Probe Hole Research Articles

Study of the distribution of residual stresses across the surface layer depth following machining through probing hole drilling and digital image correlation

The article aims to study the distribution of residual stresses across the surface layer depth following the machining of test specimens (free orthogonal cutting and burnishing). The machining by cutting and burnishing of 45 steel specimens was carried out using a milling machine with numerical control under varying machining factors. For a comparative analysis, the processes were also modeled via the finite element method using identical experimental values of geometric parameters and machining modes. In order to obtain residual stress distributions across the surface layer depth, probe holes having depths of 0.5; 0.75; 1; 1.5; and 2 mm were drilled. By differentiating the displacement of specimen surface particles, measured using digital image correlation, radial strains around the probe holes were determined. Then, these values were used to determine the residual stress components for each probe hole, and the averaged values of each residual stress component were calculated using the calculation algorithm presented in this article. After burnishing the specimen with a force of 3400 N, the test value of the σx component within the depth range (from the surface) of 0.5–0.75 mm amounted to -250 MPa. Model and experimental distributions of residual stress tensor components across the surface layer depth were obtained following machining via two methods. The experimental values of residual stresses were found to have good convergence with each other and with model distributions at depths up to 1 mm from the machined surface at a drill diameter of 1.7 mm. The proposed approach provides a means to obtain the residual stress distribution across the surface layer depth by drilling probe holes of different depths and estimating radial strains on the specimen surface using the digital image correlation method.

Fields of residual stresses near open assemblage holes of aircraft wing panel

The results of fatigue tests of two geometrically identical and similar in design models of the lower wing panel of a commercial aircraft are were analyzed. The panels differed in the way of installing mounting bolts, which connect the skin and stringers. Cold expansion of holes drilled both in the skin and stringer has been performed for the first panel before joining. The second panel includes no additional treatment after drilling pilot holes and final reaming. Bolts are mounted with an interference fit varying from 1.3 to 2.1% and from 2.9 to 3.2% for the first and the second panel, respectively. Changes in the interference fit are the consequence of a scatter attributed to the presence of a tolerance zone for the diameters of both bolts and mounting holes. A two-step comparison of both technologies is based on the experimental study of residual stress fields. The first stage, being a subject of the present study, includes the analysis of residual stress fields, which arise after removing bolts and separation of skin from stringers. Hole drilling and gradual crack growth were used to determine the components of residual stresses. Deformation response is measured by electronic speckle-pattern interferometry. High quality interferograms, which provide a reliable resolution of the interference fringes of ultimate density over the hole edge or directly along the notch borders, have been obtained for both ways of local removing the material. The first point-wise method based on drilling a probe hole, provides a quantitative determination of the residual stress components, starting from 1.4 mm distance from the assemblage hole edge. The second technique implements the crack compliance method of subsequent lengthening of the notch, starting directly from the mounting hole edge. This approach provides for a quantitative analysis of residual stress fields, related to different bolt mounting technologies, proceeding from the comparison of SIF values. A high level of compressive residual stresses near open holes is characteristic for both types of panels. Both experimental approaches showed the benefits of joints, where bolts are mounted into cold-expanded (reinforced) holes. For this case, the estimation of the relaxation parameters of the principal component of residual stresses in the direction of the external load is presented.

Comparison of Single Hole, Two Hole and Four Hole Probes for Three-Dimensional Flow Measurements

The present paper compares calibration curves and sensitivity curves of calibration coefficients of a four hole probe, two-hole probe and single hole probe for three dimensional flow measurements. A 2.54 mm hemispherical cantilever four hole probe is calibrated in the yaw and pitch angle range of -60° to 60° and -50° to 30° at an interval of 5°. This calibration data is used to calculate calibration coefficients and calibration and sensitivity curves of calibration coefficients for the four hole, two-hole and single hole probes. From these curves the two hole probe is identified as the best configuration for three dimensional flow measurements.

Home Made Four-Point Probe: Case Studies of the Wobbly A and B Probes

A simulation on the effect of probe deviation on sheet resistivity value (Rs) of Cu/Ni thin film was carried out in a home-made four-point probe (HM-FPP) type. This began by solving the Rs formula for normal probes, and then for wobbly probe when it was either A, or both A and B. The formula was implemented on a thin layer of Cu/Ni, which was a low temperature sensor material obtained from electrodeposition for 60s assisted by a 200G magnetic field at a current density of 0.07A/mm2. An electric current of 0.20118A was flown from probe A to D in order to produce a potential difference between probe C and D of 0.0005 volts. Furthermore, the distance between the probes was 5 mm and the deviation of each probe A and B were simulated from -0.5 mm to 0.5 mm. The maximum allowable limit for the relative error of Rs or SRs is 5%. The results showed that the ideal Rs value was 0.113 ohm/sq. Furthermore, for HM-FPP in which the wobbly probe only A, there is no problem encountered with the variation of the deviation because all SRs are less than 5%. For wobbly probes A and B, if they are on the same side of the center point of each probe, the maximum allowable deviation is 0.3 mm. The SRs for this case were 4.6%. However, if they are on different sides of the center point of each probe, the maximum allowable deviation is 0.1 mm with SRs of 2.9%. With these results, HM-FPP craftsmen must be more careful in making the size of the probe hole.

Ultrafast hole relaxation dynamics in quantum dots revealed by two-dimensional electronic spectroscopy

Elucidating the population dynamics of correlated electron-hole pairs (bound excitons) in semiconducting quantum dots (QDs) is key for developing our fundamental understanding of nanoscale photophysics as well as for the optimal design of devices, such as lasers. For decades, it was assumed that holes did not contribute to band edge bleach signals in QDs. Here, we employ two-dimensional electronic spectroscopy to monitor electron and hole dynamics in both CdSe and CdSe/CdS/ZnS QDs to probe electron and hole dynamics. Based on a combination of time and frequency resolution, we observe a previously unresolved bleaching signal in CdSe QDs on timescales faster than 30 fs due to hole cooling. Atomistic semiempirical pseudopotential calculations are used to rationalize the order of magnitude difference in the observed hole dynamics in CdSe and CdSe/CdS/ZnS QDs. This picture advances our understanding of QD excitonics past the prevailing continuum effective mass theories generally used to describe QD electronic structure and dynamics.

Developing a novel method to measure texture changes of semi-solid food during a continuous compressive motion with high deformation using repeatable dual extrusion cell (RDEC)

Mechanical changes during mastication are difficult to evaluate without using a novel method because the size of the sample is continuously and randomly reduced. The repeatable dual extrusion cell (RDEC) has been developed to measure the breakdown characteristics of a semi-solid food (i.e., minced pork gel) from initial solid states to a small particle size during repeated high deformation compressive motions. The force–time curve of RDEC was recorded, followed by a calculation of work values for each cycle and fitted by Peleg’s model. The decrease of k1 (1.7–1.19) and k2 (1.56–1.42) values in Peleg’s model with an increase of moisture content (56.5–62.5 %) indicated the easily deformable characteristics of soft food. During RDEC measurement, as long as the characteristic length of the sample was larger than the diameter of RDEC probe hole (>4.5 mm), the initial sample size showed no significant influence (p < 0.05) on the measurements. RDEC demonstrated similar ratios of particulate size with human subjects up till 20 cycles of processing. The equilibrium force value from RDEC and SEM images demonstrate that the connective tissue in pork gel mainly contributed to the end-product texture properties after continuous mastication. This study provided an application of the novel RDEC device to estimate the texture and structural changes of minced pork gel under a continuous high deformation compressive motion.

Fatigue Modeling and Numerical Analysis of Re-Filling Probe Hole of Friction Stir Spot Welded Joints in Aluminum Alloys.

In the present study, the fatigue behavior and tensile strength of A6061-T4 aluminum alloy, joined by friction stir spot welding (FSSW), are numerically investigated. The 3D finite element model (FEM) is used to analyze the FSSW joint by means of Abaqus software. The tensile strength is determined for FSSW joints with both a probe hole and a refilled probe hole. In order to calculate the fatigue life of FSSW joints, the hysteresis loop is first determined, and then the plastic strain amplitude is calculated. Finally, by using the Coffin-Manson equation, fatigue life is predicted. The results were verified against available experimental data from other literature, and a good agreement was observed between the FEM results and experimental data. The results showed that the joint’s tensile strength without a probe hole (refilled hole) is higher than the joint with a probe hole. Therefore, re-filling the probe hole is an effective method for structures jointed by FSSW subjected to a static load. The fatigue strength of the joint with a re-filled probe hole was nearly the same as the structure with a probe hole at low applied loads. Additionally, at a high applied load, the fatigue strength of joints with a refilled probe hole was slightly lower than the joint with a probe hole.

Cosmic censorship conjecture in a general Kerr–Newman black hole

Using some probes, the violation of cosmic censorship conjecture in a general Kerr–Newman black hole is investigated. The result depends on many factors, like the relative sign of charge and rotation direction of the probe and black hole. Moreover the comparison of the angular momentum of the black hole and its charge has an impressive effect. Considering all these together, we have found the range of the angular momentum, energy and charge of the probe for which the event horizon disappears. We have found that cosmic censorship conjecture violation is possible only for near extremal black hole if the parameters of the probe are too large and fine tuned. Taking into account the hoop conjecture, we see that the cosmic censorship conjecture is respected for a general kerr–Newman black hole subject to a large enough number of falling particles and also field quanta.

Grouting knowledge discovery based on data mining

The existence of highly complex and heterogeneous geological and hydrogeological conditions makes it cumbersome to determine grouting parameters for a cost-efficient grouting process. Although many empirical, numerical and analytical models have been proposed previously, there are still some gaps between the existing predictive models and practical grouting applications, leading to the fact that practical grouting design mainly depends on onsite engineers’ experience. In this study, we propose to use data mining to discover grouting knowledge from onsite data of a project in Singapore. After systematic analysis of data concerning the geological information, hydrogeological conditions and grouting records, an artificial neural network was structured to further extract grouting knowledge, based on which the grout take can be estimated under given geological and hydrogeological conditions. The grout take at individual station is found to be closely correlated with overall water inflow and Q value of rock mass, making it promising to estimate the potential grout take, once probe hole and face mapping information are given before pre-grouting. The degree of correlation between input parameters and the corresponding model accuracy are significantly affected by the classification methods used.

Detection of BCR-ABL1 fusion gene transcripts in the saliva of Nigerian patients with chronic myeloid leukemia.

The presence of BCR-ABL1 fusion gene resulting from a t(9; 22) reciprocal chromosome translocation is the molecular hallmark of chronic myeloid leukemia (CML). In the diagnosis and treatment of CML, peripheral blood or bone marrow samples are usually taken for analysis. However, both methods are invasive sample collection methods, thus a noninvasive saliva sample method for the detection of the fusion gene transcripts (BCR-ABL) was investigated in some Nigerians with CML. Real-time (RT)-polymerase chain reaction (PCR) analysis was used to detect BCR-ABL1 fusion gene in the saliva and blood of 42 Nigerian CML patients. RNA was extracted using RNeasy kit and reverse transcribed by random hexamer priming using murine Moloney reverse transcriptase. BCR-ABL1 transcript types were first detected by multiplex PCR and then quantified by a duplex RT-PCR-TaqMan chemistry with MGB probe and Black Hole Quencher. Of the 42 subjects, transcript types were detected in 36 (85.7%) samples, e13a2 fusion transcript sub-type was detected in 9 (21.4%), whereas e14a2 subtype was found in 27 (67.3%); six (14.3%) of the samples did not reveal any of the fusion transcript subtypes. The median BCR-ABL1 messenger RNA values were 9.38 × 102 in saliva and 10.29 × 104 in blood (P < 0.05). Similarly, the median ABL1 value in saliva (3.11 × 103) was significantly lower (P < 0.01) than in blood (4.22 × 103). However, the median BCR-ABL1 ratio in saliva (14.5%) was not significantly different (P = 0.8) from that of blood (12.0%). Saliva may offer an alternative easy-to-collect, readily available, and noninvasive sample for the diagnosis and treatment of CML.

Defect formations and pH-dependent kinetics in kröhnkite Na2Fe(SO4)2·2H2O based cathode for sodium-ion batteries: Resembling synthesis conditions through chemical potential landscape

Thermodynamics and kinetics of intrinsic point defects in Na2Fe(SO4)2·2H2O, a high-voltage cathode for Na-ion batteries, are studied by means of first-principles density functional theory. Electronic structures of charged defects are calculated to study their influences towards electronic and electrochemical properties as well as to probe hole polaron formation. As defect formation energy strongly depends on atomic chemical potentials, we initiate a systematic approach to determine their valid ranges for the pentrary Na-Fe-S-O-H compound under thermodynamic equilibria and correlate them with approximated pH parameters in solution-based synthesis. Given chemical potential landscape and formation energy, we find that FeNa1+,VNa1-,0andNaFe1-,0 are dominant and their concentrations could be manipulated through pH condition and oxygen content in the precursor solution. It is predicted that the channel blockage due to FeNa would appear under strong acidic growth condition but could be diminished under weak acidic condition (4.7 ≤ pH ≤ 5.6) where NaFe facilitates a faster migration between each diffusion channel. Our results do not only explain the origin of intercalation mechanism and improved electronic conduction, but also demonstrates the pH influence towards conductivities in the cathode material.

Residual stress determination by optical interferometric measurements of hole diameter increments

The main questions, related to the residual stresses determination in thin welded plates by the general approach, are considered. The values of hole diameter increments in principal stress directions, obtained by both reflection hologram interferometry and electronic speckle-pattern interferometry, serve as the initial experimental information. The analytical basis shows that the formulae, which connect experimental data with residual stress components, represent unequivocally solution of the properly posed inverse problem. Simultaneous measurements of the local deformation response on the opposite faces of thin-walled object under study, when a single probe hole is drilled, is the essential condition of the general approach implementing. To do this, an optical system of combined interferometer is developed. The main feature of this optical set-up resides in a capability of simultaneous recording fringe patterns inherent in electronic speckle-pattern interferometry (ESPI) and reflection hologram interferometry on opposite specimen faces for the same through hole. The accuracy of the proposed method with respect to the residual stress components determination has been assessed by three different ways. It is shown that ESPI based interference fringe patterns of high density provides a fast and reliable way of determining residual stress values of the order 160–180 MPa at the weld seam proximity. Residual stress evolution due to cyclic loading is described through the use of ESPI data.

Assessment of electrical resistivity imaging for pre-tunneling geological characterization – A case study of the Qingdao R3 metro line tunnel

Water inrush during tunneling is a significant problem in the underground infrastructure construction. Electrical resistivity imaging (ERI) is a technique that can detect and characterize a water body in an open fracture or fault by exploiting the resistivity contrast that exists between the water body and the surrounding materials. ERI is an efficient method for pre-tunneling geological characterization. In this study, a case study is presented in which tunnel-face and borehole ERI (TBERI) is performed by using the probe hole to detect a water body during tunnel construction. The construction site is a metro line site, situated in the city of Qingdao, China.Unlike the traditional cross-hole observation mode, TBERI only use a single borehole. The installation of injection electrodes inside the probe hole and the installation of measuring electrodes on the tunnel face is proposed as the observation mode. Furthermore, a numerical simulation is carried out before the real field experiment, and the simulation results show that the TBERI is capable of detecting a deeply buried water body. In addition, the water body in the field case is also identified by TBERI. The water body appears as a strongly conductive anomaly relative to the background materials. This study highlights the respective strengths and weaknesses of the TBERI for pre-tunneling geological characterization. This method is a relatively rapid means of investigating the studied area. This study clearly demonstrates the suitability of TBERI in a tunneling scenario.

THE EFFECT OF CYCLIC LOADING ON THE RESIDUAL STRESSES AND STRESS INTENSITY FACTORS

The evolution of the fracture mechanics parameters for cracks in the vicinity of welded joints of aluminum plates, caused by the redistribution of residual stresses under cyclic loading, is considered. The investigations were carried out under uniaxial tension-compression of rectangular specimens along the welded seam for two loading programs with different cycle parameters. Residual stresses are determined by the joint application of the hole drilling method and measurement of the increment of the probe hole diameters along the main deformations by the method of electronic speckle pattern interferometry. A crack with its origin located on the contour of the probe hole is modeled for each specimen by a sequence of narrow incisions perpendicular to the welded seam. The values of fracture mechanics parameters are determined on the basis of the modified version of the Crack Compliance Method at various stages of cyclic loading without applying an external load. Residual stresses, opening at the crack tip crack mouth opening displacement (CMOD)RES, and Stress Intensity Factors for cracks in the residual stress field are shown related to the number of loading cycles. The presented results provide evidence of the effectiveness of the developed approach for evaluating the durability of welded joints of thin-walled elements of aviation structures.

Probing and Tapping: Are We Inserting Pedicle Screws Correctly?

PurposeAlthough there are a significant number of research publications on the topic of bone morphology and the strength of bone, the clinical significance of a failed pedicle screw is often revision surgery and the potential for further postoperative complications; especially in elderly patients with osteoporotic bone. The purpose of this report is to quantify the mechanical strength of the foam-screw interface by assessing probe/pilot hole diameter and tap sizes using statistically relevant sample sizes under highly controlled test conditions. MethodsThe study consisted of two experiments and used up to three different densities of reference-grade polyurethane foam (ASTM 1839), including 0.16, 0.24, and 0.32 g/cm3. All screws and rods were provided by K2M Inc. and screws were inserted to a depth of 25 mm. A series of pilot holes, 1.5, 2.2, 2.7, 3.2, 3.7, 4.2, 5.0, and 6.0 mm in diameter were drilled through the entire depth of the material. A 6.5 × 45-mm pedicle screw was inserted and axially pulled from the material (n = 720). A 3.0-mm pilot hole was drilled and tapped with: no tap, 3.5-, 4.5-, 5.5-, and 6.5-mm taps. A 6.5 × 45-mm pedicle screw was inserted and axially pulled from the material (n = 300). ResultsThe size of the probe/pilot hole had a nonlinear, parabolic effect on pullout strength. This shape suggests an optimum-sized probe hole for a given size pedicle screw. Too large or too small of a probe hole causes a rapid falloff in pullout strength. The tap data demonstrated that not tapping and undertapping by two or three sizes did not significantly alter the pullout strength of the screws. The data showed an exponential falloff of pullout strength when as tap size increased to the diameter of the screw. ConclusionIn the current study, the data show that an ideal pilot hole size half the diameter of the screw is a starting point. Also, that if tapping was necessary, to use a tap two sizes smaller than the screw being implanted. A similar optimum pilot hole or tap size may be expected in the clinical scenario, however, it may not be the same as seen with the uniform density polyurethane foam tested in the current study.

Influence of therapeutic ultrasound on the biomechanical characteristics of the skin.

BackgroundSkin function is dependent on its biomechanical characteristics, resistance, malleability, and elasticity. Therapeutic ultrasound may increase cutaneous malleability thus and optimize the rehabilitation process on specific diseases. The aim of this study is to evaluate possible alterations of biomechanical characteristics of the normal skin after therapeutic ultrasound application.MethodsThirty-one volunteers took part of the study, and the average age was 31.61 ± 8.37 years old. Biomechanical characteristics evaluation of the skin was performed with the Cutometer MPA 580 (Courage + Khazaka Electronic—Köln, Germany) of 2-mm probe hole and 500-mbar vacuum. Skin characteristics were analyzed before and after therapeutic ultrasound application, and the variables R0 (distensibility), R2 (gross elasticity), and R6 (viscoelasticity) were used for the study. Areas of therapeutic ultrasound application (continuous, 3 MHz, 1 W/cm2 SATA) were defined at the upper limbs and standardized using a neoprene template. Sociodemographic data of volunteers were analyzed using SPSS 15.0. To analyze the distribution of the data, the Shapiro-Wilk test was used, which showed the normal distribution for R0 values, R2 and R6. For this procedure, the PROC TTEST from SAS® 9.0 software and Minitab 16 software, with significance, was set at the 0.05 level.ResultsIn relation to R0, a significant increase (p = 0.001) was observed for the distensibility, when compared to values of pre- (0.3273 mm) and immediately post- (0.3795 mm) resource application which feature a greater distensibility. Related to R2 values, a significant increase (p = .001) of the gross elasticity at pre- (0.8419) and post- (0.8884) therapeutic ultrasound application was found.ConclusionsTherapeutic ultrasound promotes significant alterations of the biomechanical characteristics of the skin.Trial registrationClinicalTrials.gov, 1111-1146-7342

Direct Observation of Photoexcited Hole Localization in CdSe Nanorods

Quantum-confined 1D semiconductor nanostructures are being investigated for hydrogen generation photocatalysts. In the photoreaction, after fast electron transfer, holes that remain in the nanostructure play an important role in the total quantum yield of hydrogen production. Unfortunately, knowledge of hole dynamics is limited due to lack of convenient spectroscopic signatures. Here, we directly probe hole localization dynamics within CdSe nanorods (NRs) by combining transient absorption (TA) and time-resolved terahertz (TRTS) spectroscopy. We show that when methylene blue is used as an electron acceptor, the resulting electron transfer occurs with a time constant of 3.5 ± 0.1 ps and leaves behind a delocalized hole. However, the hole quickly localizes in the Coulomb potential well generated by the reduced electron acceptor near the NR surface with time constant of 11.7 ± 0.2 ps. Our theoretical investigation suggests that the hole becomes confined to a ∼±0.8 nm region near the reduced electron acceptor ...

Friction stir spot welding of aluminum alloys: A recent review

Abstract The application prospect of aluminum alloys in aerospace, high speed train manufacturing, shipbuilding and automotive industries is increasing and friction stir spot welding (FSSW) is adjudged to be a non-fusion and suitable joining technology for it. Conversely, friction stir spot welding has challenging attributes such as objectionable FSSW tool pin performance and short life span in mass production stage, creation of crack initiation sites like hook defect, material flow voids and probe hole, as well as restrictions on thickness of materials that can be welded. These challenges have caused a lot of tool profile innovative modifications and technological advancement in friction stir spot welding of aluminum alloys. Nevertheless, some of these vital issues are still unresolved and this notion makes FSSW an evolving solid state joining technology. A succinct view of literature on FSSW of aluminum alloys reveals that most researchers have limited their research to the characterization of microstructure and mechanical properties of aluminum welds; thus leaving a blatant research gap in post-weld tool examinations. Tool wear mechanism and void formation mechanism in FSSW processes as well as characterization of friction stir spot welded aluminum alloys are research areas that need critical examinations. Nevertheless, this publication combines the innovative and recently developed friction stir spot welding technologies of aluminum alloys and assesses their generalized process parameters; it also covers microstructural and mechanical properties of aluminum alloys available in literature. This report classifies FSSW of aluminum alloys based on three criteria namely, probe amendment, shoulder adjustment and complexity of tool movement.

Design of Capacitance Probe Sensor in Deep Hole Diameter Measurement

Based on the working principle of the capacitive sensor, according to the requirements of deep hole diameter measuring, a capacitance probe sensor was designed, and then the design and type-selection of probe structure, cable inner structure to the capacitance probe sensor were done. At the same time, in order to overcome the measurement error caused by eccentricity, the capacitance sensor probe and inner hole of the corresponding fastener both are designed to a taper, taper positioning is relatively accurate positioning way. The design is to avoid the measurement position offset, and ensures the coaxality on the mechanical structure. The equipotential ring technology effectively overcomes the problem of edge effect of capacitance sensor, and makes the probe’s effective measurement electrode under the condition of limited long, can effectively guarantee the measure precision. By moving the capacitance probe in the hole to the different position, we will realize the deep hole diameter measurement in different cross section.

Deployment and evaluation of a dual-sensor autofocusing method for on-machine measurement of patterns of small holes on freeform surfaces.

This paper presents and evaluates an active dual-sensor autofocusing system that combines an optical vision sensor and a tactile probe for autofocusing on arrays of small holes on freeform surfaces. The system has been tested on a two-axis test rig and then integrated onto a three-axis computer numerical control (CNC) milling machine, where the aim is to rapidly and controllably measure the hole position errors while the part is still on the machine. The principle of operation is for the tactile probe to locate the nominal positions of holes, and the optical vision sensor follows to focus and capture the images of the holes. The images are then processed to provide hole position measurement. In this paper, the autofocusing deviations are analyzed. First, the deviations caused by the geometric errors of the axes on which the dual-sensor unit is deployed are estimated to be 11 μm when deployed on a test rig and 7 μm on the CNC machine tool. Subsequently, the autofocusing deviations caused by the interaction of the tactile probe, surface, and small hole are mathematically analyzed and evaluated. The deviations are a result of the tactile probe radius, the curvatures at the positions where small holes are drilled on the freeform surface, and the effect of the position error of the hole on focusing. An example case study is provided for the measurement of a pattern of small holes on an elliptical cylinder on the two machines. The absolute sum of the autofocusing deviations is 118 μm on the test rig and 144 μm on the machine tool. This is much less than the 500 μm depth of field of the optical microscope. Therefore, the method is capable of capturing a group of clear images of the small holes on this workpiece for either implementation.