help with a mate problem i'm having

donald_8

i'm NOT a CAD person! i know enough to get into trouble that's it. i'm trying to make a backhoe for my lawn mower and i can't get the mates to work. the angles for the cylinder and arm are most likely wrong, but that's why i'm drawing it on OnShape first.
any help would be appreciated.
thank you.  
PS how do i attach the drawing

shanshan

please see the attached image, click the icon marked  with red circle, you can upload the attachment here

NeilCooke

To share the document go to the share button top right and make it public. Then paste the URL from the top of your browser here. 

donald_8

i doubt this is right 
https://cad.onshape.com/documents/56d9097ae4b0747e94b95328/w/0fc280872b93cdaa9bc0da08/e/c5052505afee9f50afee4205

philip_thomas

Thank you for sharing. Efficient mating is not super intuitive so here are some guidelines;
1) Mate groups really reduce the number of mates - any two or more components that do not move relative to one another should be in a group
2) Sub assemblies really unclutter your tree
3) Mate connectors in parts and subassemblies make life easier.
4) try not to create chains of dependencies that must all be satisfied. For instance if i am building a 4 bar linkage, i will use 3 revolutes and 1 cylindrical mate relations. This accommodates any thickness variation between the 4 parts and visually moves any mis matched thicknesses to the cylindrical mate (and doesn't fail).

Thank you for your support of Onshape.

https://cad.onshape.com/documents/56d9ab56e4b0747e94b96693/w/7238edef32d289b762e69856/e/499eb516272ee9ddab370e8c

donald_8

thanks i wish i knew how you did it. i'll have to study it for a while, also need to know what groups are.

donald_8

why do you have 2 sliders on the actuator?

philip_thomas

donald_8 said:

why do you have 2 sliders on the actuator?

Because i was running late to a meeting!
Fixed - you only need one

donald_8

so how do you use groups? i mate 2 parts to each other, delete the mates then group them ??

philip_thomas

Thats one way. If you design the parts in-situ in a part studio, then you can skip the 'mate first' step. Its a good way of replacing 'n' fasten mates with a single group or replacing multiple 'fixed' components with a single group. Even better, you can add more components to a group at a later time justs by editing the group and adding the new parts.

donald_8

so when i drew it in the part studio i make it a group?

donald_8

how do you position the parts when you add them if you don't mate them

donald_8

i would like more examples of some of this basic stuff for dummies like me

philip_thomas

When you insert a part or parts from from a part studio into an assembly, they are inserted in the same positions relative to the origin as they are in the part studio. Simply select 'group' and then select/window the parts. Also - if you ever want to know how something works, just click on the '?' in the dialog and you will be taken directly to the relevant help section . . . 

https://cad.onshape.com/help/index.htm#cshid=mategroup

donald_8

i'll give a whirl thanks