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Recent content by stuff

  1. stuff

    6DOF Micron-resolution adjuster design

    I am starting to design a sensitive alignment device to carry an optical part and position it with 6 degrees of freedom relative to an optical system. It must stay with the product as periodic realignment will be required. The spec details are: Optical part dims: 25mm x 20mm x 5mm Range: 2mm...
  2. stuff

    hypothetical optics question

    In the design of light condensing optics for a slide projector, we use standard practise of placing a shallow spherical mirror behind the lamp filament. The filament is a 1:2 ratio rectangle and the filament tip is concentric to the spherical mirror. This creates a mirror image of the filament...
  3. stuff

    Sheet metal design

    We have many trigonometry problems like this with our projects. I worked this out: A - desired face angle (acute angle) B - side taper angle (your 45deg) C - corner angle in plan view (your 30deg) then A = atan(1/sinB*tanC) for your example A = 67.792deg (I hope!) Hope it helps Matt
  4. stuff

    Suck or Blow?!

    Thanks for everyone who has answered this thread so far. The answer is obviously product-dependent. Whilst there are parts withing this device that would require spot cooling I have confidence that a careful placement of inlet vents would suffice. Reducing the convection turbulence is a...
  5. stuff

    Suck or Blow?!

    Thanks for the input, this is useful. The 'dirty air' consideration is important but we have EM sealing and 5 micron dust filters planned so perhaps I shouldn't worry so much about that one. Stuff
  6. stuff

    Suck or Blow?!

    Gents, I'm designing an electronics package and am now looking at the unit's thermal design issues. I need to cool a box of optics in the unit that operates at 40-45 deg C, with 200W dissipated by the lamp. I am selecting a tacho radial blower with 16cfm flowrate (overspec for now) but...
  7. stuff

    Value of helical split and toothed lockwashers

    I can't offer you any unbiased data on the vibration peformance of those washers, but I have seen a great demonstration of their failure by the guys who sell Nord-Lock washers. I am not affiliated with Nord-Lock, by the way. They used the Junker test (?) - a load cell is under compression in a...
  8. stuff

    Position,Velocity,Acceleration!!

    A set of statements to contemplate: The force due to gravity has the effect of acceleration on a mass when there is no opposing force on that mass. A mass in a gravitational field results in a force. This is a concept that man has still not conquered! It requires force (or net force to be...
  9. stuff

    How to convert an assembly into one solid block?

    Have you tried exploding the assembly? You need to explode sub-assemblies and parts aswell but you are left with non-parametric solids. I always end up doing this when exporting to another software program. Matt
  10. stuff

    Shrinkage of GRP Mouldings

    Thanks for the responses. The part is fabricated from a glass-fibre csm and polyester resin. I thought it was a polyurethane foam but I could be wrong. The mould is a combination of GRP and fibreboard. Our vendor is pretty good at counteracting shrinkage but can only promise a build...
  11. stuff

    Shrinkage of GRP Mouldings

    Peeps! My Design: I am designing a structural GRP moulding which needs to have connection interaces with extremely high accuracy. The part is 3m long, 1.5m wide and 1m deep (10' x 5' x 3.5') and will be built by separately moulding key features and linking them with a set of laminated PU...
  12. stuff

    Measuring Projector Light Output

    Hi Lylek, Visit this link to Barco's website. It has a useful explanation of measurement methods. We use many LCD and CRT projectors in our applications and the practical value of CRT lumens is usually much lower than the manufacturer's spec. This is because the brightness is expressed as a...
  13. stuff

    materials in mass properties analysis

    This was never documented well. Find the file mcad.mat from "programme files /autocad 14 / desktop / support" or similar. Drag and drop it into Notepad and there is some help text and the materials list you're after. Just add extra material definitions to the list. You don't...
  14. stuff

    Fatal error in drawing start up ?????

    I'm only on MDT2 but have seen this problem when the model has been saved in an unstable state. - ie. a part has not been updated after its parameters were changed. This can happen when you don't expect it. Try loading MDT and typing 'recover'. Hunt your file and let MDT try and fix it. Or...
  15. stuff

    Getting Dialog Boxes to show up?

    Have you tried CMDDIA? It also controls dialogue boxes.
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