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  1. MagnetDave

    H2S affect on Samarium Cobalt & Coating

    I would look at a phenolic resin, rather than an epoxy in this case. Or, if that's not enough, a parylene. Those will give you the best chemically inert seal.
  2. MagnetDave

    What is an optimal configuration of (neodymium)magnets for induction.

    I assume there will be a more coherent version coming. To help that along, let me add a few things: What's the outer collar made of? Which way is the magnet poled? And you should generally make the coil overlong. Helps mechanically and magnetically.
  3. MagnetDave

    50/60 Hz passive detecting system

    Skogsgurra, That was directed to rmarchesi.
  4. MagnetDave

    50/60 Hz passive detecting system

    Do you have any literature on this? I would like it when I am discussing people who want to use refrigerator magnets for joint pain, and are convinced of the value of low magnetic fields. I have been considering your project, and my feelings rhyme with "spoondoggle." If you can't just throw...
  5. MagnetDave

    Silicon iron bars

    Who did you talk to at Carpenter?!?!?!??!?! I can never get any material out of them.
  6. MagnetDave

    Silicon iron bars

    Try Scientific Alloys.
  7. MagnetDave

    MRI scanning equipment info needed

    Yes, bronze. Again, I would not send a bronze tool INTO the MRI for the same reasons you need a non-conductive table. However, they will be safe to have in the room, as they are nonmagnetic. They are sometimes also listed as "nonsparking" tools - and they are generally the preferred metal for...
  8. MagnetDave

    Identifying a Magnet

    It looks like a very early NdFeB magnet (as MagMike said). As he also said, if you want to determine anything useful, you need to go to a reputable vendor to have it tested to determine exactly what it is (in a functional sense) and how it can be replaced. We can perform a non-destructive (okay...
  9. MagnetDave

    MRI scanning equipment info needed

    Can I assume you will have a ferrier on site to de-shoe and re-shoe the horses as necessary? Apart from that, I would say just avoid metals on anything going IN to the MRI, and avoid ferrous metals in the room. (Bronze tooling has regrown to fill this niche market.)
  10. MagnetDave

    MRI scanning equipment info needed

    "anti-magnetic?" This is not a commonly used term - could you describe what you are trying to get to? Taking a stab at it, I think you want to limit yourself to insulating materials, such as plastics, fiberglasses, and ceramics. Even non-magnetic conductors, such as aluminum and 300 SS will...
  11. MagnetDave

    I need info on the heating properties of...

    I assume you have hit up MatWeb already - it does generally do a nice job with thermal properties. My general experience with carbon fiber is that its thermal expansion is an order of magnitude less than metals (including titanium). I find titanium to be a poor thermal conductor, carbon fiber...
  12. MagnetDave

    I need info on the heating properties of...

    That's a really broad question. Are you looking for thermal expansion, thermal conductivity, heat capacity? Also, keep in mind that carbon fiber is highly anisotropic.
  13. MagnetDave

    EMS Magnetic software

    Let me second dgallup - and I've tested/used a LOT of magnetic software (ANSYS, Opera, AMPERES, COSMOS) and I also consider MagNet my favorite. And definitely spring for the parameterization module. One other thing: almost all commercial FEA packages will let you do a trial. Since this is a...
  14. MagnetDave

    New engineer feeling like failure

    huskybuilder, My turn! As far as burnout, because I've been there plenty of times. The best answer I have is "get a hobby," but let me elaborate. You need to find some downtime and let yourself recharge. You are constantly emptying the tank, and never taking time to refill it. I have variously...
  15. MagnetDave

    Radially oriented magnetic field in a sphere

    One of us is. What path is flux leaving through?
  16. MagnetDave

    Response time of an electromagnet

    Treat your electromagnet as an inductor. The inductance of your circuit should dominate your calculations.
  17. MagnetDave

    Radially oriented magnetic field in a sphere

    This is a popular test question in our field. I have actually encountered a few customers who have wanted designs based on magnetic spheres. At the end of the day, Gauss's Law prevents any object like this from working, regardless of how clever you are with diamagnets (even very weak...
  18. MagnetDave

    Need help: Perm. Magnets and temp. changes

    Bretman, I am back from vacation, so let's see what we can do. At the moment I am still at our factory in Switzerland, so you will have to work with me on the time zone issues until I get back to the East Coast. This link has a lot of information on the various types of Samarium Cobalt out...
  19. MagnetDave

    Need help: Perm. Magnets and temp. changes

    At the risk of tooting my own horn, to achieve that level of reliability you really need someone like me. This is the value we provide - we can give you EXACTLY what you want with tight quality controls, and take this very specialized area of engineering off your list of things you need to learn...
  20. MagnetDave

    Need help: Perm. Magnets and temp. changes

    Did you want a pony with that? As far as machining: Magnets have to be ground. Period. They are intermetallics and machine like ceramics, only more brittle. The techniques for doing it are pretty specialized, and there only about four companies in the US that do it, and they usually have pretty...

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