Scoring a Polishing Lap

[@mohammedmubashirqadeeri]

Hi, I have got some big scratches on my zinc lap due to the stone was suddenly broken from the dop. Should i fix it with a sandpaper or a hack saw blade?

[@gemstoneartist]

DO NOT SAND A METAL LAP. You might embed grit or fragments in it. I also don't recommend using the hack saw blade technique, either. The scoring is often way too deep. Begin by washing, scrubbing with soap and a nylon bristle brush. Then, use a NYLON scrubbing pad and some mild solvent like WD-40 to scrub the lap by turning it reverse from the direction it was in when the stone broke. Finally, inspect by eye and with fingertips feeling for embedded fragments of the stone. If you can find nothing, test the lap gently using a soft stone like window glass or marble that's been faced to pre-polish level. See if you're getting scratches. If it's not scratching, you're probably OK. If it continues to scratch, use the glass to find the spot on the lap that's scratching and then pursue spot decontamination using the scrubbing pad. DO NOT USE STEEL WOOL. I often will use a stainless steel brush - one of the small toothbrush sized ones. You might possibly use a razor blade. These are techniques that fall short of sending the lap for machining a new surface. With care and effort you should be able to avoid that. Any other questions, feel free to send an email through the web site. Good luck.

[@mohammedmubashirqadeeri]

@@gemstoneartist thank you for your reply i will soon try to fix it.

[@christopherolson5401]

Stair stepping is exactly my issue John . This video on sighting the rifle was very helpful. One quick followup question. Once sighted do you always go back to zero "0" on the cheater for cutting the next stone's pavilion and then always go to the marked cheater number after transfer for the crown? I assume the answer is yes, unless you change gears but would like confirmation. Thanks so much for the tip!!!

[@InsightThoughtSystems]

+Christopher Olson I think there's some confusion. The zero mark on your cheater is ZERO. That means the location of "zero twist" after transfer. This only works if you cut the pavilion there - and also cut the crown there (at your MARKED) zero. If you begin a pavilion at the "0" on your cheater - and then move to your mark (assuming it's not ON the "0") - you're going to impose even more twist. To be clear: The ZERO that you MARKED - that is your "true zero" - at which to begin all stones, and where to return after all transfers. I hope this answers the question - and prevents errors. Other questions, just ask!

[@narendravaghasiya2855]

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[@Simon28298]

Do you know a good supplier for these ceramic lap? I'm looking around and don't find too much. Thanks,

[@drickfreak8509]

Dude, your awesome. Great tips and advice for a novice cutter like myself. Could you touch on polishing on plastic laps? Thanks

[@InsightThoughtSystems]

+drick freak Thanks for the kind comments. Treat plastic laps the same as Corian. Score / resurface them the same way. Charge them the same way, etc. Same for polycarbonate, etc. Hope this helps!

[@drickfreak8509]

Thank you. Your knowledge is treasure. Im using a very old machine but it works great. Polishing is the greatest mystery to this artform for the amature. Morning stone, barion oval sunstone 15 ct.

[@keithvsvs7422]

I wish I would of seen this a week ago. I'd assume this works equally with a lead polishing lap.

[@InsightThoughtSystems]

+Keithvs Sorry it took me so long to post back - just saw your comment. DO NOT use this technique on a lead polishing lap - it's likely you'll leave grit embedded in them. Most of the advice I've seen about scoring metal laps uses things like razor blades or other metal scoring tools. In my experience, those also cause problems. My favorite tool for scoring metal polishing laps is a coarse STAINLESS STEEL wire brush (do not use other metals). I brush in long strokes from center to outer edge - and just enough to "paint" the surface with brush marks. DO NOT use these techniques on BATT or BA5T laps. They do not need to be scored and doing so will harm their performance rather than help it. I hope this helps!

[@laurieparker203]

Hey!! You need to post some rocks or something

[@claireinbrum]

Hi I was wondering whether it's possible to resurface a phenolic lap? I have one that I have used for many years but recently I have had consistent scratches with it when I polish quartz. More so than the usual quartz mayhem... I have some visible scratches but I can't feel them under my touch so I am unsure about this. I don't suppose it's a lap that would be scored though...

[@InsightThoughtSystems]

If your lap has gotten glazed or contaminated, it could be the source of your scratching issue. You can easily resurface a phenolic lap the same way you do any other composite. Have a look at this video: kzbin.info/www/bejne/jIXUoWWtr7J3e6s Hope this helps.

[@claireinbrum]

Hi John many thanks for your reply. I didn't realise the phenolic lap could also be sanded down. I will try it!

[@zentpermata]

Is the fising using copper good, sir?

[@InsightThoughtSystems]

I don't understand that question.

[@TomMyersComedy]

Instead of sandpaper what would you recommend for a metal lap, specifically a gearloose zinc+? I ended up putting a decent gouge in mine and it sure is frustrating. Thanks for all your videos, I hope to attend the academy someday soon.

[@gemstoneartist]

The reasons for scoring are mooted by modern alloys (BATT, BA5T, etc). So, I wouldn't recommend scoring those. For scoring other metal laps like traditional Tin or even Copper, I do NOT recommend the traditional methods like razor blades or pieces of hacksaw blades. Those things are WAY overkill. All we want to do with scoring on metal laps is to break slightly roughen the surface - to "break the glaze". We want those things to be fine, and really all over the lap. I personally use wire brushes with stainless steel bristles. I start with a small, fine-bristled brush that's just bigger than a toothbrush, and if I think that's not enough I'll use a more coarse one (almost never feel the need). I put the lap on the machine, and drag the brush from next to the nut outward to the edge. This rotates the lap just enough for the next almost-radial swipe. I wouldn't recommend scoring a Zinc+ prepolish lap, either. It's not needed and will just impart undesirable surface problems. If you've gouged one of those to the point it's a problem, send it back to Gearloose for re-surfacing - or buy a replacement. There are still seats for the May event, and your comment here will earn you an extra discount if you seize the day...

[@ricois3]

Very interesting, I didn't know about that

[@gemstoneartist]

I'm glad to share something useful.

[@InsightThoughtSystems]

@ismail adam Many people never score their tin lap. Some people do them very aggressively - often ruining them... If I'm using a lap for diamond polish, I won't score it. If I'm planning to use e.g. Tin with Alumina, I'll score, but I use a very gentle method - and recommend others to do the same. It's very easy to over-do. The goal isn't to carve troughs into the lap, just to "break the shine", so a simple brushed finish will work just fine. I keep some tooth-brush-sized stainless steel bristle brushes. DO NOT use regular steel, as they'll shed rust that can stick in the surface of the lap! When a tin lap gets shiny, it may polish slowly and/or start throwing cat-hair scratches. That's when I de-shine it with the stainless steel wire brush. Just strip the lap with some alcohol or something else to get it really clean and oil-free. Then, drag the brush from center to the outside, moving slightly off center so it turns the lap a little bit. Work your way around and create a nice brushed finish. Wash / scrub it again to make sure it's clean, then go back to work. It's a very quick and easy process, and the brushed finish holds the polish well. Polishing with oxide is tricky at first. The most common mistakes are using too much polish and too much water. Remember water is only a catalyst and you want VERY little of it. I use a hand pump bottle that throws out a fine mist of water. I spray above the lap and let it settle onto it - NO dripping or spraying straight at the lap. Hope this helps.

[@gemstoneartist]

For more faceting training, visit the Faceting Academy web site (link in the video).