How do you manage purchased assembled parts (such as bearings) as a single part for BOM purposes?

chrisjh777

I import bearing 3D CAD models from various vendors on Traceparts, etc.

Bearing Vendors generally supply 3D Cad Models as assemblies (perfectly logical).

This is an issue with the CAD packages I use, (SW & Onshape).  I want a simple ball bearing assembly to appear on a Parts List BOM a single purchased part, rather than a list of bearing parts such as:

Outer Race x 1

Inner Race x 1

Balls x Number of Balls

Seal x 2

How do you handle this situation?

NikolaiN

I guess the simplest way is to use "Exclude from BOM" flag (see parts' properties in part studio).
Make sure that flag is taken into consideration in the software which is used for handling BOMs. Eg. in OpenBOM just set "Exclude from BOM = False" filter and you will not see those internal parts in your BOM. Then, when do BOM export, don't forget to choose "use current filter" option.
Note: yes, it's a bit annoying to set that flag up for all those internal parts manually. It would be nice to inherit that flag from the source of your models, but not sure it's possible (you can check that additionally, I may be wrong).

robert_morris

Here's a couple of other options you can do:

1. Join all the parts into a single part with either a Boolean or an Extrusion that connects everything together (this is what I usually do).
2. Insert the part pieces into it's own subassembly, use a Group mate to hold them together, and then insert that subassembly into your main assembly.

The downside of number 2 is that you and your team always have to remember to insert the subassembly and not the part studio when you go to use it somewhere else. That's why I try to do option 1 most of the time - it makes it easier for everybody.

john_mcclary

robert_morris said:

Here's a couple of other options you can do:

1. Join all the parts into a single part with either a Boolean or an Extrusion that connects everything together (this is what I usually do).
2. Insert the part pieces into it's own subassembly, use a Group mate to hold them together, and then insert that subassembly into your main assembly.

The downside of number 2 is that you and your team always have to remember to insert the subassembly and not the part studio when you go to use it somewhere else. That's why I try to do option 1 most of the time - it makes it easier for everybody.

Yes, option 1 is better whenever you can get away with it.
There may be times where you have moving purchased parts, like a pneumatic cylinder for example. Where you should definitely use option 2 

john_mcclary

I usually just add it to an assembly, then set the BOM app to only read the top level.

If you have a multi-level BOM, you could also to a boolean-union on the parts if you do not need motion.

Now if you look at the properties of a part, you seen an option at the bottom to exclude from BOM


I haven't experimented with that yet in OnShape/openBOM, but at least it is close to being implemented if not already by a BOM app. Exclude from BOM is my typical practice in SolidWorks, so If it is working in OnShape, that would be the correct solution in my opinion.

NikolaiN

I guess the simplest way is to use "Exclude from BOM" flag (see parts' properties in part studio).
Make sure that flag is taken into consideration in the software which is used for handling BOMs. Eg. in OpenBOM just set "Exclude from BOM = False" filter and you will not see those internal parts in your BOM. Then, when do BOM export, don't forget to choose "use current filter" option.
Note: yes, it's a bit annoying to set that flag up for all those internal parts manually. It would be nice to inherit that flag from the source of your models, but not sure it's possible (you can check that additionally, I may be wrong).

chrisjh777

@john_mcclary @NikolaiN

Thanks for the tips.  I'll experiment with this.  I suspect "Exclude from BOM" will result in the part being fully excluded from the BOM, and potentially missed altogether in a "What to buy" list.

The only way to manage this efficiently, without manual manipulation, would be to empower users the choice as to whether the assembled purchased part is a "Part" or an "Assembly".

Having given this some thought, I think I will turn this discussion into an Improvement Request.  My vision is OS could add another field to "Properties".  This would give an another advantage over their competitors.

My current method is to:

1. Create a BOM at part level.
2. Manually delete all unwanted parts that make up the buy in part, one at a time, except one (say Outer Race).
3. Rename the "Outer Race" to a meaningful Bearing description, say "Bearing 6001-2RS".
4.  Add other info such as Vendor, Cost, etc as required.

john_mcclary

There should be no reason to have all the individual parts in your main assembly. They should be sub assemblies, Then you add your purchased information and descriptions to the sub assembly containing the bearing pieces.

Then insert the bearing sub assembly into your main assembly for each instance.

Instead of setting BOM to be at part level, set it to Single level BOM, and choose your main assembly.

This should make it so you don't need to remove all of the individual pieces from the BOM, and set a specific piece of the bearing to be the "main" part that contains all of the information. Honestly setting the information to one of the pieces could be difficult for someone else editing your information later on, as they may not be aware that is how you set the properties, and may have to do some detective work to figure out what part is driving the BOM.

robert_morris

Here's a couple of other options you can do:

1. Join all the parts into a single part with either a Boolean or an Extrusion that connects everything together (this is what I usually do).
2. Insert the part pieces into it's own subassembly, use a Group mate to hold them together, and then insert that subassembly into your main assembly.

The downside of number 2 is that you and your team always have to remember to insert the subassembly and not the part studio when you go to use it somewhere else. That's why I try to do option 1 most of the time - it makes it easier for everybody.

john_mcclary

robert_morris said:

Here's a couple of other options you can do:

1. Join all the parts into a single part with either a Boolean or an Extrusion that connects everything together (this is what I usually do).
2. Insert the part pieces into it's own subassembly, use a Group mate to hold them together, and then insert that subassembly into your main assembly.

The downside of number 2 is that you and your team always have to remember to insert the subassembly and not the part studio when you go to use it somewhere else. That's why I try to do option 1 most of the time - it makes it easier for everybody.

Yes, option 1 is better whenever you can get away with it.
There may be times where you have moving purchased parts, like a pneumatic cylinder for example. Where you should definitely use option 2 

oleg_shilovitsky

@john_mcclary

Exclude from BOM is a new property that was recently introduced by Onshape. It wasn't documented and we just learned about it 2 weeks ago. OpenBOM will support it in the next OpenBOM production update (end of Feb). 

If you have questions, let me know - oleg @ openbom dot com

Best, Oleg

chrisjh777

Thank to everyone who contributed to this discussion.  I had been using the "group" mate method to define purchased bearing assemblies, but wasn't aware of the "Exclude from BOM" option, because it is located off the visible part of the Properties Dropdown, (right at the very bottom, if you scroll down).   OpenBOM's current behaviour is explained by Oleg in the post above.