Ramp & Twist HELP!!!!

[mobenavides]

I'm working on a radial wall which has a an elevation change of 3 feet. The coping needs to "ramp & twist". I have not been able to sucessfully get the coping to twist. Any ideas or hits would be greatly appreciated.

 

Thanks in advance.

Ramp & Twist Coping.zip

[eric_monceaux]

When needing a profile to ramp and twist, you have to use HELIX and then sweep your profile along the curve.

[eric_monceaux]

When required to have a profile "Ramp & Twist" it cannot be performed with a standard 2D arc. You have to use a command called HELIX. The trick in applying the profile, is in the command itself. Here is the final product of the process for your ramp.

 

 

Command: helix

Number of turns = 0.0916    Twist=CW
Specify center point of base: cen of
Specify base radius or [Diameter] <376.5000>:
Specify top radius or [Diameter] <376.5000>:

Specify helix height or [Axis endpoint/Turns/turn Height/tWist] <36.0000>: t
Enter number of turns <0.0916>:

Specify helix height or [Axis endpoint/Turns/turn Height/tWist] <36.0000>: h
Specify distance between turns <392.8673>: *Cancel*

Specify helix height or [Axis endpoint/Turns/turn Height/tWist] <36.0000>: w
Enter twist direction of helix [CW/CCW] <CW>: ccw

Specify helix height or [Axis endpoint/Turns/turn Height/tWist] <36.0000>:  
Regenerating model.

Resuming HELIX command.

Specify helix height or [Axis endpoint/Turns/turn Height/tWist] <36.0000>:
>>Enter new value for ORTHOMODE <1>:
Resuming HELIX command.

Specify helix height or [Axis endpoint/Turns/turn Height/tWist] <36.0000>: 36

 

Once you have created the helix, you can then SWEEP your profile along the helix path to generate your "ramp and twist"

 

Here is the completed helix (in blue). It still needs a little tweaking, but you might have to revise your base and landing coping.

 

Side note, is this for cast stone?

Ramp & Twist Coping.dwg

[mobenavides]

Thanks for all the help....... these coping pieces will be granite along with radial wall panels.

[eric_monceaux]

No problem!

 

Also, to better explain the critical path behind the measurements, here is the break down.

 

A helix is basically a cylinder that is cut on an angled degree. So the radius of the helix is that of the cylinder before it is sliced.

Specify base radius or [Diameter] <376.5000>:
Specify top radius or [Diameter] <376.5000>:

 

This is the important part.

Specify helix height or [Axis endpoint/Turns/turn Height/tWist] <36.0000>: t
Enter number of turns <0.0916>:

The distance of the ramp is determinined by the following formula: d=360/a where a= Total angle of the 2D arc path. In this case, the total angle of the arc path is 32.881̊ degrees. So, 0.091386=360/32.9881

 

This just changes the direction the helix turns.

Specify helix height or [Axis endpoint/Turns/turn Height/tWist] <36.0000>: w
Enter twist direction of helix [CW/CCW] <CW>: ccw

 

This is the final step. This is where you input the total height of the ramp to give your rise.

Specify helix height or [Axis endpoint/Turns/turn Height/tWist] <36.0000>:  36

 

I hope this helps.

[fuccaro]

In the old days, without the helix command, this is how we worked: http://www.cadtutor.net/forum/showthread.php?t=1100