Fish scaling

[Nick_GParticipant @nick_g]

[Nick_GParticipant @nick_g]

.

I know that the fish scaling finish on metal was originally designed for practical reasons as it held oil upon a surface. This has been since used a decorative effect on materials that do not require that protection of oil such as stainless steel and aluminium.

But how is this effect achieved by a 'home machinist' ??

Cheers, Nick

[Ed DuffnerParticipant @edduffner79357]

Hi Nick,

If you mean the pattern like they embelish onto expensive watches, I believe it's called engine turning and another fancy name I can't remember.

Ed.

[Jeff DaymanParticipant @jeffdayman43397]

To do engine turning or "damascening" in the home shop, for small items a regular pencil with rubber eraser works great on soft materials. Just chuck it in the mill or drill press rubber end down, and rig some method of indexing / spacing the work, and you are away. A brief touch of eraser to work is usually enough to mark it.

For larger circles use hard urethane rubber as found in die shops for stripping stock off punches. Some valve grinding compound on the end of the rod often helps when larger sizes are being done.

Good luck, JD

[I.M. OUTAHEREParticipant @i-m-outahere]

Also known as jewleling in the gun trade ,it is used to smoothen the sliding action of the bolt as it retains the oil film on the bolt.

[JasonBModerator @jasonb]

Nick something mildly abrasive in the mill and carefull setting out to get the right overlap is all you need. Cratex pads are said to work well, garryflex as are some of the scotchbright type pads in the Dremel sizes. John (Bogstandard) did a good thread about it which I will see if I can find.

If all else fails I have seen it in the form of sticky back plastic

J

 

 

Edited By JasonB on 03/04/2016 08:18:00

[capnahabParticipant @capnahab]

do you mean this ?, done with a scraper, usually Biax. sorry it's not in English.

 

Edited By capnahab on 03/04/2016 08:40:57

[MWParticipant @mw27036]

Yes those are oil pockets, you can actually get bearings riddled with holes for the same purpose on shafts.

Michael W

[Michael GilliganParticipant @michaelgilligan61133]

Posted by capnahab on 03/04/2016 08:39:56:

do you mean this ?, done with a scraper …

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I'm not sure what Nick had in mind … but the advice given thus far concerns something more like this.

[… which is 'a different kettle of fish' and can look rather vulgar]

MichaelG.

Edited By Michael Gilligan on 03/04/2016 09:38:40

[Rik ShawParticipant @rikshaw]

I use soft wood doweling with fine grinding paste. Last job was on stainless sheet and it did a lovely job.

Rik

[Rik ShawParticipant @rikshaw]

"bearings riddled with holes"

​That sounds like OILITE to me.

[jaCK HobsonParticipant @jackhobson50760]

I think your fish scaling is scraping, as capnahab suggests.As you say, the bump flakiing is a pattern advised for retaining oil. I've had a go at scraping to get surfaces flat and this leaves a pattern more like mother of perl.

There are lots of good resources online including a whole book on making maching tools accurate.

The pic comes from http://www.circuitousroot.com/artifice/machine-shop/surface-finishing/hand-scraping/

 

Some of the other terms get overused which makes it difficult to identify what someone means when they say damast or engine turning.

I personally reserve engine turning term for patterns cut into the surface on an engine turning lathe or a straight line machine. (Anyone who wants a go on a straight line machine can come to Soper Hall 9/4/2016 at the open day I've been spamming people with). The range of patterns is almost unlimited.

I use the term 'spotting' for the circular finish patterns made by abrasives – such as the rubber technique mentioned above. Snailing on wheels. Don't know what to call the finish that looks a bit line milling.

I avoid damast unless I want to enjoy an argument. It can mean any surface pattern that emulates the watered pattern on old sword. I prefer to use wootz partterns (contrast between different crystal structures within a singe metal composition) or pattern welding (contrast between layers of different metals).

 

 

 

 

Edited By jaCK Hobson on 03/04/2016 09:50:15

Edited By jaCK Hobson on 03/04/2016 09:51:20

[Nick_GParticipant @nick_g]

.

Thanks for the advice guy's.

I 'was' considering it for the top of the mounting base for the Hoglet based engine I am building.

I did however make this initial post quite late last night after I had just finished the platform. – But 'in the cold sober light of day' I am thinking along the lines of Michael Gilligan that it would look quite vulgar and a bit OTT.

Many thanks for the replies. I can if done well and in sympathy of the application look very effective in addition to being practical. ………….. But on second thoughts I don't think my initial idea for the base was one of them.

Cheers again, Nick

[JasonBModerator @jasonb]

Posted by Nick_G on 03/04/2016 09:55:24:

But 'in the cold sober light of day' I am thinking along the lines of Michael Gilligan that it would look quite vulgar and a bit OTT.

Just right for an American inspired engine then

[Nick_GParticipant @nick_g]

Posted by JasonB on 03/04/2016 10:11:33:

Just right for an American inspired engine then

.

You have a very good and valid point there Jason.

On reflection I think I will try and source some Mickey Mouse or John Wayne wallpaper and just stick it to the top of the base. ………… Should look 'cool and radical man'

[AjohnwParticipant @ajohnw51620]

I think Michael is correct – often vulgar Nick, especially in relationship to the object shown in the link. If some one has a drill press with an extremely flay surface it can be use to correct minor surface departures from flatness.

I'd better stop away from it, scraping and oil pockets arguments but often get tempted.

John

–

[Russell EberhardtParticipant @russelleberhardt48058]

It has it's place:

Russell

[Michael GilliganParticipant @michaelgilligan61133]

If that's yours, Russell … We may have to pay to read your posts 

**LINK** 

^^^ sourced from here

MichaelG.

Edited By Michael Gilligan on 03/04/2016 16:39:53

[John HinkleyParticipant @johnhinkley26699]

I just dug out an old engineering book that belonged to my father. It was a fifth reprint in 1939, but it gives an interesting insight into the engineering world of the day when stuff was big – really big! Anyway, there was this snippet about scraping and what they called "frosting". Hope it doesn't take up too much space.

And, just for fun…..

Is this a small man or a huge micrometer?

John

Edited By John Hinkley on 03/04/2016 18:11:53

[MWParticipant @mw27036]

A small man would be a midget, if he had short arms and legs he'd be a dwarf.

And a huge micrometer is hard to use to say the least. you'd need a ladder just to twist the barrel. Why did they build that? surely it would've been easier to atleast make it a floor fixed gantry with some steps going up to the top to operate it. 

Michael W

Edited By Michael Walters on 03/04/2016 22:42:01

[John ReeseParticipant @johnreese12848]

I have never been a fan of engine turning. I think it makes an object look cheap. After seeing photos of the bugatti I may have to reconsider….

[John HinkleyParticipant @johnhinkley26699]

Michael W – to answer your question – "Why did they build that?" – and at the risk of hijacking this thread with lots of photos – presumably to measure something like this ………

Unless, of course, the factory is located in Middle Earth.

John

[Brian HParticipant @brianh50089]

As apprentices many years ago, we had to make our own scrapers out of old files and once the foreman was happy withe quality of them, we had to learn how to use them. The company made large industrial and marine engines with journals in the 10" to 15" range. We weren't allowed to practice on bearings that were to be fitted at the works but instead we scraped in bearings that were to be supplied as spares.

These were scraped in to a mandrel with a thin film of red lead and when to size we had to scrape a criss cross pattern that, we were told, would retain enough oil for initial starting. This criss cross pattern had to look really good as this was what the customer saw on receipt.

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