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  1. rwsasser1

    Rate for contract work

    I would love to do contract work eventually full time, but right now I need more experience and my PE. Are there any independent contract engineers out there that could give me some helpful advice or info. How do you go about building up steady clientel? I imagine the only overhead would be...
  2. rwsasser1

    Rate for contract work

    I am a relatively new mechanical engineer with a little more then one year experience. Recently I have had a friend need me to do some detailed fabrication drawings of certain metal displays and such that his company designs. Another friend recently asked me to do the same thing with a...
  3. rwsasser1

    Validation of Equation

    Ok, I just found this in my thermo book, Q=mCp(Ti-Tf)/time so I believe it now.
  4. rwsasser1

    Validation of Equation

    I am trying to figure out the maximum temperature increase in the material. So If I assume no heat is lost then wouldnt that give me the maximum temperature increase possible?
  5. rwsasser1

    Validation of Equation

    let me rewrite the equation (W*Cp*Delta T)/(3.412*Time)
  6. rwsasser1

    Validation of Equation

    It doesnt I guess, but thats ok, for my needs I can use a worst case scenario. So you agree with this equation(assuming no heat loss during heating)?
  7. rwsasser1

    Validation of Equation

    Wattage required to heat material: Weight of material (lbs) x Specific Heat (Btu/lb °F) x Temperature rise (°F)/3.412 btu/watt hr. x Heat-up time (hr.) = Watts I found this on a website, does this fly with you guys? My heat transfer book has nothing on this.
  8. rwsasser1

    Water cooling in a vacuum

    The drum is water cooled also.
  9. rwsasser1

    Water cooling in a vacuum

    There is no shield in place as of yet. We are trying to determine if this is feasible. The shield is 3/16" plate and right now I have it designed at a distance of 0.0787" away from the drum. It is a sputtering process with argon but the target(nickel) must have a charge in order for the argon...
  10. rwsasser1

    Water cooling in a vacuum

    I am speaking of heat transfer by convection form the copper shield to the water traveling through the copper tubes via the surface area of the inside of the copper tubing. I know the original temperature of the cooling water. I will be measuring the flow rate when I travel to the site and...
  11. rwsasser1

    Water cooling in a vacuum

    Here is the deal, I have a copper shield in a vacuum that is exposed to q=0.69kw of radiant energy. I need to cool this shield to prevent any warpage. I am going to weld copper tubing to the shield to use for water cooling. So the heat will be removed from the copper shield via convection...
  12. rwsasser1

    Force required to spin shaft

    The film drives the roller via friction. And there are diameter limitations. Like I said before there is a steel shaft in place now, so I am going to have maintenance clean and grease the bearings and see what effect that has, and if that gets it close I can replace steel with aluminum and...
  13. rwsasser1

    Force required to spin shaft

    Loading is not an issue, this application is just an idler roller that film runs across, but if the roller does not turn in sequence with the film it will scratch it. So I figured I would try to get some lower friction bearings and a lighter shaft.
  14. rwsasser1

    Force required to spin shaft

    Lets forget about the bearing for now. A steel shaft is currently in place and I am wondering if an Aluminum shaft would require less torque to spin. I am guessing they would be the same since polar moment of inertia has nothing to do with type of material... correct? But my instincts tell me...
  15. rwsasser1

    Force required to spin shaft

    I have a 25mm OD Al 6061 shaft supported by a ball bearing on each end. How can I find the force required to rotate the shaft from rest?

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