Whats the easiest way to add a rigid joint to the chamfer below the thumb screw head to the chamfer on one of the holes in the fixture? In solidworks I would just select both faces and add a coincidence mate. Is there a way to do this without adding an offset? sometimes I feel the joints work well but so often I miss the solidworks mates for their simplicity and versatility.
I can use a rigid joint to and pick the center point but it won't make the two surfaces coincident. I could use a joint origin but then I would need to create a sketch and calculate what distance I would need to get the faces coincident. I'm not sure that with the joint origin or an offset I would be able to maintain the surfaces being coincident if I change the size of the chamfer on either part. In solidworks the coincident mate would maintain the contact of the two parts even as the chamfers are adjusted. I feel like I must be missing something obvious considering this is no different than constraining a flat head bolt to a countersunk hole.
Probably I totally misunderstand what you want to achieve, but if both chamfer angles are equal, the method @vex proposed should work.
This is what I got that way:
I can see how your example would work because your chamfers are the same length. My problem is a bit different because the chamfered surfaces are not the same length and the joint centers don't line up axially. I know I could use a joint origin but It would be a pain to make it so it would change parametrically if the chamfer length on either part is modified. The one example of something similar is a autodesk video mating a flat head machine screw to a countersunk hole assumed the top of the bolt would coincident with the top of the chamfer. The example didn't take into account that someone might want to have a larger countersink to guarantee clearance in which case the top of the bolt is not at the top of the chamfer. anyway here is a section view of what i get if i dont use an offset.
Chosing the lower edges of both chamfers is not an option? The chamfers can be of a different length.
Of course if the diameter of the lower chamfer is larger than the bolt, the bolt will drop below the upper chamfer edge.
I'm guessing you need to keep the chamfers in sync.
Ludo in your examples the bottom edges of your chamfers are the same diameter which is why they work. What I want to do is to join parts regardless of the bottom or top diameter. My parts are close to the same diameter on the bottom but not exactly so they still are not coincident when choosing the lower edges. This is why I think Fusion needs the ability to add a coincident Joint/mate. I would be interested to hear from someone at autodesk as to what they would do to constrain these parts.
Here's an example using a contact set and a cylindrical joint. You can drag the pin up and it will pull back to a touch.
Owner, Hughes Tooling
I've been brain storming a solution for you. It might be a bit more involved than you would like... but it should work:
Since you're dictating the chamfer dimension for both from a parameter, why not use that information for your rigid join along the lower center point?
For instance, if you know the diameter of the thumb screw to be 1/4" and the chamfer to be a 1/4" on the thumb screw and a 1/4" on the recess, then your parameter for the rigid on center will be 0.
If you increase the chamfer on the thumb screw to 1/2" the offset remains the same: 0
If you increase the chamfer on the recess to 1/2" (thumb screw is 1/4") the offset is: 0
(unless of course you are determining height from another point; threads, standoffs, etc)
The only time I can think of in which the offset would not be 0 is if the chamfer on the recess is steeper than the chamfer on the thumb screw, or if the ID of the chamfer is greater than the OD of the thumb screw. In the latter case it's a relatively simple math problem to ping the parameters for the diameters and chamfers to dictate the offset:
(For an symetrical chamfer) Offset is equal to (ID-OD)/2.
For an asymetrical chamfer it gets a little more involved so I won't go in to it unless you need me to.
Does that help at all?
I'm not actually using parameters on these parts. The Thumbscrew is a linked part anyway so It would be modified outside of the assembly. I'm not entirly shure I follow you Vex. If I use the bottom of each chamfer as the reference it never lines up correctly with an offset of 0. Right now I'm using a cylindrical mate with a rest point below the chamfer and a contact set to limit it. The problem with this is that the contact set doesn't seem to always update reliably and sometimes I have to manualy drag it to get it to snap back into place. I'm not sure what I'll do when I have 30 or 40 flat head machine screws that need a head clearance on the countersink. I imagine using joint and a contact set is far more of a burden on the processor than necessary anyway. I'm really thinking a feature is missing here as this seems like a common and very basic thing to need to do.
Are all the thumb screws identical and the chamfers on mating part, if they are you only need to get one right using a contact set then align the top faces for all the others using a planer constraint.
Simple example file attached
Owner, Hughes Tooling
Hmmmm, I'll have to play around to see if what I imagine is possible. I know it is in Inventor, albeit a little more round-about way than simply utilizing the parameter screen (actually writing code to pull the information from the linked part in the assembly).
As an alternative you could create user parameters for the various ID/ODs of the parts and just update those user defined fields in the parameter screen without continually updating the individual component values (IE update two values vs 2n component values).
EDIT: Looks like my original intention of relying on the chamfer angles is a no go as Trig functions appear to not be a valid input in the parameters. Can still do an offset based on OD/ID though--but doesn't really help you in this situation.
Here's a workaround using 2 hole features. The first hole sets up the countersink through hole to the smallest size of the cone on the screw so you can use it for the joint. After setting up the screws using joints use a second hole feature to make the clearance hole. With all the joints setup you can edit the countersink diameter or the clearance hole and the screws will stay seated in the countersink.
Owner, Hughes Tooling