helical cut as machined

[grogan5]

I am trying to model a prototype part that has been machined. I have a cylindrical tube that has a helical cut added. It was created by plunging an endmill thru the wall, cutting a 360 degree helix on a 1" pitch, then retracting the endmill. Is there a way to do this in Solid Edge without distorted ends on the cut?

Robert Grogan
Grogan Five Enterprises

http://groganfive.com

POB 488, Salem, SC 29676

 

[beachcomber]

Hi Grogan5,
These questions are getting harder for me because I haven't used Solid Edge for the last 6 months, and I don't really know how much has changed in the last 2 or 3 versions.
(Unfortunately I'm using Solid Works - no doubt this statement will cause some comment from the SW lovers).
Ideally the way to do this would be to create the End Mill as a solid and sweep it around your helical path to create the cutout. However SE doesn't allow you to do this so you will have to do it in bits.
The solution I am giving assumes that the cross-section for a helical cutout has to be perpendicular to the axix of the helix - as on V15. Things may have changed in later versions.
I would suggest creating a helical cut with a smaller size than required. Then create a plane perpendicular to one end of the helix. On this plane draw a rectangular sketch to represent the tool. Now SWEEP this rectangle around the helix to give the full cut.
To get the round ends create circular cut-outs.
Hope his makes sense.

bc

 

[donyoung]

Hi,

another possible simpler solution would be to create the
tube in .psm, unbend it, insert the coutout and rebend
See sample:

http://multiterra.mooload.com/file.php?file=files/1138270942/Helcutout.zip

You have to unsuppres all features after unzipping it (this
was don to save space)

dy

 

[grogan5]

Thanks to both of you. I will try both methods. Solid Edge is a great product, and I have found very little that it can not do, either directly or using a work-around. I have used SE since the beta versions, and in its price range I don't think you can beat it.

Robert Grogan
Grogan Five Enterprises

http://groganfive.com

POB 488, Salem, SC 29676

 

[swertel]

In version 18 of SE, you now have the Wrap Sketch command. You can use this to wrap a sketch around a cylinder thus creating a helical curve to follow with your sweep. Get out you math books to remember how to straighten out a helix. I just did it recently, but sadly it must be explained by use of a diagram.

--Scott

For some pleasure reading, try FAQ731-376

 

[beachcomber]

Hi Chaps,
Just to elaborate on the method I described earlier, when doing the sweep create a cross-section at both ends of one side of the helix, but use both sides of the helix as the guide curves,
and use the multiple curves option when starting the command.
I put my original helix with one edge as the centre-line of the "tool", then put the sweep cross-sections centrally on this edge. I also extended the cross-section above and below the walls of the tube.

How do I post a picture on the forum ?
Can I paste it here ?

bc.

 

[donyoung]

@Beachcomber

direct uploading is not possible but:

http://www.imageshack.us/

upload images

http://www.mooload.com/

upload files (max 50MB, no list)

dY

 

[beachcomber]

I've put some images of what I did here - it's the first I've done so apologies if it doesn't work.

http://img234.imageshack.us/img234/695/helix19yu.jpg

http://img234.imageshack.us/img234/2474/helix22ea.jpg

http://img234.imageshack.us/img234/6937/helix34lt.jpg

http://img234.imageshack.us/img234/1230/helix43fg.jpg

The narrow cyan profile was the first helix cut-out.
The wider white profile is the sweep.
The circular cut-outs are positioned on a plane at the end of the LH line of the white profile.

Just another thought on this topic - could you generate an interference solid using the motion environment to rotate the tube and traverse the tool. You could then import and subtract this solid from the tube.

bc.

 

[beachcomber]

Sorry everyone, I forgot that the interference volume is calculated at each frame of the motion, so you would get lots of small volumes, so this would not work.
You would also have to traverse and rotate the tool ony.

bc.

 

[fwc]

Hi

Just another method.

You can start with 2 circular cutouts.

http://img372.imageshack.us/img372/8817/helical012ht.jpg

Then cut the rest with helical cutout (using rectangular profile)

http://img372.imageshack.us/img372/8148/helical021kh.jpg

fwc

 

[grogan5]

fwc,

Thanks. That was the way I started, but if you look closely, you will see distortion at the tangency points. That was what I could not have.

Robert Grogan
Grogan Five Enterprises

http://groganfive.com

POB 488, Salem, SC 29676

 

[fwc]

You are correct, I also noticed that. I thought that you wanted an approximate representation of the feature. I guess not.
Please check this thread from SW,
thread559-138062

fwc

 

[beachcomber]

grogan5,
Have you looked at my mehod ?
I'm sure there is no distortion at the ends because the cylindrical cuts are parallel to the start and ends of the helix.
One thing I'm was not sure of though - does your cut go all the way through the wall of the cylinder ?

bc

 

[fwc]

To emphasize on bc's point;

Take a look on the first image.

http://img490.imageshack.us/img490/5130/helicalcut014ya.jpg

The top cutout is swept cutout and the bottom is a helical cutout.The 2 cutouts have different starts and ends.

For the second image;

http://img470.imageshack.us/img470/761/helicalcut026iw.jpg

After adding the circular cutouts, the distortion is visible for the bottom cutout and not for the top.


fwc

 

[fredericmenage]

Hi,

You could also start with the second step of fwc method (Feb 1) but go quadrant to quadrant (not center to center) so that the helical cutout is longer (+2*Radius) :

Then use the round command on the 4 inside edges which won't create the distorted ends (just give a round value slightly smaller than the radius of your cut)

Fred