How to correctly loft this profile

peter_paton

Hi, I confess I asked this question a couple of years back but I have forgotten how this is done.

The issue is in getting the profile to render correctly a. without a twist and b. with the vertexes correctly aligning.  From earlier comments I used curves as guides but I can't find the tutorial I followed on that occasion and so far I am beat as to how to get the profile correct.  Any assistance will be greatly appreciated!

https://cad.onshape.com/documents/18b36221966cb70574443e0f/w/2bd1ce5572682bb39881d3e3/e/26fc7644be05dcc4f902efcd

bruce_williams

Today the easiest is to use the newer feature 'Match Connections'

peter_paton

Thanks Bruce, that is what I was getting but it is not correct - the cetral vertexes should connect with the outer top edges of the rectangular profile not end in the centre. 

bruce_williams

OK.  There are always design choices and Match Connections is very flexible, although a little esoteric on how to put more pairs of points in.  After putting a pair in, close that Connection selection with the v and then enter another pair.  You can use explicit vertices, or attach to curve and drag the positioner by eye, or add points to choose before using Loft.

Hopefully the picture below makes it clear.  Also check out Help Loft Point 8 instructs on Match Connections

bruce_williams

Or you can even do the below, although the angled side lines are a tiny bit (30 microns) from the lower rectangle's corners.  It is pretty cool that Onshape decides how close those points can be and still work.  You would need to use multiple surface lofts to get it right on.

See this copy of your doc for this example.

peter_paton

Thanks for the input Bruce, you are correct re it being cool.   I am at work at the moment, I'll have a look at your suggestions later tonight and see if I can puzzle some of it out.  

Prachi

Here's another option that comes up clean with no micron error. Lotta steps though. To bad the slider won't travel right to the vertex.
https://cad.onshape.com/documents/44300b8443e31a8a7552cb4e/w/9ece92663a727e60560de254/e/16bfe04dba93e1918d42c010

Prachi

My OCD kicked in. Check part 2. 7 features  instead of 13 and no surfacing.
https://cad.onshape.com/documents/44300b8443e31a8a7552cb4e/w/9ece92663a727e60560de254/e/16bfe04dba93e1918d42c010

peter_paton

OK, call me thick but this has got me totally beat!  From Bruce's earlier example I think what I am missing are the guides (the purple lines in your earlier example?). Can someone explain how these are added?   Thanks in advance!

Prachi

There are no guides in part 2 of the sample. It's done with a loft from square to square then a triangle to point remove loft.

peter_paton

Thanks Glen, that is an easier way to achieve what I was looking for rather than creating a loft between two plains.  Having said that, I would still like to learn how to use loft guides to loft between differing profiles between two (or more) plains.

bruce_williams

@peter_paton

Look carefully at my second example, esp. the dialog box..  The purple lines are from Match Connection NOT Guides.

Read the help and practice, you will get it.  Lofts have lots of options and requirements.

peter_paton

Thanks for the help Bruce and Glen.  I was able to spend a bit of time this afternoon and happy to report I now have two different ways to achieve the result and have learned some now features in the process.