. 

It's what I have to make a 12x12x1"(ish)" thick tooling plate. The thickness will end up being the thickness of the plate minus this scale.

Is the best way to do this with a flycutter with a carbide tool. I used a solid carbide roughing end mill for the sides and it worked like a champ.

-IM


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## John Hasler (Aug 29, 2016)

Iceman said:


> Any tips.
> 
> HSS tool in a fly cutter is obviously not going to work. The A36 actually altered the tool profile essentially upon contact. So wrapped around this soft machinable steel is some sort of mithril/adamantium/unobtanium.
> 
> ...


Mill scale is iron oxides, not carbon.  You can remove it with pretty much any rust removal method.  Hydrochloric acid is fastest.  You can usually machine it off with HSS as long as you take a deep enough cut to get under it.


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## TakeDeadAim (Aug 29, 2016)

If a file will cut it HSS should.  I would experiment with tool geometry.


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## 12bolts (Aug 29, 2016)

I would get at it with a 4" grinder and then fly cut it

Cheers Phil


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## dlane (Aug 30, 2016)

I'ed try a hand belt sander, plate secure to somthing, or acid


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## Charles Spencer (Aug 30, 2016)

dlane said:


> I'ed try a hand belt sander



I've never done that but I normally use my Craftsman belt/disk sander to remove scale from pieces small enough to hold.  I don't see why it wouldn't work.


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## RJSakowski (Aug 30, 2016)

TakeDeadAim said:


> If a file will cut it HSS should.  I would experiment with tool geometry.


The mill scale is harder than the file but is brittle.  While a file will flake away the scale and cut the steel underneath, it dulls fairly quickly.  I usually remove the scale by chemical stripping or abrasion before milling or turning.


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## TomS (Aug 30, 2016)

Agreed.  Mill scale is tough on cutting tools.  I have a small HF blast cabinet that I use to remove the scale.

Tom S.


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## Iceman (Aug 30, 2016)

It's pickling in diluted vinegar - it's probably 6 cups of vinegar and 5 gallons of water. Tastes slightly acidic so hopefully it's enough to do the job.


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## Iceman (Aug 30, 2016)

I have some good files and it wouldn't even touch the top scale. Worked for deburrig the edges. But not the mill scale.


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## Iceman (Aug 30, 2016)

3 hours in the pickling bath - already seeing a good amount of bits sitting on the bottom of the drum and a good amount of bubbles forming on the surface. I plan on letting this go for 24+ hours then neutralizing in an alkaline bath (baking soda and distilled water) before lightly coating with oil to prevent any surface rusting as I continue on with the fabrication. I still plan to fly cut / surface the plate on both sides before locating and drilling/boring the many holes. This plate is destined to be my first tooling/fixture.

Since I am waiting for the carbide tooling to arrive for the surface operation I am in no rush.


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## Iceman (Aug 30, 2016)

Here is the before pickling picture:


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## RJSakowski (Aug 30, 2016)

Iceman said:


> It's pickling in diluted vinegar - it's probably 6 cups of vinegar and 5 gallons of water. Tastes slightly acidic so hopefully it's enough to do the job.



Dilute vinegar will probably not do it for you or if it does, it will take a very long time.  You might try electrolysis.  It works to remove rust and should work on the scale.  I tried a piece of hot rolled mild steel.  About 40 sq. in. and 10 amps of current.  After about ten minutes, there was a noticeable decrease in the scale.


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## Iceman (Aug 30, 2016)

I have played around with that method in the past with somewhat good results. I figured I would start with this. I actually have had my best results with an alkaline solution as the electrolysis medium for removing rust and electroplating.

And yes, I am the man with the "golden" monkey wrench.

-IM


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## Iceman (Aug 30, 2016)

So if I am unhappy with the pickling experiment I will use the neutralizing bath as an electrolysis medium and go that route next.


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## savarin (Aug 30, 2016)

I use neat vinegar, slow but works well.


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## John Hasler (Aug 30, 2016)

Iceman said:


> 3 hours in the pickling bath - already seeing a good amount of bits sitting on the bottom of the drum and a good amount of bubbles forming on the surface. I plan on letting this go for 24+ hours then neutralizing in an alkaline bath (baking soda and distilled water) before lightly coating with oil to prevent any surface rusting as I continue on with the fabrication. I still plan to fly cut / surface the plate on both sides before locating and drilling/boring the many holes. This plate is destined to be my first tooling/fixture.
> 
> Since I am waiting for the carbide tooling to arrive for the surface operation I am in no rush.


You can speed it up a bit by brushing the crud off the surface of the part.  It's going to be slow with vinegar, though.


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## Iceman (Aug 30, 2016)

Well wasn't seeing much activity in the acid pool - gave it a rinse in the part washer and built it a cozy alkaline bath with sodium carbonate.


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## Iceman (Aug 30, 2016)

Before (but after pickling - which I do believe actually softened the surface material - easier to scratch with file)



Careful application of some DC power-




After and hour - just a light metal brushing:



I dare say it is working.

I don't know why 2/3's of my pictures decide to orient themselves 90* anti-clockwise post-upload. 

-IM


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## Iceman (Aug 30, 2016)

Its about 1-1/2 cup sodium carbonate (washing soda) to roughly 4-5 gallons of water. I can say, having used baking soda (sodium bicarbonate), that the washing soda appears more effective as an electrolysis medium. Just a note for those thinking about attempting this. The Rigol power supply is massively overkill in complexity and limited in its current output (it is designed more for electronics work than this). But with its complexity also comes excessive build quality and a continuous duty cycle. No worries about overheating, it is barely breaking a sweat.


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## Iceman (Sep 1, 2016)




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## Iceman (Sep 1, 2016)

New Tormach Superfly.... Pretty fly.:.:. For a mill guy?


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## Iceman (Sep 1, 2016)

I like how much smaller this tool is - the no name 3" fly cutter I found at McMaster was less than stellar - I feel that tool may be too big for my PM-25 - now I have two TTS tools and In starting to think that going TTS and then using ER collets in my Glacern ER 25 collet chuck should help minimize long tooling swaps. Meh - still want to engineer a powered drawbar.


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