Reference pattern oddities

[GV_SVN]

Hi, I am using reference patterns to pattern the bolt groups in my assembly. The first reference pattern is great and everything generates as expected. See pictures attached for details.

The next reference pattern of the two socket head cap screws is a bit weird since the instance dots in the feature menu show the second instance being in the wrong location. Upon generation, it appears in the correct location but it is unsettling.

The third reference pattern (four bolts) shows the instance dots in the right location in the feature menu, but upon generation, only the washer is in the correct position. The bolt, nut side washer, and nut seem to locate themselves at the first instance location. It is really weird because I have the bolt group constrained the same way as the first bolt pattern in my model tree which worked fine.

Any thoughts on how I can resolve this? TIA

[Dale_Rosema]

You have to be very careful on references in patterning a group.

Here are a couple other article about it. One that talks about references and one where I wasn't able to find a good solution to patterning a group.

https://community.ptc.com/t5/3D-Part-Assembly-Design/Patterning-patterned-group-of-features/m-p/772652

https://community.ptc.com/t5/3D-Part-Assembly-Design/Instance-in-a-Family-Table-In-a-Group-Patterned/m-p/190570

[Chris3]

Usually Ref patterns get confused when you have references that are part of multiple patterns. For instance You have a hole that has a raised boss where your fastener is going through. Maybe the hole is one pattern and then the raised boss feature is a different pattern and when you try and do a ref pattern it gets confused about which pattern to use.

Suggestions for you:

1. Ungroup and do patterns on each individual component.

2. Submit your data to PTC on a ticket and they can help point out what references are being problematic for the ref pattern.

[mashton-2 · Accepted solution]

I find you need to make sure all your references are consistent. That is all parts are referenced to the lead feature in driving pattern.

If you have your spring washer for instance referenced to your plain washer rather than the lead hole in the pattern on your plate you can get the effect you are seeing with all the instances in a reference pattern on top of each other.

What I do is assemble the plain washer to the  lead hole in the part then do the same with the spring washer (even though its face maybe assembled to the plain washer face I assemble the hole in each washer to the lead hole in the part) then the shaft of the screw is assembled to the lead hole in the part. Then you can group the screw and washers and pattern the group.

I have used washers and a screw but the principle stands for any parts.

[GV_SVN]

Hi Mashton, your method has worked for me, but in a weird way. All I did was change the bolt reference from being centered on the bolt side washer to being centered to the slot axis (to match the bolt side washer references as you suggested) and tried the pattern again. It works great now! It's weird because I didn't have to do anything to the nut side washer or the nut. They're constrained to be centered on the bolt, not the slot axis, yet they patterned properly unlike before. I guess you just have to work down the model tree until the pattern is achieved.

[mashton-2]

GC_SVN I am glad that worked for you, what you did was probably enough to order the references correctly. I just find if you relate each part to the lead feature in the driving pattern things work much better.