Post by Woodyrock on Dec 6, 2011 1:58:18 GMT -5
Here is the wee blurb I wrote up a while back about oil. I use a low viscosity pharmaceutical grade white mineral oil.
About petroleum coolants for lapidary saws.
We all know that our saw blades need be run with a coolant, which in all but the smallest saws will be an oil. Now, the diamond itself can withstand far more heat than we can expose it to, but the matrix, and the blade itself cannot. The heat produced from frictional forces in cutting rock generate substantial heat, and this cause expansion, and warping of the blade if run without a coolant. The coolant not only serves as a lubricant, which reduces the frictional forces between the blade, and the rock, but also must carry away the residual heat generated by friction, flush away the rock particles created by the cutting action. This cutting debris, if allowed to accumulate is abrasive enough to cause excess blade wear. It also prevents the blade from making good contact with the rock thus reducing the cutting efficiency.
So, what do we need for a coolant oil? First, we need an oil that lubricates the blade, next, we need to cool the blade, and third, we to clean away the debris created by the cutting action. A high flash point is also desirable. The viscosity we need should be in the range of 65 to 110 SUS at 100º F. Lower viscosity oils cool, and clean debris better than do heavier oils, but also produce more mist. Odor is also a big concern to many…………especially women. My wife, can smell both Pella A, and Almag on a washed slab at 100 yards. The white mineral oils have no odor, but are slightly more expensive. White mineral oils, can be somewhat hard to find in small quantities, but nearly all oil suppliers will sell by the drum of 55 gallons at about $650 per gallon.
The simplest solution is a mixture of kerosene, and motor oil. A mixture of three parts kerosene to one part of 10W non detergent motor oil is an old standby. It does cool the blade quite effectively but suffers in its ability to clean the debris away, and the odor produced is intense to say the least. It is readily available, inexpensive, and cleans off the slab readily.
For many years lapidaries have used Pella A, made by Shell, and Almag by Texaco for coolant oils. These oils are about 45 to 50 SUS, work very effectively, but have the disadvantage of a strong odour, and produce a heavy mist. The flash point of these oils is 285º F. Neither of these oils clean off slabs easily nor does the smell clean off hands effectively.
A better choice, would be a white mineral oil that is USP grade (US Pharmacopeia) or a food grade oil. The only difference between a USP grade white oil, and a food grade is the requirement for food grade to be packaged in a clean room. They both come out of the same tank. If you have a large bakery near you, that could be a good source for small quantities of these oils. The bakeries use them as a dough divider oil, and to oil the baking pans. Duoprime White Mineral Oil 70, is a 70 SUS odor free oil with a flash point of 330º F available from Vanguard Distributing. Exxon markets white mineral oils as Marcol 52, and Marcol 82. The numbers indicate the SUS viscosity. They also have a 330º F flash point. There are many more white mineral oils available then just these two. All of the white mineral oils clean off slabs easily as well as from your hands.
Half way between the Pella/Almag oils, and white mineral oils, are the pale mineral oils, which seem to have all the advantages, and disadvantages of both the above oils. They have both a slight colour, and slight odour.
Woody
About petroleum coolants for lapidary saws.
We all know that our saw blades need be run with a coolant, which in all but the smallest saws will be an oil. Now, the diamond itself can withstand far more heat than we can expose it to, but the matrix, and the blade itself cannot. The heat produced from frictional forces in cutting rock generate substantial heat, and this cause expansion, and warping of the blade if run without a coolant. The coolant not only serves as a lubricant, which reduces the frictional forces between the blade, and the rock, but also must carry away the residual heat generated by friction, flush away the rock particles created by the cutting action. This cutting debris, if allowed to accumulate is abrasive enough to cause excess blade wear. It also prevents the blade from making good contact with the rock thus reducing the cutting efficiency.
So, what do we need for a coolant oil? First, we need an oil that lubricates the blade, next, we need to cool the blade, and third, we to clean away the debris created by the cutting action. A high flash point is also desirable. The viscosity we need should be in the range of 65 to 110 SUS at 100º F. Lower viscosity oils cool, and clean debris better than do heavier oils, but also produce more mist. Odor is also a big concern to many…………especially women. My wife, can smell both Pella A, and Almag on a washed slab at 100 yards. The white mineral oils have no odor, but are slightly more expensive. White mineral oils, can be somewhat hard to find in small quantities, but nearly all oil suppliers will sell by the drum of 55 gallons at about $650 per gallon.
The simplest solution is a mixture of kerosene, and motor oil. A mixture of three parts kerosene to one part of 10W non detergent motor oil is an old standby. It does cool the blade quite effectively but suffers in its ability to clean the debris away, and the odor produced is intense to say the least. It is readily available, inexpensive, and cleans off the slab readily.
For many years lapidaries have used Pella A, made by Shell, and Almag by Texaco for coolant oils. These oils are about 45 to 50 SUS, work very effectively, but have the disadvantage of a strong odour, and produce a heavy mist. The flash point of these oils is 285º F. Neither of these oils clean off slabs easily nor does the smell clean off hands effectively.
A better choice, would be a white mineral oil that is USP grade (US Pharmacopeia) or a food grade oil. The only difference between a USP grade white oil, and a food grade is the requirement for food grade to be packaged in a clean room. They both come out of the same tank. If you have a large bakery near you, that could be a good source for small quantities of these oils. The bakeries use them as a dough divider oil, and to oil the baking pans. Duoprime White Mineral Oil 70, is a 70 SUS odor free oil with a flash point of 330º F available from Vanguard Distributing. Exxon markets white mineral oils as Marcol 52, and Marcol 82. The numbers indicate the SUS viscosity. They also have a 330º F flash point. There are many more white mineral oils available then just these two. All of the white mineral oils clean off slabs easily as well as from your hands.
Half way between the Pella/Almag oils, and white mineral oils, are the pale mineral oils, which seem to have all the advantages, and disadvantages of both the above oils. They have both a slight colour, and slight odour.
Woody