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  1. smitty1322

    RC car Controller schematics

    rlapierre, you might want to check out www.howstuffworks.com for information on the RC cars. They have a vast database of basic instructions on everything from gas engines to photosynthesis. may help, may not.
  2. smitty1322

    How do you design a 120VDC Permanent Magnet DC Motor?

    The main difference in changing from a low voltage DCPM motor and higher voltage is the winding and the commutator. Higher voltages need more commutator bars. Lower voltages use less. For example, a 24 volt motor with 16 slots in the laminations would have a 16 bar comm. a 115 volt motor...
  3. smitty1322

    Drive train effieciency/power loss

    Everyone, Thank you for your responses, that was what I was looking for. I have heard a rumor that a good estimate for efficiency loss is 10% per gear reduction, does that sound about right? I also saw in a university study that transaxle motors at free speed are about 70% eff. Under load...
  4. smitty1322

    Drive train effieciency/power loss

    ecampos, Thank you for your reply. I should have added the fact that I am trying to size my motor by calculating backwards through the gearbox. I know what torque I need at my output to move the load at the customers specifications. I have an electric motor that will do the job. What I...
  5. smitty1322

    Drive train effieciency/power loss

    I have noticed a common quesion in this forum lately on the effeciency of a gear train. I have a question to add to this. I am designing a drive for a hospital bed. I have my motor at the performance I need (motor only). I am using a transaxle, much like the electric scooters have, and I am...
  6. smitty1322

    Fractional HP motor wind design

    teco, the posts have been quite helpful but I don't really have an answer yet. If interpoles are only used in bi-direction, why would they use it in a saw? Saws only turn one way. The only, and I do mean only, difference between our motor (armature and field) and theirs is this lamination...
  7. smitty1322

    Fractional HP motor wind design

    Teco, Thank you for your response. Could you elaborate on how exactly the smaller coil acts as an interpole? We have already filled the field lamination with the largest wire size we can wind with. So we can't get any more low end torque than we have right now. Which brings me to another...
  8. smitty1322

    Fractional HP motor wind design

    Teco, Here is more information for you. The motor (armature) is going approximately 17K RPM. It goes through a 3.4:1 gear reduction. The laminations have 16 slots and the commutator has 32 bars. All of this is pretty much the same between the hand saw and our armature (rotor). The problem...
  9. smitty1322

    Fractional HP motor wind design

    I am currently working on a design for a customer (construction OEM) that used to buy SKIL handsaws and cut the handles off. They have asked my company to design a 115 VAC, 1 HP complete motor for them. The problem I have is in the design of the field. We have developed a motor and the...
  10. smitty1322

    Standard for Drawing practices

    Steve Smith, Thank you for the directions. I have heard rumors that standards can also be found on Amazon.com for cheaper than buying them direct, have you heard this?
  11. smitty1322

    Which motor to use?

    fro120, I know of PM motors that are used in the healthcare industry to lift wheelchairs and such into vehicles. There are some that use worm gearing that can lift 300 lbs using only 12 VDC. These may be of no use to you, depending on distance of lift, but they are less than 1 HP and may be...
  12. smitty1322

    Standard for Drawing practices

    Does anyone know how or where I can get my hands on the ANSI standard for drawing practices? My company is trying to standardize all our old hand drawn prints. I was wondering if there was somewhere to get ANSI standards without purchasing them directly.
  13. smitty1322

    Involute Spline

    Trallee, Minimum actual tooth thickness is the value of the max effective tooth thickness minus the manufacturing variations fo lead, profile, adn spacing (gamma) minus the machining tolerances. Tmin=Tvmax-(gamma+m). Maximum effective tooth thickness (Tvmax)has three different formulas all for...
  14. smitty1322

    Involute Spline

    trallee, try looking at ANSI standard B92.1b-1996. Well at least that was the addendum we had here. There are equations for max. effective tooth thickness, and minimum actual tooth thickness. Let me know if you do not have access to this standard.
  15. smitty1322

    Winding Universal Motors?

    I assume due to the lack of responses that I should clarify my question a bit more. I have a "universal" motor which has a field(stator) and armature (rotor). Now, in a PM DC motor the wind can be change to get a new performance by using a linear relationship. Well at least this...
  16. smitty1322

    Winding Universal Motors?

    I was told that when designing a wind for a universal motor, the ratio between the number of turns in the armature and the number of turns in the field should ideally be 2:1. However, when asking for the theory behind this, the only response I got was that this is the way it has always been...

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