Well Ukrinsky, as you can see, get 6 cutters into a room, and you are likely to get 6 different answers. Everyone does what works for them.
On larger stones, I will often start with a 100 lap to rough the stone in. My belief is don't send a boy to do a man's job. I'm not about to spend a lot of time with a 600 roughing in a stone, when in a few minutes I can do it with a much coarser lap. My normal 2 to 6 ct finished stones start out with a 260 or 320 to rough in, then cut in the actual facets with a 1200, or 600 NuBond. In my experience of several thousand stones I have not seen subsurface damage, at least none that was left after my last cutting lap. If I cut with the 1200 lap, then I polish with a dual charged "wing" lap with 8000 or 3000 diamond on the outside and 100,000 on the inside. From the 600 NuBond I will often go directly to final polish with a well charged 60,000 diamond on Batt. I don't cut for fun, I sell everything I cut, so time is important. I can not afford to spend many many hours working on a stone.
Post subject: Re: Working with large facets and Speed settings.
Posted: Fri Dec 26, 2014 5:52 am
Established Member
Joined: Sun Aug 03, 2014 10:27 pm Posts: 17
I am going to try the batt with 8000 and 60000 and see the difference for myself.
Has anyone tried both natural and synthetic diamond? I imagine the results should be very similar.
Who uses water based diamond over oil based powder and why? I can understand the mess of the wd40 and maybe some slight heating issues but are the rewards worth it?
Again your time and input is much appreciated! I am lucky to be part of this great community! Thanks again!
I use powdered diamond and cutting oil. I don't like the smell of WD-40, and frankly have found that I get a quicker polish using the oil instead of the WD-40. Just a little dap will do it however. To much and the stone will float on the oil, which I think could be your issue with the 1200 NuBond. Too much water. You want to feel the stone grip the lap, this means the lap is working. Gliding over with very little friction, and very little work is being done.
Post subject: Re: Working with large facets and Speed settings.
Posted: Fri Dec 26, 2014 8:35 am
Valued Contributor
Joined: Fri Jun 04, 2010 8:21 am Posts: 421 Location: Australia
I have use both natural and synthetic diamond powder. The diamond powder that came with my first machines was De Beers natural powder. I prefer the synthetic due to the price. When I first ordered from Eastwind Abrasives I explained that I wanted if for lapidary and they sent me polycrystalline diamond powder. I had no complaints about it's performance so I specified polycrystalline in subsequent orders. Lately there has been a fair bit of discussion and polycrystalline diamond seems to be the powder of choice or it may just be my interpretation of the discussion because i prefer polycrystalline.
There has also been a lot of ink spilled over water vs oil. I use water or water based products for almost everything. I used seat my diamond using metho. I found that it worked well particularly with the finder grits as they tended to float in the oil rather then pressing into the lap. I now mix my diamond into cold cream and dispense it with a syringe. It works quite well and is also ware soluble. It is also much easier to dispense without spilling the damn stuff everywhere. I still use WD40 to clean my laps prior to putting them away. It cleans them nicely and helps to protect them in storage. A light wipe over with metho before cutting removes the oily residue left behind by the WD40.
_________________ It’s still magic even if you know how it’s done.
Post subject: Re: Working with large facets and Speed settings.
Posted: Fri Jan 23, 2015 1:06 am
Platinum Member
Joined: Wed Apr 26, 2006 12:44 am Posts: 2056 Location: San Francisco
The trick with your nubond is to make sure that it isn't glazed. Get some 2000 grit sand paper and scour the surface till it's dull. That'll bring it right up.
If your getting some large scratches in your 1200 prepolish, you can add some crystal lube to the lap and a spritz of water. Make a film, you can run that up to speed 5 or 6, it will cut slower but it will be closer to 3k than 1200. It will also cause it to cut much finer w/out the scratches that you get with just water.
It looks like to me that your lap maybe glazed and not cutting efficiently.
re: Diamond. I've use both oil based and water based. The water based diamond that gearloose sells puts an almost liquid gleam on the sapphires I polish with it. I see a noticeable difference with those compounds vs oil based. A matrix lap along with water diamond does the trick.
_________________ Custom Gemstone Cutting and various other activities!
Post subject: Re: Working with large facets and Speed settings.
Posted: Fri Jan 23, 2015 3:15 am
Gold Member
Joined: Tue Jul 02, 2013 9:00 am Posts: 1322 Location: Wylie Texas but in Alaska for a while
On water vs oil. I started with Jon's snake oil and it worked very well. Then he came out with his water cutting diamond sticks.
I use them all the way from 320 for roughing, 600 for cutting (on a batt), a 1200 for final adjustments, and then I go to a diamagtrix, with wither water oxides, or his 100,000 water poly.
MUCH EASIER, easy cleanup, no smell, and I have never looked back.
Post subject: Re: Working with large facets and Speed settings.
Posted: Fri Jan 23, 2015 6:41 am
I just finished a 20ct quartz and found 1200 sintered was the best for fine grinding. I then went a cerium oxide on tin lap that is split and final polish on 100,000 for just a split second to knock off the oxide lines. I prep the oxide section by first running 100,000 synthetic diamond powder with aniseed oil and oxide over the top of this. Aniseed is very fine and evaporates quickly is food grade and smells great. Of course my lap is a three in one.
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