Superior Tube Company. Tube Crop and Deburr Process Improvement. Phase 4

Transcription

1 Superior Tube Company Tube Crop and Deburr Process Improvement Phase 4 Senior Design Fall 2010 Joshua Blechman Thomas Daddario William Ogram Matthew Ward

2 2 Table of Contents pg. # I. Customer Description 3 II. Identification of Needs and Wants 6 III. Constraints 8 IV. Project Scope 8 V. Metrics 9 VI. Alternative Concepts 9 A. Automation 9 B. Shear Cutter 10 C. Cutting Blades 10 VII. Deburring Tool 11 A. Design Overview 11 B. Motivation 11 C. Design Details 11 D. Design Verification 15 E. Path Forward 18 VIII. Reusable Nylon Bundle Ties 20 A. Design Overview 20 B. Motivation 21 C. Design Verification 21 D. Path forward 24 IX. Concluding Remarks 25 X. Appendices 26 A. Drawing Package 26 B. Prototype and Testing Images 36

3 3 I. Customer Superior Tube Company Superior Tube Company manufactures tubes in a wide range of sizes and alloys. Tubes are custom fabricated for over 1000 outer diameters ranging from and numerous wall thicknesses. Materials processed range substantially; with the hardest being a work-hardened 718 alloy and the softest being nickel 200. There are fifty plus different alloys in between these book ends of various strengths and mechanical properties. The general process flow is illustrated on the following page. Tubes are drawn over a mandrill to a specified size. Afterwards they are transported to a cropping station. Currently cropping is performed by a single operator using an abrasive radial saw. Cropping is necessary at this stage because the ends of the tubes are clamped during the drawing process and these pinched off ends must be removed prior to degreasing. If they are not removed there will be excessive grease clogging up the system and the tubes will be unfit for future processing. The degreasing step involves submerging the tubes in a solvent to remove the 201 lubricant or plastic superkote that had been previously applied to the tube prior to drawing. Once the tubes are cropped and degreased they are moved to a reaming, deburring, and blow out station. Here a single operator manually feeds the tubes onto the deburring machine to remove any burrs that could be problematic in future processing. The operator must then blow out the tubes individually with a pressurized air gun to remove any debris. For specific orders, cloth wads are inserted into one of the tube prior to blow out to maximize debris removal. Burrs and debris that are not properly removed can lead to the development of tube defects. At this point, tubes can take one of two different paths. Commonly tubes are sent to be annealed and then sent through the entire process over again starting at drawing. Typical batches experience the drawing, cropping, deburring, and annealing cycle 5-10 times before they reach the desired size. Once this proper sizing is achieved tubes are sent out for post processing, finishing, and evaluation.

4 4 Input Intermediate Processing (Annealing, Drawing, etc.) Storage/Transport (Tubes greased, ends clamped) Cropping Storage/Transport Storage/Transport (Tubes greased, edges rough) Inner and Outer Tube Deburring and Blow out Storage/Transport (Edges rough) Degreasing Storage/Transport Post Processing (Finishing, Error Correction, etc.) Output

5 5 The current set ups for both the cropping and deburring stations are illustrated below. Cropping Station (left), R&D Station (Right); dimensions approximate At the cropping station, the operator feeds tubes along the rollers until they line up appropriately with the saw. Generally this is not a precise operation and the primary goal is to cut off the clamped ends. Otherwise, stoppers are positioned so that the tubes can be pushed up against the stopper and then cut to the desired length. Tubes are stored pre and post cropping on the marked tables. At the deburring station a single operator feeds the tubes, one end and one tube at a time, onto the reaming and deburring tool heads. They must then walk around to the other side of the table and ream and deburr the opposite end of the tube. The tubes are then rolled over to the far side of the table to be blown out. Between each processing step the tubes must be transported and stored. Overhead trolleys are used for moving larger batches of tubes. Storage and materials handling comprise a large portion of each tubes manufacturing life.

6 6 II. Customer Needs/Wants The needs/wants of the customer are focused on the cropping/reaming/deburring/blowout processes and include the following: Increased process productivity Reduced process cost Increased system efficiency Decreased rate of defects Minimize room for operator error, increase user friendliness Combining multiple steps of the process into a single step In order to get a better idea for the needs of the system we performed a time study in early September. This involved monitoring operators working at both the cropping and deburring s stations and recording the time spent performing each little task. In addition, the study provided a baseline figure for the production rate of the current process. The results are summarized in the following tables: Cropping Production Rate 150- tubes/hr. 200 Time Breakdown Task Cutting Preparation Upkeep % of Total Time Ream/Deburr/Blow Out Production Rate 100 tubes/hr. Time Breakdown Task R/D Blow Out Wadding Preparation % of Total Time These figures will be used as references when evaluating the perceived benefit of any proposed system improvement. In addition to revealing baseline statistics about Superior Tube s processes, this study also highlighted the significance of tube preparation and handling time. In addition to the research above, a value stream map was filled out for the processes to break down the allotment of time to each task and show key areas for improvement. The results are summarized in the following table:

7 7 Value Stream Mapping for Tube Cutoff/Ream/Deburr/Blowout Task Value Adding Task Time (seconds) Time since last task completed Movement 1. Cropping 0-3 days Carrying with crane/waiting a. Unbundle tubes No 30 Untying ropes b. Gather Handful of tubes No 15 Gather tubes c. Align tubes No 10 Push tubes against flat surface d. Cut ends off Yes 15 Use abrasive saw e. Move to other end No 10 Slide tubes f. Align tubes No 10 Push tubes against flat surface g. Cut end off Yes 15 Use abrasive saw h. Move to finished area No 10 Slide tubes i. Bundle Tubes No 60 Tie ropes around bundles 2. Degreasing Yes 0-3 days Carrying with crane/waiting 3. Ream/Deburr/Blowout 0-3 days Carrying with crane/waiting a. Unbundle tubes No 30 Untying ropes b. Lay tubes on table No 10 Roll tubes c. Turn on machine No 5 Flip switch d. Ream tubes Yes 10/tube Press tube on tool e. Deburr tubes Yes 10/tube Press tube on tool f. Turn off machine No 5 Flip switch g. Move to other end No 10 Slide tubes h. Align tubes No 10 Roll tubes i. Turn on machine No 5 Flip switch j. Ream tubes Yes 10/tube Press tube on tool k. Deburr Tubes Yes 10/tube Press tube on tool l. Turn off machine No 5 Flip switch m. Wad tubes (optional) No 10/tube Put wads inside tube n. Blowout tubes Yes 10/tube Place air nozzle in tube o. Bundle tubes No 60 Tie ropes around bundles This is a Value Stream Mapping for the process. It includes each step performed in the process, whether or not the step adds value to the product, the time of each step, and the time between each step. Highlighted in this table are the tasks with longer step times which are the focus for improvements. The greatest time delays occur between processes where tubes are sitting around waiting to move along in the system. The longest individual times include bundling and unbundling tubes in each process. The long times per tube processed includes reaming each tube, deburring each tube, and blowing out the chips in each tube. Overall, this table provides insight into where waste occurs in the process.

8 8 III. Constraints The following constraints were imposed upon us by Superior Tube Investments must pay for themselves within ~ 2 years Available space is limited by the current factory setup Must be compatible with process flow Time IV. Project Scope The goal of this project was to enhance the processes at Superior Tube, with a specific focus on tube cropping, reaming, deburring, and blow out. The current system was observed and evaluated to determine areas in need of improvement. Tube degreasing became a prohibitive step that made the combination of processes into a single workstation unfeasible. As a result, the cropping station and deburring station were examined as separate, although related, entities. At this point we considered several possibilities. We looked into automation but it did not appear viable for the costs due to Superior s small production quantities and variability in tube sizing. Alternative cutting options were also evaluated but were found to be either prohibitively expensive due to the need for a die for each tubing size or marginal improvements not worthy of an investment. The focus of our project became improving the deburring process. A tool was designed with the capability to simultaneously remove burrs from the inner and outer diameters of tubing while rapidly adjusting to the desired sizing. Additionally, we noticed an abundance of non-value adding material handling steps. To reduce this waste we examined the benefits of transitioning from rope ties to reusable cable ties.

9 9 V. Key Performance and Cost Metrics The following were determined to be important performance metrics: Process time includes cutting, reaming, deburring, blow out, and time between processes Process cost includes cost for each process listed above Quality diameter and length compatibility as well as defect rate Essentially the primary metric will be to upgrade the process so that it is more cost effective. Quality and time metrics are important mainly because of how they relate to cost and productivity. System updates will be evaluated based on their ability to produce economic gains for superior tube, whether it be through reductions in cost or increases in productivity. VI. Alternative Concepts A. Automation Original Phase I designs were based on streamlining the cropping and reaming/deburring stations into one process. The cropping station would be connected directly to a reaming and deburring station, which would theoretically eliminate the transportation requirement between the two stations. As designs were developed, the idea of automating the process was highly encouraged. Eliminating an operator would allow the company to save money in the long run. Currently, the process uses a different operator for each station, as well as additional operators for the transportation between stations. However, it was revealed after Phase I that none of these concepts would be possible. This was due to the Degreasing step that must occur between the two steps. Degreasing cannot occur before the tube ends are cut off because of the one pinched end of the tube created during pultrusion. Operators would also not want to work with greasy tubes during the reaming and deburring of the tubes. Therefore, it was not possible to streamline the process, which made the main ideas of the initial concepts obsolete. Automating a single station does not seem cost effective due to the large variety of tube sizes that are manufactured at Superior Tube. With limited space, it would not be possible to come up with different automations for separate processes. It is recommended that if automation is to be considered in the future, the entire tube manufacturing process should be reevaluated. This senior design process was limited by the number of stations which could be evaluated and changed.

10 10 B. Shear Cutter While researching different cutoff methods, a shear cutting tool was found to be one of the possibilities that could replace the current saw. The tool would be able to cut off a tube without leaving any burrs in the cutoff area. This would have been highly beneficial because it would have eliminated the entire reaming and deburring station. Eliminating this station would also eliminate an operator, and free up some space in the factory. The drawbacks of this device were that it could only handle one tube at a time, and it would require a separate die for each different diameter tube. The current cutoff method has an operator cut a whole bundle of tubes at once. However, if it could in fact eliminate the reaming/deburring process, it still seemed like a great replacement tool. After some collaboration with the sponsor, it was found that there were a thousand different outer diameters that the tubes could have. Each of those sizes would require a different die, so the implementation of this machine quickly became unlikely. It would be extremely expensive to buy the machine and a thousand different dies. The dies would have to be changed between each process, and new storage would be required for such a large number of dies. With limited space and budget, the device was ruled to be outside of our parameters and was thrown out. C. Cutting Blades The current abrasive saw uses aluminum oxide discs, which have a low life and need to be replaced frequently. These disks can be replaced with other abrasives that are harder such as silicon carbide, or even cubic boron nitride. The harder discs will have a longer life and will not need to be replaced as frequently. Although other abrasives are harder, it is common in cutting steels to use aluminum oxide as silicon carbide has a tendency to chip when cutting steel and can result in an uneven cut. A cubic boron nitride disc will cost roughly times as much as an aluminum oxide disc and the life of this disc is not long enough to justify that cost. Also the harder discs need to be run at a lower speed than the aluminum oxide discs, and the current abrasive saw used at Superior Tube can only run at this high speed set for aluminum oxide. A new abrasive saw will need to be purchased in order to run these harder discs at a lower speed. The quality of the cut of an aluminum oxide disc is about the same as with a harder disc. Therefore it is not cost effective to change the current abrasive discs used.

11 11 VII. Deburring Tool A. Design Overview Currently, the deburring station involves two tool heads that each tube must encounter. The first is to take off burrs on the outside of the tube (deburr), and the second tube takes off burrs within the inside of the tube (ream). This combined tool head will condense this 2 step process into 1. The spring loaded feature allows for it to accommodate a range of tubes from 0.25 to 1.5 inner diameter. High speed steel blades are used to cut and handle a wide range of materials that Superior Tube deals with on a daily basis. B. Motivation The deburring tool is focused on streamlining the current Ream and Deburr process at Superior Tube. Due to Superior s wide range of custom tubing both in ID/OD and material selection a tool head that would be able to ream and deburr a majority of them without any change would be very advantageous. A combined tool head specifically would help streamline the station, and provide less work for the operator to do. This design specifically targets these ideas. C. Design Details The chart below lays out quantity and material used to fabricate the prototype: Part Layout Quantity Material Reaming Cone 1 Aluminum 6061 Deburr Casing 3 Aluminum 6061 Guide Tooth 2 Aluminum 6061 Blade Holding Tooth 1 Aluminum 6061 Spring (2 ID, k=10lb/in) 1 Galvanized Steel Attachment Base 1 Aluminum 6061 Attachment Rod 1 Steel 4 40 Screws 18 Steel Blades 2 High Speed Steel

12 12 Assembly Protocol: Note that it is important to follow the steps using the same views as those shown in the figures below. 1. Attach first Deburr casing to both linear guides with screws as shown: Figure 1 - Align Linear guides as shown, and screw together 2. Attach second deburr casing to right linear guide with screws: Figure 2 - Align Linear Guide with Current assembly and screw together 3. Attach Slotted Linear guide to casing from previous step, it is important that this guide is attached so that its right face is still exposed: Figure 3 - Note Right side face of slotted guide is exposed

13 13 4. Finally attach last deburr casing with tapped hole to complete Sub-Assembly 1: Figure 4 - Sub Assembly 1 now complete 5. Align Reaming cone with Sub Assembly 1 and simply drop in to complete Sub Assembly 2: Figure 5 - Clearance fit allows for easy placement 6. Align Spring and place over the bottom end of the reaming cone, align base and screw in attachment rod, complete Sub Assembly 3: Figure 6 - Sub Assembly 3

14 14 7. Place blade into reaming cone by compressing deburr casing down and tightening a set screw: Figure 7 - Hole for set screw is easily accessible by compressing deburr casing 8. Place final blade into the slotted linear guide and utilize tapped hole to tighten a set screw in place: Figure 8 - Deburr casing is not shown in right picture to show blade in place This completes assembly of the prototype. See Appendix A for complete drawing package. See Appendix B for photographic images of completed prototype.

15 15 Figure 9 - Multiple views of completed Assembly D. Testing A. Description of Procedure and Data Collection Purpose: The Aluminum prototype must be tested in order to prove that the concept is valid. The different material and lack of a proper deburring blade requires that the device be used on materials of lower strength and hardness. Materials: Fully assembled prototype PVC pipes of various diameters Aluminum pipes of various diameters Vice Hacksaw Lathe

16 16 Procedure: 1. Make sure that the prototype is fully and properly assembled. 2. Fit the prototype s bottom shaft into lathe as close to the bottom plate as possible. This will help to minimize vibrations and bending. 3. Adjust lathe to the lowest gear setting possible (82 rpm low, 163 rpm high). 4. Set the lathe to low. 5. Select PVC pipe and measure actual OD and ID range. 6. Place pipe firmly in vice so that it does not rotate. Do not tighten excessively to avoid crushing the pipe. 7. Use the hacksaw to cut off an end of the pipe. This will create burrs on the OD and ID. Remove pipe from vice when fully cut off. 8. Write down the pipe description and rpm used. Photograph the pipe with the burrs on it. Turn on the lathe. 9. Press the burred end of the pipe into the blades on the rotating prototype. Continue pressing the pipe onto the blades until all burrs are removed. 10. Remove the pipe and turn off the lathe. Record how much time the pipe was pressed on the prototype. 11. Evaluate how much difficulty the tester experienced while using the prototype and record. Use a scale of 1 to 5; 1 being not very difficult, 5 being very difficult. 12. Repeat steps 5-11 for several different pipe sizes. 13. Set the lathe to high and repeat steps Repeat steps 5-12, but for aluminum pipe.

17 17 B. Results and Analysis: Description RPM Operator difficulty Time OD OD ID ID min max min max 1.25 PVC PVC PVC PVC PVC PVC PVC PVC PVC PVC Aluminum Comparing the low rpm to high rpm, it is clear that it takes less time to fully remove the burrs on a higher rpm. The testers also had a much easier time in using the device when it was spinning at the higher rpm. PVC pipes are clearly easier to work with, and its burrs are much more apparent when present. This represents a larger scale version of how the actual device would work on stainless steel, thin walled tubes. The prototype created a chamfer on the inner and outer diameters of the pipes which completely removed all burrs from those areas. This is exactly what the concept is designed to do. Aluminum pipes give a better idea of how the device will handle a metal. However, aluminum cannot be attained in thin walled form, so it is on a slightly larger scale than the stainless steel tubes. The prototype successfully removed all burrs from all test samples in a reasonable time. Operators experienced a low amount of difficulty in using the device, which seemed to decrease for higher speeds. These tests prove that the prototype is capable of being used on many different size pipes and pipes of different materials. See Appendix B for photographic images from testing.

18 18 E. Path Forward Updated Design and Manufacturing Modifications The performance of the prototype was promising but also revealed opportunities for design improvements. If Superior wishes to move forward on this idea we recommend the following modifications to the prototype design. These changes will increase the quality and consistency of the tools performance as well as make the device more user friendly to operate. Prototype to Design Materials Update: The prototype was manufactured from aluminum; however the final tool will be manufactured from steel and will utilize the same cutting blades as the deburring tools currently in use at Superior. This will give it the structural and cutting capability to perform on the wide range of alloys that it will encounter. Wire EDM Forming of the Deburring Casing: In order to increase the precision and integrity of the design we recommend that the deburring case be machined as a single part from stainless steel using wire EDM technology. Wire EDM will allow for the intricate internal geometry to be machined directly. In the prototype, the deburring casing was broken into 3 sections and the components were attached with screws through the guide teeth. In the updated design the three teeth and three pieces of the deburring casing will be combined into a single steel piece, also removing the need for 18 screws and simplifying the assembly process tremendously. The single part casing constructed via wire EDM will allow for a more ideal geometry to be realized without the slop and difficulties that arise from a part with a high number of components. The actual wire EDM job will be outsourced to a company who specializes in the field. The following is the web address to a list of 40 vendors who offer EDM services:

19 19 Reducing Chatter: The prototype was observed to have considerable chatter. The slip fits used in several interfaces throughout the tool create slop which allows the various components to tilt and slide relative to one another. This movement decreases the quality of the alignment of the tubes and the cutting surfaces. In order to improve the design we recommend the incorporation of linear guide blocks to control the movement of the deburring casing relative to the inner reaming cone. Position Control: The spring for the prototype was intended for testing purposes and was formed manually using steel wire. The updated design will include a specifically designed spring. Custom springs can be obtained from the following website: Based on our experiences working with the prototype, we recommend a spring force of 10 lbs/in. This will provide the resistance required while minimizing the strain on the operator. The addition of a set screw will provide additional control by giving operator the option to lock the device in the position desired. The set screw will work in conjunction with the linear guide block. Tightening the screw will secure the guide block in place, allowing the operator to deburr tubes of a given size without having to apply the force necessary to overcome the spring. Another advantage of a set screw to lock the position of the tool is that it will generate a consistent cut over an entire batch of tubes.

20 20 VIII. Reusable Nylon Bundle Ties A. Design Overview For small diameter production batches, which are particularly susceptible to bending, ropes are used to tie the tubes into bundles for handling. Operators are required to tie and untie the ropes, a time investment that quickly adds up when each bundle is tied by two to four ropes. By converting to releasable nylon cable ties the time required to bundle and debundle tubes can be reduced considerably. Nylon is resilient enough to withstand both the physical wear and tear of processing as well as the corrosive chemical environment present during the necessary degreasing steps. The nylon ties will last much longer than the ropes currently being used, which wear over time and are frequently discarded.

21 21 B. Motivation Tube preparation and tube handling accounts for approximately 40% of the total processing time spent at the deburring and blow out station. This percentage is significantly higher for batches that do not require wadding. Much of this time is spent debundling tubes to prepare them for processing or repacking tubes into bundles for post processing storage. Transitioning from hand tied ropes to reusable cable ties will make the bundling and debundling tasks much quicker and more efficient. Tube handling is not a value adding process so anything that can be done to reduce the time and energy spent on it is beneficial to the overall system. Furthermore, rope ties are inconsistent, varying from operator to operator. The nylon ties will bring increased consistency and repeatability. C. Design Verification i. Testing: Procedures and Data Cable Ties Time Study: Time trials were performed using three operators. First, the operators were familiarized with the cable ties and allowed to practice with them until proficiency. Five practice runs were typically sufficient for the operator to drop down to a consistent pace. Next the operator was timed for how long it takes them to apply and remove the cable tie. Since no tubes were available, a cylinder of approximately the same diameter was used. To better simulate the difficulty of tying actual tubes a handle was attached through which the ties must be threaded. Ten trials were performed for each operator and the results are summarized in the table below. Operator 1 Operator 2 Operator 3 Trial # Bundling De-Bundling Bundling De-Bundling Bundling De-Bundling Avg

22 22 Rope Ties Time Study: Two operators were observed and timed while performing the rope tying operation. Operator A was familiar with the task while operator B was just introduced to the task, but given time to learn the fundamentals before being timed. The times required for them to tie the ropes are summarized in the following table. Operator A Operator B Trial # Bundling Bundling Avg The images below depict the traditional rope ties and the reusable nylon ties as they would be in use.

23 23 ii. Results and Analysis The important results of the time studies are summarized in the table below. Rope Ties, Average Time to Bundle (s) 10 Nylon Ties, Average Time to Bundle (s) 4.63 Quantitative Time Savings, per Tie (s) 5.37 Percentage Time Savings, per Tie 54% The cable ties cut the bundling time by 54%, or to less than half of its original value. This is a very significant improvement. Each bundle typically has between two and four ties on it. Furthermore, each tube undergoes a great many bundling and debundling operations throughout its factory life. The time gains achieved throughout the process will quickly add up. Based on our process observations from September, it can be estimated that tubes are processed at a rate of 8 bundles per hour, with each bundle requiring an average of three ties. The value of this result is summarized in the following table. Time savings (seconds/tie) 5.37 Bundles/Hour 8 Ties/Bundle 3 Time Savings (seconds/hour) 129 Productivity increase 3.6% Operator cost savings ($/hour) 0.72 Based on conservative estimate which do not even taken into account the reduced time needed to debundle tubes tied by cables versus ropes, the cable ties will increase productivity by 3.6%. This equates to $0.72/hour savings in operator costs based on a worker salary of $20.00/hour. These figures are not tremendous, but, considering the simplicity and ease with which the transition could be made, they are enough to demonstrate the validity of the design. An additional benefit of the cables ties is that they will bring consistency and repeatability to the tying and handling of bundles. When it comes to using ropes, the individual operator determines what type of knot will be tied. Although most follow a general pattern of rapping the rope around the tube prior to tying it there are still quite a few deviations. Using the cable ties, however, resulted in a consistent output. Furthermore, the training required to become adept with the cable ties is less than that required to achieve the same level of proficiency with the rope ties. This will be beneficial when acquainting new operators to the task.

24 24 D. Path Forward - Procurement It is recommended that Superior Tube begins a wide scale transition from rope ties to reusable nylon cable ties. This will add increased productivity and consistency throughout the tube production system. The initial investment will more than be made up for by savings in operator time and higher production rates. Once the initial investment is paid off, the ties will continue to bring consistency and economic benefit to the system for years to come. Nylon ties are available in a variety of sizes and qualities. This site has 15 ties sold in packs of 4 for $4.19. Superior Tube has already purchased a package of these ties and is performing evaluations to verify the durability of these ties when exposed to certain chemical conditions &ff4=263602_304652&viewitem=&guid=082adb4412c0a0a9f ff772ba2&hlp=false&rvr_id= &ua=%3F*F%3F&itemid= This is an example of how ties can be found in large quantities for quite cheap using sites such as EBay. Since there is a buy it now option this is not much different than ordering from any other online retailer. This site offers heavy duty 29 ties for approximately $1.00 per tie. This option offers the highest quality as well as the greatest length which allows for bundling of larger diameter tubes.

25 25 IX. Concluding Remarks While revamping the entire manufacturing system at Superior Tube was beyond the scope of this project, we were able to focus in on some key aspects of the process. The deburring tool prototype showed how a device could be constructed to simultaneously deburr both edges of tubes of varying sizes. The preliminary design, updated with knowledge gained through testing and evaluation, can be updated and fabricated for use on the factory floor. While the testing confirmed the validity of the concept, it may take some time for the economic benefits of updating and fabricating a working tool to be realized. The implementation of reusable cable ties will provide almost immediate productivity gains while reducing wasteful material handling. Due to the low cost at which the nylon ties can be obtained, their investment will quickly pay for itself. We recommend a full transition, where possible, from rope ties to cable ties. In addition, it would be worthwhile for Superior to look across their entire factory to determine how materials handling and other non-value adding steps can be streamlined to reduce waste and create a leaner manufacturing system.

26 26 X. Appendices Appendix A Drawing Package

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36 36 Appendix B Prototype and Testing Images Side View of Prototype Shot of Blade Front View of Prototype

37 Prototype Chucked in Lathe 37

38 38 PVC 1.25 pre high RPM cut PVC 1.5 pre high RPM cut PVC 1.25 post high RPM cut PVC 1.5 post high RPM cut