Paul,
I've done this many dozens of times. One thing that I've always had to do
is make the threads looser because of the buildup on material in the roots
of the threads. I am working on a complete tutorial right now on how to
properly make accurate helical threads. This can be for 3D printing,
presentations, & with very small parts it can help get accurate volume
which is important with the expense of materials now days. Acme,
buttress, tapered pipe threads, they all can be done & actually it is not
that difficult.
I need to make some screenshots & a bit more work to complete the
tutorial.
Regards,
Joe S.
On Tue, Jul 31, 2012 at 6:28 PM, Brent Drysdale <
-> wrote:
> Hi Paul,
> Not with Rapid Prototypes but have made 3D threads to be diecast
> previously and made plenty of actual machined threads back when I did my
> toolmaker training.
>
> Usually I recommend people pick up a copy of Machinery's Handbook (any
> edition) and use the information in there to make 3D threads.
>
> Specifically in ProE you usually use the Helical Sweep command and the
> initial trajectory you sketch is the "length" of the thread along say a
> bolt shaft. You can usually tweak the trajectory so that you get run out
> and run in. This trajectory is usually used to show the path of the tips
> of the thread (on a shaft) and though you can use it in other ways it just
> makes it more confusing.
>
> You then get to sketch the shape you want to helically sweep. I normally
> make this a surface sweep and not a solid cut as this allows me more
> flexibility (read robustness) and cut the surface out of the solid later.
> You get controls such as left and right hand spirals and whether you want
> your sketch to be parallel to the rotation axis or normal to the helical
> sweep. For threads it is the former by convention.
>
> You do not mention anything about thread size but for RP larger sizes will
> be easier as the surface roughness will affect fit less. This
> will also apply to coarser threads compared to finer ones. If you have the
> RP facility yourself you can experiment by making a true thread sketch to
> make a helical thread sweep then make an offset from this to allow for the
> RP roughness.
>
> Hope this ate least gets you underway.
>
>
> Regards,
>
> *Brent Drysdale*
> *Senior Design Engineer*
> Tait Communications
