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Joined 1 year ago
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Cake day: July 1st, 2023

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  • Just installed one recently. Got $500 back in a rebate from the electric company and will get 30% back in taxes at the end of the year. These incentives alone bring the cost down to an equivalently sized traditional electric water heater. I haven’t had it running long enough to see what the average electric bill reduction will be; however my last bill (and first full one with the new heater) was my cheapest in the 5 years I’ve been here ($125 vs $150 from the same month last year). I don’t expect it will take long to fully pay for itself compared to the highly inefficient 20-year old model it replaced.




  • I think there is a very important distinction between accuracy and tolerance in engineering. +/- .010" is not a dimension, but a tolerance that can be applied to a dimension. However if your example was changed to a .010" dimension, I would agree with you as I stated in my last comment. There is no need to give any further accuracy to that dimension if you are just adding zeros to the end (unless you are using block tolerances that rely on a specific number of digits to correspond with a standard tolerance). Unfortunately, not everything is designed using the same units and you will inevitably end up with a part designed in mm that uses a bolt-on component using a hole span in inches (for example, a nice round 1-in span). If you want a +/-1 mm tolerance on that part, you wouldn’t want to round every dimension to the nearest mm because you may end up with a tolerance of 24-26 mm when you really wanted 24.4 to 26.4 mm. I like to provide true dimensional accuracy (to microns or .0001" if I’m not just adding zeros) and then apply a suitable tolerance independently, using GD&T.

    Regarding paperless manufacturing, I agree that many components are made straight from the models these days and imported directly into a CNC machine. However, there should always be a drawing or a digital equivalent a drawing. This is the contract that specifies acceptable tolerances to the manufacturer, and it will be used during QA inspection to determine if an acceptable part has been delivered.




  • I don’t see anywhere in the article where Musk says “tolerance”. He specifically says “accuracy” and goes on the talk about listing more decimal places instead of rounding. Any mention of tolerance is done by the author of the article. If certain dimensions are not naturally rounded to one, or even two decimals, there is no reason not to list it to three or more on modern drawings. GD&T can specify whatever tolerance is necessary without relying on a decimal-based block tolerance. I’d be interested in seeing the original email but it seems like there is a misunderstanding by the author given the context being discussed.

    I default to three decimal places for all my basic dimensions on both in and mm drawings. One of the benefits of GD&T is that you can give provide additional dimensional accuracy, completely independent of the tolerance being specified.