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 Post subject: Preforming tips_Use a cabbing wheel or the lap
PostPosted: Wed Nov 04, 2020 2:57 pm 
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I usually just cut my stones on the lap and don't really preform them. On stones 6mm and up it seems like that increases the time spent on the stone quit a bit.

I was wondering what other cutters do.

Question: Do you preform on a vertical cabbing lap or try to shape it freehand on the flat lap on your machine or just cut it from scratch and not worry about preforming.

If you use a cabbing type lap what diamond grit do you use?

I am looking at cutting the amount of time it takes to cut a stone and this is one area that seems to add a fair amount of time.

Thanks in advance--Randy

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 Post subject: Re: Preforming tips_Use a cabbing wheel or the lap
PostPosted: Wed Nov 04, 2020 3:52 pm 
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I preform all stones before cutting. Preforming is where you solve problems in the rough, establish shape and dimensions.

When I have a large stone that needs to have a lot of material removed I use my Pixie cabbing machine and one of the two coarsest wheels.

When it is expensive rough I usually do it on my faceting machine with either a 260 or 600 grit lap.

Preforming makes dopping much more accurate. It speeds up cutting time a great deal.

Preforming is where you save and make all the money when cutting stones.


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 Post subject: Re: Preforming tips_Use a cabbing wheel or the lap
PostPosted: Wed Nov 04, 2020 7:13 pm 
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I have to say that 99.9% of the time I preform, like Steve addressed preforming allows time to deal with and plan the cutting. How much time invested in the preforming depends on each individual piece. I can say that outside of placing a virtually flat temp table on a piece I use a 600 Sintered 5/8" wide wheel on a arbor, if need be I will trim with a 4" saw then proceed to the arbor. I find with my fat fingers and aging eyes I can still manage with sizes down to 5-6mm. But fading away fast. Then there comes the question of just how much time to invest in the complete process of finishing a faceted gem. Well that question has plagued the faceting arena for a long time. Well who was, who is the fastest faceter ever officially recorded, I've heard chatter in the past that there are some that can roll off a SRB in under 30 minutes, I can see that in a single cut round buttttttt I don't know from start to polished finish and a somewhat decent looking job.
I find that if you find methods that will trim time at each step can help. Dual-Banded laps, polish as you go can help.

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 Post subject: Re: Preforming tips_Use a cabbing wheel or the lap
PostPosted: Wed Nov 04, 2020 7:25 pm 
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Depending on the polish needed it is very normal to cut a 1 carat or under size RBC in an hour. This assumes you only need a 14K finish on the polish. This is the standard in production cutting. To do this, the only facets that are cut and then polished in two steps are the mains top and bottom. The stars and girdles are cut/polished in one step on a fast turning 14K charged copper or iron lap.

The time above considers that one person is handling all operations on the stone. If your are cutting in production teams it is easy to get time actually spent on each stone to under 30 minutes each.


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 Post subject: Re: Preforming tips_Use a cabbing wheel or the lap
PostPosted: Thu Nov 05, 2020 1:36 pm 
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Steve and Glhays: Thanks to both of you for your quick replies and good ideas and info.

Question for Steve: At about what size rough would you use your wheels rather than your machine to preform?

Question for both Steve & Glhays: Regarding your 1 hr. SRB-Does that include a rounded girdle and not a faceted girdle?

I was taught to cut with a faceted girdle but think I need to switch to a rounded girdle as it must be much faster.

Of the different steps required in cutting a SRB, I was wondering where the most time savings would be.

I would think preforming and rounding girdle would offer the most time savings, is that correct? Maybe the 14K polish would be next. I may start trying that and also use 14K on the pavilion and 3K/100K on the crown only. I have always thought it was kind of a waste of time to do a super polish on the pavilion anyway as I don't know if there is any optical benefit for that. If there is, please correct me.

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 Post subject: Re: Preforming tips_Use a cabbing wheel or the lap
PostPosted: Thu Nov 05, 2020 4:40 pm 
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First what are we talking here? All species or certain species of gemstones.

I haven't got a 1hr or less cutting process, I do not disagree that it can't be done.
I am not a fan of faceted girdles on most shapes and that's just my preference. Does it save time? How much time do you spend on a faceted verses a rolled would be for you to figure out in your setup and style. Try doing a couple of SRB 6-7mm stones and time for your self.

Gaining experience is your best spent time in making your self more proficient with the time spent on each stone. Not all gems are created equal in all ways, but all gems have a beauty to expose.

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 Post subject: Re: Preforming tips_Use a cabbing wheel or the lap
PostPosted: Thu Nov 05, 2020 8:40 pm 
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deanins wrote:
Steve and Glhays: Thanks to both of you for your quick replies and good ideas and info.

Question for Steve: At about what size rough would you use your wheels rather than your machine to preform?

Question for both Steve & Glhays: Regarding your 1 hr. SRB-Does that include a rounded girdle and not a faceted girdle?

I was taught to cut with a faceted girdle but think I need to switch to a rounded girdle as it must be much faster.

Of the different steps required in cutting a SRB, I was wondering where the most time savings would be.

I would think preforming and rounding girdle would offer the most time savings, is that correct? Maybe the 14K polish would be next. I may start trying that and also use 14K on the pavilion and 3K/100K on the crown only. I have always thought it was kind of a waste of time to do a super polish on the pavilion anyway as I don't know if there is any optical benefit for that. If there is, please correct me.


It is not about the size, but the value of the rough and the amount of material I have to remove that determines my preform process.

I cut on a Facetron using the dial indicator. This enables me to get perfect symmetry and fast cutting using a faceted girdle.

A 6mm round preformed to within 1 to 2 mm of finished diameter should take only about 5 minutes to cut a faceted girdle.

The bulk of the remaining stone removal takes place cutting the girdles, I cut the 16 girdle facets on the numbers and the 6s with a 600 grit wheel. Using the gauge, and keeping the faceted girdle lets me cut a perfectly straight girdle line by lining up the depth of cut.

I then switch to my dual zone, sintered/60K wheel. Another quick trip around the girdle facets where I take the scratches out and polish in one trip around.

Next I cut in the 8 mains on the numbers plus 3. I cut them in on the sintered outer zone, and polish them on the inner zone in one pass.

During cutting of the mains I must know whether I want a rounded girdle of faceted girdle in the finished stone. If faceted I leave the mains just a tiny hair undercut to leave room for rounding the girdle later. If facets girdle is the goal I take the mains right to the girdle line.

The pavilion is then done.

A quick glue job in the transfer jig, and I am off to do something else while the glue dries. When it is ready, I remove the dop from the table with heat and I am ready to cut the crown.

The crown goes much the same way.

First the girdle facets on 600 to remove material and establish a nice thin straight girdle..

Then the two zone lap to polish them.

At this point if I am going for a rounded girdle (my norm) I remove the dop from the quill and hand spin the girdle on the outer zone of the sintered lap. Can be done in about a minute. I do this at this point so I can cut the mains to exactly the girdle line.

Then cut in the mains and polish in one go on the dual zone. If I want unstacked mains I cut on the numbers plus 3 again. If stacked mains the numbers minus three.

Next the stars are cut and polished 1/2 way between the mains (numbers plus or minus three opposite the mains).

Finally the table. If the stone was epth challenged I will have already ut the star meet points to where they need to be so only have to polish the table. If there was extra depth available I will need to cut the table down to the star meet points then polish.

The sintered lap leaves a fine enough finish on the girdle for me. If it is rounded I may take it to the polish wheel on my cabbing machine to final polish. Almost instant.

The stone is now done and goes into the Acetone to come remove the dop.

If it is an easy species, and/or cause no problem it is a pretty common to finish within an hour on the machine in a 6mm size. If you run into issues with polishing, splinering, or surface reaching inclusions who knows how long it can take.


With this system i find that most of my students can cut their first stone (usually a 15mm quartz of some type) in two, 2 to 3 hour classes, and achieve great results. These large quartzes aren't cut with a two zone polishing method. So it takes longer. There is an extra lap and prepolish step. I would let them near my two zone sintered lap for sure. No way, that thig is gold to me.

My goal is to teach my students how to cut like this in any shape, and with a variety of facet patterns without the use of diagrams. Most reach this point in their first year. Some will never get there however.

I hope you can visualize my process from this description, and it gives you ideas.


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 Post subject: Re: Preforming tips_Use a cabbing wheel or the lap
PostPosted: Sat Nov 07, 2020 2:31 pm 
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I don't agree that the money is made in preforming.

I think the money is made in wise rough buying, and marketing of the finished stone.

A stone 3 to 5% larger won't bring in the return that selling at a higher price can. I see people who have done a great job of marketing Montana Sapphire, and are selling Montana stones for not very good color for over $1000 per ct in 1 to 2 ct sizes. These same stones I would normally sell for $250 per ct. So what difference is there if say Steve cuts the stone with his methods and gets a 1.49 ct stone, and a better marketer cuts it and gets 1.2 cts but sells it for 4 times the price per ct.?

I see the same thing with lab created stones. Same material, some are getting $175 per ct, others 70 per ct.

As far as buying rough wisely, a cheap junk piece of rough can only at best result in a perfectly cut cheap stone.

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 Post subject: Re: Preforming tips_Use a cabbing wheel or the lap
PostPosted: Sat Nov 07, 2020 2:36 pm 
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Randy, about polish, I use a dual charge Batt lap for most stones with 8000 on the outside and 50,000 diamond in the center. For a typical 6 or 7 mm round with out issues, it's no problem to cut the stone in 1 to 1.5 hours. I dop with wax and transfer into epoxy, so I'm considering the time for the epoxy to cure as that's not really working time. I'll usually one day cut a few stone's pavilions, and then the next day cut all the crowns.

Sure you could save a little time by leaving the facets with an 8000 polish, but your eye can see the difference, even if you only did this on the pavilions. A properly charged 50,000 so put a finished polish after 8000 in only a few seconds per facet.

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 Post subject: Re: Preforming tips_Use a cabbing wheel or the lap
PostPosted: Sat Nov 07, 2020 6:43 pm 
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Thanks again to Steve and Glhays for your responses. Glhays advice on timing myself is good and I have done that and the rounded girdle is quite a bit faster but I have found that I don't have anything to cut to-a target so to speak that I have with a faceted girdle so I can get a little confused.

To Steve: Thank you so much for taking the time to write out your procedure for cutting a SRB. That is really helpful. Especially the part about rounding the girdle after faceting it. I was doing one or the other.

Question for Steve: I see you have faceting classes fairly close to me in Huntington Beach, Ca although it sounds like they are shut down due to Covid. How would I sign up for something like that? It sounds like it is just what I need.

Randy

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 Post subject: Re: Preforming tips_Use a cabbing wheel or the lap
PostPosted: Sat Nov 07, 2020 6:53 pm 
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My statement on performing was not meant to say that it is the most important part of the gem business overall. Sourcing, marketing, and business structure, relationship building, and acumen, are the keys to being successful in any enterprise including the gem/jewelry business as Gene properly points out.

My position is that in the cutting processes itself, the decisions you make when preforming, and the talent you have. It is most often where you maximize the potential, and value of a given piece of rough.

Performing cannot make a bad business good. Great business skills can easily overcome weaknesses in preforming. Preforming is not an "always", or "only" skill.


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 Post subject: Re: Preforming tips_Use a cabbing wheel or the lap
PostPosted: Sat Nov 07, 2020 6:55 pm 
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Precision Gem: Thanks for your input. That's something I never thought about as I always figured there is the market and not a lot of variance in price.

It would be interesting to find out what type of marketing would let you sell a stone for 4 times the basic market rate. They must have a huge supply of gemstones to pick from or something going for them.

I use a diamatrix lap with 3K on my Batt part and 100K Blakstick on my Diamatrix so I am using a double lap.

I have resisted only using prepolish on the Pav facets just because like you say it doesn't take long and I notice the difference.

I think my biggest problem is to stop looking so much as it adds a lot of time to cutting a stone.

Question: Do you cut mains in first on the Pavilion & Crown or the Breaks? I was taught to cut the Breaks in first but think doing the mains first could save me some time also.

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 Post subject: Re: Preforming tips_Use a cabbing wheel or the lap
PostPosted: Sat Nov 07, 2020 7:42 pm 
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Randy, I cut with a GemMaster II, so very little looking once you have the first facet in a tier cut. I have an Ultra Tec 5 also, but find the GemMaster much more accurate and faster to cut on. Another time saver I do on the GemMaster but not on the V5 is I cut the table at 0 degrees, so there is no time spent putting the stone in the 45 degree adapter.

As far as market, much can be are you selling wholesale or retail. I have a friend with a family jewelry store, where they cut most of their own stones. They can sell a stone for three times the price I would get. Also some people have created sucessfully the aura of higher quality and higher quality cutting. For then, they can cut something identical to what you may cut, and get 1.5 times or more than what you or I are selling at.

On a standard round, I would cut the breaks in first.

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 Post subject: Re: Preforming tips_Use a cabbing wheel or the lap
PostPosted: Sat Nov 07, 2020 9:46 pm 
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You can only learn from the advice being given here.

I wouldn't get to hung up or fooled by the $ amounts given in this thread that is for sure. You will not get the exceptional rough spoken here at decent money making prices these days. This to has been debated many times here on the GO board.

My wife and I have and still own and operate a jewelry buisness for many years, we create custom jewelry and provide custom cutting, I find each customer looking to go with colored stones in their jewelry can be very different on what they see as a worthy purchase in colored stones. Many are just as happy buying a low cost, ok cut commercial stone off eBay. Average customers with budget restrictions I find would rather cut out the cost of custom cutting or previous custom cut inventory when added to decent gem rough like emerald, ruby and sapphire. We also find that knowledgeable folks may decide to go the synthetic route first and I typically will not get more than 30-40$ a carat after cutting, no where close to Gene's numbers. Synthetic rough selling for pennies and nickels a carat, your labor cutting investment do not pay a healthy return. Maybe if we all just give up the biz others may get those high$ per carat prices.
I have always found you can ask for the moon but just because the GemGuide publishes that the industry believes Montana blue sapphire 1.00-1.69ct. stones should get you from 250-1,000 p/carat, you will need buyers at these rates. Yes if your one that purchased rough back before the market on a given species became highly sought after, and you do not need to let it go for less than what the few industry markets state. Then that someone can hold out for stated rates. For someone thinking they can run and get a 3 carat Montana blue sapphire tomorrow at a decent price(?) and go back and run it thru the 1 hour speed facet and then just turn around and sell it for $1500 is very unlikely. Randy, maybe as an experiment see if you can find that 3ct rough, cut it as fast as you can while still doing a decent job. Then offer it to Gene for $1000.00.

Back to the cutting, do you find yourself with the 100k spending more time on then the 3K outer? If so you may rethink going to 50-60k.
Or take Genes recommendations and go to 8k instead of the 3k, although you have already designated as 3K so that would be an investment into another lap.

Yes Breaks first, establish the girdle line and cut in the mains. Like Steve said on smaller stones you can place the mains with a 3k or 8k no need to cut just pre-polish them in.

I too like Gene stated can cut the table directly from the quill at 0 degrees with out a table adapter on the Scintillator. Just need to be a little bit cautious of potential chatter as both the surfaces perfectly perpendicular to each other and your holding the quill differently then you are in the 45 degree adapter.
It does save some time.

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 Post subject: Re: Preforming tips_Use a cabbing wheel or the lap
PostPosted: Sat Nov 07, 2020 10:06 pm 
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Randy,

Did you ever post what kind of machine you are cutting on?


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