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 Post subject: Darkside issues
PostPosted: Sat May 05, 2012 4:10 am 
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Hi,

My first post, I'm brand new to faceting and was cutting my first stone tonight, everything was going well until I went to polish on the darkside.
As soon as I made one sweep I felt a tic in the lap, thinking I had some speck on it I cleaned the lap and went back again. Same Issue, I could feel the spot with my finger and used a loupe to look for the issue. I found 2 raised area's that look like mfg defects but I'm not sure as I have no idea what a contaminated lap looks like.

I'm using a brand new ultra tec, am keeping everything spotless.

The scratches left in garnet look to be ~.003" wide but deep.
The 2 images are of the same spot, different depths of field, in grayscale to help contrast.

Image

Image


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 Post subject: Re: Darkside issues
PostPosted: Sat May 05, 2012 8:20 am 
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Welcome Nick,
The creator of these laps is a member on here.
I'm sure he will assist in this matter asap to get things sorted, that's the kind of guy he is.
Out of curiosity, did you purchase direct from his site or through other means?

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Keep em comin!!! :)


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 Post subject: Re: Darkside issues
PostPosted: Sat May 05, 2012 8:31 am 
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There are still lathe marks on the lap.
With a water drip, give it a cleaning with an SOS or Brillo pad and rinse well.
Those are polymer gels. Breaking in the lap a little with a piece of scrap would accomplish the same thing, but a little slower. Darksides do not usually need extensive breakin, but playing with a practice piece first with any lap is a good way of learning the feel without using an actual stone.


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 Post subject: Re: Darkside issues
PostPosted: Sat May 05, 2012 10:26 am 
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Hi,

Of curse, the laps should be flat. You might clean your darkside as suggested by Gearloose.

However, the darkside or metal laps, the lap material itself is no harder than garnet. Your description of the scratches is sharp and deep, unlike the bumps in the pictures. I would think the scratching issue may come from another cause. The most common cause I have seen is the small piece of garnet chipped on the edge, the chip rolled under the facet causing scratches, and embedded somewhere on the lap.

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Mitch

I am a slave to cutting a stone completely free of chips and very much enjoying it.


Last edited by mhuynh on Sat May 05, 2012 12:06 pm, edited 1 time in total.

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 Post subject: Re: Darkside issues
PostPosted: Sat May 05, 2012 12:01 pm 
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What laps and grit sizes were used for prepolishing and polishing?


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 Post subject: Re: Darkside issues
PostPosted: Mon May 07, 2012 12:42 am 
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Hi,

My cutting process was: sintered saw on an ultra tec to rough in, new inland 1200 sintered that was broken in with corundum for ~5 minutes, batt with 8k also broken in with corundum until it had a very slight but even mat finish(loaded it very slow, did not want to over load), then onto the darkside that I did not break in as i assumed it did not need it.
8k to prepolish was slow, will be promoting to 3k when i get it in the mail.

I have a 600 on its way to speed things up along with some 3k to promote the batt with 8k

Update on the lap:

I used a piece of synthetic corundum to break in the lap, the rise (left red square) is still there after sweeping the lap for about ~8 minutes after I gave it a long scrub down in the sink. The rise can still be felt with the piece of corundum along with the finger, it is a bit less now, the tic is softer and it does not scratch. it just seems like a rounded rise/bump in the lap now.

Image


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 Post subject: Re: Darkside issues
PostPosted: Mon May 07, 2012 6:54 am 
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Ah, good. Thanks for the news.
Those little gels are resilient for a few days, and cure more slowly than the mass of material, so sometimes appear after machining.They are infrequent, though. The lap eventually becomes quite shiny after a few stones, and the polishing improves further. Finishes have been better the last few years after I switched to diamond turning tools, but the little rubbery gels are sneaky.
This is the first report I have had of them causing trouble, so thanks for the photographs. I'll let the laps age a bit longer before machining, and increase the milling power.
I had to come out wth the 8K because of the zinc laps..People were going right by the meets with 3k on zinc.

If the gel persists, I'll just swap you a new one for it. Darkside usually requires very little break-in work, if any.


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 Post subject: Re: Darkside issues
PostPosted: Mon May 07, 2012 1:10 pm 
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Thanks for the info, I will give it another scrub down and run some corundum over it again for ~10 minutes and post a follow up on it.


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 Post subject: Re: Darkside issues
PostPosted: Wed May 09, 2012 2:35 am 
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After breaking it in for another 30 minutes I am not seeing much improvement. It seems like the spot I highlighted is harder than the surrounding and is raised.

Image


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 Post subject: Re: Darkside issues
PostPosted: Wed May 09, 2012 7:20 am 
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Thta was way too much effort for an "easy" lap. I'll send another today. I'll study that lap, also.
Address PM'd


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 Post subject: Re: Darkside issues
PostPosted: Thu May 10, 2012 1:56 pm 
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I cant read PM's yet, will email you from your web site.
Thanks!


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 Post subject: Re: Darkside issues
PostPosted: Thu May 10, 2012 2:06 pm 
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You can read PMs now NickC.


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 Post subject: Re: Darkside issues
PostPosted: Sat Dec 08, 2012 8:08 pm 
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Well, well. I seem to be the last to know about some issues, but here's a good one:

Email just came in:

" I just read the article by Roy Brain, the winner of the USFG Masters 2012, in the December 2012 news letter telling how he used a Darkside to prepolish and polish his winning stone. "

The cheapest lap I make. I coulda been sumthin.


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 Post subject: Re: Darkside issues
PostPosted: Sat Dec 08, 2012 10:47 pm 
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Roy said he used a Darkside with a diastik 3000 for prepolish and used another Darkside with 100,000 diamond for final polish using CZ. I am not sold on the Darkside as being the best lap for diamond with CZ but Roy made it work for a winner.

Using a Darkside for prepolish, who would have guessed it could be done.

David


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 Post subject: Re: Darkside issues
PostPosted: Sun Dec 09, 2012 7:48 am 
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I have had numerous reports of people using the Darkside to prepolish with 3K.
I do not reccomend it because these grit sizes erode the lap. In time, the lap would lose its flatness..in other words, wear prematurely from a True Flat surface.
And of course, there is the aesthetic issue of "Black Stuff" being annoying.

But the principles that make the lap work are valid for prepolishing. But so far the Darksides have been lasting for years, polishing, for people.
Granted, they are inexpensive, so it is the User's choice, as always.

Work on a real prepolishing lap continues and is approaching the test stage, anyway.(Aquarius), so all this could become moot.


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