[Jo...] Posted June 30, 2022 Share Posted June 30, 2022 I am currently programming a part with a 36X M5 bolt hole pattern, with holes in this pattern in the Z+, Y+, Y-, X+, and X- planes in relation to the alignment I'm using. I suspect there is possibly something wrong with the best fit method I am using. The holes in the Z plane (in line with my base alignment plane) come out fine but the holes on the sides, front and back all produce bogus results. I can say with certainty that the holes are not out of location by 2 inches or more.... I could go through and apply positions to the holes individually with much more reasonable results, but technically isn't the correct way to do a hole pattern when the pattern essentially functions as one feature simultaneously. I've allowed translation and rotation, I've tried using Gauss vs. View Tolerance, it always produces nonsense. Anyone have any ideas where I may be going wrong? Link to comment Share on other sites More sharing options...
[Ro...] Posted June 30, 2022 Share Posted June 30, 2022 You need to be looking down the axis of the hole when evaluating position. You'll need to create more than 1 characteristic for the holes, and use the Special button in the characteristic to rotate the alignment to look down the axis of the holes. For example, if you had a cube with 4 thru holes on each side, you would need 3 characteristics to report the holes. 1 looking straight down for 4 holes, 1 rotated 90 degrees to check the sides, and 1 rotated 90 degrees to check the front/back. If you have unconstrained degrees of freedom you can best fit the holes, but all the holes have simultaneous requirements if they have the same datum callout. So you would create 1 best fit alignment with all the holes, allowing for fitting, then use that alignment, along with the Special button, in all 3 of your characteristics to report them to the same best fit. Link to comment Share on other sites More sharing options...
[Jo...] Posted June 30, 2022 Author Share Posted June 30, 2022 Please sign in to view this quote. I wish I could have a visual of how this would look in the features and characteristics window. I think I understand what you are describing, but I can't visualize it. I am familiar with having to make secondary alignments, with only rotations to the base alignment, to make it so you are looking down the hole as you've described but I have not always been successful using the pattern function when the pattern exists on multiple planes. My part, simplified, is basically what you described; a cube with holes on all sides except the bottom. And a few hundred different features on that cube. 🤣 Where I don't have a characteristic for the M5 holes (since they are threads and thus do not have a size to report) are you suggesting I give them a diameter for the characteristics side and use that to do my rotations? In this case I would probably constrain to normal vector and size, I'm using a helix paths on threads. Link to comment Share on other sites More sharing options...
[Ro...] Posted June 30, 2022 Share Posted June 30, 2022 Do you have a print or something you can show the datums and callout? I'm trying to understand what type of best fit your doing and what degrees of freedom you're fitting on a cube with holes on each side. Normally hole patterns are on one plane and/or are parallel to each other. Best fitting holes on multiple planes at once isn't going to work with 2d bore pattern. You'd need some sort of 3d best fit. Link to comment Share on other sites More sharing options...
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