mating threads

Does anyone have an example of how to create multiple assembly
configurations that represent 2 threaded parts (male and female) that
thread together at different, with a distance mate controlling the
thread depth? An example might be a jack screw where the body is fixed
and the screw itself threads in and can be adjusted by "turning" the
screw down to a specific height. Normally I wouldn't care about
matching up the actual threads in simple cases, but in this case I need
to have various configurations where the male part maintains the proper
axial alignment with its mating part, no matter what distance is input.
I could probably manually calculate the angle for each increment,
based on my known travel distance and the thread pitch, etc., and then
use an angle mate in addition to my distance mate, but I was hoping
that there was a magic solution that would mate the geometry of the
treads and determine the radial orientation based on simply varying the
distance constraint.

Hopefully this description makes sense to someone out there. Anybody
have experience with this type of problem, or am I just "screwed"
doing it the hard way?

 

I am pretty sure you can do what you are after by using an equation to
drive your angle mate. Set your distance mate to be configuration specific,
and your angle mate to all configurations. The equation that would drive
the angle mate would look something like this: "angle dimension" =
(distance*tpi-int(distance*tpi))*360. Under some unpredictable
circumstances, this will require a ctl-q when switching configurations to
update properly, but sometimes it works all on its own.

 

Thanks for the advise guys. I'll let you know how it goes. I hope to
get back to this by tomorrow.

 

Well, I first tried using mates, with no luck (probably a way to make
this method work, but I gave up early and moved on). Next, I tried
using an equation and it seems to work well now.

I didn't quite understand your (Brian's) example equation above (maybe
because I didn't have experience using SW equations until now), but
using the following equation I achieved satisfactory results...

"D1@Angle1"=("D1@Distance1"/"D4@Helix/Spiral1@bag_stop_movable.Part")*360+.0001

or more generically speaking...

ROTATION ANGLE = (AXIAL TRAVEL DISTANCE/PITCH)*360

NOTE: "D4@Helix/Spiral1@bag_stop_movable.Part" is a direct reference to
my pitch dimension in one of the parts, which should hopefully allow me
to change the pitch downstream, without messing up my mates (the pitch
is something that I plan to fine tune later, so wanted this
parametrically linked).

ALSO NOTE: One puzzling thing was, without the "+.0001" at the end of
the equation, my result in the default configuration set the angle to
zero, since the distance was zero, which the equation editor did not
like. The following error was displayed: "This equation evaluates to a
value that lies outside the modeler resolution", so I just added .0001
to the end result since this slight angle shift wouldn't really be
noticed in my assembly.

Any idea why this was a problem, since SolidWorks normally allows
angles to be set to zero, right?

Thanks again for your help!

-JOSH

 

Basically the equation I gave stripped off the integer value for rotations

for example, if it took 4.3 rotations to achieve your distance, the equation
would only return the .3 ... or 108 degrees. You may need to do something
similar unless your rotation angles never exceed 360 degrees.

 

Why not use a design table with the above mentioned equations in it?
Excel is much easier to use. All you need is a value for how many turns
into the material the thread is engaged (in a decimal value). From that
you should be able to figure out the Distance Mate value and the Angle
Mate value....Obvously you'd also need a cell to enter in the
threads/distance.

Ken

 

Brian,

My assembly (in this case) should actually not ever exceed 360 degrees
of rotation, however I am still interested in your method for this and
other cases, since it seems to be better math. Can you please explain
it to me once more, with an example. Sorry I'm not getting it exactly
from your previous descriptions.

Much thanks,

-JOSH

Tin Man,

Thanks for the tip. I haven't tried design tables in a while, but I
can see where this may be helpful.

-JOSH