FREQUENTLY ASKED QUESTIONS

 

Q. Can I comfortably carry my entire Shaw geotechnical soil sampling kit, including drilling water supply, extra extensions and bits in my backpack for geotechnical work in rough country or in otherwise inaccessible locations?

A.  Yes; The entire kit of Shaw soil sampling equipment, which varies somewhat in weight depending on the number of extensions used, typically weighs less than 55 lbs. (25kg.) including two gallons of drilling fluid. This load is not nothing, but tolerable for most individuals who are in good physical condition.

 

Q. For successful use of Shaw soil sampling equipment, how important is it to add polymer (e.g. EZ Mud) to drilling water?

A.  Polymer amendment of drilling water for Shaw drill geotechnical sampling is very important: it (1) greatly reduces water usage, (2) allows drilling and sampling of clay due to its’ clay particle encapsulation behavior, (3) lubricates the rotating drill string, the non-rotated sampler capsule and the soil sampler core bit, thereby improving the cutting rate, and (4) prevents clay adhesion to metal surfaces of the drill bit, drill string, and drilling fluid injectors in the soil drill bit.

 

Q. How much polymer should I add to my drilling water?

A. It is best to carefully add as much polymer as needed to achieve a product which has the viscosity of a smooth, no lumps, gelatinous (ropy), medium to heavy syrup (see video below). Polymer product, either in liquid or dry form, should be introduced very slowly and carefully to water as it is a powerful, rapid action water gelling agent. Wear gloves to prevent terrific glue-like adhesion to the skin of your hands. While being added to water, a wire whip (kitchen tool) or electric mixer should be used vigorously to break up lumps. The completed mixture will naturally stratify; therefore, it must be re-mixed every thirty minutes or so in its container. The amended water solution drilling fluid tends to gain some viscosity after mixing as partially mixed polymer grains or liquid continue to gel the water.

 

Q. How important is it to precisely measure gasoline and two-stroke engine oil volumes for the 50:1 optimal ratio fuel mixture of the Shaw drill Kawasaki TJ 53 engine?

A. The need for really accurate measurement of oil and gasoline for the Shaw TJ Kawasaki two-stroke engine fuel can hardly be over emphasized. A lean gasoline to two-stroke engine oil ratio fuel mixture can, and unfortunately for Kawasaki 53 owners, sometimes does burn engine piston heads and cylinder walls. A too high oil to gasoline ratio mixture causes oil fouling of the spark plug, carburetor and muffler which, in turn, impedes engine starting.

 

Q. What drill penetration rate is best for Shaw soil sampling?

A. This must be determined by the drill operator, depending mostly on the earth material being penetrated. For example, a soft, moist, uniform silt soil can reasonably be penetrated fairly quickly, as long as drilling fluid emerges steadily onto the ground surface, indicating good circulation. A rocky soil, on the other hand, would necessarily take longer to penetrate even if the rocks were soft, comprised of, for example, limestone (Mohs scale 3). An even slower rate of penetration would be required if the included rocks were hard, such as those comprised of granite (Mohs scale 6.5 - 8.0). A slow rate of penetration would also be called for when drilling in swelling clay, which is probably a core driller’s worst enemy due to its’ diamond bit “slicking” behavior and its great adhesiveness to drill string metal parts, especially the drilling fluid injectors of the soil drill bit.  

 

Q. Diamond bits can be quickly worn in abrasive soils. How can excessive bit wear be avoided?

A. Shaw soil sampling bits are made with wide, sintered diamond segments with generous clearance on both internal and external surfaces for extended bit life. These segments are also made with a hard (high cobalt concentration) matrix and high diamond concentration to resist abrasion. There is nothing that the drill operator need do to achieve good Shaw soil bit life, except maintain good drilling fluid delivery to the bit at all times when drilling is proceeding.

 

Q. If the Shaw soil sampler is quite different in its action than other types, how does it work?

A. There are actually several novel parts of the Shaw soil sampling system which allow it to sample a wide variety of earth materials without torque, compression or percussion damage: (1) wide kerf, hard matrix, sintered diamond segments of its’ bit are capable of cutting almost any earth material, accompanied by a good flow of drilling fluid around bit face working diamond crystals, by simple abrasion, (2) recessed drilling fluid injectors, nearly immune to clogging by soil or clay, fill empty spaces with fluid between the segments where it is mixed with drill cuttings, (3) skirts on the inside edge of the bit face prevent drilling fluid from eroding soil cores, (4) a sampler tube (brass) protects soil cores from drilling fluid contact and erosion, (5) a sampler cap which has only a loose slip fit with the sampler tube and a minimal contact with the rotating male bayonet coupling nose above it, nearly eliminates torque transfer from the bayonet to the largely stationary sampler tube during sampling events, and (6) a valved air vent mounted in the cap prevents air compression and resistance to sampler filling, and, after capture, holds sample cores inside the sampler by vacuum (clam gun effect).

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BASIC SHAW DRILLING PROCEDURES

 

 

Bit dressing

Sintered diamond core bits can only cut rock when diamond crystals protrude above the bit segment metal matrix surface. In abrasive materials such as sandy soil, erosion of the matrix around the diamond crystals is rapid: the bit can cut at its maximum rate. In non-abrasive rock drilling, however, in hard, uniform materials such as granite or jadeite, the working diamonds of the bit segments tend to be planed down to the level of the segment matrix and thereby lose their cutting power. In this hard rock drilling case, the segment matrix must be artificially worn away to expose the diamonds and thereby restore the bit’s abrasiveness. This process is called “bit dressing”.

The best way to dress a Shaw diamond core bit is by running it fast and hard in a bucket of industrial sand blast grit. The grit can be screened slag, or silicon carbide or other hard, broken, thereby sharp-edged material. As the bit matrix is quickly eroded in this process, the bit diamonds become prominent and are cleaned such that they sparkle in sunlight. The exposed diamonds can be further improved as cutting elements by striking the bit surface with the edge of a hard flat file which shatters some crystals, leaving sharp cutting edges and points.

 

replacing worn bits

When a Shaw saber (rock) bit or soil bit has lost nearly all of its clearance or segment length, then it must be removed from its’ core barrel and replaced. The bits are threaded to the core barrels and may have been used for several hundred feet of boring; therefore, although the threads have been doped with copper based anti-seize, they may be hard to get off. In the case of bayonet coupled core barrels, the best approach to the job is to leave the engine drill attached to the core barrel, apply one pipe wrench (clockwise) to the water swivel (hardened steel) and the other (counterclockwise) to the bit segments. With opposing strain on the wrenches, the bit thread will loosen. The new bit thread should receive some clean, copper based anti-seize lubricant.

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opening Shaw bayonet couplings

Shaw clockwise turned bayonet couplings, if they are kept clean and spayed frequently with dry, grit repelling Teflon lubricant, can normally be opened by hand. Rarely, two open-end wrenches (supplied) must be applied to flats on the couplings to cause the male and female parts to separate.  

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opening Shaw threaded couplings

The Shaw hollow stem system for deeper borings requires threaded couplings which typically more force to open than the Shaw bayonet type. Two pipe wrenches (supplied) are required for the job, one applied to the male coupling and one to the female coupling. The wrench jaws should be positioned over the coupling knurled surfaces for good grip. The 3 mm wall spring steel couplings are relatively strong and resilient, but it should be remembered that these are, after all, thin-walled tubes; care must be exercised in applying to them pipe wrenches, which are very crude and potentially destructive tools. 

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replacing bayonet coupling o rings

The three rubber (Buna N Nitrile) o ring seals mounted on the ends of Shaw male bayonet couplings can last a long time even with substantial use if kept clean and religiously coated with spray Teflon (PTFE) after decoupling. However, the repeated passage of the rings through hard edges of the female couplings during coupling and decoupling causes the rubber to become worn.

To replace the Shaw o rings, dig out the worn rings with a thin, pointed tool such as the tip of a knife blade or a tiny screw driver to lift them out of their grooves in the male coupling. Stretch new o rings over the male coupling nose and push them backward into the grooves where they will contract and fit their grooves firmly.

 

selecting bits

Shaw offers several kinds of bits to be used for penetrating and sampling a variety of earth materials. There is only one kind of Shaw soil bit, the 7 mm width diamond impregnated segments of which are made with a hard matrix and high diamond concentration to resist the often very high abrasiveness of sandy soil or sandy stream (placer) deposits. Shaw rock bits, on the other hand, are of two segment widths and two matrix hardnesses, hard or soft, for use in a a variety of rock types.

Appropriate selection of Shaw rock bits is somewhat counterintuitive. Soft materials like soil or asphaltic concrete are best cut with the use of a hard matrix diamond bit. Hard, non-abrasive materials like quartz, or garnet are best cut with the use of a soft matrix diamond bit. In the first case, abrasive sand quickly erodes the segment matrix, causing the diamond crystals to be undercut and removed prematurely, therefore a hard matrix is called for. In the second, hard rock case, there is not enough abrasiveness to keep the diamonds well exposed and effective as cutting elements; therefore, a soft, easily eroded matrix is needed.

 

bit filing

The Shaw “saber” pedestal embedded segment diamond core bit cuts at least twice as fast as core bits of the same kerf width and outer diameter and, because the saber diamond segments are longer, has a bit life several times that of conventional diamond bits. But with these substantial advantages comes the cost of greater maintenance. Drilling fluid half circle waterways in the Shaw bit pedestal steel between the segments must be kept open. This waterway maintenance can be done with small rotary grinding tools (Dremel or other) in the shop or by hand filing with a 4 mm diameter rat tail file in the field.

Hand filing produces nicely circular waterways of the right diameter and can be done almost anywhere but it does require care and acquired skill. It is best to do it with a bit mounted on its core barrel so that the bit is stable while the file is stroked against it. Once learned, hand filing becomes instinctual and easy to do. The process is best shown by the video below.

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mixing drilling fluid

Mixing polymer products with clean water, especially under uncontrolled field conditions is an art, as the products vary in their viscosity producing power and exact volumes of water and volumes of polymer product, likely to be used in tiny amounts, usually cannot be measured with certainty.  Generally, polymer product, especially dry powder, is a powerful gelling agent which must be added to water slowly and carefully to prevent formation of big, stubborn lumps. In the field, a wire whip is useful for vigorous mixing of polymer product into water as it is being mixed. The video below will illustrate field preparation of polymer amended water drilling fluid.

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ordering expendables and parts

We provide all related parts and consumables related to the equipment. You can contact our sales-representitive by clicking the "contact us" button on top and bottom of our website.

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capture and transport of soil samples

Once captured in the sampler tube and then extruded from it, two-inch (51 mm) diameter soil samples, typically 13 inches (35 cm) to 15 inches (40 cm) long, can be described and then discarded in the field. If it is desired to bring some or all soil samples back to the geotechnical laboratory, then it is suggested that the samples be wrapped in PVC stretch wrap product (Saran wrap and other brands) (PVC) to holdprotect them together forin transport and to preserve their moisture content. The wrapped cores should be carefully labelled with a permanent marking pen. Core boxes are useful if available.