[To...] Posted November 9, 2020 Share Posted November 9, 2020 I have a cylindrical part, laying along the X axis. The drawing calls for 4 Datum A target points, 2 at each end. Imagine the part sitting in 2 90° v-blocks. Datum B is the end face. And Datum C is a flat in the Z plane on the top. I created a Geometry Best Fit of the 4 Datum A target points, with full translation and rotation. Next, I created a normal secondary alignment. I changed the Alignment reference to the previous GBF alignment and added Datum B plane for the X origin and the Datum C line for the planar rotation. Is this correct?Screenshot 2020-11-09 090438.jpgScreenshot 2020-11-09 085412.jpgScreenshot 2020-11-09 085436.jpg Link to comment https://qualityforum.zeiss.com/topic/14134-alignment-with-datum-targets-and-geometry/ Share on other sites More sharing options...
[SH...] Posted November 9, 2020 Share Posted November 9, 2020 No datum target on datum B and C?. Link to comment https://qualityforum.zeiss.com/topic/14134-alignment-with-datum-targets-and-geometry/#findComment-73478 Share on other sites More sharing options...
[Ma...] Posted November 9, 2020 Share Posted November 9, 2020 I would fit cylinder to 4 points with locked radius. Drawing should contain base dimension for that. But i don't know if 4 points will not have issues with cylinder. Or you can make 2 circles with locked radius and construct 3d line from them. Link to comment https://qualityforum.zeiss.com/topic/14134-alignment-with-datum-targets-and-geometry/#findComment-73480 Share on other sites More sharing options...
[SH...] Posted November 9, 2020 Share Posted November 9, 2020 I can't understand the logic of adding datum target to this like simple geometry. Datum targets are added for complicated contour or geometry that can't be work with standard practice. I think that four points for designing Fixture. Link to comment https://qualityforum.zeiss.com/topic/14134-alignment-with-datum-targets-and-geometry/#findComment-73482 Share on other sites More sharing options...
[Cl...] Posted November 9, 2020 Share Posted November 9, 2020 I'm guessing those 4 points would be the contact locations of the tangent points of the v-block to the cylinder OD. Link to comment https://qualityforum.zeiss.com/topic/14134-alignment-with-datum-targets-and-geometry/#findComment-73484 Share on other sites More sharing options...
[To...] Posted November 9, 2020 Author Share Posted November 9, 2020 Please sign in to view this quote. No Link to comment https://qualityforum.zeiss.com/topic/14134-alignment-with-datum-targets-and-geometry/#findComment-73486 Share on other sites More sharing options...
[To...] Posted November 9, 2020 Author Share Posted November 9, 2020 Please sign in to view this quote. The diameter on the drawing is not BASIC. A cylinder requires a minimum of 5 points. Link to comment https://qualityforum.zeiss.com/topic/14134-alignment-with-datum-targets-and-geometry/#findComment-73488 Share on other sites More sharing options...
[To...] Posted November 9, 2020 Author Share Posted November 9, 2020 Please sign in to view this quote. 🙂 Did u read my post?...LOL Link to comment https://qualityforum.zeiss.com/topic/14134-alignment-with-datum-targets-and-geometry/#findComment-73490 Share on other sites More sharing options...
[To...] Posted November 9, 2020 Author Share Posted November 9, 2020 I honestly feel this is a misuse of datum targets. ASME Y14.5, states 6 datum targets, 3 on each end, to establish a datum axis. Link to comment https://qualityforum.zeiss.com/topic/14134-alignment-with-datum-targets-and-geometry/#findComment-73492 Share on other sites More sharing options...
[To...] Posted November 9, 2020 Author Share Posted November 9, 2020 Please sign in to view this quote. Check out Datum Targets in Y14.5 Link to comment https://qualityforum.zeiss.com/topic/14134-alignment-with-datum-targets-and-geometry/#findComment-73494 Share on other sites More sharing options...
[Ma...] Posted November 9, 2020 Share Posted November 9, 2020 Please sign in to view this quote. If it is like contact point, then you can use locked radius. But i didn't see drawings. Link to comment https://qualityforum.zeiss.com/topic/14134-alignment-with-datum-targets-and-geometry/#findComment-73496 Share on other sites More sharing options...
[Cl...] Posted November 9, 2020 Share Posted November 9, 2020 Please sign in to view this quote. Imagine the part sitting in 2 90° v-blocks. Gotta slow down I guess. Link to comment https://qualityforum.zeiss.com/topic/14134-alignment-with-datum-targets-and-geometry/#findComment-73498 Share on other sites More sharing options...
[Ja...] Posted November 9, 2020 Share Posted November 9, 2020 I can see the dilemma. Datum A is supposed to constrain Y,Z location, but with 4 points arranged like that, how can it? The diameter/center point of the part could be anything and still fit on those 4 points. Maybe you could forget it's a cylinder and think of it as an irregular shape but that doesn't change the inability to establish Y,Z nominal. I maybe wrong, I don't know. Link to comment https://qualityforum.zeiss.com/topic/14134-alignment-with-datum-targets-and-geometry/#findComment-73500 Share on other sites More sharing options...
[SH...] Posted November 9, 2020 Share Posted November 9, 2020 Please sign in to view this quote. So, your part is either a casting, forging or molded,not a machined surface.IMG_20201110_021333.jpg Link to comment https://qualityforum.zeiss.com/topic/14134-alignment-with-datum-targets-and-geometry/#findComment-73502 Share on other sites More sharing options...
[To...] Posted November 9, 2020 Author Share Posted November 9, 2020 Please sign in to view this quote. Absolutely. When I looked at Y14.5, it said 2 sets of 3 equally spaced points at each end of the cylinder should be used. Link to comment https://qualityforum.zeiss.com/topic/14134-alignment-with-datum-targets-and-geometry/#findComment-73504 Share on other sites More sharing options...
[To...] Posted November 9, 2020 Author Share Posted November 9, 2020 Please sign in to view this quote. Check out paragraph 4.24.10 Also, datum targets on standard geometry could be used to identify where measure or fixture the part. Link to comment https://qualityforum.zeiss.com/topic/14134-alignment-with-datum-targets-and-geometry/#findComment-73506 Share on other sites More sharing options...
[Cl...] Posted November 10, 2020 Share Posted November 10, 2020 If the Datum targets represent the contact (tangent) points of the part resting in v-blocks, why not Construct a theoretical cylinder from those four points and use that for the spatial rotation in your alignment? Are the Y & Z coordinates for the datum points .4808? I want to try something out. Link to comment https://qualityforum.zeiss.com/topic/14134-alignment-with-datum-targets-and-geometry/#findComment-73508 Share on other sites More sharing options...
[Cl...] Posted November 10, 2020 Share Posted November 10, 2020 I don't think my ideas going to work. Link to comment https://qualityforum.zeiss.com/topic/14134-alignment-with-datum-targets-and-geometry/#findComment-73510 Share on other sites More sharing options...
[Jo...] Posted November 10, 2020 Share Posted November 10, 2020 I have a few parts with this type of structure. It's maddening. Can you physically place the part in a VEE block and use the planes as your tangent ? Link to comment https://qualityforum.zeiss.com/topic/14134-alignment-with-datum-targets-and-geometry/#findComment-73512 Share on other sites More sharing options...
[Cl...] Posted November 10, 2020 Share Posted November 10, 2020 Create the 4 nominal datum points at .4808 Z & X (whatever in Y) and construct two symmetries. Construct a 3d line from the symmetries = X+ (in your example) Spatial or Planar Rotation? Link to comment https://qualityforum.zeiss.com/topic/14134-alignment-with-datum-targets-and-geometry/#findComment-73514 Share on other sites More sharing options...
[To...] Posted November 10, 2020 Author Share Posted November 10, 2020 Not to sound ungrateful but nobody answered my original question about how one might create an alignment using datum targets and geometry. Let's forget about 4 target datums on a cylinder and make it a multi-level plane-like surface with 4 datum targets at different heights. 😃 Link to comment https://qualityforum.zeiss.com/topic/14134-alignment-with-datum-targets-and-geometry/#findComment-73516 Share on other sites More sharing options...
[Cl...] Posted November 10, 2020 Share Posted November 10, 2020 Then that sounds like an offset plane? Link to comment https://qualityforum.zeiss.com/topic/14134-alignment-with-datum-targets-and-geometry/#findComment-73518 Share on other sites More sharing options...
[Ri...] Posted November 10, 2020 Share Posted November 10, 2020 I don't know if I'd let it tumble is all 6 axis. I would suggest only having Translation in the Y, Z, and Rotation in the Y, Z active. Have you tested it to see if the results you are getting make sense? I've just started using Geometry Best Fit, and I actually have a lot of questions myself regarding it. Typically the experience I have had with a 3d Best Fit though would be in the Base Alignment, and looped at least 3-5 times. Your case is unique though. Link to comment https://qualityforum.zeiss.com/topic/14134-alignment-with-datum-targets-and-geometry/#findComment-73520 Share on other sites More sharing options...
[An...] Posted November 10, 2020 Share Posted November 10, 2020 _ Link to comment https://qualityforum.zeiss.com/topic/14134-alignment-with-datum-targets-and-geometry/#findComment-73522 Share on other sites More sharing options...
[An...] Posted November 10, 2020 Share Posted November 10, 2020 _ Link to comment https://qualityforum.zeiss.com/topic/14134-alignment-with-datum-targets-and-geometry/#findComment-73524 Share on other sites More sharing options...
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