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 Post subject: polishing help - oregon sunstone
PostPosted: Sat Dec 29, 2018 11:44 pm 
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So I did get a faceting machine and I've cut a couple stones on it. And now I am back to ask for help again. I've now been trying to cut an oregon sunstone. I thought I read somewhere that it should't pose too much of a problem to polish on the cleavage of sunstone, but I've been having a terrible time. I've got it cut in an elongated pear shape and one of the pavilion mains is dead on the cleavage plane. Anyway, I got everything good, I noticed two of my facets close to the cleavage were more frosted at prepolish, but thought it would polish ok. One was fine, but the other seemed to scratch and tear out horribly. I kept polishing (trying to have a much lighter touch if that was a problem). There were strange reflective spots that appeared as I went, but did get cut out. When I went back to the other facet to try to even it out, the whole facet started showing a reflective 'layer' and then the whole layer started breaking off. So I polished through this, finally got both facets to polish. Recut every other facet to even it out. Then, I go to polish a facet next to the two original problem facets and the same thing happens.... scratches / pieces, then the reflective layer started to appear and break off...

Well, I'm frustrated. Is this typical, or am I doing something wrong? I haven't tried cutting a stone with cleavage problems before. Will the stone just keep breaking off at certain depths? Or should it polish if I am gentle enough? I'm using a cerium oxide lightning lap.

Thanks for your help


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 Post subject: Re: polishing help - oregon sunstone
PostPosted: Sun Dec 30, 2018 3:14 pm 
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Sounds more like a topaz than sunstone. In most cases reorientation is the only fix. Unfortunately. You can try to lower the angles slightly on the problem facets to possibly get off the clevage. Yes that means some meets will not be perfect.
Greg

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 Post subject: Re: polishing help - oregon sunstone
PostPosted: Sun Dec 30, 2018 6:06 pm 
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David Rilling has worked out a technique of polishing Sunstone that otherwise exhibits "picking" during polishing. He is a member of the Columbia Willamette Faceters Guild. This is a tribochemical method that uses the Lightside polishing lap.

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 Post subject: Re: polishing help - oregon sunstone
PostPosted: Sun Dec 30, 2018 9:34 pm 
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Some fixes from one of the old guys, worked out by even "older-timers"...

In using your Lightening lap and CeOx, reverse the direction of the lap to the facet, by either going to the opposite side of the lap nut, or reversing the motor direction. Can help with near-cleavage [plane orientations.

Add a bit (25% or so) of green chrome oxide powder to your cerium oxide, along with a few drops of liquid dish detergent (sink type).

Lastly, try diamond polish (I use 50k) on a metal lap, tin, Batt, etc.

These are things we would try before adjusting angles. Also, you could replace the single pavilion main with a vertical split main, +/- 1 index from the original, then adjust the other facets around it, good use for GemCad or that newby cutting program...

Good luck!

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 Post subject: Re: polishing help - oregon sunstone
PostPosted: Sun Dec 30, 2018 10:29 pm 
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I have found that a Spectra lap works well on Oregon Sunstone that otherwise presents problems polishing. Light pressure on the facets that are causing you trouble.

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 Post subject: Re: polishing help - oregon sunstone
PostPosted: Sun Dec 30, 2018 11:43 pm 
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Thanks everyone for your help. I only have a few steel cutting laps and some lightning lap toppers, so I probably need to invest in more varied equipment in case of problems like this. It's definitely a sunstone, it has copper schiller in it.

Ok, but now I have more questions...

1. What is the difference between the batt and the ba5t lap? Just quickly reading, it seems like the ba5t makes the facets sharper, but is it harder to use / charge?

2. I hear people like the dual banded laps. I understand that the centrifugal force keeps the coarser grit from the finer, but I don't understand how you don't contaminate the inner part when you move your facet over to polish unless you thoroughly clean the stone every time. That would seem to kill any time saved. (btw - that dual banded twistor I've read about sounds like a great idea)

3. I've been thinking about buying gemcut studio since I have a mac computer. I downloaded it and tried it a few times but kind of forgot about it and now my trial is over. I've never used gem cad before so I was wondering which program people recommend. I know I would have to download another program to run gem cad on my mac. I like how in gemcut you get to see the light performance preview as you modify the stone, which I understand gem cad does not do.

4. Spectra lap is just the film lap they call the ultra lap correct?

Thanks again.


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 Post subject: Re: polishing help - oregon sunstone
PostPosted: Mon Dec 31, 2018 10:34 am 
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I've cut quite a bit of Oregon Sunstone and I've also had issues with this. But, it only seems to happen when schiller is present. I've found that cutting with 1,200 sintered or 600 Nu Bond and prepolish with 8k on Zinc+, then polish with Zirconium Oxide on Darkside works for me every time.

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 Post subject: Re: polishing help - oregon sunstone
PostPosted: Mon Dec 31, 2018 2:31 pm 
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changing the direction of the lap and rapid back and forth motion helps also...along with light pressure.....some times a stationary lap helps or VERY slow speed


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 Post subject: Re: polishing help - oregon sunstone
PostPosted: Mon Dec 31, 2018 3:15 pm 
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A Spectra lap is the mylar film that you use along with your master lap. Wet the master lap a bit and lay on the film, then rub it down until the air bubbles are worked out.

With the dual charged laps, I polish all the facets of a tier on the outside, then wipe the stone clean, then do the final polish on the inside. Dual charged laps save time over switching between a pre polish and polish lap.

I too use Mac computers, and GemCutStudio runs very well on it, I highly recommend this program.

The Ba5t lap is a little harder material than the standard Batt lap, and also a little thicker. Both laps will polish very flat facets with sharp edges. Charging seems to be identical for me.

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 Post subject: Re: polishing help - oregon sunstone
PostPosted: Mon Dec 31, 2018 6:22 pm 
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I highly recommend Gem Cut Studio, it's far more user friendly than Gemcad/Gemray. Not only is it cheaper, it's does what both Gemcad and Gemray do in one convenient program.

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 Post subject: Re: polishing help - oregon sunstone
PostPosted: Mon Dec 31, 2018 8:08 pm 
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As another said, Ba5t is harder. I prefer it to the Batt though it is more expensive.

Spectra Lap is the same as the Ultra Lap film, used the same way.

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 Post subject: Re: polishing help - oregon sunstone
PostPosted: Thu Jan 03, 2019 6:33 pm 
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rattlesnakeagate wrote:
3. I've been thinking about buying gemcut studio since I have a mac computer. I downloaded it and tried it a few times but kind of forgot about it and now my trial is over. I've never used gem cad before so I was wondering which program people recommend. I know I would have to download another program to run gem cad on my mac. I like how in gemcut you get to see the light performance preview as you modify the stone, which I understand gem cad does not do.


I’m the author of Gem Cut Studio. I don’t have any tips for polishing sunstone (I’ve been in your situation before and eventually gave up) but if you need an extension on the software trial, just contact me via email (rej@gemcutstudio.com) or using the contact form on the website and I’ll sort you out, no worries.

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 Post subject: Re: polishing help - oregon sunstone
PostPosted: Thu Jan 03, 2019 7:36 pm 
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Rej, any news on the iPad version?

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 Post subject: Re: polishing help - oregon sunstone
PostPosted: Thu Jan 03, 2019 9:32 pm 
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I appreciate all the responses. I've put the stone to the side for the time being :). Rej, I will definitely take you up on the trial extension.


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 Post subject: Re: polishing help - oregon sunstone
PostPosted: Thu Jan 03, 2019 10:25 pm 
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Precision Gem wrote:
Rej, any news on the iPad version?


Working on it now, but I'm also on holidays and flying between relatives all across Canada so it's slow development. It already runs on ipad but still needs a few final things like pinch zoom and a way to enter number and text fields. Fingers crossed sometime around Tucson, or shortly after.

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