Helical tunnel borer

paul_britton

Hi,

I have been trying to model the drilling auger on this tunnelling machine...


Ignoring the propeller bit at the tip for now...

The central core is an ogive curve (like a rocket nosecone), I think. I can construct that fine...

I can get the helical path around it, but I can't get the cutter edge to sweep correctly. The swept shape seems to 'revolve' as it sweeps..

https://cad.onshape.com/documents/bfcab79745e70a807cb87497/w/181434d7c1ba5e4cda7ffba1/e/e5bc6e8a6dffd92eabc29438

Can someone tell me what I'm doing wrong please?

paul_britton

mahir said:

@paul_britton , that's funny. Reading your question, I was about to suggest my Sweep Normal FS, but you beat me to it Glad it worked for you. I should probably make it a real FS document instead of burying it in my sandbox.

It is just the job.... if it could be incorporated as an option into the normal Sweep function, it would be great... Onshape, are you listening? :-)

ilya_baran

@paul_britton
We are always listening   Over time, as priorities allow, we will incorporate more options into our sweep.  Out of curiosity, though, now that you know it exists, what is the downside of using the custom feature?

paul_britton

ilya_baran said:

@paul_britton
We are always listening   Over time, as priorities allow, we will incorporate more options into our sweep.  Out of curiosity, though, now that you know it exists, what is the downside of using the custom feature?

I already have about 10 custom features added, and the dropdown is now too long! (although some ie '3Dspline' are probably now redundant as you've added '3D fit spline' into the main feature set.)

philip_thomas

Hello Paul!

Not obvious until you have seen one.
This is a constant-pitch/variable-diameter sweep.
"Bone Screws' (orthopedic surgical device) are very similar. Here is an example.

https://cad.onshape.com/documents/d3d8ded2a3002695f2f92b3b/w/63b87a811a1f307b9cd4c36b/e/72177004b5befa06cb7cd722

paul_britton

Philip, I had already seen that, but neither the valley to remove, or the spine to add are circular in my scenario.....

I have just found a featurescript feature called Sweep Normal that appears to keep the spine profile in the correct orientation during the sweep, ie it's plane normal to the surface of the core profile.. If only OS had this as a tick option in the standard sweep as well as the 'Keep profile orientation'

Which gets me to something like this...

https://cad.onshape.com/documents/bfcab79745e70a807cb87497/w/181434d7c1ba5e4cda7ffba1/e/e5bc6e8a6dffd92eabc29438

philip_thomas

Looks like you did it!
FAB!

mahir

@paul_britton , that's funny. Reading your question, I was about to suggest my Sweep Normal FS, but you beat me to it Glad it worked for you. I should probably make it a real FS document instead of burying it in my sandbox.

paul_britton

mahir said:

@paul_britton , that's funny. Reading your question, I was about to suggest my Sweep Normal FS, but you beat me to it Glad it worked for you. I should probably make it a real FS document instead of burying it in my sandbox.

It is just the job.... if it could be incorporated as an option into the normal Sweep function, it would be great... Onshape, are you listening? :-)

ilya_baran

@paul_britton
We are always listening   Over time, as priorities allow, we will incorporate more options into our sweep.  Out of curiosity, though, now that you know it exists, what is the downside of using the custom feature?

paul_britton

ilya_baran said:

@paul_britton
We are always listening   Over time, as priorities allow, we will incorporate more options into our sweep.  Out of curiosity, though, now that you know it exists, what is the downside of using the custom feature?

I already have about 10 custom features added, and the dropdown is now too long! (although some ie '3Dspline' are probably now redundant as you've added '3D fit spline' into the main feature set.)

ilya_baran

Got it.  We are also working on toolbar management functionality to make this problem easier.