Resin-bonded 60K diamond lap

[RoughCreations]

I have recently purchased a 60K resin-bonded diamond lap from a China-based seller on Ali Express. Full cost including postage $175 AUD February 2025.



I was after another polishing option for hard stones (topaz, corundum, garnet etc) where I didn't have to faff around with loose diamond powder on a tin alloy or composite lap, and could use water as the lubricant. I haven't had the chance to fully run it through its paces yet, however first impressions are promising. I will add to this thread as I use the lap more, and it will become more of a review.



First thing that stands out is the thick layer of compound on this disk. That yellow-tan coloured resin material layer is a whopping 7.5mm thick. If the layer contains diamond powder through the full thickness, then it will potentially last many, many years. I have an 80 grit resin-bonded disk also (https://aussielapidaryforum.com/forum/index.php?topic=6844.0), so I am definitely operating at the two extremes of diamond grit size. The second thing that stood out to me was the spiral pattern of the resin, starting from the inside and moving outwards. This seems to be an integral part of the way the resin layer was created during manufacture.



The finish on the disk isn't quite as nice as my 80 grit disk, the glue bonding the resin to the alloy backer disk is a little messy, however this is only a cosmetic observation. Upon fixing it to my machine and spinning it up, there is no measurable flutter to speak of as measured with the encoder. This disk has a very even and level finish. There was a slightly rough texture on the resin of the disk, I didn't like the feel on a testing stone, so I decided to give it a slight lapping using 600 then 1000 grit wet and dry paper on a piece of glass. This treatment worked well, and acted as a sort of breaking-in step prior to serious use with the 'stone feel' much improved.



The stone used for testing was a piece of O'Briens Creek topaz that I have had difficulty polishing using other methods - as it turns out I was right on the cleavage (duh) I will document my topaz experiences on a separate thread to follow this post (https://aussielapidaryforum.com/forum/index.php?topic=7153)

I used my 800 grit ebonite diamond lap (which produces a finish more like a 1200 lap) first and got a 'pre-polish' finish that was better than I could get with 3K diamond on tin. I then proceeded straight to the 60,000 grit resin diamond lap. I could have probably done an additional 8K diamond pre-polish step first, however I thought I would see how things went. I got a good polish on the quite large facet, it took a bit of time, but this was expected. All behaved well, with no great surprises. The finish was pretty good in my opinion, however I suspect the experienced facetors out there could get a better result using their favourite method, than my first attempts with this new lap. I think as I get more used to this lap, and wear it in fully I will get even better results - time and more stones will tell - stay tuned. I would be interested to hear if anyone else has a resin-bonded lap of this fineness, and any particular techniques you use.

Also, I have a used Gearloose brand 8" Creamway lap in excellent condition for sale. AUD $120 plus postage (I'm located in Tasmania). No, I'm not going through hard times, just using the proceeds to offset this purchase! PM me if interested.

RC

[Bucket]

RC, great report. I'm guessing it looks like a 6 inch lap? I'm keen to see the results with your first stone. Those dang cleavage planes! I've had success with a pewter lap (I have 2 or 3 of those) with 50K diamond in a vaseline/oil suspension, used sparingly.

[Faceting Frank]

Never used them or even seen one. So, interested in how they go RC.

[RoughCreations]

Yes, 6" lap. It's not a full write-up yet, polishing is such a subjective thing.
See: https://aussielapidaryforum.com/forum/index.php?topic=7153

[RoughCreations]

Never used them or even seen one. So, interested in how they go RC.

Me too, lol.