Mates Problem - Groups Error message

peter_cuthbert

Hi folks

I have been trying to assemble the drawing of a simple steam engine.  I seem to be having Mates Nightmares.  I have discovered that using too many Revolute Mates gives rise to the error message "Mate over-defines assembly".  It seems that the solution is to swop one Revolute for a Cylindrical Mate.  So far so good.  I then discovered that parts that had been successfully 'Fastened' the previous day were quite happy to go into free fall the next.  Apparently the answer to that is to assemble a few parts (successfully) and then 'Group' them into a singel object.  Great idea, so as soon as I got to do it I have discovered a brand new error message; "Mate cannot be added between member of same group".  Basically it seems that the bolts I had installed with no complaint earlier do not like to be Grouped.

The assembly has now descended into a mess which is to be found here:

https://cad.onshape.com/documents/52b041b9391de90c49ad35a7/w/880a0cc8ec7b9c3243844d93/e/c42002bfcbb29754ef6f7e49

I will leave it up for a while but when I get time to draw again I will need to start from scratch.

I would welcome your ideas and suggestions.

Regards

Pete

rick_randall

I don't think you need to start over. when you create groups the group locks all parts into one static piece.

Groups & mates are basically incompatible. Use groups sparingly and suppress the offending mate(s) that the group triggers (the red ones)

Leave the mates! Later if you decide to dissolve the group(s) , simply unsuppress the mates and you're all good. Hope this helps

rick_randall

One other thing I noticed, When you populate your assembly with fasteners - best practice is to insert only one fastener of each size, mate that one bolt, then use the replicate command to fill in all other places it's needed (be sure to check out all the various options this command has to offer). This is a very powerful command and will keep the instance list nice and tidy.

look at the changes I made in the instances list - i.e. the replicate 1 (suppress & unsuppress to see changes). I only did the one bolt size and may not have got all instances - but you get the picture.

https://cad.onshape.com/documents/ff85a2ff180d9eda6145d73a/w/68bdf7ff65b71a2f408c5837/e/8585325354c38db1f9dbfb6f

peter_cuthbert

Good Morning Rick from a miserably wet Cymru

Thank you so much for your posts.  That is helping to clear the mists of my confusion.  I am impressed by Replicate as that had not come up on any of the training videos I have watched.  Having discovered the Standard Content option I did as I so often do and used it to excess so Replicate is the perfect antidote for my Bolt Fever.

I think I will persevere with Groups, if only to explore all the possible error messages, but more seriously I think that the cylinder blocks should form a group as I also have drawings of the designer's original intent.  The current 'blocky' items were drawn to make exploration of the necessary Mates a little easier.  Once all that works it ought to be possible to swop the Blocky Group for the Artistic Group.

Regards

Pete

rick_randall

Glad to hear it helped. Don't give up on groups, use them when you need them. When trying to decide whether you should make a group or not, use this simple  rule (If your collection of parts act as one single part-use a group). I do agree with you that the cylinders could be a group, just suppress the assembly mates and the warning labels should all clear themselves.

And yes training & practice is part of the game,  glad to see you are experimenting with commands and features (don't forget to explore all the details that are in the UI boxes). Remember that the undo button is your friend. I think you're off to a good start - keep it up, you'll get there.

romi_chase

The "Mates Problem - Groups Error" message suggests a problem with grouping entities in CAD software. Reviewing mate constraints and ensuring proper grouping and alignment can help resolve this issue effectively.