From DDL Wiki

First Report

We received your report on the rotating tie rack, and we were very impressed indeed. Your analysis was clearly very thorough, and your report is well documented. You also came up with a few opportunities for improvement that can help us out. Details follow:

• You suggest reducing the number of gears – how feasible is this? Fewer gears would require larger gears, right? Would the size fit, and would costs stay low? (answered in Tie rack geartrain and circuitry analysis page found in Other Improvements)
• The belt is an interesting piece. Do you believe it was constructed as a loop in the injection molding pieces, or was one end fused to the other afterward to form the loop? (answered in table on Tie rack components page)
• Why do you suppose a belt is used to connect the motor to the geartrain instead of mounting one of the gears directly on the motor? (answered in Tie rack geartrain and circuitry analysis page found in Other Improvements)
• You suggested substituting a higher torque motor to deal with possible failure of the geartrain – we’re not sure how this would help.
• Do you have a feeling for how long the batteries would last and whether a customer would be dissatisfied with the frequency of changing batteries? (answered in Tie rack geartrain and circuitry analysis page found in Other Improvements)
• You’ve found some interesting opportunities, including speed variability, the difficulty reaching belts through the ties, and the separate light bulb switch. Because you mention the need to increase battery life, we might suggest looking at LEDs. (Discussed in other improvements -- LEDs not feasible).
• We appreciate your careful referencing of part numbers in the discussion.
• Does the light only work while in motion? Does this cause difficulties for low light situations, especially if the rotation is too fast? (answered in Conventional use and Other Improvements)
• We appreciate the well documented assembly
• Your DFMA analysis is quite thorough – we are very impressed.
• Your FMEA analysis appears to have a few bugs. Also, we were surprised not to see an item for a possible belt jam. Some customers have reported problems when a tie or a belt hanger becomes snagged on other closet items. (Updated in Tie Rack FMEA page).
• Your DFE analysis is also very insightful, and we appreciate the details in your preliminary LCA sketch.
• Also, please include a free body diagram and numerical analysis examining the geartrain's effects on torque and speed of the motor and use it to determine if moving to a fewer number of gears will be feasible and desirable.

Additional Components

While highly impressive, the massive amount of information renders the page very long and a little cluttered. It might help the page if a few of the larger tables were transfered to separate pages.

Revision

We received your updated report 1, and we are satisfied with the responses.