RE: Inspection of parts...

From: John Wright (johnw@ra-ltd.co.uk)
Date: Thu Jan 25 2001 - 12:50:42 EET


Doug

Is this spline a form on top of another form, like a styling line on say a
plastic moulding or does it present a definite edge.

If it is the former, you will probably have to generate a number of sections
through a 3d scan. However if it presents a definite edge, why not drive the
cmm so that the shank of the probe actually contacts the face. You would
need to take either use a small stylus, smaller than the shank, and just
collect a series of points along the face.
Alternatively find somebody with something like a Renishaw Cyclone, and ask
them to generate a series of 2d profiles along the face. This would take a
cyclone a few minutes only - but make sure they output the data as points
not polylines.
We use this method very frequently when reverse engineering things like
mobile phones - we get very accurate profiles and then by matching in some
cross-sectional contours - it becomes a doddle (if you know what you are
doing!)

You could always resort to a standard shadowgraph and plot the spline from
the cad system onto an overlay - but seeing as this is a bit low tech, and a
traditional toolroom technique not many people in our world use them.
Sometimes the old tools are the best ones. Just go to a local jig and
fixture shop - they should have one. It should take all of 5 mins to set up
and use.

Best Regards

John Wright
Response Associates Limited

Tel: +44 01747 841 475
Fax: +44 01747 841 476

email : johnw@ra-ltd.co.uk

  -----Original Message-----
  From: owner-rp-ml@bart.lpt.fi [mailto:owner-rp-ml@bart.lpt.fi]On Behalf Of
Impact - Doug Johnson
  Sent: Tuesday, January 23, 2001 6:45 PM
  To: RP Mailing List
  Subject: Inspection of parts...

  Hi All,

  Here is what I am looking for help with:

  I have a part that has a spline on it.
  I need to check the profile of the spline to make sure it is within
tolerance.
  We have been unable to do this with a standard CMM.

  Is there a video inspection system that can use a visual go/no go gauge?

  We don't have time to make a physical go/no go.

  Any ideas?

  Thanx,

  Doug
  Doug Johnson Prototyping Program Manager

  IMPACT Engineering Solutions

  3315 North 124th Street

  Suite N

  Brookfield, WI 53005

  ph:262-317-8135

  fx:262-317-8101

For more information about the rp-ml, see http://ltk.hut.fi/rp-ml/



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