What are sintered laps and are they worth the money?
OK, a sintered laps is a type of lap that basically is solid diamonds all the way through the lap.
The diamond is bonded into the actual metal of the lap and the entire laps is made of diamonds, yes they are expensive, but well worth the money if you can afford them or need them for business.
Because the lap is solid metal/diamonds these types of laps tend to be very expensive. Both because they have a very high amount of diamonds in them and also because production of these types of laps tends to generally be low. There is just not a lot of people that can justify the cost of buying them.
What are the major advantages to using a sintered lap? Well the major advantages are that they cut extremely well, they are usually quite aggressive, cut fast/smooth and stay that way for a very long time.
Sintered laps will last a very long time and out live a standard bonded lap by a very significant period of time. I have seen a lot of people claim that a sintered will last longer then 10 plated laps or a life time. Basically I would not make these claims, there are no real life statistics on how long a sintered lap will wear or how much longer it will wear than “x – number” of regular plated laps. Suffice it to say that a quality sintered lap will wear and cut a very long time…
What are the major disadvantages or sintered laps? Cost is probably the main disadvantage to sintered laps, they are expensive. Availability maybe a slight disadvantage, because of the cost most dealers do not stock them. The other disadvantage of a sintered laps is how they wear. Remember these laps are solid metal/diamonds, not plated. So as time goes by and these laps wear, if the cutter is not careful and uses one or two particular areas on the laps, the laps will become grooved and not flat (eventually, note this type of thing takes years).
Not flat of course is a major problem for a faceter. The way to avoid grooving the sintered lap is of course to be careful and use the whole lap surface and do not over cut in any certain area of the lap. I would note that in general on a coarse lap a bit of wear and not flat is not really critical. But on a fine lap like a 1200 it is very important to keep the lap flat.
My experiences… As I have said sintered laps are very aggressive, which I really like. But… using the sintered lap in my experience I cannot go directly to an oxide polish, like I can from a well worn plated lap.
I have to use a 3K pre-polish. On one hand this adds another step to my cutting, but on the other hand the 1200 sintered is so aggressive that I basically never use the 600 laps any more and it eliminated a step. So it tends to be a wash, time wise. I will note that my 1200 has very, very slowly become a bit finer as I have continued to use it. It maybe possible for the lap to be fine enough some day to go directly to polish, but no time soon. So plan on the 3K pre-polsh step, at least at first.
Note: Some kind of pre-polish is needed usually, could be 8k on tin or some other combination, like a 3k on phenolic.
Who should buy a sintered lap? Well anyone that likes fine tools will appreciate one. But basically these laps are for the serious cutter and unless people cut quite a bit or a long time, there is really no need for a sintered lap. Unless of course you just want one.
I like them and use them, but these types of laps are expensive and not for everyone…
I generally do stock sintered laps