Solid Threads?

[Guest]

Hey all!

 

Still tinkering around with the demo and solids and just wondering how you can draw a thread on a round part (solid). I have a 7.5" diameter from the right side extruded 1.5" long and that diameter is an acme 3 TPI.

 

Any ideas, or can I even do this?

 

Maybe my new tagline should be 'If I only had solids!' (darn cheap company!)

[DavidB]

When we modal components we never modal the actual thread. We modal the correct diameters needed and add a note to the drawing with the thread details.

 

Im taking a guess here to draw the thread as a solid can you sweep the cross section along a helix?

[Guest]

I am trying to do a sweep right now, cannot get it to work

 

Drew a triangle at the correct depth, then drew a helix. I have tried to sweel the triangle shape along the helix and keep getting a parasolid error.

 

Seems like there must be a way to this

[Chris Rizzo]

Are you doing a sweep cut or a sweep add? It can be accomplished either way, however I prefer sweep cut...just think like a lathe.

 

-Extrude your body/shaft to the major dia.

-Draw a helix "inside" the shaft to the minor diameter.

-Draw your triangle in a plane that lies on the plane of an end point of your helix. I draw the depth of the triange to intersect the endpoint of the helix (self-explanitory). However I let the "other end" of the triangle extend beyond the part. If you extend it too far, or not enough I'll get a parasolid error.

 

let me know if you want pics.

 

eg. for a 1"-8 thread external thread and sweep cut

 

IN top plane solid extrude a 1.000" dia. (or whatever your major is)

-Also in top plane create a helix with a .849" dia.

-Front plane draw a triangle with a point that intersects the .849 helix, however extents beyond the 1.000" major.

-solid sweep cut

[Greg Williams]

Hi it is generally considered bad practice to solid model threads, One of the main reasons is they use a large amount of graphics to produce and they can gobble the RAM

[DavidB]

They also serve no purpose from a programming point of view.

[Guest]

quote:

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Hi it is generally considered bad practice to solid model threads, One of the main reasons is they use a large amount of graphics to produce and they can gobble the RAM

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I learned that in UG, I myself just wanted to see if I "could" do it.

 

quote:

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They also serve no purpose from a programming point of view.

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No they don't but they look pretty

 

 

Still having no luck though

[DavidB]

jm you have to much spare time

[crazy^millman]

This is a logged bug cnc00016208 in X. I have already been down this road and it is suppose to be fixed for the next release.

 

HTH

[Chris Rizzo]

Hey Ron, what exactly is the bug? I've gotten them to work in X before.

 

Yeah they are pretty useless from a programming standpoint. Good exercise for turorials to teach sweep function.

[crazy^millman]

Well I could not get it to work and I presetned this to them when a thread was started about this. May have been fixed since then but I could not get what worked in V9 to work in X but I have had tons of problems with that computer that others have not been having at work as well so could have just ben that computer.

[horsepowered]

Make your triangle smaller so as to leave a flat on the unswept portion of the cylinder. If the triangle is equal or greater than the pitch of the thread it will generate an error due to overlap.

[Guest CNC Apps Guy 1]

If I NEED to show a thread, I cheat. (That's a surprise). I'll extrude my Major Dia in top view, then in front view, I'll create my triangles (depending on how much thread I want), then sweep the triangles along the curve I used to create my Major Dia. Yeah, it's not a helix, but helixes take up so much system resources that to me it's not worth it.

[crazy^millman]

yeah I usually make mine .001 to .002 smaller to avoid the overlap problem. Another thing is to make sure you have the spline in line with one of the edges as well or it will give big problems.

[horsepowered]

Another way of making them similar to James's method ( suitable for some applications )is to make a profile with the vee's and create a revolved surface. It wont be a helix, but it looks like threads to the unobservant.

[88Matt]

Why not just use roll die? Try creating your crest and root geometry then roll it. Create surfaces (I used ruled I think). I did this for a machined spring to get the proper 5 axis tilt but it should work the same way. You could probably do a revolved surface and trim to get the lead it thread.

 

Now you got me curious. Think I'll try it today.

[beej]

There are times when threads need to be modeled up. Lots of Plastic injection parts and die cast parts use threads that have to be cut right into the partshape. Picture a plastic gas can or little tikes table with screw on legs, pepsi bottles and such. It's important for a modeling software to be able model a thread. these are often cut with small ballnose cutters.

[P_Scott]

MillingMan,

 

It is possible to model a true thread shape using Mastercm Solids. Others above have described the method pretty well but it does take lots of computer power and practice.

 

jmparis,

 

quote:

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Seems like there must be a way to this

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I can show you how when you come for Solids class.

[Guest]

Unfortunatly Peter, I don't think I will be attending a class that far south. Getting my company to send me 3KM away from the front doors of the shop is like pulling teeth enough.

 

Let alone, them buying solids for me. As always, Grrrr. Oh well, I will keep playing with the demo until such time as they buy it, or I leave here for and find a better shop with a better MCX (which I am in the interview process...)

[P_Scott]

MillingMan,

 

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Unfortunatly Peter, I don't think I will be attending a class that far south.

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LOL Too bad. There's also a way to learn online with Mastercam tutorials from Streaming Teacher. There's a link for it on our website S4A website from the Services-Training-Day classes page. The training class comment I had written was actually for jmparis. He has "threatened" to come in for our Solids class in the near future.

[Guest]

quote:

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He has "threatened" to come in for our Solids class in the near future

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daa da da dum

 

daa da da dum

 

daaaaaaa

[beej]

I didn't know the let bronco's fans take solid modeling classes??!?

[P_Scott]

beej,

 

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I didn't know the let bronco's fans take solid modeling classes??!?

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We do. It just costs a little extra.

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. J/K John