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How to mate between a sphere ball and a rounded sphere groove in a cylinder
omri_r
Member Posts: 10 ✭
Hi!
I'm trying to mate between a sphere ball and a rounded sphere groove in a cylinder in a way such that the ball would slide only within the groove.
Both the ball and the groove have the same radius.
I tired to use the tangent mate, but it does not do the work (I'm not sure why).
It seems there is some overlap between the ball and the groove (see images below)
Any ideas how to accomplish that would be very appreciated.
https://cad.onshape.com/documents/c1fb23babb4668e97ce5a361/w/8cd120f13393056585a21bf4/e/74d56c1158535498da0cb145
Thanks!
Omri
I'm trying to mate between a sphere ball and a rounded sphere groove in a cylinder in a way such that the ball would slide only within the groove.
Both the ball and the groove have the same radius.
I tired to use the tangent mate, but it does not do the work (I'm not sure why).
It seems there is some overlap between the ball and the groove (see images below)
Any ideas how to accomplish that would be very appreciated.
https://cad.onshape.com/documents/c1fb23babb4668e97ce5a361/w/8cd120f13393056585a21bf4/e/74d56c1158535498da0cb145
Thanks!
Omri
0
Best Answers
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owen_sparks Member, Developers Posts: 2,660 PRO*Edit for rubbish terminology used.
I'd suggest 4 mates and 3 relations.
One revolute for each shaft and a slider for the ball followed by:-
(1) Rack and Pinion from Shaft 1 to Ball, exactly like above.
(2) Gear Mate between Shaft 1 and Shaft 2
(3) Gear Mate between Shaft 1 and Shaft 3
Cheers,
Owen S.Business Systems and Configuration Controller
HWM-Water Ltd6 -
John_P_Desilets Onshape Employees, csevp Posts: 248@omri_r I would avoid using any tangent mates for this example. @owen_sparks and I are on the same page for using a combination of gear, rack and pinion, and slider mates. I made another example for you to take a look at. In order to properly position the screws at the right timing, you will need to edit the individual mate that was used to create the relationship.
Offsetting the ball to the centerline of the screw.
Adjusting the timing for the screw. Rotate around the Z axis.
This workflow should give you the proper result you are looking for.
https://cad.onshape.com/documents/4bfd3fda008625fceced4150/w/752f205a6eba08f9e1d5fd88/e/320f6ce5bc5588cd5af81110
8 -
John_P_Desilets Onshape Employees, csevp Posts: 248@omri_r I would recommend sketching it all out first. Properly align the helix to the correct starting point for each screw. Take some measurements and use 2D sketch entities for reference. A layout sketch will help your features to regenerate when small changes need to be made.
Starting point for each helix is timed correctly.
Proper timing of the screws at the assembly level.
7
Answers
https://cad.onshape.com/documents/cefa2aff693213e49c73600e/w/c23e3a714b33eceace9f7ead/e/1a26b46dc5d55658f8df5884
I created a revolute mate for the screw and mated it to the origin.
Next, I created a slider mate from the center of the ball to run parallel to the screw. The ball needed to be offset to the thread depth.
After I created a rack and pinion relation between the revolute mate of the screw and the slider mate of the ball.
Hope this helps!
I'm newbie and tried to repeat what you did with minor tweaks to the depth of the groove and the pitch of the helix, and I don't succeed to achieve the same thing.
See here...
https://cad.onshape.com/documents/c1fb23babb4668e97ce5a361/w/8cd120f13393056585a21bf4/e/74d56c1158535498da0cb145
The above is the first step of what I want to achieve in the end: This is three threads that revolve in a synchronous way and hold a ball between them like in the image attached below.
Do you think the slider + rack and pinion mates done on all three threads would assist me achieve that?
Thank you!
Omri
https://cad.onshape.com/documents/c1fb23babb4668e97ce5a361/v/345c1518ef86fd9edbcfbf07/e/74d56c1158535498da0cb145
(the above link is done with the tangent mate but it does not work all the time and not accurate since there is minor overlap between the ball and the groove)
I'd suggest 4 mates and 3 relations.
One revolute for each shaft and a slider for the ball followed by:-
(1) Rack and Pinion from Shaft 1 to Ball, exactly like above.
(2) Gear Mate between Shaft 1 and Shaft 2
(3) Gear Mate between Shaft 1 and Shaft 3
Cheers,
Owen S.
HWM-Water Ltd
Offsetting the ball to the centerline of the screw.
Adjusting the timing for the screw. Rotate around the Z axis.
This workflow should give you the proper result you are looking for.
https://cad.onshape.com/documents/4bfd3fda008625fceced4150/w/752f205a6eba08f9e1d5fd88/e/320f6ce5bc5588cd5af81110
HWM-Water Ltd
I really appreciate your response and time you put to answer my question with much details!
The timing is a big issue.
I can "guess" what should be the timing for each screw. But it's a guess and it would never be accurate.
Initially, when I tried the tangent mate, it (almost) solved for the right timing. And as you can see in the image below, the solution for the timing is some kind irrational phase between the screws.
I want to be accurate since the next step would be fit a cogwheels on the shafts that would create this synchronized movement.
Do you have an idea how the timing or phase can be calculated from the assembly w/o guessing?
Omri
HWM-Water Ltd
Starting point for each helix is timed correctly.
Proper timing of the screws at the assembly level.
Thank you very much! I really appreciate that non-trivial help.
Can you share a link of the above so it would be easier to me to understand what you did?
https://cad.onshape.com/documents/a6e7be729c745ccfdc726535/w/640755938ea1d07b729e7d25/e/1b66f8404dc6f8d7b70bb968
This is a rough mockup of what you are looking to do. Please let us know how you made out!
I followed it step by step. Currently just trying to understand what you did.
Learning tons of new techniques and ideas how to accomplish things
How did you calculate an offset value of 46.5mm?