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

37 replies, 8 voices Last updated by Gregory Hays 2 months, 2 weeks ago
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  • #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.

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