Sweep cutter path through a cylinder

Kevin_Gallichan

Hi, I want to create a cut shape that emulates a milling cutter path in the outer surface of a cylinder. The cutter path will rotate around the centre axis of the cylinder.

I can create a wrap shape that puts the cut into the cylinder  but this creates an angle between the edges/faces which would not be created by a milling cutter - it should have parallel sides.

Hop that makes sense.

Any tips ?

Thanks

glen_dewsbury

I did a study of this some years ago and had access to Solid Works tool path which help me to understand what is going on.
The center line of the milling cutter path does not meet the center line of the milled part at 90deg so does not provide parallel sides to the bottom of the cut unless your cut is only unless to cut is straight around at 90deg to the axis of the part. The more the spiral cut is steepened the more the curve at the bottom of the cut is exaggerated.
There are IRs asking for tool path function if you want to add your vote.

glen_dewsbury

@kevin_gallichan
BTW. Previous note refers to cutting into a solid. Hmm. If the bottom of the cutout does not need to be flat then it won't matter at all. Just cut deep enough to get the needed parallel sides and provide a dimension for that. In this model I used an approximation of bottom cut with a conic.
If you're cutting a tube through the shell it can get parallel sides all the way through.
https://cad.onshape.com/documents/7eb0268068ad1df7402d9ae0/w/fc10c59ef2b8f25d926f0b6f/e/7cf665bc9826fd2b2773bbc8

martin_kopplow

I guess you are after something like this: 

https://cad.onshape.com/documents/11f42ea54e63af8231579dbb/w/0746ef562b92ff83367356e7/e/44d335e00969a52a2a48b636?renderMode=0&uiState=656b9a4d464e7708812e251e

The magic ingredient is, that if you use the cutter profile from a cross section projected on a plane perpendicular on the helix, you would also have to use the groove ground cross section projected in that same plane, not only the side walls.

Konst_Sh

You may find usefull this Body sweep feature. It creates the tool envelope surface while it moves through some trajectory curve. Its not perfect and tool envelope always has some inner offset from the perfect shape, but can work for some cases.

glen_dewsbury

This looks interesting. I'll give it a try.