Pattern around a cylinder, differntial pitch

[mncad]

I have a cylinder that has shallow slots cut in the OD parallel to the centerline. I now need to pattern the slots around the centerline of the cylinder. I cannot use circular pattern because I need the angle between each slot to vary. There are 10 slots so I need 36 deg between 1st and 2nd, then 37 between 3 and 4, then 35.5 between 5 and 6 and so on. I tried a sketch driven pattern, but that doesn't seem to work. Any ideas?

Thanks,
mncad

 

[MDGroup]

mncad,

You don't have to pattern all of the slots around the cylinder in one shot. You can do each slot one at a time.

So, 'Circular Pattern', select the slot feature, then pattern it only once at an angle of only 36deg.

Then, 'Circlar Pattern', select the feature, and pattern it to the next angle increment. .....

Depending on the angles, you may need to do this 9 times, one for each slot, but it should do what you are asking.

Maybe someone else has a faster way.

 

[ArtemTat]

I think you should use Sketch Driven Pattern instead.

You should create a set of points which located on specified angle. And pattern the feature using this sketch.

Artem Taturevich
CSWP

 

[drawoh]

mncad,

You have two choices, I think.

[ol]
[li]Use one sketch to define all your slots. Simple.[/li]
[li]Model one slot. Use a two item pattern of the first slot to define each of the other slots. I would do it the first way, but semantically, this may be logical for you.[/li]
[/ol]

JHG

 

[williedawg]

ArtemTat,
Was able to set up a Sketch of Points (only) for a pattern, but how do you get the succeding slots to become tangent with the cylindrical surface?

 

[mncad]

LMonaco,

I had planned on doing it that way, just wanted to see if there was something else. I then have parts that go into these slots and I wanted to do a feature driven pattern, but now I will need one of those for each circular pattern. The sketch driven won't work because it keeps the orientation of the slot and doesn't rotate it around the OD of the cylinder. Making all of the slots in one cut isn't possible either, these are a complicated helical slot. Just talked to my VAR and they confirmed I will have to do it the way LMonaco said.

mncad

 

[williedawg]

Along with mncad's suggestion of the Circular Pattern;
The Curve Driven Pattern works fine too.

One way to ensure accuracy of your angular divisions is to type in a formula for the D1 variable.
For instance, given a 4"dia cylinder and a first angle of 36deg, you can use 4*pi*36/360 (1.2563706).
This Distance being along the Curve of the cylinder OD.

Succeeding slots will need to be in reference to the original "seed", not the last Inserted Feature.

For the 2nd slot, the D1 value becomes;
4*pi*(36+37)/360 (2.54818071)

 

[williedawg]

pic of 2nd slot.....
.....

just read your last post, mncad

sounds like the slots are all dissimilar,
so, perhaps the Curve Driven Pattern is not suitable