Creating a Helical Curved Surface

[Spurs]

I am having problems creating a helical curved surface like a screw thread. I cannot get the root diameter of the screw thread to match up with an extruded cylinder at the root diameter.

I cannot use a method where I create the tooth profile so that it is drawn below the root diameter because I am trying to produce a fillet radius without using the fillet function separately.

Can anyone walk me through the procedure so that I can verify what I am doing wrong?

Thanks in advance for your help.

 

[CorBlimeyLimey]

If you are trying to add the thread profile to a cylinder ... don't!

Treat the part as if it were an actual solid bar being turned on a lathe & cut away the metal that you don't want, so that you end up with part you do want. This way your root fillet will be automatically produced ... just the way it is in the machine shop.

from (the City of) Barrie, Ontario.

Everyone has a photographic memory. Some just don't have film.

 

[krywarick6]

CorBlimeyLimey is on the right track. Consider a cut sweep cut instead of a sweep boss/base.

Remember also that SW prefers some sketch inteference with the main body, compared to tangencies and collinear relationships. It handles the boolean functions better when dealing with curved or irregular surfaces.

Hope this helps.

Christopher Zona
Litens Automotive Partnership
Concord, Ontario, Canada

 

[Spurs]

CoreBlimeyLmey & Christopher

I have tried your suggestion, and it has the same problem as when I create the profile as before.

If you compare the root diameter created by this method with a cylinder of equal diameter, there is a step present. The geometry does not match like one thinks it should.

This problem never used to happen in SolidWorks 2000. Any other ideas? I can email a file in SW2003 that shows the problem is you think that would help in dicovering the solution.

Just let me know where to email it to.

 

[krywarick6]

Could you forward a copy to the e-mail address listed in my profile?

Christopher Zona
Litens Automotive Partnership
Concord, Ontario, Canada

 

[CorBlimeyLimey]

email address is in profile.

Check out thread559-90639, in particular the last few posts

from (the City of) Barrie, Ontario.

Everyone has a photographic memory. Some just don't have film.

 

[TheTick]

Swept helical surfaces are approximated surfaces, not analytical surfaces (such as planes and cylinders and cones). This means the edges of a helical sweep feature will deviate slightly from the theoretical diameter position of the sketch vertices.

In short, you can't count on your tangent edges staying at the root diameter.

If you need a tangent edge at the root of your thread, start with a cut (like CorBlimeyLimey suggested). If you really need a tangency at the root, make the cut section sketch with a sharp corner at the root, and then add a fillet.

Due to illness, the part of The Tick will be played by... The Tick.

http://www.EsoxRepublic.com