Granite Surface plate

[okdirt]

I was in Tulsa the other day,picked up a surface plate to save the shipping. Now I have a question, will Prussian Blue stain or hurt it?

Elements of Machine Work describes the process of marking a flat surface for scraping with an Iron surface plate and "RED LEAD". So what is Red Lead? I was taught to use Prussian blue.

[GWIZ]

Don't know.

The general purpose black surface plates that the morons used in the shop, went thru hell and I never seen a stain.
No not me.
Any damage that I seen was from dropping something on them, hi impact chipping.
I did use MEK to clean them at one time, that's strong stuff and no problems.

On the other hand maybe they changed the material, try your blue on one of the sides of the plate.

Did you get a pink plate ?
I just have this blue stuff in the picture, standard for machine shops.

[midmosandblasting]

When the guy comes in to certify the surface plate he will clean with methyl or ethyl alcohol .The way they resurface those things is neat. Diamond dust and straight piece of steel.

[moe1942]

Granite is porous so it will stain. Just ask anyone who has stained a high dollar counter top.

Why would you get the prussian blue on the plate? When applied to metal it dries very quick. It doesn't rub off that easy.

Anyway. if you get it on surface it isn't going to affect its intended purpose.

[precisionworks]

So what is Red Lead?

The best high pressure lubricant ever invented ... banned by the EPA only because it was toxic to human life The fancy name was Red Lead & Graphite in Mineral Oil (RLGMO).

A granite flat is not typically used as a scraping reference. Wide 'camelback' straight edges are used to determine contact. For a photo of one, click here.

[moe1942]

Originally Posted by precisionworks

The best high pressure lubricant ever invented ... banned by the EPA only because it was toxic to human life The fancy name was Red Lead & Graphite in Mineral Oil (RLGMO).

A granite flat is not typically used as a scraping reference. Wide 'camelback' straight edges are used to determine contact. For a photo of one, click here.

Barry, I remember white lead. Used to put it in the little reservoir on the tailstock. Does that make me older than red lead??

[jpill]

Originally Posted by moe1942

Why would you get the prussian blue on the plate? When applied to metal it dries very quick. It doesn't rub off that easy.

Moe are you talking about hard blue or soft blue? We call toolmakers die at work hard blue, it comes in a spray can and when dry is hard to wipe off used for layouts. The prussian blue we use is what we call soft blue one drop of the stuff on you and you will have it everywhere. We use it for contact checks on gearing it doesn't ever dry.

[moe1942]

Originally Posted by jpill

Moe are you talking about hard blue or soft blue? We call toolmakers die at work hard blue, it comes in a spray can and when dry is hard to wipe off used for layouts. The prussian blue we use is what we call soft blue one drop of the stuff on you and you will have it everywhere. We use it for contact checks on gearing it doesn't ever dry.

I used prussian blue. Don't know if it was hard or soft. Layout dye is all I know. Ours came in a small can with a wool dauber like shoe polish.

Similar to John Wayne toilet paper. Hoped you lived long enough for it to wear off.

[GWIZ]

Originally Posted by moe1942

Why would you get the prussian blue on the plate? When applied to metal it dries very quick. It doesn't rub off that easy.

Here you go.
Non drying, Prussian Blue in a tube.

See picture.

[jpill]

About the only scraping i have done myself is babbited bearings in high speed gear units. It was only for final fitting to get full contact across the bearing, usually only to take out a slight taper after the bearing was bored.

I have seen older mechanics here hand scrape machine ways and tables during rebuilds it definately is an art.