Defining limit mate max and min with a design table

[killswitch]

I'm creating a cylinder assembly with DT to control the stroke. I have 3 configurations : extended, retracted and floating.

I've been able to set and change the limit distance value for the floating configuration with the design table but I need to be able to set the minimum to be zero. If the floating mate position is anywhere but zero when the limit distance is changed by the DT, the current position is assumed to be the minimum and the DT value is added to that minimum.

Any thoughts?

Killswitch
SW 06 SP3.4

 

[CorBlimeyLimey]

SW does not allow zero dimensions, but you can have zero offset planes and surfaces. You should be able to set the config up to work from planes or surfaces, the positions of which are controlled by the DT?

 

[killswitch]

I have a distance mate to control the extended and retracted configuration where I use the DT to set the value to zero for the retracted and XXX for the extended. Controlling this from the DT works fine for these two configurations. I now want to add a third "floating" config where I suppress the distance mate and unsurppress an advanced limit distance mate so that the cylinder rod can slide in the body between zero and full stroke. I can create the mate and I can add it to my DT but I can't use the DT to set where this limit starts measuring from.

 

[JMirisola]

Instead of using your current settings of zero and xxx, create distance mates between, say, the base of the barrel and a clevis end. One value for retracted, one for extended.
Another idea would be to simply create a floating config that has no distance mates at all. If you're using the cylinder in an upper level assembly, which is what I'm assuming, then you can let the parts it's mating to control the overall distance while it slides freely.
Overall, it would help to know what you want to do with the cylinder in the end.

Jeff Mirisola, CSWP

http://designsmarter.typepad.com/jeffs_blog

Dell M90, Core2 Duo
4GB RAM
Nvidia 3500M

 

[Regg]

What we do is create a retracted mate, an extended mate, a limit mate and no (floating) mate because you cannot mate the cylinder to a locked position in an upper level assembly with the limit mate active. I would not recommend messing around with a design table in this case. You can see you already had problems.

Regards,

Regg

 

[killswitch]

Thanks for al the input. I was able to figure it out this weekend.

Basically, SW creates an advanced limit mate by utilizing its limit tolerance on a mate defining the distance between 2 surfaces. Now my DT can add the correct max and min (max being the cylinder stroke and min being zero) for the floating configuration.

I'm using this DT approach because I'm creating a library cylinder that will be used by many designers. The cylinder will need the 3 configuration (extended, retracted and floating) when the cylinder is inserted into an assembly.

If the cylinder was only 1 stroke length then the DT wouldn't be necessary, but since designs require cylinders with different strokes, I want to give the designers the ability to select from a standrard list of stroke lengths and have the configurations reflect the new length.

I use zero and xxx (stroke length) because I don't want my designers having to add an arbitrary constant to the mate to get the extend and retracted positions. Zero for retracted and stroke length for extended is simple and easy to understand.

The floating configuration allows a designer to move the cylinder and its load though the full range of motion to ensure no suprises. Many times the extended and retracted positions can look perfect but there's a collision that can only be found by moving the design through its range of motion.


Killswitch
SW user since 1996