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Author Topic: Bornite copper malachite  (Read 443 times)

Iacopo

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Bornite copper malachite
« on: September 11, 2018, 03:52:24 AM »


This is a beautiful material which can be used for making tops;  it is not hard, (Mohs hardness 3), it can be turned on the lathe, and becomes very nice when it is polished.  The green parts are malachite, the golden parts are bornite copper. 
The bornite copper is partly transparent and there are reflections in it that change depending on the direction of the light.



I used this material for my latest top:



This top, (Nr. 36), has the same design of the Nr. 35;  the tip is a 3/16" ball and can be replaced with a new ball when it is weared.
Balls of whatever material can be used.  The tip is external, (not recessed), so the top can spin on flat surfaces.
The grub screws in the flywheel allow for a perfect balance of the top.
Spin times up to 20 - 25 minutes.
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Iacopo

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Re: Bornite copper malachite
« Reply #1 on: September 11, 2018, 07:46:06 AM »

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Jospin

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Re: Bornite copper malachite
« Reply #2 on: September 11, 2018, 10:59:03 AM »

That looks amazing!
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Iacopo

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Re: Bornite copper malachite
« Reply #3 on: September 11, 2018, 11:35:25 AM »

Thank you, Jospin.
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ta0

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Re: Bornite copper malachite
« Reply #4 on: September 11, 2018, 11:43:37 AM »

Gorgeous!  8) 8) 8)

I think I know what I want this Christmas . . .   ;)
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Christop

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Re: Bornite copper malachite
« Reply #5 on: September 11, 2018, 12:58:33 PM »

Wow that is a stunning top. I have got to get a lathe, lol.
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vegabomb

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Re: Bornite copper malachite
« Reply #6 on: September 11, 2018, 01:59:21 PM »

What a great looking top!
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butterfingers

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Re: Bornite copper malachite
« Reply #7 on: September 11, 2018, 06:08:59 PM »

That's really pretty. I wasn't aware that minerals could be turned on a lathe. How does the hardness compare to the acrylics that are used for pens? Are the two polished with similar techniques? Thank you for posting.
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the Earl of Whirl

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Re: Bornite copper malachite
« Reply #8 on: September 11, 2018, 07:32:46 PM »

Iacopo has done it again.  Very good!
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Iacopo

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Re: Bornite copper malachite
« Reply #9 on: September 12, 2018, 02:40:51 AM »

Thank you for all the good words !

Butterfingers, acrylics are softer and easier to turn on the lathe, but stones too can be turned, if they aren't too hard.
I had been able to turn turquoises, (Mohs hardness 5 - 6), using a sharp carbide blade on the tool post.
Stones are generally a bit abrasive, so I resharpen often the blade when I turn them.
Then I use sandpapers until 3000 or 5000 grit.
In the end I polish the surface with diamond pastes.
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Iacopo

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Re: Bornite copper malachite
« Reply #10 on: September 12, 2018, 09:14:43 AM »

These are the original pieces of bornite copper malachite I got;  I had been lucky because their shape is not far from what I need in my tops, so I hadn't to remove much material.



This is a way how I use turquoises;

I hammer a turquoise in little fragments, then I glue them with cyanoacrylate in a slot I made in the top for them;



When the glue has hardened, I fill the gaps between the turquoise fragments with epoxy resin, (I use a kind of resin that does not turn yellow by the time);



The whole object is then turned on the lathe, to remove the excess of resin and turquoise fragments embedded in it.
HSS blades become dull rapidly when turning turquoise, so I use a carbide blade, and even this last one I have to resharpen often.
Trying to turn turquoise with a dull blade makes the turquoise to become very hot, the resin becomes soft and can change in color, the corners of the turquoise fragments can become chipped, it doesn't work.
I finish the surface with sandpaper and diamond pastes. 



Stones can be turned on the lathe, at least stones with hardness up to 5 - 6.
It takes much time anyway, especially the harder stones, so I avoid to turn large, hard stones on the lathe.
« Last Edit: October 09, 2018, 01:48:03 AM by Iacopo »
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Jeremy McCreary

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Re: Bornite copper malachite
« Reply #11 on: September 18, 2018, 06:11:10 PM »

Exquisite, my friend! Gorgeous choice of materials and finishes, as usual, but this is your best stone insert to date. No surprise that Nr. 36 needed a balancing system given the inlay's inherent heterogeneity in density.
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Iacopo

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Re: Bornite copper malachite
« Reply #12 on: September 19, 2018, 09:41:24 AM »

Exquisite, my friend! Gorgeous choice of materials and finishes, as usual, but this is your best stone insert to date. No surprise that Nr. 36 needed a balancing system given the inlay's inherent heterogeneity in density.

Thank you, Jeremy !  I balanced the top two times, first without the screws, adding and glueing tiny pieces of lead in the bottom of the holes in the flywheel.  Then I used the screws, for fine tuning the balance of the top.
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Iacopo

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Re: Bornite copper malachite
« Reply #13 on: October 08, 2018, 01:38:47 PM »


This is a top I have just finished, same design of my Nr. 23, but with bamboo coral instead of the turquoises:





Video:

https://www.youtube.com/watch?v=uRKO3-OS-B8
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butterfingers

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Re: Bornite copper malachite
« Reply #14 on: October 08, 2018, 02:32:38 PM »

very pretty! Thanks for the description of the process - fascinating!
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