Diminishing Screw Thread

[JulianW]

Hi folks,

'm having trouble trying to work out quite how to model a screw thread that remains constant for a distance, and then after a certain length, the thread depth reduces until it becomes a smooth shaft.

I've attached a picture to try to illustrate what I'm after.

does anyone have any ideas how to do this easily but acurately?

cheers,


JW.

[HowardM]

you could either lathe the screw all one size then taper the end...or make a descending spline profile, and lathe that!

[JulianW]

Hi,

thanks for the reply howard, but I think you're barking up the wrong tree ;). I'll try to clarify what I'm after..

Imagine a rod of metal in a real life Lathe, now you machine a screwthread into it along its length. Nice and simple to do in LW so far.

Now you decide that you don't want a screwthread along the whole length so you machine down one end of the rod until its just the same thinckness as the bottom of the thread is..

Now the problem area for modeling is the area between the smooth shaft and the screwthread. What I want is for the depth of the thread do reduce over a turn or two so that it neatly blends the two halves together.

hope that clears it up, and thanks for the reply,


JW.

[HowardM]

huh?
:)
you making a screw here? :)

make a spline and lathe it!

[NeilNafus]

Make a profile of the thread itself (not the entire length of it, just the general shape) then lathe it with an offset on what ever axis you want it to travel and then use the taper tool. If you want an inset (or one created using a threading kit) then you could do the same thing only invert your initial profile and boolean subtract it from your screw.

-Neil Nafus
FX Monkey

I'll post a pic when I get home from work.

[VWTornado]

HowardM, now you know that doesn't look like a thread! Your idea is close, but screw threads go up the shaft like a circular staircase, not like you have it there.

[HowardM]

ahhh youre right, i guess Neils way is the way...:)

[HowardM]

neils way, minus the boolean....
make a poly, lathe it with offset, then taper.

[VWTornado]

Here's what I came up with. :)

http://vwtornado.baked.net/PICs/Screw_you_Web.jpg

A flat box in the back view, rotated 45 degrees, then Lathed to 2000 degrees with an offset of 6 m.

[HowardM]

nice!

[NeilNafus]

rock on, that looks good.



Guess I dont need to post a pic ;)

-Neil Nafus
FX Monkey