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multiple stretch and array actions

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Message 1 of 8
GilesPhillips
4914 Views, 7 Replies

multiple stretch and array actions

I'm trying to create a dynamic threaded coachbolt. I'm having trouble with the array action that created additional turns of thread when the bolt is streched - the problem I think is compounded by the fact that the array itself is moved with another chained stretch action.

I've attached my attempt so far..

Any pointers towards getting this to behave properly would be appreciated.

ACad, MEP, Revit, 3DS Max
7 REPLIES 7
Message 2 of 8
Libbya
in reply to: GilesPhillips

Your distance between threads is 4.  Your stretch list is in increments of 5.  The shank length increase per increment is 2.  That combo can't work.

 

I didn't see a need for so many parameters and eliminated thread length and shaft length and placed their actions on the length parameter.  I changed the overall length increment to 6 and changed the distance multiplier for the shank length to 1/3 (2) and the distance multiplier for the array to 2/3 (4).  I made the action that moves the point a move action rather than a stretch as it was leaving the end of two of the lines behind.

Message 3 of 8
GilesPhillips
in reply to: Libbya

Tidy - I didn't think about using 2 different stretch actions on the one parameter - I tend to put loads of parameters on a block just to 'keep an eye on things' though that doesn't always work as you can tell.

I'll probably tweak some of the values a bit as the length increments need to correspond with standard parts, but I can probably tweak the thread pitch as it's mostly pictorial data anyway.
ACad, MEP, Revit, 3DS Max
Message 4 of 8
Libbya
in reply to: GilesPhillips

While I worked on your block before, I had the thought that it might work better with a polar stretch, that way you could stretch and rotate it in one move.  It took me a while to get it all sorted, but this seems to all work correctly.  It is actually a lot more complicated than it seems.   

Message 5 of 8
m_rogoff
in reply to: Libbya

Hi, can you please explain to me how the distance multiplier and array parameters interact with each other? I do not understand the "Stretch/array 2/3" parameter in the original block.

 

I have a similar lag screw I need help with. I set the overall Length stretch at 1" increments and the array at 1/2". I would like the unthreaded length (towards the head of the screw) to stretch at 1/4 (.25) of the overall length. Help is greatly appreciated. I would prefer to know the method of how this works becuase I have several different sizes I would like to include in visibilty states, and will have to replicate this several times.

 

Thanks!!

 

(Lag dynamic.DWG is attached)

Message 6 of 8
Libbya
in reply to: m_rogoff

Here's your file back with your bolt working correctly, although, I deleted your linear/stretch and made it into a polar.  I don't see a reason to prevent it from rotating at the same time.  

 

As far as the inner workings, it has the polar parameter with 1 grip.  It also has the linear parameter with array action.  The polar parameter has three polar stretch actions associated with it.  The distance multipliers of each are important to understand.  The first one stretches the tip of the bolt with a distance multiplier of 1.0.  I moved the array so that its base point is the same as the polar stretch base point in order to make the polar angle change work easily.   

 

The main polar parameter has a distance multiplier of 1.0 and has within the polar stretch selection set the tip of the bolt.  It has within the 'rotate only' selection set the head of the bolt.  You stated that you wanted the shank to grow at a rate of 25% of the growth of the threaded portion.   To accommodate that, the second polar stretch has a distance multiplier of 0.25 and the polar stretch selection set includes the arrayed portion of the thread and the two lines that run between that arrayed piece and the head of the bolt.  The third polar stretch action has a distance multiplier of 0.75.  If 25% of the growth is the shank, then 75% is the growth of the threads.  The last thing I did was add an increment to the polar stretch action.  The increment is 1-1/3.  The increment is set so that exactly one thread appears with each increment.  To arrive at the increment you need to know that each arrayed thread is 0.5 units and that each thread is also 75% of the increment with 25% being the shank growth.  (3/4)X=(1/2) units with X being the increment value.  (1/2)/(3/4)=2/3.

 

You currently have the block set up with a shank diameter of 1.  Because of that, I don't see a need for visiblity states for the various sizes.  In the block properties I switched 'scale uniformly' to YES.  Now when using the block, if you want a different size, just select the block and enter that size into the Scale X property.  The block will scale so that the shank is that dimension.  

Message 7 of 8
m_rogoff
in reply to: Libbya

Libbya,

 

    WOW! Thanks for the help. I was able to re-create this block from your instructions. It is very interersting how the distance multipliers and array are intertwined with each other. One note I'd like to add is to make the Linear/Array a Chain Action. As a personal preference I used a linear parameter and the alignment tool as opposed to polar stretch. The uniform scale is a great trick to get rid of all the repetative dynamic work.

 

Thanks again!

Message 8 of 8
Luongk
in reply to: Libbya

Hi Libbya,

 

I am new to Dynamic Blocks and this example is exactly what I am looking for!  Although, I am having trouble following the steps you are describing...  Is it possible for you to create a screen cast so I can visually follow the steps to achieve the end result?

 

I like to eventually apply this to the different types and size of bolts we normally use on drawings...

 

Kiet

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