Reference Patterns

[pjw]

My Problem: I have a hole pattern (360

 

[ProFishent]

Make sure you pattern a refrence datum, whether it is a on the fly datum or a seperate feature. Dimension and constrain to this datum, and not stationary datums.



As far as refrence patterns go sometimes they do not work correctly. I would suggest deleting your patterns, and grouping your cut and protrusion together then patterning the group. This is a much more stable method. If you need to add a new feature to the pattern you can try reference pattern, or you can redefine the group to include the new feature.

 

[dougr]

One trick I always use to avoid these problems with hemispheres is to create a construction circle in your sketch concentric to the OD of your part.



Then either align it to the OD or dimension it.



Use this construction circle to help locate the center of your protrusion. (If the center of this protrusion lies on the OD then align the construction circle to that).



Also, make sure you don't put your pattern dimension in the sketch - this should be done by make-datum or an external datum-plane as described above. (if you're not used to groups then you're going to have to when you go to Misfire).



PS Hope Wild Foul didn't get rid of construction circles too !!!

 

[mmead0ws]

ProFishent and dougr's methods both work. But if you are still adventurous with the transform, it does work.



I've been using surface transforms for several years without any issues. So I had to test your part to see if there was an issue. I just mocked up your part and there doesn't appear to be anything wrong with surface transform. There are three things to check when making this transform, the number of instances in the transform's pattern, the Patch or Use Quilt feature following the transform, and the transform copy option.



1. When you transform and pattern radially, the number of instances in your pattern is one less than the total number of instances. So your transform's number of instances is 7, not 8. If you use 8, the Patch or Solid > Use Quilt feature will fail.



2. Patch can cut and add material all at the same time. However all the edges of the surface being patched must align to existing geometry. When I tried to copy all the surfaces of the cut and protrusion, they didn't completely align to (touch) the edges of the existing geometry. So I broke it into two features.



The cut was easy as a surface transform and patch. I created the protrusion as an extruded quilt with capped ends so I could quickly and easilly transform the quilt. After I transformed and patterned it I used Solid > Protrusion > Use Quilt to convert the original quilt to solid geometry. Finally I used quilt again to change the transform into a solid and then patterned it.



3. Be sure to make a copy of the original feature when creating the transform or you won't get any dimensions for patterning.

 

[dougr]

Sounds like sledgehammer and nut time..

 

[ProFishent]

True Dat!



Surface tranceform is a pretty cool, and effective way to do it. But it's more suited to a more complex design like a helical gear. A bit of an overkill in this situation. But a good technique for pjw to learn.

 

[mmead0ws]

I agree surface transform is overkill for this part. I didn't mean to suggest surface transform was the end-all, be-all for pattern scenarios. The only two reason I've ever found for using surface transform is to reduce feature count (regeneration time) and to pattern geometry that wasn't built to pattern.



I just didn't want pjw to think transforms didn't work or that they were a bad technique.