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  1. imcjoek

    BLDC motor and battery config for drone boat

    Quick napkin math. Tesla 100kW*hr battery. Something like 1000lb of mass, so not a tiny boat to fit it in. 1HP of motor, so barely moving your big heavy boat. The tide would probably win. 100Kwhr/746W = 134 hours run time. About 6 days. Conclusion: High tech battery and a motor way too...
  2. imcjoek

    Rifling Design - Machining Limitations

    So. A fuel injector? Did I guess right? Can you just buy one?
  3. imcjoek

    Bearing position tolerances

    The divide by 300 bit looks weird to me. If it's a constant value, why not just bake that into the chart? More likely the tolerance is just the "T5" value. That puts you at 6um [~0.0002" for our imperial viewers] which is more in line with what I'd expect to see for a bearing bore tolerance...
  4. imcjoek

    Most efficient IC recip engines

    Do these BSFC curves take into account the "Power Enrichment" that is needed at higher load (presumably max torque is max load by BMEP?), or do they presume an impractical stoich mixture at all operating points? I'm kind of surprised that reduction in pumping losses from the WOT manages to...
  5. imcjoek

    Pulley bolted connection torque

    I second this. Works good on the crank damper of many engines. There are a lot of ways to do pulley->shaft that will be reliable. The one you have shown there isn't one of them. It would even be better to do a bolt circle of M3's if you absolutely must have a face-to-face connection.
  6. imcjoek

    actuation motor for seat design

    There's a picture with the forces labeled in the calculator. (You shouldn't need an online calculator for this Napkin Grade calculation, honestly). Radial = force trying to separate the pinion & rack. (Primarily because of the pressure angle of the teeth) Axial = force along the axis (shaft)...
  7. imcjoek

    actuation motor for seat design

    [ponder] Look at their diagram again. Radial force is great if you want to separate the pinion from the rack, but it's not what you want to push your seat...
  8. imcjoek

    actuation motor for seat design

    300Nm with 25mm pinion = ~24,000N Force. (Use pinion pitch-radius as the moment arm). Where'd you come up with this 300Nm estimate, anyways?
  9. imcjoek

    actuation motor for seat design

    FWIW I was thinking 25mm diameter as a more realistic size... So 24,000N.
  10. imcjoek

    actuation motor for seat design

    Raising 100kg up a 45deg incline = ~693N load. (Ignoring losses). 300Nm on a pinion driving a rack where the pinion is, lets say ~25cm diameter = 2400N force. Either your pinion is rather bigger than I imagine or one of us did some math wrong someplace.
  11. imcjoek

    Highest fatigue strength options for hand tool with significant stress concentration.

    I don't know what this thing does, so my suggestion may be completely off-base... Can you redesign to make these easy to replace and stamp out a million from some "simple" alloy rather than going for the solid-gold approach? Make it a twice-a-week preventive maintenance problem instead of...
  12. imcjoek

    Custom Bearing - Calculate # of Ball Bearings

    I suspect your grooves would need to be ground & hardened for this to work. So you're looking at substantially large chunk of 52100 or similar. Can you use crowned profile cam followers or needle bearings arranged around the periphery? How about curved linear rail?
  13. imcjoek

    Relationship between power and torque

    If you take (torque(w) * w) you should get power(w). Where w is a chosen RPM.
  14. imcjoek

    Expertise & Recommendation on Variable Speed AC Motor 3HP - 5HP Required

    Previous posters already said it, but I'll say it again. You need to be careful here. Where did the 5HP number come from? A 5HP Motor running @ 50RPM vs. 5HP Motor running @ 1750RPM through a 35:1 gearbox = 50RPM output. These are substantially different in the torque department... Typical...
  15. imcjoek

    Motor Construction in Laymans Terms

    It might be worth noting that motors of the same frame size can have significantly different overall lengths. Example: 1/4HP 11.88" OAL 56C-575 1HP 13.48" OAL 56C-706 Obviously only an issue if the mounting location of the motor is cramped.
  16. imcjoek

    Anti Rotation in Nut with low torque to start with

    Another option, http://www.whittet-higgins.com/part.php?series_id=6
  17. imcjoek

    Origin Indicator

    Place the origin on the "snap point" of the radius where the horizontal line is tangent to the radius. Click and drag the origin horizontally, you should see a dashed phantom line extending the horizontal line. Hover the origin over the "snap point" where the radius joins the vertical line, and...
  18. imcjoek

    A stronger alternative to 7075-t6?

    Hardcoat anodize? You need more wear-resistance/surface hardness and/or slap the operator. Yield strength is not going to help you.
  19. imcjoek

    Handy Features to Have on Drawing Templates

    Calculated weight gets a bit weird if you are modelling a purchased component or otherwise simplifying the internal guts of something. Example: A 3d model of a motor will not have a remotely correct weight unless the designer went in a hollowed it out to match the catalog spec.
  20. imcjoek

    Aircraft Engine Power

    Stoichiometric at full load would require rather low compression and/or retarded timing to prevent knock. That isn't so hot for max power output either.

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