Sinusoidal Cut Path on Surface of Cylinder

[sinusoid16]

Using intersection curve, I have produced a sinusoidal path on the surface of
a cylinder and using sweep cut, I was able to cut a rectangular channel
along the path.
The problem I am having is that the channel does not have a constant width
because the rectangular sketch I am using as a profile to cut with seems to
traverse and slide laterally as it follows the cut path, instead of turning to
always stay normal to the path and create equal width channel. I have tried
multiple combinations of guide curves and swept cut options with no luck.
A picture of the situation is attached.
Help is appreciated!

 

[Eltron]

Have you tried the options in the sweep dialog like Normal To Curve?

Dan

http://www.eltronresearch.com

Dan's Blog

 

[sinusoid16]

Yes, but have had no luck. Do you know how the program makes the profile normal to the curve? When I click most of the sweep dialogue options, the resulting cut does not make sense according to the option chosen so I am wondering what the program is actually doing for a lot of them. Is it something to do with adding a relation between the path and the profile?

 

[CorBlimeyLimey]

Try the Solid Sweep cut option.

 

[williedawg]

not up to speed on SW's methods that CorB and Eltron mentioned, but if (as it appears from the pic) that you're milling a path for a cam follower or similar, the rectangle that is used for the "cutter profile" has to remain perpendicular to the sinusoidal path; not parallel to one of the principal planes, (such as the front plane).

 

[Theophilus]

If Solid Sweep doesn't work, I think williedawg is onto this. When I do a sweep, I almost always create a plane normal to the sweep's guide curve and sketch my profile on that plane--that way I KNOW it's normal to my cure--at least starting out.



Jeff Mowry

http://www.industrialdesignhaus.com

A people governed by fear cannot value freedom.

 

[sinusoid16]

Thanks for your suggestions everyone. Making a reference plane normal to the sweeps cut path did the trick.

The next question I have is if it is possible to use a mathematical equation to create a path on the surface? Or if it is possible to generate the path in a principal plane and then wrap it around the cylinder surface?

 

[rstupplebeen]

Equation driven curve is new in 09' it is only for 2d though. Put in another vote for 3d curves.

Rob Stupplebeen

 

[handleman]

It would be possible to generate on any plane that is tangent to the cylinder and then wrap.

-handleman, CSWP (The new, easy test)

 

[Updraft]

Can't we make 3D points from an Excel file (generated by the equation) and then fit a 3D curve through those points? Wouldn't that do the trick?

- - -Updraft

 

[sinusoid16]

Thanks again for the help.

I used the equation driven curve to generate a 2 cycle sinusoid and tried wrapping it around the surface of a cylinder, however, the wrap function requires a closed spline/curve. Is there any way to wrap it and then close it on the surface, as the two ends of the curve will be touching?

Also, is it possible to achieve this projection of mathematical curves using the split line function?

 

[ArtemTat]

You can use the "Projected Curve" Feature (Insert->Curve->Projected from the menu) instead.

It allows to project opened single curve on the surface. In case you have correct curve length which equals to the cylindrical length (2*Pi*r) the two ends of the curve will be in touching.

Artem Taturevich
CSWP

 

[williedawg]

Was able to get this "cutter path" to work in a cylinder model; so if anyone wants to know what I used, I'll post tomorrow or Sunday.

 

[sinusoid16]

All,
Thanks for your help. On Friday I installed SW09 and it seems that the swept cut feature in 09 has a few more options than 08. The 09 options allowed us to do what we wanted and more.
Thanks again.

 

[williedawg]

Here's what I did to get the "cutter path".
Made 2 Excel files for Curve> Curve Through xyz points.
1) for the sinusoidal path on the cylinder surface, & 2) a second sinusoidal path that is used for the 1st Guide Curve.
This Guide Curve is what becomes the center of the cutter at depth of cut (DOC).

For instance, I used a sinusoidal wave of amplitude 1.375 and 1.500 radial distance (3" cylinder), then had Excel calculate X & Y values from 0deg to 360. (it was set up this way so that it will start at 0 and end at 360 with a 3deg increment in the autofill mode of Excel. Any increment will work as long as it comes out evenly)
Then, those values were converted to Radians and Excel did it's magic.
The Z value was in a third column and the function was; = SIN(angular value in Radians)* Amplitude.
Once all xyz values were generated, just those values were copied and pasted into a txt file in Notepad.

This curve was then Inserted into a model of a cylinder with base at 0,0,0, and Extruded 6" Midplane in the Z direction (Front Plane)

The Guide Curve was similar, however; the radial distance to calculate the x & y values is now 1.375 for the .125" DOC.

All the Z distances are the same as the first curve; but the xy values will change because of this .125 "offset".
The xyx values were copied and pasted into Notepad as before, then this 2nd Guide curve was Inserted into the cylinder model as well.

A Sketch representing the cutter was Inserted into the Right Plane using these Curves and a Pierce relationship to a construction line from the origin.
The 2 curves are shown in blue in this jpg

A Plane was Inserted perpendicular to a Plane from an Axis at the Origin (using the Top and Front Planes) and a Point at where the first Sinusoidal Curve and the Right Plane intersect.

In this Plane (Plane 2) a 3" Circle was Sketched to represent the OD of the cylinder. Using this Circle, I could confirm the cutter width of .375 the .125" DOC.

And lastly, a Drawing was made to show the dimensions of this feature, and that the sides of the cut are less than .125" because of the geometry at that Section View.

Hope this will help those wanting to construct a Sinusoidal cut.
If anyone wants to see the (abbreviated) Excel file, I've got a jpg of that as well.
I could also make the SLDPRT available too, however it's in SW2006.

 

[sinusoid16]

Thanks for that detailed post.

So, I have made multiple types of cuts with varying sinusoidal paths to simulate slow and quick linear motion, but now I am having a problem with mating parts.

I use "Equation Driven Curve" to generate the desired sketh of the path and then wrap that around the cylinder surface. The cut works great, however, SW09 seems to treat each part of sketch as its own entity even after it's wrapped. For example, my path is made up of sin(x) and sin(2x) and I can highlight each sinusoid part separately even though they are in the same sketch. This is a problem when I try to mate parts as now I cannot mate a peg to follow completely around the cut path as I can only highlight and mate to one part of the path.

Is there any way to merge these separate parts so they are treated as one continuous path? Any other suggestions on how to get the peg to follow the entire path?

 

[Updraft]

Put your two parts in a subassy to keep them together then use that subassy to mate to your cam.

- - -Updraft

 

[sinusoid16]

I think my post was a little unclear.

One of the parts in our assembly is a cylinder on which we have a cut a path into for a follower. This path was created using "Equation Driven Curve," wrapping our curve around the surface of a cylinder and then sweep cutting along the path. However, I could make the whole cut in one piece, but had to use multiple profiles and sweeps for the different sin equations used, as even though they are in one sketch, SW still treats them separately.

Now with this cut path in the cylinder, we are trying to mate a follower to the path, but we can only mate it to one sin equation section rather than all of these sections joined together.

Clear as mud?

 

[williedawg]

Although I'm not using the "Equation Driven Curve" method and because I'm still in SW2006; referring to my previous post about Inserting Curve through xyz points, (Excel generated), a Part e.g. cam-follower or pin can be Inserted into an Assembly and mated to the cylinder so as to provide a linear motion as the cylinder is turned.

In an Assembly, Insert an Axis using Top & Right Planes.
Insert the cylinder as a component; mating the cylinder main Axis to this Axis
Mate the Origin of the cylinder to the Front Plane.
This allows rotation of the cylinder.

Make and Insert a Part that represents your cam-follower.

Mate the follower to the cylider & Assembly as shown in this jpg.

When the cylinder is turned, the follower stays in the slot and moves linearly.

 

[williedawg]

...thought I'd clarify a bit more about the mates,

(-) Pin<1>
Mates in Assem1
Coincident Axis of (Pin<1>, Right Plane of Assem)
Parallel1 Axis of (Pin<1>, Front Plane of Assem)
Tangent3 Side Face of Cut in (Cylinder 3 inch<1>, Cylindrical Face of Pin<1>)
Coincident6 Face @ Bottom of Cut of (Cylinder 3 inch<1>, Origin of Pin<1>)