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Guest Message © 2012 DevFuse

THX-1138's Profile User Rating: -----

THX-1138's Photo
Reputation: 12 Neutral
Group:
Senior Members
Active Posts:
91 (0.05 per day)
Most Active In:
Applied Chemistry (23 posts)
Joined:
28-June 07
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User is offline Yesterday, 02:05 PM
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Member Title:
Meson
Age:
Age Unknown
Birthday:
April 11
Gender:
Not Telling Not Telling
Location:
In orbit around Sol at 1.0 AU
Interests:
Electronics, open software, machining, chemistry.. science in general.
Biography:
Open software expert

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  1. In Topic: Bearings for home-built gyroscope?

    24 May 2012 - 06:00 PM

    View PostdoG, on 6 May 2012 - 05:28 PM, said:

    How well does that handle radial loads?


    Hmm. If the sleeve is Teflon™ or some low-friction high-temperature plastic, and it's supported by being sunk press-fit into the gimbal frame, this might work really well.

  2. In Topic: Bearings for home-built gyroscope?

    4 May 2012 - 08:10 PM

    View PostdoG, on 3 May 2012 - 05:49 PM, said:

    The tapered bearing will have a little more rolling friction than a similarly rated angular contact ball bearing generally. More important though is that you have the means to get the rotating assembly balanced. 1 kg spinning that fast could be quite dangerous if it comes apart.


    Absolutely! Are you saying that one style of bearing is better than the other for that? How about a Wingqvist bearing?

    Thanks!

  3. In Topic: Bearings for home-built gyroscope?

    3 May 2012 - 02:19 PM

    View PostdoG, on 1 May 2012 - 07:33 PM, said:

    Generally so. I've seen many angular contact ball bearings that don't have a flange though. Mainly in screw compressor applications where the inner race bottoms against a shoulder on the through shaft.


    That (inner race against shoulder on the spindle) is my current plan for axial support. (See my diagram for the Graphalloy solution.)

    I can't lay my hands on the rotor at the moment, but here's a drawing I made of it; also attached to this reply. (Careful examination might reveal that it is, in fact, itself the outer race of a Fafnir ball bearing that never made it to the assembly stage. :rolleyes: ) From the drawing it should be possible to calculate the part's volume and hence its approximate mass, but I lack the geometry skills to do that. Although I might try modeling it in SketchUp and seeing if that can tell me the volume. :lol:

    A tapered roller bearing would probably suffice for the radial and axial loads -- but I don't think it would be too happy doing so at 20_000 RPM. :blink:

    Thanks!

  4. In Topic: Bearings for home-built gyroscope?

    1 May 2012 - 04:40 PM

    Well, the Graphalloy folks finally got back to me. They do sell small quantities retail -- at US$100 apiece. That's too dear for me, so I'm checking the other suggestions. (Single-threading due to mental resources.)

    Personally, I've always been rather fond of Fafnir. :-)

    I frequently see bearing dimensions specified as 'NNmm × NNmm × NNmm,' but I haven't been able to figure out which dimensions those numbers specify. I'm guessing ID, OD, and width (thickness/bore depth), but that's just a guess -- and I don't know in which order they'd be listed, anyway. For a bearing supporting axial loads, somewhere in there I'd expect the diameter of the load-bearing inner-race flange.

    This is probably in Machinery's Handbook somewhere, but my copy is at home and buried. :-/

  5. In Topic: Bearings for home-built gyroscope?

    23 April 2012 - 08:42 PM

    View PostInigoMontoya, on 19 April 2012 - 02:38 PM, said:

    You don't say what your intended application is but...

    An air bearing might be fun to build.


    The application is a fairly massive gyroscope (I'm guessing the rotor is about 1kg) spinning at whatever RPM I can safely manage. The bearings are to mount the spindle in the inner gimbal, so they need to be able to support the axial thrust and provide low-friction support of the spindle rotation. And be strong enough to support the precession forces if the gimbal is locked and an attitude change is attempted.

    The Graphalloy stuff looks like it would work very well:

    Posted Image

    provided the flange can support the axial load and act as a keeper.

    Unfortunately, I haven't heard back from the Graphalloy people..

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