Bronze system with special polishing alloy centre lap.

Polishing is the make or break for most cutters.So having the best final polish lap is the key to most successful cutters. I started 35 years ago with a locally made pure tin lap that was nothing more than a few millimetres of tin on a thin steel backing plate. Tin laps notoriously ripple very easily due to there soft nature.So to avoid the necessity of the regular trip for re-machining  I purchased my own lathe and found a tin supplier.I was soon making all my own laps,the  first was a 50/50 tin lead ,then type metal then I ventured into alloying pure tin using bearing metal formulas.All gave good results,some better than others with the best being type metal.

Along came the new age and lead being a dirty word I switched to Zinc and sat with that for many years. I started splitting my laps around this time adding the pre-polish into the process and abandoning oxide polish to an all diamond finish.The search continued and finally the special alloy

Its not a harder alloy,but has characteristics of retaining diamond well and having good machining and surface finish,is brittle and porous so it needs to be mounted on a backing disc. The down side is the cost. Its not tin or lead dominate, the alloy is much more expensive and denser. It is the best polishing lap I have ever used.It likes fast speeds but still works well at low speeds.I split it into pre-polish  at 3000K with a 100,000K final polish.Another feature is that I have seen very little if any scratching not related to too much polish or negligence.It always give a perfect finish on both grades the pre-polish is so hard to tell from the final finish when it is well worn in that i have to double check to see if I already did that facet.Its still very fast and solves all the issues of facet peel.

I sold one recently to an experienced cutter who has the Batt Lap and he commented that splitting the lap increased his cutting speed and the finish was much flatter than his batt lap. I spoke to John from Gearloose and got the impression he was aware of this alloy and he commented that as a solid lap which is his trade mark the cost would be prohibitive. The difference is noticeable to a seasoned professional but don't rush out and change as batts are the best of the tin laps and John is dedicated to his brand and bringing you new and proven quality products.

As my signature I always add it to a cutting system and above is a 1200 sintered bronze rim.

I produce this lap in 6 inch  A$125,and 8 inch A$195.00 It is balanced for higher speeds and split for dual action polishing.You will also need a knurling tool and I make a specially formulated polishing compound as a kit for an additional A$75.00 At present the rims are still being finalized in both price and alloying.

Customising your system

Every stones is different.It has a different hardness,density,refractive index,crystal system,and then there are physical properties related to the individual stone even in the same group or crystal system. This means a different approach is needed to fit the properties of that particular stone to the cutting,pre-polish and final polish laps. As an example a copper 3000 pre-polish lap from a half hard plate or round bar section will cause facet peel with tourmaline, zircon,peridot and demantoid garnet just to name a few.Facet peel is where the facets appears half polished and half ground.It can be a difference in hardness or a crystal direction phenomena and eliminating this means abandoning the pre-polish early and doing alot more final polishing.This means that the copper is too hard and a softer metal pre-polish lap is needed for maximum pre-polish results before proceeding to a final polish lap.So by using a zinc to pre-polish the result is immediate. Why? because you have reduced the hardness of the lap and the imbedability of the diamond particle.A softer lap will allow the diamond to deeper impregnate the lap surface giving a softer finish eliminating or reducing the facet peel effect. This is the same for a 1200 nickel plated lap compared to a bronze sintered lap.While the nickel will improve over time,nickel is much harder than bronze so the finish for the same grit will be different,not too mention quality differences between manufacturers. A sintered diamond copper lap will give a greatly different finish compared to a bronze sintered lap of the same grit.By getting the best final cut before pre-polish you have lessoned the time to finish following processes, saving allot of time.The lap set pictured above is a 1200 sintered copper fine grinding rim lap with a zinc cast pre-polish lap with a special tin alloy final polishing centre lap.  Another lap in a lap in a lap.

This configuration gives me a final grind that is both aggressive and very silky smooth. I often dont need a course grind from rough on smaller stones.I then move the stone to a 3000 pre-polish on the zinc. You may notice that I have knurled the lap using a single blade medium hand held tool.This makes thousands of indentations at right angles to the facet flow direction acting as both a counter measure and feed source for the diamond paste I use.Finally I go to the special alloy I use to make a cant miss final 100,000 polish. This I also knurl.

Do not knurl copper or sintered diamond laps.

Fast Faceting System

I design and manufacture gemstone faceting systems to quicken the actions of faceting by combining the grinding, pre-polish and final polishing into one disc while maintaining the accuracy of slower 3 individual disc systems.This removes the need to re-find facets multiple times by fully completing the facet in its exact position.

The first section is a fine diamond sintered bronze disc water cooled with an inner disc of  copper  for pre-polishing with a further disc in the centre of that disc of tin alloy for final polishing.A disc in a disc in a disc. All are machined level for facet correctness between disc sections.