Talk:Paintball marker
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We received your report on the [http://ddl.me.cmu.edu/ddwiki/index.php?title=Paintball_marker&oldid=4821 paintball marker] and are very impressed indeed. Your analysis and documentation are well executed, and your conclusions and recommendations are clear and up front. We are excited to see what you come up with in the next report. Detailed comments follow: | We received your report on the [http://ddl.me.cmu.edu/ddwiki/index.php?title=Paintball_marker&oldid=4821 paintball marker] and are very impressed indeed. Your analysis and documentation are well executed, and your conclusions and recommendations are clear and up front. We are excited to see what you come up with in the next report. Detailed comments follow: | ||
| - | * comment - We were impressed by your insightful discussion of modularity – this is an important element for our product line, and we actually spend a lot of effort pricing upgrades to avoid cannibalization (ex: loss of demand for high end gun if price difference is too great compared to low end gun) | + | * '''comment''' - We were impressed by your insightful discussion of modularity – this is an important element for our product line, and we actually spend a lot of effort pricing upgrades to avoid cannibalization (ex: loss of demand for high end gun if price difference is too great compared to low end gun) |
| - | * comment - Your executive summary is very clear | + | * '''comment''' - Your executive summary is very clear |
| - | * X - task - You mention the target velocity of 300 ft/s, what would be an acceptable range, and does the product fall within the range? | + | * '''X - task''' - You mention the target velocity of 300 ft/s, what would be an acceptable range, and does the product fall within the range? |
| - | * comment - Nice discussion of customer needs | + | * '''comment''' - Nice discussion of customer needs |
| - | * X - task - We noticed that you did not include the user as a stakeholder. For us the user and any possible players who may be targets are our first stakeholders, and safety is a primary issue, even under conditions of misuse, since sometimes children can get hold of the marker and try to use it without proper instruction. | + | * '''X - task''' - We noticed that you did not include the user as a stakeholder. For us the user and any possible players who may be targets are our first stakeholders, and safety is a primary issue, even under conditions of misuse, since sometimes children can get hold of the marker and try to use it without proper instruction. |
| - | * task - It is interesting how many steps are involved in setting up marker. What types of failures result if the steps are not followed properly? A labeled picture would help in understanding here (ex: hopper not labeled in first figure). | + | * '''task''' - It is interesting how many steps are involved in setting up marker. What types of failures result if the steps are not followed properly? A labeled picture would help in understanding here (ex: hopper not labeled in first figure). |
| - | * comment - Your opportunity of firing multiple projectile is quite interesting – I’m surprised that this does not already exist. | + | * '''comment''' - Your opportunity of firing multiple projectile is quite interesting – I’m surprised that this does not already exist. |
| - | * comment - Wonderful diagram – it really helped with explanation of function. A few questions: Is the striker pressed against the valve pin when at rest (before cocking) by the striker spring? The seal appears to be formed by the valve pin being held against the valve body (against an o-ring, I assume) by the valve spring. How long will the valve remain open after being struck by the striker? Is this just a function of the spring constant of the valve spring, or also the gas pressure? Also, it seems that the bolt first moves the ball forward and then the gas completes the job – is this a two-part propulsion? Why does the bolt need to contact the paintball first? | + | * '''comment''' - Wonderful diagram – it really helped with explanation of function. A few questions: Is the striker pressed against the valve pin when at rest (before cocking) by the striker spring? The seal appears to be formed by the valve pin being held against the valve body (against an o-ring, I assume) by the valve spring. How long will the valve remain open after being struck by the striker? Is this just a function of the spring constant of the valve spring, or also the gas pressure? Also, it seems that the bolt first moves the ball forward and then the gas completes the job – is this a two-part propulsion? Why does the bolt need to contact the paintball first? |
| - | * comment - Nice job highlighting conclusions from each section | + | * '''comment''' - Nice job highlighting conclusions from each section |
| - | * task - You mentioned that part 10 is “milled and turned on lathe”. Do you think it is milled from an initial block stock? It seems like a large amount of material loss for each part. | + | * '''task''' - You mentioned that part 10 is “milled and turned on lathe”. Do you think it is milled from an initial block stock? It seems like a large amount of material loss for each part. |
| - | * comment - Your exploded view CAD drawing is very helpful in documenting product | + | * '''comment''' - Your exploded view CAD drawing is very helpful in documenting product |
| - | * task - Good thoughts on DFMA and DFE. Don’t forget that it takes energy to compress air, so if many cartridges are used in the lifetime of the marker, it’s not just the CO2 from the cartridge released, but also the CO2 from the coal burned to run the compressor to producer the cartridge, etc. How many cartridges are used per year per person, do you think? Is this negligible, or something we might want to consider? | + | *''' task''' - Good thoughts on DFMA and DFE. Don’t forget that it takes energy to compress air, so if many cartridges are used in the lifetime of the marker, it’s not just the CO2 from the cartridge released, but also the CO2 from the coal burned to run the compressor to producer the cartridge, etc. How many cartridges are used per year per person, do you think? Is this negligible, or something we might want to consider? |
| - | * task - You have some good ideas for FMEA; however, we typically expect use of the standard table that identifies severity, occurrence, and detection for each mode – please include in your next report. Also, what are your conclusions – should we pursue any of these issues? | + | * '''task''' - You have some good ideas for FMEA; however, we typically expect use of the standard table that identifies severity, occurrence, and detection for each mode – please include in your next report. Also, what are your conclusions – should we pursue any of these issues? |
| - | * task - Can you provide a numerical analysis of the pressure in each chamber before and after triggering and estimate the force on the paintball – see if this matches the ballistics you observe. | + | * '''task''' - Can you provide a numerical analysis of the pressure in each chamber before and after triggering and estimate the force on the paintball – see if this matches the ballistics you observe. |
===Additional Comments=== | ===Additional Comments=== | ||
| - | comment - Your executive summary is very well written and covers a wide number of topics. | + | '''comment''' - Your executive summary is very well written and covers a wide number of topics. |
| - | X - task - Your FMEA, while thorough, could use a more organized layout. | + | '''X - task''' - Your FMEA, while thorough, could use a more organized layout. |
Revision as of 15:00, 7 March 2007
We received your report on the paintball marker and are very impressed indeed. Your analysis and documentation are well executed, and your conclusions and recommendations are clear and up front. We are excited to see what you come up with in the next report. Detailed comments follow:
- comment - We were impressed by your insightful discussion of modularity – this is an important element for our product line, and we actually spend a lot of effort pricing upgrades to avoid cannibalization (ex: loss of demand for high end gun if price difference is too great compared to low end gun)
- comment - Your executive summary is very clear
- X - task - You mention the target velocity of 300 ft/s, what would be an acceptable range, and does the product fall within the range?
- comment - Nice discussion of customer needs
- X - task - We noticed that you did not include the user as a stakeholder. For us the user and any possible players who may be targets are our first stakeholders, and safety is a primary issue, even under conditions of misuse, since sometimes children can get hold of the marker and try to use it without proper instruction.
- task - It is interesting how many steps are involved in setting up marker. What types of failures result if the steps are not followed properly? A labeled picture would help in understanding here (ex: hopper not labeled in first figure).
- comment - Your opportunity of firing multiple projectile is quite interesting – I’m surprised that this does not already exist.
- comment - Wonderful diagram – it really helped with explanation of function. A few questions: Is the striker pressed against the valve pin when at rest (before cocking) by the striker spring? The seal appears to be formed by the valve pin being held against the valve body (against an o-ring, I assume) by the valve spring. How long will the valve remain open after being struck by the striker? Is this just a function of the spring constant of the valve spring, or also the gas pressure? Also, it seems that the bolt first moves the ball forward and then the gas completes the job – is this a two-part propulsion? Why does the bolt need to contact the paintball first?
- comment - Nice job highlighting conclusions from each section
- task - You mentioned that part 10 is “milled and turned on lathe”. Do you think it is milled from an initial block stock? It seems like a large amount of material loss for each part.
- comment - Your exploded view CAD drawing is very helpful in documenting product
- task - Good thoughts on DFMA and DFE. Don’t forget that it takes energy to compress air, so if many cartridges are used in the lifetime of the marker, it’s not just the CO2 from the cartridge released, but also the CO2 from the coal burned to run the compressor to producer the cartridge, etc. How many cartridges are used per year per person, do you think? Is this negligible, or something we might want to consider?
- task - You have some good ideas for FMEA; however, we typically expect use of the standard table that identifies severity, occurrence, and detection for each mode – please include in your next report. Also, what are your conclusions – should we pursue any of these issues?
- task - Can you provide a numerical analysis of the pressure in each chamber before and after triggering and estimate the force on the paintball – see if this matches the ballistics you observe.
Additional Comments
comment - Your executive summary is very well written and covers a wide number of topics.
X - task - Your FMEA, while thorough, could use a more organized layout.
