Sintered Diamond Laps

As well as special systems I also make sintered diamond six inch laps. Lets start with diamond quality. Diamond grit comes in many grades and some are designed more for plating than sintering. There three main groups for metal bond diamond sintered laps.Metal bond being in bronze or copper, so lets start with 433 diamond. Its well friable diamond particles resembling irregular shaped lumps designed to self sharpen by breaking down. These are most often used in sintered grinding wheels and discs. The next grade would be 768,which is a combination of the higher grade 989 and 433. Its most often used for tools made for the glass industry to give a good clean grind and long wear factors between redressing. 989 and 999 diamond are blocky crystals designed to take a higher pressure grind on tougher materials and are more resistant to heat build-up during grinding. Of course there is a huge price difference between 433 and 999 up to six times in fact and considering you need about 50cts of diamond in a standard 6 inch laps having a 3.5mm thickness the cost is considerable.These grades apply to discs from 25- 400 grit,anything 600 and above are generally available in synthetic which is blocky crystals. So if you find yourself redressing your roughing laps and wheels often then maybe there only 433 grade diamond. What I have found is that everybody only wants to talk quantity, thickness and price but not diamond quality. Sort of a salesman saying we buy the best available knowing only a cheap grade was available. I’ve only made a few grinding wheels and ended up turning the mold frames into disc molds because my wheels were three times the price of what was available in China. However, my wheels are still straight and sharp and the Chinese wheels are bowed out in the middle and not dressable back to flat. So I make 768 and 989 diamond grade roughing discs. NO 433
I also make sintered copper laps without the diamond but I still add in the powder lubricant.These laps are soft copper having been to 800 degrees centigrade and porous being not over pressed during sintering. This makes them a very good copper lap, far superior to discs made from plate or bar which is usually half hard. The finish is very apparent when you have used both discs.
I also do a combo lap in copper for pre-polish and special alloy (I need to find a name for this lap) centre lap for  final polishing with compounds in both 6 and 8 inch versions.

You can contact me by Email: rough2cut@gmail.com

Latest System

 

This is my latest fast faceting system. This one is special, as the alloy has been softened and has a built in lubricant in the metal matrix.This 1200 mesh ring produces a fast aggressive cut with a silk smooth finish especially on quartz.On CZ it gives a scratchy finish with the special alloy pre-polish taking care of that very nicely and sapphire you still get facet peel,but it was reduced in Tourmaline from previous alloys.The centre is my special alloy with a 3000 compound applied to the outer section and 100,000 to the  centre. I polished ten tourmalines so far and its been the most efficient so far of all my lap combinations. I also polished a sapphire and found that it dulled the copper section of the lap a little and still produced a facet peel effect but not as prominate as on previous bronze discs.The final polishing for sapphire I upped the polish to 200,000 to remove very fine white cat  hair lines.To restore the copper finish I faceted a garnet and it restored the lap to original after half a dozen facets without the need for dressing with a grit stick. The lap was tested during the faceting process on all speed ranges and performed well fast and slow,but fast  gave a faster polish.

The polishing compound I use on the special alloy is a waxed based grease with the same lubricant as the sintered lap.This along with the properties that the polishing lap  gives a very high lustre pre-polish and very low to no scratch finish on the 100,000.

Ive also  tested an 1800 sintered copper and from the results so far it is smoother by a small margin over the 1200 and showed promise as a jump to 100,000 final finish eliminating the pre-polish altogether. A 3000 sintered diamond ring as an outer or an inner ring added to the system is also a possibility. There are many other insert discs such as a copper/tin centre lap or a zinc/special alloy. Bronze  and special alloy is a perfect aqua lap. Typemetal is a great quartz cerium oxide  polish lap or corian.

Im now in production of this system and it is available as a 1200 sintered copper or a more aggressive bronze with the built in lubricant. It is 8 inch diameter with a six inch recess for a special alloy split polishing disc.I use my own formulated polish compound with my laps.I also add a 360 mesh six inch lap for the centre to rapidly rough out and smooth finish the mains and girdle.My machine allows me to extend the dop across the 1200 lap to rough grind the girdle on the 360 centre then retract the dop to fine finish the girdle ready for polish.

The system ring is $345A with the 360 mesh insert disc $295A. the special alloy lap is $125A and the polishing kit is $75A. Additional laps available are the typemetal, zinc/special combo, tin alloy and corian. All are POA.  Email me at: agemcutr@yahoo.com.au

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.