Proper Way To 'clean Up' A Surface Gage...surface?

[whiskylogic]

I recently picked up a used Starrett surface gage (257?), and while it appears to be in really good condition for the price I paid, there are some nicks and corrosion significant enough to catch a fingernail.

I did a little searching around the forums, but I couldn't find anything about cleaning up the surface of a surface gage - mostly just ways to chemically remove oxide from tools in general.

So does anyone have a proper method for cleaning up the surface? My first instinct was Scotch-Brite, but I'm suspecting that won't do much for the roughness, even if I remove the oxides.

My second thought was a quick lap with >1000 grit wet/dry laid down on my surface plate - however, given that it's a Starrett surface gage, and a Grizzly surface plate, I think I might do more harm than good with that approach.

My last thought was a quick stoning with a fine India or Arkansas stone, but again, I'm not sure if I'd be doing more harm than good.

I've attached a picture (below) of what I'm talking about. It's minimal, really, but worth tending to - and I'd like to do it right.

Advice?

Thanks!

 

[westsailpat]

I would go with your last thought and then your 2nd. thought . From the pic. it doesn't' look like anything really nasty is going on (nice pic by the way) How does the bluing look ? Really all you want to do is get off any burrs' . But a nice polish with 1,000 would be nice .

 

[wawoodman]

I like #2, as well.

 

[Hawkeye]

The stone may not be perfectly flat. I'd use the 1000 over the granite, but only enough to get rid of the ridges.

 

[Ulma Doctor]

a stoning would not hurt.
if it is really bad...
i would go ahead with lapping the surface gauge.
i use dollar store windex and a quality brand of wet/dry sandpaper
you are free to go as fine as you like, 1000 is very fine
high points are the only areas of concern.
after your lapping operation, clean your plate thoroughly, and then clean it again.
add some blue and blue up the surface gauge.
IMHO ,if you get 85-90% contact, call it good and move on.

 

[chips&more]

I would NOT use any type of abrasive. I would just clean the rust stains with Evapo-Rust. Then, if your surface plate (SP) has sides with enough surface area and flat. I would lightly run the gage bottom with oil along the side of the SP. You will see shiners noting your progress. STOP this process as soon as it looks half good and just use your gage. Using it properly will get it even more condition and still retain the original factory lapping look on the bottom. I have tried all types of cleaners on my SP’s. They all work, but the Starrett brand cleaner works a little better…Dave

 

[Bob Korves]

I have two surface gages that I scraped in. One is an old Starrett one that is quite hard steel. It still scraped well enough to get it flat, using a carbide scraper. I do not think I would lap it, too easy to wear the corners more than the center and end up with a surface gage that rocks. A rocking base is the problem that both of my surface gages had, and lapping is not the best way to correct it. A surface grinder would also work.

 

[rgray]

I second Bobs thought on whether it is flat or not. Be sure to check that it is indeed flat and does not rock on the surface plate.
I have bought lots of those used and some times the bottom looks fine but is no longer flat. The rusting could be the least of your worries.

 

[Bob Korves]

I am pretty sure that they rock from "lapping" occurring during use on the surface plate. It is easy to test for by mounting a tenths indicator and indicating against the surface plate itself or an angle block. Move the indicator around to check all four corners and sides. Just tapping down on top of the corners and sides with a finger, while the base is resting on a surface plate in current calibration, will tell you quickly if you have a problem.

 

[whiskylogic]

(nice pic by the way)

Haha, not sure if sarcasm... I have a $40 Windows phone, does everything I need - moderately well - including mediocre pictures...

How does the bluing look ?

Looks better in person, but again - my phone camera leaves a lot to be desired...

I have two surface gages that I scraped in. One is an old Starrett one that is quite hard steel. It still scraped well enough to get it flat, using a carbide scraper. I do not think I would lap it, too easy to wear the corners more than the center and end up with a surface gage that rocks. A rocking base is the problem that both of my surface gages had, and lapping is not the best way to correct it. A surface grinder would also work.

That's exactly what I'm afraid of - and why I didn't just 'dive in' and lap it. I feel like there are too many variables, and that Starrett + rust > Me & Grizzly + 1000 grit...

Unfortunately, I bought this used to go with my Alina No. 88 (.0005") and my Grizzly surface plate for checking out and scraping in my import mini lathe (Grizzly G0765 - which, incidentally, continues to shock me with just how horrific the quality is), so I don't have anything of higher quality to check it against.

I have access to a large quality surface plate and an Interapid .0001" at work, but the guys in the QC lab don't exactly take the best care of them, and I have nothing to clamp it in.

Trying to get set up with some basics of moderate-to-good-used quality tooling. Seems I always need something to check out the thing I'm using to check out other things...