starrett pink

No, but it could make you red and sore....

Remember folks, to please practice safe surface plate play....

Jim

On Tue, 07 Dec 2004 00:44:00 GMT, Charles Morrill calmly ranted:

Don't rest your hot, terribly oily hands on the surface. It voids the warranty and puts it out of tolerance by many, many tenths. Watch the humidity and temperature of the shop, too. 42% at 72° +-0.1%/°

And whatever you do, don't let any metal come into contact with that precision surface. It'll scratch it.

(Whirrrrrrrrrrrrrrrrrrrrrrrrrrr. Click! Kerplunk!)

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Watch out, your wife might want a large one to pound bread on. Or counter tops!

Last time I looked, quartz is harder and will cut steel.

Best be careful anyway. One must lay steel on it to measure, set the cast iron base of the measurement instrument on it also.

Martin

Don't put your money on that one.... I put a lot of Crystal Pink in cemeteries across NC and VA, before Starrett bought the quarry. You can pop off pieces and scratch hell out of it with a pinch bar......

On Tue, 07 Dec 2004 06:08:59 GMT, "Martin H. Eastburn" calmly ranted:

You don't GROK facetious irony, do you, Marty? ;)

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I worked at a big place that slowly went downhill in the pre-1985 oil slump. Lots of things went in company auctions. I got a lathe and mill myself.

But one day, I saw this irate fellow staring at a black granite, 3X4 ft surface plate, wondering how he was going to get it home. His wife had just bought it, thinking it would make a nice coffee table. (She was right!!)

Oh, it would be perfect, if it didn't go right through the living room floor! Hmm, a 3x4' plate would be 4" minimum, probably 6" if a Starrett inspection grade or better. That could be over 750 Lbs, not counting the legs. I think things like that are a lot safer if placed on a concrete slab floor, especially the way they build houses now.

Jon

Actually, I doubt that a wood floored house would have a problem with

750 lbs. Most Texas houses today have slab floors anyway. brownnsharp

That would be roughly the weight of a baby grand, no?

Ack, no basement.

Best regards, Spehro Pefhany

Sounds like the pinch bar is a cobalt grade or molly or both material for strength.

The 1-10 is Mohs Hardness Scale - that of rocks and minerals. The testing kit below :-) has knife blade at 5.5 and steel file at 6.5. Notice in the first table Quartz is 7. So the bar was harder than a steel file. Not common 'steel' but a hard, strong, not brittle steel.

Martin

I went to lunch one day at a 'sub' house, but parked out behind it. Across the alley was a MECH shop. They either just bought second hand or moved out the old one or needed space... The slab was maybe 48 x 144 x 12 or more. That was a monster! I suspect a special made for the shop / job. It looked in good shape, but dusty on the sides. Just out in the sun.

Martin

Hey, makes perfect sense to me - but I'm single, what do I know? ;-P

You leave the surface plate inside in the living room as a coffee table, where it's temperature controlled and reasonably protected.

And when you need to measure something you take the big Coffee Table Book (Y'know, "The Illustrated History of the Automobile") and the Vase with the Silk Flowers off the coffee table and plop your part and gages down on it.

"It's Okay, Honey - I'll have the part back in the garage and the table wiped off in time for your bridge club on Friday..."

(Yeah, Right, Sure... World War Four erupts in three, two, one...)

-->--

To further muddy the waters, I would point out that starrett's pink plates are not made of pure quartz. The white stuff is quartz, the reddish stuff in between is, I think, plagioclase.

The quartz forms accurate high spots, the pink stuff is a bit lower and softer - this gives the nice feature that flat items don't wring to the surface plate.

Jim

Yeah, but granite is a mixture of quartz and feldspar. Proportions vary so hardness varies.

--RC

Projects expand to fill the clamps available -- plus 20 percent

Sometimes the colored stuff is even tougher - e.g. sapphire and garnet and feldspar ... Have a Minor in Earth Science. Simply calling it Pink Granite is fine for metal, but is like a pink car or ... not complete.

But the area of 'pink' should keep out most lever bars unless a point is used... Compression scars are possible where the tough material is compressed into lesser material.

Martin