1-Visitor

Question

Helix sweep, flat end

Forum|Forum|10 years ago
July 17, 2015
11 replies
5654 views

I am trying to create a screw type part. The best way to imagine it is a flat rectangular bar that is twisted. I know how to make a screw, but i always end with edges i dont want and then cannot find a way to clean it up nicely.

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General

M

MauroStefanovic

1-Visitor

I think there are better solution, but this is without any equation.

T

TomU

23-Emerald IV

Might want to look at this: How to use get uniform pitch in warp/twist

You may need to model it slightly longer and then just cut the ends off.

Patriot_1776

22-Sapphire II

As always, the answer is.....it depends. From what I see, it's a constant helix simply cut off at both ends. Helical sweep, or a VSS (Variable Section Sweep) will easily do that. Simple. IF, however, you need the twist to change and it to end up tangent to the long axis on both lead-in and lead-out, then you need to use either the Warp command (tough to get exactly what you want, but very powerful) or a VSS with the proper trajectory.

Without more accurate info on EXACTLY what you want, it.....depends.

I

Inoram

14-Alexandrite

The DNA comment had me thinking. So I was messing around, but if you zoom in everything is pretty distorted, disappointing actually.

Patriot_1776

22-Sapphire II

Well, that shouldn't be surprising considering that you're twisting existing geometry. I would expect that. It's taking circular cross-sections of the rails normal to the longitudinal axis, and twisting the geometry around that, leaving the sections round.....normal to that axis. Which "smears" the circular section into an ellipse if viewing it along the helical trajectory, and it smears the rungs as well. The way to probably use a warp like that, would be to use a flat surface, pattern points along an edge, twist that, then use the edges as trajectories for the rails, and then pattern the rungs from the points.

Patriot_1776

22-Sapphire II

Ok, I made a quick model. You can play with "offsetting" the marque on both ends (use absolute, then the offset on both ends is in "units"), to minimize the tangency, but that's not really a cure because you might lose some twists.

Anyways, like I said, without knowing the exact desired geometry......

R

rohit_rajan

15-Moonstone

proe wildfire 4.0 file attached,please have a look.

1_helical_sweep_flat_ends-prt-1.zip

T

TomD.inPDX

17-Peridot

In the proper conditions, even if you could control the twist in a constant pitch IRL, the "section" of the part would warp into a twist. So any straight cross section in the actual part would not be a true representation of the native material's shape upon close inspection.

That said, duplicate the exact shape and treat the ends for further processing. With the constant pitch, that shouldn't be difficult.

This is the technique that has proven quite reliable;

make a VSS of the center surface; thicken it about the middle; and add a full round on each edge.

Now you will see the true and warped section at the ends when you twist metal in this manner.

1_prt0632-prt-2.zip

E

emathivanan

1-Visitor

In sheet metal we have twist option. that may be useful for your need.

Patriot_1776

22-Sapphire II

IF it does not need subsequent features that will prevent it from being a sheetmetal part. That's my main issue with sheetmetal. There should be sheetmetal FEATURES that you can use at any time in the middle of a regular part.

B

blim

1-Visitor

I think it will be like when you use a blend rather than a helical sweep.