Prosthetic Arm Force Reducer Team 1 – Halliday's ... - Ohio University

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Collar Pulley Axel Fig. 7.2.5 - Pulley Unit Assembly 13) Remove pulley and axle apparatus and loop and clamp cable to the front of the pulley. 14) Loop second cable around pulley and loop and clamp around mounting hole bolt. Clamp down with a nut. ( Mount on left side for a right arm and right side for a left arm) 15) Maneuver the front cable so that it falls through the cable exit hole and axle is in the tracks. 16) Using nuts tighten down the tracks on the ring. 17) Screw in split hook. 18) Loop cable from exit hole in cable post and clamp in place. Make sure pulley is pulled all the way forward in the tracks. Figure 7.2.6 - Cable Path and Final Assembly 44
7.3 Cost Analysis & Bill of Materials It is an important factor to try to keep the overall cost of this system to a minimum. Even though this is a new and innovative system, the people that will benefit will still need it to be in the appropriate price range. Since there is not another example of this system on the market it is hard to compare it to price. Tim Lang’s full arm prosthetic cost approximately 6000 dollars. So it would seem reasonable to keep this system upgrade to 10-15% of the total full arm prosthetic. The first initial consideration for the cost analysis is the materials for the alpha prototype as shown in Table 7.3.1. There are a lot of wasted materials to complete the initial prototype. For example only one of the twelve inches of the 2.5 inch stainless tubing is used. Also the bearings that were purchased were proven to be not useful to the overall design. Even though they are not in the current system they still have to be considered for the material cost of the alpha prototype. There was also an excess of bolts, washers, and oval sleeves purchased. These inefficient uses of materials lead to the high material cost of $178.17. It is expected that there will be a drastic decrease in materials for the beta prototype and for the production of multiple units. Table 7.3.1 - Material Costs for Alpha Prototype Part Use Price Quantity 2-1/2" DIA. Round Piping Rings $72.89 1 1/2"x1/2" Square Piping Tracks $7.82 2 Pulley Pulley $20.46 1 Double-Shielded Bearings Bearings $8.00 2 1/4" DIA. Stock Axle, Misc. $5.95 1 3/32" Wire Rope Cable $1.34/ft 10 ft Oval Sleeve for 3/32" Rope Cable Attachments $8.43/pack 1 pack 1" OD Flat Washer Bolts for Attachment $8.64/pack 1 pack Truss Head Attach Rings $10.64/pack 1 pack Machine Screw Set Screw Shaft Collar to <strong>Arm</strong> Lock Pulley in Place on Axle $2.84 2 Total Cost for Alpha Materials : $178.17 The next consideration is the manufacturing costs of the system. For the alpha prototype approximately 40 hours was spent on the completion. This was mainly due to trial and error of certain aspects of the design. For example the tracks had to be re-manufactured because there was not ample room to attach the nut to the bolt. A section of the track had to be milled away so there would be enough room to secure it in place. From Table 7.3.1 the cost of labor was $15 dollars per an hour, the overhead factor was one, equipment factor was a half, and the tolerance factor was 0.25. The reason for the generalized tolerance factor is the system had some tolerances that are more open than others. So with a value of 0.25 both examples of the tolerances are considered. With all this in consideration the overall cost of the alpha prototype was $1828.17 dollars. This is 31% of the overall system cost of $6000 dollars. The majority of this is labor costs and is assumed to decrease as more prototypes are produced. 45
Page 1 and 2: Prosthetic Arm Force Reducer Team 1
Page 3 and 4: 1.0 Introduction Limb loss generall
Page 5 and 6: 2.1 Weighting of Customer Needs Wei
Page 7 and 8: which could limit the use of rubber
Page 9 and 10: design of the two load hook allows
Page 11 and 12: Fig. 4.1.6 - Utah Arm 3 MAGNUM Para
Page 13 and 14: Feature Hosmer Model 7 Work Hook Ot
Page 15 and 16: hook is closed. The harness idea is
Page 17 and 18: purchase it. Safety is another exte
Page 19 and 20: Figure 5.1.2 - Solid Edge Model of
Page 21 and 22: 5.1.4 Concept D - Upgraded Springs
Page 23 and 24: 6.0 Concept Selection 6.1 Data and
Page 25 and 26: Figure 6.1.4 - Input Force FBD The
Page 27 and 28: Since the torques of the both the r
Page 29 and 30: Once the design of the system was u
Page 31 and 32: 7.0.3 Professional/Ethical Standard
Page 33 and 34: Table 7.0.2 - Risk Priority Number
Page 35 and 36: The actual FEA testing involved uti
Page 37 and 38: Another sector that has aided in ou
Page 39 and 40: Figure 7.0.10 Cable Path for Mechan
Page 41 and 42: 7.2.1 Rings (Part #’s THH-001 [El
Page 43: 7.2.4 Collars 1) Using lathe turn o
Page 47 and 48: manufacturing costs are $525.00. Th
Page 49 and 50: operation necessary. This convertib
Page 51 and 52: Appendix A - Split Hook Sample Calc
Page 53 and 54: George Platounaris - Interview (12:
Page 55 and 56: Appendix C - Tim Lang’s Forearm D
Page 57 and 58: Health Progress, “Disables Enteri
Page 59: Drawing Package 1. THH‐001……

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