Replicate is broken

n_schoemaeker

Hi everyone,

I have been having an issue with a recent OnShape update (I am pretty sure this used to work). It's definitely not from the latest update, but from a few months ago.

I never took the time to report it, now I do.

It has to do with how "Replicate" works now, and I think its usefulness has been greatly reduced. Basically, now, a part that is Replicated can only have only one mate applied to it (the mate that is concerned with the Replicate).

If some part is Replicated several times in an Assembly, it's okay. But the moment we need to mate another part to it, it breaks the replicate and this is very limiting and frustrating (IMO).

I've made a document example to showcase this: https://cad.onshape.com/documents/08d8e0c02b60c481e028b021/w/2938dc90dec5b40f4b175d77/e/ee64011f2c9b53e20d7ab4a0?configuration=default&renderMode=0&uiState=61b1d3bc2ce2757a75741905

- I have my base part "Test Part" which has 4 screw holes in it which I import in my main Assembly

- I then add a washer to the first hole, on the top-left corner, through Standard Content. This creates a Fastened Mate that I have renamed "Washer" in the Mate Features

- I then use Replicate on the Washer and select the Test Part's top face => 3 new Washers appear on the other 3 holes as intended. I renamed the Replicate feature "Replicate Washers"

- Then by clicking the Configuration Checkbox "Add & Mate Screw" it adds a Standard Content screw on that initial Washer. But at that point, the Replicate Washer gets broken.

It used to display an error message saying only one mate was allowed or something like that, now it displays "One or More seed parts are not mated to other supported geometry"

This is a big problem because Replicate can be useful for a lot of things, not necessarily screws. And I regularly have "sandwich" parts that I replicate and need to add some other mates too, and this is not possible anymore (I think it used to work).

Note: the document I linked is a test document, to showcase the issue, I know that in this trivial case, I have several options to fix it :

- I can add the washer and the screw, and *then* replicate the pair. It works perfectly for those use-cases (I sometimes use it indeed). But this is limited: sometimes you add all those washers, but you have several different screw lengths, so you can't just use that "one replicate".

- other possibility is not to use Replicate at all, but add all instances with the Standard Content: this would also work, but I prefer not to use that, because when I have to make adjustments (like change the length of the screws), it's easier to have one seed part, then replicated because that way you change the seed part and it works. (I know there is the option to "replace all instances", but that won't do it either, because sometimes you have the same reference screw placed elsewhere whose length you don't want to change).

- I could also use linear pattern, etc.

Anyway this is just a test document, made to show how replicate is, IMO, broken.

Is this something that others have faced? Can it be worked on by the OnShape dev team?

GWS50

I have been having similar issues with the Replicate tool. The workaround is to apply the mate to one of the replicated parts and not the origin part of the replication. This seems to work for me, although I tend not to use the tool so much anymore because of this issue.

tim_hess427

I don't use Replicate much, so I can't speak to whether anything has changed. However, reading through the help page, there is a tip that says: "Seed instances may have only one external Mate; that is, there may only be one Mate to the entity onto which to replicate the seed instances."  That sounds to me like there can only be one mate replicated at a time (maybe?). 

Can you replicate the washer and then replicate the screw in a second step? 

n_schoemaeker

GWS50 said:

I have been having similar issues with the Replicate tool. The workaround is to apply the mate to one of the replicated parts and not the origin part of the replication. This seems to work for me, although I tend not to use the tool so much anymore because of this issue.

Oh I see, I've just tested this and indeed this works well enough. I don't know why I haven't thought of this.

I still think Replicate should be fixed, but in the meantime, that's another trick one can use to circumvent this problem.

Thanks for sharing!

n_schoemaeker

tim_hess427 said:

I don't use Replicate much, so I can't speak to whether anything has changed. However, reading through the help page, there is a tip that says: "Seed instances may have only one external Mate; that is, there may only be one Mate to the entity onto which to replicate the seed instances."  That sounds to me like there can only be one mate replicated at a time (maybe?). 

Can you replicate the washer and then replicate the screw in a second step? 

What this says is that, indeed, if you have a part with two mates, Replicate cannot be used (probably because it doesn't know which mate to replicate, so it makes sens. I'm fine with this.

My issue is that, once you have Replicated a part (which has only one mate), you cannot add another mate to the seed part, even after Replicate was used.

So essentially "Can you replicate the washer and then replicate the screw in a second step?" is exactly what I try to do in the document I linked: but it doesn't work because when you place the first seed screw for the second Replicate, it breaks the first.

tim_hess427

@n_schoemaeker - I see. I didn't have the time to copy your document so that I could edit and dig deeper into how your mates and replicate features were set up. 

Reading your original post again - I would guess that your first workaround (replicate the pair) is how I've done this type of thing in the past and is probably the recommended workflow the justifies this feature as working correctly (i.e. not a bug). 

So, I don't think I personally would call this broken, but your use-case does seem like a reasonable improvement.