Patent Description:
Material testing systems measure the characteristics and/or behaviors of material specimens (e.g., metals, ceramics, plastics, etc.) under various conditions. Specimens that are brittle, cracked, porous, and/or otherwise sensitive may benefit from cold (also known as castable) mounting in an epoxy resin before testing. Cold mounting is a process of specimen encapsulation in an epoxy resin. Once mounted, the epoxy resin can aid in supporting porous or cracked features of material specimens.

Cold mounting vacuum systems pour an epoxy resin over a material sample in vacuum (or near vacuum) conditions. Conventionally, filling voids (e.g., pores and/or cracks) was difficult due to the air pressure within the voids. However, this difficulty is significantly reduced when a vacuum (or near vacuum) is applied. The vacuum conditions help to remove trapped air from the voids. Subsequent curing at increased pressures will force or push the resin into the voids. This process can enhance help retain and/or support delicate and/or friable material samples.

Limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with the present disclosure as set forth in the remainder of the present application with reference to the drawings. <CIT> relates to a pinching valve.

These and other advantages, aspects and novel features of the present disclosure, as well as details of an illustrated example thereof, will be more fully understood from the following description and drawings.

Where appropriate, the same or similar reference numerals are used in the figures to refer to similar or identical elements.

Preferred examples of the present disclosure may be described hereinbelow with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail because they may obscure the disclosure in unnecessary detail. For this disclosure, the following terms and definitions shall apply.

As used herein, the terms "about" and/or "approximately," when used to modify or describe a value (or range of values), position, orientation, and/or action, mean reasonably close to that value, range of values, position, orientation, and/or action. Thus, the examples described herein are not limited to only the recited values, ranges of values, positions, orientations, and/or actions but rather should include reasonably workable deviations.

As used herein, "and/or" means any one or more of the items in the list joined by "and/or".

As used herein, the terms "e.g.," and "for example" set off lists of one or more non-limiting examples, instances, or illustrations.

As used herein, the term "fluid," when used as a noun, refers to a free-flowing deformable substance with no fixed shape, including, inter alia, gas (e.g., air, atmosphere, etc.), liquid (e.g., water, solution, etc.), and/or plasma.

As used herein the terms "circuits" and "circuitry" refer to physical electronic components (i.e., hardware) and any software and/or firmware ("code") which may configure the hardware, be executed by the hardware, and or otherwise be associated with the hardware. As utilized herein, circuitry is "operable" and/or "configured" to perform a function whenever the circuitry comprises the necessary hardware and/or code (if any is necessary) to perform the function, regardless of whether performance of the function is disabled or enabled (e.g., by a user-configurable setting, factory trim, etc.).

As used herein, a control circuit and/or control circuitry may include digital and/or analog circuitry, discrete and/or integrated circuitry, microprocessors, DSPs, etc., software, hardware and/or firmware, located on one or more boards, that form part or all of a control circuit, and/or are used to control a vacuum system.

Some examples of the present disclosure relate to a vacuum system for mounting of material samples, comprising a flow control device, comprising a sheath having a central bore and a slot, and a dispensing knob received in the central bore of the sheath, the dispensing knob having a channel configured to receive a dispensing tube, wherein the dispensing knob is configured to move laterally between an extended position, where the channel is in alignment with the slot, and a retracted position, where the channel is out of alignment with the slot.

In some examples, the channel has a depth that varies based on a rotatable position of the dispensing knob. In some examples, the dispensing knob is further configured to move between a first rotatable position and a second rotatable position when the dispensing knob is in the retracted position. In some examples, the depth of the channel proximate the slot is less in the second rotatable position than in the first rotatable position, such that fluid flow through the dispensing tube is more restricted in the second rotatable position than in the first rotatable position. In some examples, the system further comprises a protrusion extending into the central bore, the protrusion being received by a passageway of the dispensing knob. In some examples, the passageway extends at least partially around a perimeter of the dispensing knob, thereby allowing the dispensing knob to rotate within the sheath. In some examples, the passageway comprises an arcuate portion extending at least partially around the perimeter of the dispensing knob and a lateral portion extending perpendicular to the arcuate portion. In some examples, the lateral portion of the passageway slides over the protrusion when the dispensing knob moves laterally between the extended position and the retracted position. In some examples, the arcuate portion of the passageway slides over the protrusion when the dispensing knob moves between the first rotational position and the second rotational position. In some examples, the dispensing knob is prohibited from moving between the first rotatable position and second rotatable position when the dispensing knob is in the extended position.

Some examples of the present disclosure relate to a method of controlling fluid flow through a tube of a vacuum system, the method comprising positioning the tube in a channel of a dispensing knob while the dispensing knob is in an extended position, the dispensing knob being retained within a sheath, and the channel being aligned with a slot of the sheath when the dispensing knob is in the extended position, moving the dispensing knob from the extended position to a retracted position where the channel is out of alignment with the slot of the sheath, and rotating the dispensing knob while the dispensing knob is in the retracted position, wherein the rotation causes the dispensing knob and sheath to pinch the tube.

In some examples, the channel has a depth that varies based on a rotatable position of the dispensing knob. In some examples, rotating the dispensing knob comprises rotating the dispensing knob from a first rotatable position to a second rotatable position. In some examples, the dispensing knob is prohibited from moving to the extended position from the retracted position when the dispensing knob is in the second rotatable position. In some examples, the depth of the channel proximate the slot is less in the second rotatable position than in the first rotatable position, such that fluid flow through the tube is more restricted in the second rotatable position than in the first rotatable position. In some examples, the method further comprises rotating the dispensing knob from the second rotatable position to a third rotatable position. In some examples, the depth of the channel proximate the slot is less in the third rotatable position than in the second rotatable position, such that fluid flow through the tube is more restricted in the third rotatable position than in the second rotatable position. In some examples, a protrusion moves within a lateral passageway of the dispensing knob when moving the dispensing knob to the retracted position. In some examples, a protrusion moves within an arcuate passageway of the dispensing knob when rotating the dispensing knob. In some examples, the method further comprises routing the tube from a reservoir, through the channel of the dispensing knob, to a vacuum chamber of the vacuum system.

Some examples of the present disclosure relate to vacuum systems (e.g., castable and/or cold mounting vacuum systems) that facilitate mounting and/or encapsulation of material samples in epoxy resin under low, vacuum, and/or near vacuum pressure. In some examples, a vacuum system may comprise a flow control device configured to control fluid (e.g. epoxy) flow through a dispensing tube. The dispensing tube may connect to a conduit that is sealingly fitted in a socket of a hollow vacuum chamber via a plug.

In some examples, the vacuum chamber may have an opening defined (at least in part) by a rim sandwiched between upper and lower portions of a sealing ring. A movable lid may be configured to press down on the upper portion of the sealing ring when in a closed position, so as to seal the opening. The vacuum chamber may additionally be in controllable fluid communication with a vacuum generator configured to adjust air pressure within the vacuum chamber, so as to create a low and/or near vacuum pressure environment. Control circuitry may be in electrical communication with valves that control whether the vacuum chamber is in fluid communication with the vacuum generator. The control circuitry may control the valves (e.g., based on input received via a user interface) to allow the vacuum converter to (or prohibit the vacuum converter from) changing air pressure within the vacuum chamber.

<FIG> depict examples of a vacuum system <NUM>. As shown, the vacuum system <NUM> includes a housing <NUM> and a vacuum chamber <NUM> positioned at least partially within the housing <NUM>. The housing <NUM> includes a front panel <NUM>, side panels <NUM>, a rear panel <NUM>, a floor (not shown), and a ceiling <NUM>. In the examples of <FIG>, a user interface <NUM> is disposed on the front panel <NUM>. In some examples, the user interface <NUM> may be a display screen having a touch screen interface. In some examples, the user interface <NUM> may include buttons, knobs, speakers, microphones, levers, dials, keypads, and/or other input/output devices. The vacuum chamber <NUM> further includes an electrical connector <NUM> and compressed air connector <NUM> on the rear panel <NUM> of the housing <NUM>. In some examples, the compressed air connector <NUM> is configured for connection to a source of compressed (or pressurized) air. In some examples the electrical connector <NUM> is configured for connection with an electrical power source. The user interface <NUM> is in electrical communication with the electrical connector <NUM> on the rear panel <NUM> of the housing <NUM>.

In the example of <FIG>, a reservoir <NUM> is positioned at least partially within a cavity formed in the ceiling <NUM> of the housing <NUM>. As shown, a flow control device <NUM> and a pillar <NUM> are attached to the ceiling <NUM> proximate the reservoir <NUM>. The pillar <NUM> includes a groove <NUM> configured to fit a dispensing tube (not shown). The flow control device <NUM> includes a channel <NUM> configured to receive the dispensing tube. As shown, a plug <NUM> having a conduit is further configured to receive an end of the dispensing tube, and bring the dispensing tube into fluid communication with a spout <NUM> within the vacuum chamber <NUM> (see, e.g., <FIG>). In some examples, the plug <NUM> may comprise a collar formed of a hard plastic material, so as to facilitate insertion into (and subsequent sealing of) a socket <NUM> of the vacuum chamber <NUM>. In operation, pressure differential between the inside and outside of the vacuum chamber <NUM> may move epoxy resin from the reservoir <NUM> through the dispensing tube and into the vacuum chamber <NUM> via the spout <NUM>. The flow control device <NUM> may control the flow of epoxy resin into the vacuum chamber <NUM> by pinching the dispensing tube to different degrees.

In the examples of <FIG>, the vacuum chamber <NUM> is largely defined by a cylindrical sidewall <NUM>. As shown, a rim <NUM> and sealing ring <NUM> define an annular opening <NUM> of the vacuum chamber <NUM>, along with sidewall <NUM>. In some examples, the rim <NUM> may be part of sidewall <NUM>. In the example of <FIG>, the opening <NUM> of the vacuum chamber <NUM> is covered by a lid <NUM>. As shown, the lid <NUM> is substantially flat and circular. The lid <NUM> is hingedly attached to the sidewall <NUM> via a mechanical linkage <NUM> (see also <FIG>). As shown, the hinged attachment comprises two hinges. This hinged coupling of the lid <NUM> allows the lid <NUM> to move from the closed position of <FIG> to an open position in <FIG>.

As shown, with the lid <NUM> in an open position, the opening <NUM> of the vacuum chamber <NUM> is uncovered. When the lid <NUM> is in a closed position (e.g., as shown in <FIG>), the opening <NUM> is covered and the vacuum chamber <NUM> is substantially sealed by the arrangement of the lid <NUM>, rim <NUM>, and sealing ring <NUM>, without any outside intervention. The ability to maintain the seal without any outside intervention assists with ease of use of the vacuum system <NUM>. For example, an operator will not need to hold down the lid <NUM> before starting a vacuum cycle or between vacuum cycles. Additionally, the sealing arrangement requires no oil, grease, or other lubricant, which saves time and reduces certain undesirable effects using of oil, grease, and/or other lubricants. In operation, when a vacuum (or near vacuum) environment is created within the vacuum chamber <NUM>, the lid <NUM> is pressed down further against the sealing ring <NUM> and rim <NUM>, strengthening the seal.

<FIG> show internal views of the vacuum system <NUM>. As shown, the vacuum system <NUM> includes a rotatable platform <NUM> positioned within the vacuum chamber <NUM>. In some examples, the platform <NUM> may support one or more containers <NUM>, such as may receive epoxy via the spout <NUM>. As shown, the rotatable platform <NUM> is configured for rotation via a spindle <NUM> that is in mechanical communication with a wheel actuator <NUM> via a drive belt <NUM>. In the examples of <FIG>, the wheel actuator <NUM> protrudes through an aperture in the side panel <NUM> of the housing <NUM>, so as to allow a user to easily rotate the platform <NUM> during operation.

In the example of <FIG>, the interior of the vacuum chamber <NUM> is in fluid communication with a port <NUM>. As shown, the port <NUM> is positioned proximate a lower end and/or bottom of the vacuum chamber <NUM>. In the examples of <FIG>, the port <NUM> is in fluid communication with a first valve <NUM>. The first valve <NUM> is also in fluid communication with a vacuum generator <NUM>. In the example of <FIG>, the vacuum generator <NUM> positioned within the housing <NUM>. In some examples, the vacuum generator <NUM> may instead be positioned outside of the housing <NUM>. In some examples the vacuum generator <NUM> may comprise a vacuum converter. In some examples, the vacuum generator <NUM> may comprise a pump. As shown, the vacuum generator <NUM> in fluid communication with a second valve <NUM>. The second valve <NUM> is further in fluid communication with the air connector <NUM>.

In the examples of <FIG>, the first valve <NUM> and second valve <NUM> are in electrical communication with the control circuitry <NUM>. In some examples, the first valve <NUM> and/or second valve <NUM> may be solenoid valves. In some examples, the control circuitry <NUM> may control the first valve <NUM> and/or second valve <NUM> to open and/or close in response to one or more control signals received from the control circuitry <NUM>.

In the example of <FIG>, the control circuitry <NUM> is in electrical communication with the user interface <NUM>. In some examples, a user may enter parameters of one or more vacuum cycles via the user interface <NUM>, and the parameters may be electrically communicated to the control circuitry <NUM>. The control circuitry <NUM> may control the first valve <NUM> and/or second valve <NUM> accordingly. In some examples, a user may select a series of vacuum cycles via the user interface <NUM>, as well as associated properties of the series (e.g., number of vacuum cycles, time between each cycle, time of each cycle, pressure or vacuum level for each cycle (e.g., -<NUM> Megapascals), etc.), and the control circuitry <NUM> may control the first valve <NUM> and/or second valve <NUM> to open and/or close accordingly.

In some examples, the opening and/or closing of the first valve <NUM> and/or second valve <NUM> may impact (e.g., raise and/or lower) pressure within the vacuum chamber <NUM>. For example, the control circuitry <NUM> may control the first valve <NUM> and second valve <NUM> (e.g., in response to user input received via the user interface <NUM>) to reduce pressure (and/or implement a given vacuum level) within the vacuum chamber <NUM>. In the examples of <FIG>, when both the first valve <NUM> and second valve <NUM> are open, the vacuum generator <NUM> is in fluid communication with both the vacuum chamber <NUM> and the air connector <NUM>. This may allow the vacuum generator <NUM> to reduce pressure within the vacuum chamber <NUM> (e.g., using pressurized air provided via air connector <NUM>).

As another example, the control circuitry <NUM> may control the second valve <NUM> to close and the first valve <NUM> to remain open (e.g., in response to user input received via the user interface <NUM>). In the examples of <FIG>, when the first valve <NUM> is open and the second valve <NUM> is closed, the vacuum generator <NUM> is in fluid communication with the vacuum chamber <NUM>, but not with the air connector <NUM>. In some examples, this arrangement may allow air pressure within the vacuum generator <NUM> to increase and/or equalize (e.g., via air available via vacuum generator <NUM>).

As another example, the control circuitry <NUM> may control the first valve <NUM> to remain close, (e.g., in response to user input received via the user interface <NUM>) to maintain pressure within the vacuum chamber <NUM>. In the examples of <FIG>, when the first valve <NUM> is closed, the vacuum generator <NUM> is not in fluid communication with the vacuum chamber <NUM>. This may restrict air pressure within the vacuum generator <NUM> from changing, as fluid communication of the vacuum chamber <NUM> with anything outside the vacuum chamber <NUM> is restricted by the closed first valve <NUM>.

In some examples, change in air pressure within the vacuum chamber <NUM> may rely on (or at least be assisted by) the lid <NUM> being in a closed position, with the lid <NUM> covering the opening <NUM>. In examples where the air pressure is lowered, the resulting disparity in air pressure may further force the lid <NUM> closed, increasing the strength of the seal formed by the lid <NUM>. Conveniently, the sealing arrangement of the lid <NUM>, sidewalls <NUM>, rim <NUM>, and sealing ring <NUM> is sufficiently stable on its own. Thus, once the lid <NUM> is in the closed position, vacuum cycles may be started, stopped, and/or restarted with no need for any external influence to maintain the seal.

In the examples of <FIG>, the sealing arrangement of the lid <NUM>, sidewalls <NUM>, rim <NUM>, and sealing ring <NUM> can be seen in more detail. As shown, an annular groove <NUM> is formed in the upper edge of the sidewall <NUM>. The rim <NUM> overhangs a portion of the annular groove <NUM>. A lower portion <NUM> of the sealing ring <NUM> is positioned within the annular groove <NUM>. As shown, the lower portion <NUM> of the sealing ring <NUM> has a thickness has a lateral width that is approximately equal to that of the groove <NUM>, and a height that is slightly greater than the distance between the floor of the groove <NUM> and the rim <NUM>. This arrangement results in part of the lower portion <NUM> being compressed and/or pinched between the rim <NUM> and the sidewall <NUM> forming the floor of the groove <NUM>, thereby securing the sealing ring <NUM> in place via a gripping frictional fit. In some examples, the rim <NUM> and/or sidewall <NUM> may be formed of a rigid material while the sealing ring <NUM> is formed of a more pliable, compressible material (e.g., foam, rubber, etc.) so as to facilitate this arrangement.

In the examples of <FIG>, the lower portion <NUM> of the sealing ring <NUM> connects to an upper portion <NUM> of the sealing ring <NUM> at a living hinge <NUM>. As shown, the living hinge <NUM> is a flexible hinge formed of the same material as the sealing ring <NUM>. As shown, the sealing ring <NUM> is cut or separated proximate the living hinge <NUM>, so as to allow the upper portion <NUM> to move about the living hinge <NUM>.

In the example of <FIG>, the lid <NUM> is in an open position, and the upper portion <NUM> of the sealing ring <NUM> extends upwards over and/or away from the rim <NUM>, into portions of the opening <NUM> that the lid <NUM> would occupy in the closed position. In the example of <FIG>, the lid <NUM> is in the closed position and pressing down on the sealing ring <NUM>, thereby sandwiching the upper portion <NUM> of the sealing ring <NUM> between the lid <NUM> and the rim <NUM>. Being a pliable material, the sealing ring <NUM> is compressed between the lid <NUM> and the rim <NUM>, allowing the lid <NUM> to come to its resting closed position, while filling any gaps between the lid <NUM> and the rim <NUM>, so as to create a solid seal. In some examples, the lid <NUM> may be of a sufficient weight to compress the upper portion <NUM> of the sealing ring <NUM> with no additional and/or outside assistance. Thus, vacuum cycles may be started, stopped, and restarted, with no need for an operator to hold down the lid <NUM> or make any adjustments. In operation, the sealing arrangement is further strengthened when air pressure is lowered within the vacuum chamber <NUM> (e.g., via the vacuum generator <NUM>), which further forces the lid <NUM> downward against the sealing ring <NUM> and tightens the seal. The sealing arrangement also needs no oil or lubricant to function correctly as some conventional seals require, which removes the need for repeated application of the oil/lubricant and/or other detrimental effects. Further, the sealing ring <NUM> acts as an intermediate buffer between lid <NUM> and rim <NUM>, and lessens abrasion between the two.

In operation, once the vacuum chamber <NUM> is sealed, and pressure within the vacuum chamber is lowered, epoxy may be drawn into the vacuum chamber <NUM> from the reservoir <NUM> via the dispensing tube (not shown). <FIG> show examples of a flow control device <NUM> of the vacuum system <NUM> configured to control epoxy flow through the dispensing tube. In the examples of <FIG>, the flow control device <NUM> is attached to the ceiling <NUM> of the housing <NUM> proximate the pillar <NUM>. In the examples of <FIG>, the flow control device <NUM> includes a knob <NUM> fitted within a sheath <NUM>.

According to the invention illustrated in <FIG>, the knob <NUM> is configured to move between an extended position (such as shown, for example, in <FIG>) where a head <NUM> of the knob <NUM> extends away from the sheath <NUM>, and a retracted position (such as shown, for example, in <FIG>), where the head <NUM> of the knob <NUM> is flush against the sheath <NUM>. As shown, the knob <NUM> includes a channel <NUM>, and the sheath <NUM> includes a window <NUM>. The window <NUM> includes an arcuate slot <NUM> that substantially aligns with the channel <NUM> when the knob <NUM> is in the extended position of <FIG>. This alignment facilitates easy reception of the dispensing tube into (and/or removal of the dispensing tube from) the channel <NUM> when the knob <NUM> is in the extended position.

In the example of <FIG>, the knob <NUM> is in the retracted position, and the arcuate slot <NUM> does not align with the channel <NUM>. This misalignment makes it difficult to insert or remove the dispensing tube while the knob <NUM> is in the retracted position. Thus, the flow control device <NUM> can be put in the retracted position to secure the dispensing tube within the flow control device <NUM> and prevent removal. As shown, the window <NUM> further includes two parallel lateral slots <NUM> connected by the arcuate slot <NUM>. The lateral slots <NUM> align with the channel <NUM> when the knob <NUM> is in both the extended and retracted positions. Thus, the lateral slots <NUM> allow the dispensing tube to extend into, out of, and/or through the flow control device <NUM> when the knob <NUM> is in both the retracted position and extended position.

<FIG> show further details of the sheath <NUM>. As shown, the sheath <NUM> includes a generally cylindrical body <NUM>. The body <NUM> is generally hollow, with a solid back wall <NUM> and a bore <NUM> extending through the body <NUM> and terminating at the back wall <NUM>. An indent <NUM> is formed in a top of the sheath <NUM>, at a front of the body <NUM>. In operation, the indent <NUM> may be aligned with a complementary indent <NUM> on the knob <NUM> to indicate a zero degree rotational angle of the knob <NUM> with respect to the sheath <NUM>. In some examples, some other indication (e.g., marking, texturing, coloring, etc.) may be used in place of the indent <NUM> and/or complementary indent <NUM>.

In the examples of <FIG>, a protrusion <NUM> extends into the bore <NUM> on a bottom of the sheath <NUM>, opposite (or <NUM> degrees from) the indent <NUM> in the top. In some examples, the protrusion <NUM> may be a bolt or other fastener inserted through an aperture formed in the bottom of the sheath <NUM>. In the example of <FIG>, the protrusion <NUM> is the shank of a bolt, having a bolt head <NUM>. In operation, the protrusion <NUM> may be fitted within a passageway <NUM> of the knob <NUM> to facilitate lateral and/or rotational movement of the knob <NUM>. In the example of <FIG>, the sheath <NUM> also includes attachment points <NUM> on the bottom of the sheath <NUM> facilitate attachment to the housing <NUM>. In some examples the attachment points <NUM> may comprise holes configured for reception of screws, bolts, and/or other fasteners.

<FIG> show further details of the knob <NUM>. As shown, knob <NUM> includes a head <NUM> and a shaft <NUM>. Both the head <NUM> and shaft <NUM> are generally cylindrical, with the head <NUM> having a larger diameter than the shaft <NUM>. The diameter of the head <NUM> is larger than the diameter of the bore <NUM>, such that the head <NUM> will not fit within the bore <NUM> of the sheath <NUM>. However, the diameter of the shaft <NUM> is small enough to fit comfortably within the bore <NUM> of the sheath <NUM>.

In the examples of <FIG>, the shaft <NUM> includes the channel <NUM> and a passageway <NUM>. As shown, the passageway <NUM> is formed between the channel <NUM> and the head <NUM> of the knob <NUM>. The channel <NUM> is formed between the passageway <NUM> and an end <NUM> of the knob <NUM>. As shown, the channel <NUM> extends all the way around the shaft <NUM> of the knob <NUM>, forming an annular trench. However, in the examples of <FIG>, the passageway <NUM> only extends over a portion of the shaft <NUM>, which limits the potential movement of the knob <NUM> within the sheath <NUM>. The passageway <NUM> is configured to slidably fit the protrusion <NUM> therein, such that the knob <NUM> can move over the protrusion <NUM> (and the protrusion <NUM> can move within the passageway <NUM>) when the knob <NUM> is moved between the extended and retracted positions, and between rotational positions.

In the examples of <FIG>, the passageway <NUM> includes a lateral portion <NUM> and an arcuate portion <NUM>. As shown, the arcuate portion <NUM> extends in an arc from the lateral portion <NUM> to a position approximately aligned with the complementary indent <NUM> of the knob <NUM>. As shown, the lateral portion <NUM> extends approximately perpendicular to the arcuate portion <NUM> and channel <NUM> of the dispensing knob <NUM>, and approximately parallel to the lateral slots <NUM>.

In the examples of <FIG>, the lateral portion <NUM> of the passageway <NUM> intersects with the arcuate portion <NUM>, which allows the protrusion <NUM> to transition from one portion of the passageway <NUM> to another. In operation, the protrusion <NUM> moves within the lateral portion <NUM> when the knob <NUM> is moved between the extended and retracted positions. The protrusion <NUM> is farthest from the intersection of the lateral portion <NUM> and arcuate portion <NUM> when the knob <NUM> is extended as far as possible from the sheath <NUM> (e.g., such as shown in <FIG>). The length of the lateral portion <NUM> limits how far the knob <NUM> can extend away from the sheath <NUM>.

While in the extended position, the knob <NUM> can only move laterally between the extended and retracted positions, because the lateral portion <NUM> of the passageway <NUM> is the only path available for the protrusion <NUM> to travel. When moving laterally, the complementary indent <NUM> formed on the head <NUM> of the knob <NUM> is aligned with the indent <NUM> on the sheath <NUM>. However, once in the retracted position (e.g., of <FIG>), the protrusion <NUM> will reach the intersection between the lateral portion <NUM> and arcuate portion <NUM> of the passageway <NUM>, and thus be in a position to travel through the arcuate portion <NUM>, allowing for rotational movement of the knob <NUM>.

The knob <NUM> is configured for rotational movement within the sheath <NUM> when in the retracted position (e.g., such as shown in <FIG>). In operation, the protrusion <NUM> moves within the arcuate portion <NUM> of the passageway <NUM> when the knob <NUM> rotates within the sheath <NUM>. In the example of <FIG>, when the protrusion <NUM> moves within the arcuate portion <NUM> of the passageway <NUM> out of alignment with the lateral portion <NUM>, the complementary indent <NUM> formed on the head <NUM> of the knob <NUM> likewise moves out alignment with the indent <NUM> on the sheath <NUM>. Thus, an operator can see quickly how far the knob <NUM> has been rotated, and/or if the knob <NUM> can be moved laterally.

In the examples of <FIG>, the channel <NUM> of the knob <NUM> has a depth D that varies depending on the rotational position of the knob <NUM>. As shown, the depth D of the channel <NUM> decreases as the knob <NUM> is rotated. <FIG> show examples of the knob <NUM> at different rotational positions, illustrating this decreasing variation. In particular, the examples of <FIG> show the depth D of the channel <NUM> where the dispensing tube would be positioned (e.g., in alignment with the lateral slots <NUM> of the sheath <NUM>). In the example of <FIG>, the knob <NUM> has not been rotated (i.e., <NUM> degree rotation). As shown, the depth D in <FIG> is relatively large. In the example of <FIG>, the knob <NUM> has been rotated approximately forty-five degrees (i.e., some rotation). As shown, the depth D in <FIG> is less than in <FIG>. In the example of <FIG>, the knob <NUM> has been rotated approximately ninety degrees (i.e., full rotation). As shown, the depth D in <FIG> is less than in both <FIG>.

The varying depth D of the channel <NUM> allows an operator to vary flow of epoxy through the dispensing tube by turning the knob <NUM> when in the retracted position. When the knob <NUM> is in the retracted position, the dispensing tube remains substantially aligned with the lateral slots <NUM> of the sheath <NUM>. However, the depth D of the channel <NUM> in alignment with the lateral slots <NUM> decreases as the knob <NUM> is rotated. Thus, while the dispensing tube fits comfortably within the channel <NUM> when the knob <NUM> is at <NUM> degrees of rotation (e.g., <FIG>), the dispensing tube begins to become pinched (e.g., between the shaft <NUM> defining the bottom of the channel <NUM> and the sheath <NUM>) when the angle of rotation increases. The more the knob <NUM> is turned, the smaller the depth D of the channel <NUM> gets, and the more the dispensing tube is pinched. The more the dispensing tube is pinched, the more the flow of epoxy through the dispensing tube is restricted. Thus, an operator may adjust the flow of epoxy through the dispensing tube by changing the rotation of the knob <NUM> within the sheath <NUM>.

Claim 1:
A vacuum system (<NUM>) for mounting of material samples, comprising:
a flow control device (<NUM>), comprising:
a sheath (<NUM>) having a central bore (<NUM>) and a slot (<NUM>); and
a dispensing knob (<NUM>) received in the central bore (<NUM>) of the sheath (<NUM>), the dispensing knob (<NUM>) having a channel (<NUM>) configured to receive a dispensing tube, wherein the dispensing knob (<NUM>) is configured to move laterally between an extended position, where the knob extends away from the sheath (<NUM>) and where the channel (<NUM>) is in alignment with the slot (<NUM>), and a retracted position, where a head (<NUM>) of the knob (<NUM>) is flush against the sheath (<NUM>) and where the channel (<NUM>) is out of alignment with the slot (<NUM>).