When "Limestone" contains Quartz

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Rcnewcomb
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When "Limestone" contains Quartz

Post by Rcnewcomb »

Lest the newbies on the forum think that those of us who have been doing this for a long time never run into any problems....

Not every experiment will be a success
In the past I've cut limestone, soapstone, and marble. In fact, our first paying job was carving a pair of pheasants into a limestone fireplace mantle. Indiana Limestone is about 2.5 on the Mohs hardness scale. Marble is around 3-5 on the Mohs scale. You can carve it with a Porter-Cable router and a carbide V-bit with only air cooling.

A few weeks back I saw someone giving away free "limestone" pavers. I picked up about a dozen pieces about 12-24 inches per side and about 1.75" thick.

I put one on the table today and tried a very slow, shallow (0.001") cut. As soon as I started seeing sparks under the dust foot I knew to shut it down immediately.

It seems that what my neighbor thought was limestone actually has quartz/quartzite in it -- 7 to 8 on the Mohs scale. :shock:

Lesson learned: Get the material from a stone distributor who actually knows what they have. :oops:

Well, I now know a process for inlaying solid carbide into quartz "limestone".

This is what it does to solid carbide.
IMG_3264.jpg
IMG_3267.jpg
IMG_3268.jpg
- Randall Newcomb
10 fingers in, 10 fingers out, another good day in the shop

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dhellew2
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Re: When "Limestone" contains Quartz

Post by dhellew2 »

Solid carbide bits do a great job of cutting thru metal hold down clamps :oops: :evil: Dale
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garylmast
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Re: When "Limestone" contains Quartz

Post by garylmast »

Been there, done that. :cry: :cry: :cry:

Gary

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newmexico
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Re: When "Limestone" contains Quartz

Post by newmexico »

Ditto on that!

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scottp55
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Re: When "Limestone" contains Quartz

Post by scottp55 »

Thanks for posting Randall!
Yep, pretty easy to test a piece like the Slate in pic with a penny scratch test, and to see the quartz intrusion and stay AWAY from it.
But when the quartz is mixed in homogeneously...VERY difficult! :(
Have some Italian Marble I've thought about, but keep putting off because white streaks need more hardness inspection(low priority:)
scott
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ChiloquinRuss
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Re: When "Limestone" contains Quartz

Post by ChiloquinRuss »

"Solid carbide bits do a great job of cutting thru metal hold down clamps" You must use a better grade of bits than I use, mine always snap right off! LOL Russ
AKA: The Train Guy!

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Rcnewcomb
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Re: When "Limestone" contains Quartz

Post by Rcnewcomb »

Solid carbide bits do a great job of cutting thru metal hold down clamps
So far I've avoided that. I was impressed that one of my Rockler hold down clamps actually stopped my gantry when I had the clamp overhanging the table.
rocklerholddownclamps.jpeg
- Randall Newcomb
10 fingers in, 10 fingers out, another good day in the shop

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