Surface and machine finish standards

[oldtiffie]

There is a lot of mention of surface finishes with little or no mention of standards and/or references. One persons "good" finish may be another's "poor/mediocre" finish and another's "super finish".

OK, I'm stretching things a bit - but I hope you "get my drift".

Not surprisingly there are a range of defined finishes, each of which is perhaps most effectively obtained on or from a relatively small range of machines out of a much rather range.

Each or most processes have defined finish range as well - ie milling, turning, grinding, lapping etc. etc.

When I was an Apprentice and later - 50+ years ago - we had surface finishes specified/prescribed on shop drawings. We had "scratch blocks" as standards. We would just simply scratch our work and then the standard blocks with our finger-nails - just like scratching your finger-nail over a vinyl record. It is surprising how accurate your "feel" is in this regard. We had tolerance ranges/limits for surface finish as well - just as we had for everything else on those shop drawings.

You will see surface finish defined or "called up" everywhere from finishes on engine crank-pins, pistons, roller bearings etc. - the list is endless.

I have been looking for a set of those blocks more intensely of late. All I could find on the web were electronic devices which were/are VERY expensive and not what I wanted. I happened to see them listed in my local Mitutoyo distributors catalogue and onto the phone I went and ordered one there and then (US$200!!!! - but to me - worth it). I happened to mention how scarce they were to the Technical Rep and he said they are always just walking out the door in the Industrial area in which he works.

Needlers to say there are essentially two sets of standards - the USA and the rest of the (metric) world.

This original post (OP) will consist of this text plus 7 pics over two successive posts.

The 4 pics of the test pieces and the 3 pics of the explanatory text should do most if not all of the explaining necessary.

I have no idea where the "rusty" "cast" on the first the pics came from.

So off we go.









Now onto the next post.

[oldtiffie]

[MCS]

Just found the book, have'nt found it on their site. www.Schut.com

One producer is Microsurf.

They make 9 sets, for all kinds of grinding and machining. Each set, containing 8 samples 87 euro.

They also have a wallchart, for 8 types of machining, 8 samples each, 638 euro.

Also another set "Composite 130" consisting of 30 samples, 6 types of machining, 170 euro.

References don't come cheap.

Edit: found it in their online-catalogue,

http://www.schut.com/catalog/en/en_0366.html
http://www.schut.com/catalog/en/en_0367.html

[gmatov]

So how much is an actual Profilometer? IF you can use one, it will be a little bit more certifiable than "I scratched my nails across it. It is Certified 4 microinch finish."

I gotta admit, I thought you were going to talk about the finishes you can get if you know what you are doing.

I am disappointed with this posting.

Cheers,

George

[tattoomike68]

LOL I have worked in an inspection lab before, we had a little unit that cost a pile of money like this. About half the size of a cell phone for $1,800 , you drop it and you were fired.



http://www.gagesgalore.com/Fowler/Pocket_Surf.htm

Like others have said , you can use a finger nail as a test for a whole lot less money. Shops that can afford surface gauges can afford burnishing tools.

At home I use a file and emory cloth I can get a 4-32 micro Finnish with that.

[Peter Neill]

Of course, if you're a lucky bugger like me, you have one of these in a nice little box tucked away in the workshop:



A Bowers Metrology rep came into my old company about 4 years ago to discuss the purchase of a larger Talysurf tester, and left us this neat little portable tester on trial, complete with a Moore & Wright presentation box with reference standards and other bits and pieces. This worked so well that we never bothered to buy the larger Talysurf, and the rep just forgot to come back and pick this up

Then when we closed that business down just over 2 years ago, this tester managed to find its way into my new business, together with one of these:
http://www.visioneng.com/kestrel_overview.php

Some people have all the luck eh?

Peter

[Bob G]

Try MSC Bigbook Pages 1431 & 1432.

Have Fun,
Bob G