Forums Beginner Questions Contaminated Lap?/Over Cutting Facets During Polishing

42 replies, 10 voices Last updated by gemmakermz 2 years, 8 months ago
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    • #6571

      hray
      Participant
      @hray

      I am just getting started with faceting, and have some questions about laps. I suspect my laps might be contaminated as they are very old and I am noticing some deep scratches that aren’t coming out in the polishing stage. I have read that sometimes you can remove contamination by washing the laps off. Is there a certain method to this? How do I avoid contamination in the future? Is it enough to wipe the stone clean before changing to a finer grit? Also, when polishing, do I need a master lap to go under the spectra ultra laps, or can I just put the film on top of my pre-polish lap? Is it advantageous to use a maser lap under a cutting/polishing tin lap?

      When trying to polish a citrine, the more I tried to get the scratches out the more my meets went past their point. Is there always this much cutting that happens during the polishing stage, or is it because I am not using a master under my cerium film? Is it advisable to have the points be just short of meeting in the cutting or pre-polishing stage, so that polishing doesn’t cause them to cut too deep?

    • #6573

      davidechols
      Participant
      @davidechols

      An old cutter years ago told me to use lava soap and I did and have for many years on both cutting and polishing laps for contamination. Polishing will move meets if done too much. Practice and more stones and polish and meets will get better. I would advise anyone starting to facet not too fret too much about meets but focus on getting the polish right. Good meets with good polish will come after some more stones. In other words take it in stages. Learn machine and cutting, then focus on polishing without worrying too much on perfect meets until you master getting a good polish. It will come together later.

    • #6577

      Alan Balmer
      Keymaster
      @alanbalmer

      Too little information. What type of laps are you using for cutting and prepolish? What cutting grits? Spectra Ultralaps are OK though they wear out and may round facets, and should show any contamination by visual inspection. I’d get a master lap. They’re cheap and easy to keep clean.

    • #6578

      hray
      Participant
      @hray

      @Davidchols, Thank you for this info! As a perfectionist, it is really good for me to hear your advice about not obsessing over meet points as I am first starting out. @alanbalmer, Right now I have a very worn 600 and 1200 crystalite lap. I suspect that the 1600 may be acting more like a 3000 since it is so old, so that was what I was using as a pre-polish. I am considering purchasing a BATT lap and charging with diamond for polishing. Is this preferable to using Ultra laps? Can cerium oxide polish be put on the diamond charged BATT if needed? If you or anyone here has recommendations in regards to grit/brands of cutting and polishing laps that would be helpful as I get started, I would appreciate the advice. Thanks!

    • #6580

      Frankwood
      Participant
      @Frankwood

      If your going to invest in a new set of laps I would recommend getting a set of 8” laps. Having a much bigger surface area to work with is far better.
      One plain aluminium (Australian spelling) master lap, don’t get a one with the magnetic layer on top, they’re a pain to use. Set of bonded diamond laps, they’re about a millimetre thick and go on the master lap as required.
      Don’t get the ones with the sticky back, as for grits I have 180, 360, 600 and 1200. Two Batt laps, one for 3000 grit and one for 50k diamond powder. Keep them away from each other, every time you handle the 3000 grit lap wash your hands before touching anything else.
      I’ve found diamond will polish anything but Quartz, some guys may be able to polish it but I’ve never had any luck. So I use a hard plastic lap with cerium oxide, having plenty of pressure on the stone seems to work best.
      Have a Darkside lap and a stick of Zirconia for Quartz, but found cerium the best.
      When charging the Batt laps I only use 2 drops of baby oil to mix with the diamond powder, have found Diastik’s slower so don’t use them.
      You will get a lot of advice on the forum as to what oil to use on the Batt laps. Baby oil is perfect for the job, it’s cheap and one bottle lasts a lifetime.
      Hope that covers everything.
      Frank.

    • #6581

      davidechols
      Participant
      @davidechols

      Unlike Frank I have polished everything with diamond. My quartz competition stones were polished with diamond. The old guy that taught me to use lava soap also said diamond will polish everything. Might not be entirely true but close. I started out using diamond on a tin lap. Batt lap is a harder tin lap and is better. For quartz I cut on 600 topper then 3,000 on batt and finish on a 6″ Matrix with cerium oxide. I have found nothing quicker or better than the Matrix and a small amount of cerium for quartz. Get one other Batt to use with 50,000 diamond for everything else. Two Batts and the Matrix and you will need nothing else for polishing starting out, at least that is what I have found works for me. I have no use for any cutting lap finer than 600. The cheap Chinese toppers work fine for me on a master lap. Get 2 more toppers in 260 and 100 for roughing out the stone. The 100 is only used sparingly and be sure and leave enough for the 260 to remove the 100 grit scratches. Before polishing be sure and remove all scratches with the Batt and 3,000 and your meets will not move at final polish, or at least very little until you learn more. I used those flimsy plastic ultra laps when first starting out and they will work but are much too slow for me. It does not take but a few seconds on a Matrix with cerium in water with an artist brush with a small drip of water after pre-polishing on a 3,000 Batt to polish a quartz stone. Some like those bonded oxide laps for polishing. i have tried them and like the ultra-laps they will work but more slowly than Matrix with cerium. One advantage in using them is less mess but it takes so little cerium on a Matrix to polish there is very little mess.

      While learning always remember to have fun and enjoy. You will have some trial and errors but with practice you will be competing one day. Get some cheap man made quartz and do not fret too much when it does not turn out like you want. Take it off the dop and start another one.

    • #6583

      Lowjiber
      Participant
      @Lowjiber

      The “cheap Chinese toppers” that @davidechols refers to above are incredible. A good friend from Australia put me onto them.

      It seems that China has the corner on the market for industrial diamond, making the price about half what one will pay for US toppers. They’re all over eBay. I use both 6″ & 8″ toppers almost exclusively when cutting.

    • #6584

      hray
      Participant
      @hray

      Thanks Frank, this is so helpful! In addition to washing my hands between laps, do I need to also clean the master lap and the stone somehow? I have been wiping the stone with a damp cloth, but am not sure if that is a thorough enough method.

    • #6585

      hray
      Participant
      @hray

      David, Thank you so much. I wonder if part of my problem is that the lap I used for a pre-polish wasn’t a fine enough grit. I will definitely purchase some BATTs. Do you charge with diamond powder, spray, or the diastiks? Where do you purchase the Chinese toppers from? I am hoping once I try the lava soap on my old laps they might have some life left in them, but it is good to know if they are past the point of no return (and for the coarser grits) there is a reasonably priced option for replacement.

    • #6586

      hray
      Participant
      @hray

      Thanks @Lowjiber! I hadn’t thought to look on eBay. Do you have a particular seller you have had good luck with?

    • #6589

      davidechols
      Participant
      @davidechols

      https://www.ebay.com/str/thkdiamondtools

      I have been buying from him for years. New toppers need some breaking in. Quartz works fine breaking in but the first few stones will have some scratches. Batt with 3000 will take care of them. For a beginner diasticks would probably be the way to go, easiest to learn how much and technique. I use oil, usually WD40, squirt on paper towel and apply then wipe almost all off then apply loose diamond sparingly and rub in with finger. If use you too much diamond or oil you can try wiping it of with a piece of paper towel and try again. It has been years since I used any of my diasticks but they work pretty much the same. Put some on, spread it around lap then wipe some off. With practice you will learn how much to use and omit wiping off.

    • #6590

      Frankwood
      Participant
      @Frankwood

      You have to get all the 3000 diamond off the stone and out of the crevices that form in the glue that the stones glued to the dop with.
      I hold the dop vertically with a tissue round it and wash the stone with an artists size brush with that alcohol based liquid you get at the hardware. Have a small stiff brush to clean out the crevices.

      After charging the lap with 3000 grit, just use the outer half of the lap. Initially the stone will pick up a lot of diamond/oil mix, but after a short period the lap surface will become much drier. That’s the sort of surface you want, as it dries further occasionally move the stone into the wet area to pick up more diamond.
      The lap speed I use for 3000 grit on a Batt lap is about 300rpm.

    • #6592

      hray
      Participant
      @hray

      David and Frank, thank you for all your help with this! I now have a clearer idea of the next steps to take. Thanks!

    • #6593

      scottwkelley
      Participant
      @scottwkelley

      Hi, welcome.
      I am a novice becoming a master, lol. I had all these same questions. I started out using my cabbing 8″ flat laps. Used the ultra’s and finally ended up using Lightning Laps from Kingsly North a US company. By the way guys there stuff is better and affordable, you get what you pay for. I use 100 topper to remove material fast, but it has to be large, ( time saver ), 220 topper I use to rough in to 2 mm of the size I want or am to get. From there right to my fine 1200 lap ( meets) from kingsly and I will be getting that 3000 when available. LL makes a cerium topper for $30, well worth it. I use all their laps up to and I have 200k, I am not there yet, but ready, still learning on quartz and cz. How in the heck does one polish corundum?
      Lot of good advice here.
      Thanks to everyone for being here, I am so grateful.

    • #6595

      Lowjiber
      Participant
      @Lowjiber

      @scottwkelley… You’ll need to use diamond to polish corundum.

    • #6596

      scottwkelley
      Participant
      @scottwkelley

      i get that @Lowjiber. But, i get different results, i get to 8k and after that 50k doesn’t touch it. I was blaming pre polish. i decided to ask, learn and try again. it finally came off the dop, thats when i stopped.

    • #6597

      Alan Balmer
      Keymaster
      @alanbalmer

      Scott, you can buy Lightning Laps directly from Marsh Howard, the manufacturer. Other good info on his website, https://shop.lightninglap.com/
      Marsh is a good guy, always helpful.

    • #6601

      scottwkelley
      Participant
      @scottwkelley

      @alanbalmer yes he is and has helped me many times. The prices and guarantee’s are the same, kingsly north offers much more too. Their steel laps and blades are great and I have had great experience with them. Like a 6″ trim saw blade for $5. The 10″ saw blade for $12 works well to.
      Again thanks for all you do!

    • #6635

      hray
      Participant
      @hray

      Hi again,

      I have a few questions about charging a BATT lap. I followed David’s advice and purchased 2 BATTS and a Matrix along with 3K, 60K Diastiks and a Cerium Battstik. I think I have a decent idea about what I need to do to get the BATTS charged and broken in, but I want to run it by the experts before I do anything. You have all been so helpful! As I understand it I need to apply a thin layer of WD-40, baby oil, olive oil or something comparable to the surface with a paper towel. Then draw a few lines on with the Diastik and spread it around with my finger while the machine is running. After this is it necessary to break the lap in? A few articles I have read have said to use a piece of corundum or Cz for this. I have quite a few tiny Montana sapphires that are too small or fractured to cut. Would it work to just hold on to one of those and run it across the lap a few times? I guess I have just been worried a small chip will break off and contaminate my new lap. This brings me to my next question. I am pretty paranoid about contamination. I know to wash my hands between handling laps, but what is the best way to clean the stone, mast, etc before moving to a finer grit? Do I have to clean out the splash pan? How should I clean the lap before storing it?

      Lastly, Is the process similar for charing the Matrix with Cerium? This is probably a pretty silly question, but do I charge the Matrix with diamond and cerium or just cerium? Thanks so much for the help!

    • #6636

      duncanmiller
      Participant
      @DuncanMiller

      I would not use a small piece of sapphire to embed diamond in a Batt lap. It may score the lap. Apply the Diastik lightly or use a clean finger to spread the diamond thinly, and grind or polish away. When black swarf builds up on the lap or the stone, wipe the lap with a piece of paper towel dampened with WD-40, and reapply some diamond – sparingly. Clean the stone and dop with alcohol on paper towel before polishing. I give Batt laps a cleaning wipe after use. Sometimes I clean the splash pan before polishing, but not always, and I avoid touching it. After cutting a few stones I clean the machine as best I can, but without being obsessive. The Matrix laps are also given a wipe with dampened paper towel to clean them. If you are going from an oil-based diamond to a water-based oxide, or vice versa, on the same lap wash it with water and some household detergent. (I use separate laps for oxides and diamond polish.) Most of my Gearloose laps live in the original cardboard covers they came in, just with a clean piece of paper towel on the working surface to protect it.

      The main thing is to use minimal diamond or oxide when polishing. If you get scratches it usually means the lap needs a wipe to remove excess polishing medium. If scratching persists change polishing direction through 90 degrees. Check your prepolish. Has it removed all previous grooves and pits? Clean the polishing lap thoroughly. If it is a Matrix+oxide lap scrub it with water and detergent. If it is a diamond lap wash it, dry it, and apply a synthetic rubber eraser to the lap running in reverse. Try different lap and polish combinations. If all that doesn’t work try a different stone. Resurfacing a lap is the very last resort.

    • #6641

      hray
      Participant
      @hray

      @DuncanMiller, thank you for all this info. Im glad I didn’t try the tiny sapphire for breaking in the lap! Do you think WD-40 has significant advantages over the other oil options? I have my machine setup inside my house and two young kids, so I am trying to avoid fumes if possible. Thanks again for your help!

    • #6643

      Frankwood
      Participant
      @Frankwood

      I do the same as Duncan and use different laps for different polishing agents. They live on those plastic office trays meant to store A4 paper, they stack on top of each other and stop on a shelf in a cupboard.
      I used to use WD40 before someone on this forum said baby oil was good with diamond, I agree with that and used it ever since.
      I have three liners for the inside of the pan, one for normal use, one for 3000 grit and one for polishing.
      As I mentioned before every time I touch anything with 3000 grit on it I wash my hands.

    • #6644

      duncanmiller
      Participant
      @DuncanMiller

      You want to be able to clean the facet easily to inspect the surface you are working on. WD-40 is thin and wipes off easily with paper towel dampened with alcohol. Both produce fumes, the alcohol being worse than the WD-40. You could avoid both by using Gearloose Pandemonium Universal Base Diastiks, which can be used with water as a lubricant. (I am still using up my old stock of oil-based Diastiks.)

    • #6652

      hray
      Participant
      @hray

      Thanks to everyone for all this great input! I gave it a try today and had some pretty rough results. I ended up charging with baby oil and a 3000 DiaStik. First off I got major scratching and some nasty black buildup. I tried wiping some diamond off, then got bits of metal. I added more diamond and things improved a little, but still a lot of scratching. At one point I was able to get two facets that look more frosty instead of scratched so I think I might be heading in the right direction. This didn’t last long though, and I soon got metal again. After recharging I was back to scratches, worse near the culet. I am not sure how much of this has to do with the amount of diamond I am using, or if maybe partially due to the fact that it is a new lap. I am including some pictures, so if anyone has suggestions I would appreciate it! The first two are of the scratched pavilion facets, then I have one with the two frosty facets that I think might be improving. The last is a pic of the lap. In it I am guessing the area I have been using is due for a recharge. Oh, and when I took the lap off the spindle I realized I had the sticker side face down ,I don’t think this should matter though since BATTS are double sided right?

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    • #6662

      Lowjiber
      Participant
      @Lowjiber

      Yes, the Batt is a solid lap… both sides are the same.

    • #6664

      Alan Balmer
      Keymaster
      @alanbalmer

      Hard to guess what’s going on without actually watching. Generally, if you get metal from a BATT lap, it isn’t charged enough. BATT can absorb a lot of diamond when first put in service. I did have a stone a few years ago which scraped metal off the lap at a particular angle, but that turned out to be my fault.
      I always found baby oil to be too viscous. I like WD-40, though some people can’t stand the odor. There are lots of choices for lubricant. Trombone oil is reputed to be very good. Gearloose’s Snake Oil (approved by Professor Ignatius) is great, though pricier than common oils.

    • #6667

      hray
      Participant
      @hray

      The problem of picking up metal seems to improve (at least temporarily) if I add more diamond. At this point I am more worried about the scratching. Is it possible that the lap just needs breaking in? I have only ever polished with cerium oxide ultra laps after pre polishing on a very worn 1200 grit Crystalite, so I am not really even sure what a pre-polish with 3000 should look like. Will the facets be mirror-like at all or still pretty frosty? I had two facets that didn’t show the big scratches as much as an overall frostiness.

      I have been shying away from the WD 40 due to the fumes and the fact that I am set up inside near my kids. Maybe I will look into the trombone oil or the Gearloose product. I have heard others have had luck with baby oil though, so I might not give up on it just yet. Thanks for the help!

    • #6668

      Lowjiber
      Participant
      @Lowjiber

      I use WD-40 in a liquid form, vice the aerosol version.

      WD-40 Liquid

    • #6669

      Frankwood
      Participant
      @Frankwood

      Never knew you could buy WD40 in liquid form, anyway I couldn’t tell any difference between it and baby oil as far as a carrier for diamond was concerned.
      Looking at the photo of your BATT lap it’s in a terrible state, the inside 1/3rd is what it looks like new and after a few uses the same but grey in colour from the diamond imbedded in it.
      No massive grooves and certainly not producing scratches like on your stone. I would suggest you join your local club for advice as its something your doing wrong with the lap.
      The finish with 3000 grit on corundum for example looks close to a final polish.

      I recharge mine with two drops only of baby oil (and that’s heaps), small amount of 3000 diamond powder, all rubbed in a circular motion till the lap is covered. Just checked the speed I run the lap at and its slower than I thought, it’s only 200rpm. Don’t know why this mixture ends up going black but it does. I wipe an ink marker over the first facet of that set and wipe it over a stationary lap to make sure its flat on the lap. No significant pressure on the stone when cutting. That’s it.

    • #6671

      Alan Balmer
      Keymaster
      @alanbalmer

      Don’t know why this mixture ends up going black but it does.

      Swarf is always black, in my experience – nothing to do with a particular lubricant. Probably because nanoparticles of stone in lubricant don’t reflect light.

    • #6672

      hray
      Participant
      @hray

      Yikes, I hope I haven’t ruined the lap. It sounds like maybe I am using too much oil. Also I was running my lap a lot faster than 200 rpm. I am using a Diastik instead of powder so maybe they has something to do with it too. I am going to try again today with the slower speed and less oil. I also will try the ink on the facet to make sure I am aligned correctly. Thanks for the tips!

    • #6673

      Frankwood
      Participant
      @Frankwood

      You will probably need a couple of more drops starting from a dry lap, but I have only ever used two drops recharging. The reason for the high diamond-oil concentration is I want to embed it into the lap. If you use more oil it gets all over the stone and dop and you end up wiping it all off.
      Have no idea why you have those big groves in the lap, cant see it having anything to do with amount of oil.

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    • #6675

      duncanmiller
      Participant
      @DuncanMiller

      Polishing should never groove a lap. Either the facets are not flat on the lap, or you are using far too much pressure. It’s also not the fault of the Diastik. Diastiks are self-lubricating and lubricant is only needed to spread the diamond paste evenly. I squirt a bit of WD-40 onto a piece of paper towel and wipe the lap moist with that, then apply the Diastik lightly on a slowly spinning lap. You can spread the paste more evenly with a clean finger. If the lap needs lubricating I apply a very short spray of WD-40 near the center of the lap – the tiniest squirt possible. The polishing lap should be damp, not wet.

      You can resurface a damaged Batt lap, or any other soft metal lap, on good quality 80 or 100 grit wet-and-dry paper, held down by water on a hard, flat surface, like a sheet of glass. (I use Klingspor automotive paper on a polished granite tile to resurrect second-hand laps.) Rub the lap by hand in a figure of 8, rinsing the paper with water when necessary to remove clogging metal. When it is flat, give the lap a good wash to remove any abrasive grains. The resulting random texture of scratches on the lap is fine but if you want to you can finish the lap on 600 grit paper.

    • #6691

      Gregory Hays
      Participant
      @gregoryhays

      Did not read this whole thread but have you reviewed Jon’s Batt page here Batt Charging page.

      I found taking a piece of synthetic corundum and squaring it off, chamfering the edges slightly and dopping to a sacrificial dop that can be used later for other dressing jobs, can eliminate the chance of creating gutters or scratches in the surface of your lap when holding by hand charging initially. After the first charging you only need to add more diamond. Swarf is swarf and with diamond polishing it comes with the territory.

      I will state I have tried every voodoo magic potion under the sun to polish with and I always come back to WD-40, you might not think there is a difference but there is.

      If your picking up metal, the lap is to dry, your baby oil doesn’t have the viscosity that WD-40 has for charging the lap. Watch Jon’s Charging a Batt Lap video link above.

    • #6692

      Gregory Hays
      Participant
      @gregoryhays


      @hray
      Oh, and when I took the lap off the spindle I realized I had the sticker side face down ,I don’t think this should matter though since BATTS are double sided right?

      Which side of the lap has the scratches? The side with the label or the other?

      Is it possible that when you placed the label side down on the platen, the lap was not entirely flat and was rocking slightly.

    • #6693

      hray
      Participant
      @hray

      Thanks, guys. I really appreciate all the help. I have tried again a couple different times since I last posted. I went ahead and tried the WD-40 to see if that made any difference and started fresh on a girdle facet. I also polished at the very edge of the lap where I hadn’t made any grooves yet. Things look a lot better, but I can still see quite a few fine scratches ( though not nearly as nasty as what was happening on the pavilion facets) so I am not sure much polishing is happening. I am wondering if I have some subsurface damage from contamination on my cutting laps that is showing up. I will try to take some more pics in the next few days for a comparison. Things have picked up with my job recently so I haven’t had as much time to try to figure this out. @gregoryhays, I have watched Jon’s video on charging. I am using a diastick, but he sent me a video using that too. The side of the BATT with the scratches is the side without the sticker. I am tempted to flip it over and start fresh, but am afraid I will ruin that side too. I think you are right and there is a chance that the lap isn’t sitting flat on my machine. If I have the stone just touching down at center but sweep to the right the stone no longer touches the lap. There is a decent chance my machine is out of alignment, it is a really old Mark II ultratec. I have had luck polishing on it before with a cerium oxide ultra lap, but this was about ten years ago and before a move. Someone was kind enough to direct me to a page on this site that gives steps to check the alignment, but I have not been brave enough to attempt that yet. It has also been suggested that maybe my facet wasn’t flat when I started to polish, I think this was probably accurate, and I have been pretty careful since about checking to make sure all parts of the facet are touching evenly. Another thing, If I run my machine clockwise at lower speeds it is pretty rough sounding and doesn’t necessarily change speeds consistently as I turn the nob. Usually I have to start higher and slow it down to get the change. I am really not sure the speed it says it is running at is accurate. It runs much more smoothly counterclockwise. Does it matter which direction I use?

      I feel kind of like a hopeless cause right now, there are so many obstacles. Not sure the best way to proceed, but I don’t want to give up either.

    • #6696

      Frankwood
      Participant
      @Frankwood

      Join a club and get some hands on help.
      The lap tipping so the stone only touches part of it wont scratch it, nor will having stickers or anything else that makes a slight wobble.

    • #6735

      Gregory Hays
      Participant
      @gregoryhays

      No but a lap not stable or flat can cause scratches and gouges in a lap when hand holding a piece of something when charging the lap. If the sticker keeps the lap from seating completely you may be asking for trouble, easy enough to remove. A sticker holds no value.

    • #6905

      gemmakermz
      Participant
      @gemmakermz

      hray i teach faceting and yes lava will help clean laps(cutting) don’t use on polishing laps use a master lap for the thin topper laps and the china ones are much more affordable. have 8″ but quite often use just 6″‘ers. i teach and use a GOOD tin lap. there are solids like the BATT lap and if you get one use only one same grit on both sides, use one side till you get problems then the other. if it gets contaminated you’ll have to have a .005 cut done on it by a lathe. ive searched all over and found one seller of a REAL fine quality diamond powder and i use only a TIN lap with 50,000 grit diamond powder to polish and use only water, no oils, pastes, compounds, wetting agents. i hope you have a machine that can run very slow. i use one drop per 25-35 seconds, just enough to keep lap wet but not wash off the powder when you apply it with finger tip near center. it works so well for me i’ve even polished from a 400 onto the 50k on tin. i just got Jeff Theesfeld trying it and i think he likes it too as other members are now trying with success. the person i get my 50k from is now trying to get set up in L.A. to supply the volume needed. with shipping i paid 9.5 cents/ct—-$95/1000cts and 25 cts goes a very long ways when your not flinging or washing it off the tin lap with water and powder the 50k works into the tin surface so your charging it and by masking it a not quite dry mud of it it works hard. so well i some times use it to actually polish meet my facets meets. ANOTHER thing if i think i have a potential to contaminate, clean out your splash pan before going to polish. i polish all stones all hardness’s this way so don’t need a pile of laps and polishing agent to get the job done.

    • #6910

      jmee
      Participant
      @JMee

      You say that the machine isn’t in alignment. This is the cause of your gouging. As you sweep the stone on the lap you are putting the edges of the stone into the lap and cutting grooves. The solution is to align the machine.

      Another option is to use a very small area of the lap and cut and polish in the same place (say at around 3’oclock) and use a very small sweep almost like scratching a lotto ticket. This should minimize the effect of the machine alignment.

      Besides the alignment problem a similar thing can happen if you are off on the angle from cutting to polishing. Putting a sharp edge of the stone into the lap is sure to dig in through the diamond and cause grooves.

      The good news is that groves typically won’t ruin the lap. People used to score laps after all.

      A piece of synthetic corundum at least 1/2″ square is a useful tool for knocking down edges of gouges so they don’t cause problems. Just use the same process as is often recommended for initial charging and the lap should still be usable.

    • #6911

      hray
      Participant
      @hray

      I’m glad to hear that the lap is probably still useable. I bet my machine is out of alignment, that makes the most sense. Would that also be causing all the horrible scratching on my facets when I try to polish? I will give the technique of using a small area on the lap a try and see if I have better luck. Thanks for the advice!

    • #7116

      gemmakermz
      Participant
      @gemmakermz

      hi i teach faceting to new bee’s and have been since the 70’s. having worked for/at crystalite from 68-77 making the flat laps and demo’ing them at shows i find still many of them i made back then are working good. i have also found that the china made are VERY good as they don’t skimp on the diamond. in some cases they over do it and you have to work hard to break them in, but they are the best buy and cheapest. we here use both 6″ and 8″ and i find the 6″ is good for beginners, as, if they have an accident and lap is damaged no real loss they are cheaply replaced. we use what ever coarse to get basic faceting started and formed, then go to 1200 and finalize meets and cutting. like i said we go to tin at very slow speed with water drip about one drop every 30 sec. just enough to make a muddy slur, applying diamond powder near center spindle and work out to center work area, your stone will work the dampened diamond into the lap as you polish and water drip as close to center spindle as possible. the one thing you have to be careful about it the quality of the diamond powder, i’ve bought from many sources and only found one with real quality. for cabbing i bought a syringe of 50k compound from a supplier in So. CA. and it was totally bad and caused scratches. some powders are the same. diamond does polish everything even other diamonds. the thin plastic type polishers do compress distorting the facet.

    • #8105

      gemmakermz
      Participant
      @gemmakermz

      hray david give good points. yes it is good to have a good master lap period. we use it for the china toppers. i don’t recommend those film laps as they flex soft surface- rounds edges of facets. your using a worn 1200 lap for pre-polish good. here we all go from 1200 directly to the TIN lap to polish, but as i have already posted at very slow speed and use diamond powder 50k and water only. yes i have two 6″ batt laps that i don’t use any more. i got so frustrated with the market tin laps not holding the diamond properly and giving me the polish i wanted. i ended up making my own. i found a supplier i could get tin blanks to bond to a master lap then machine to make ready. mine are 98+ pure tin and give a great polish and fast on all materials. i’ve got 15 of them out there being use very happily.

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