topic Re: How to loft a scythe blade in Fusion Design, Validate & Document Forum

How to loft a scythe blade

ws376 — Sun, 04 Mar 2018 00:22:57 GMT

I am working on this blade and the very end of it is shaped like a scythe, I've lofted the other parts of the blade, and I have lofted the scythe portion shown in the first attached image, but I am running into the issue of having it follow the inner curve, as well as having it slope down. I can't seem to find anything that shows how to achieve that complex of a shape.

The Second Image has the lines highlighted that it needs to follow instead of just a straight point to point.

Re: How to loft a scythe blade

laughingcreek — Sun, 04 Mar 2018 02:35:06 GMT

the curved line probably needs to be a rail. Can you post your file?

Re: How to loft a scythe blade

ws376 — Sun, 04 Mar 2018 03:12:33 GMT

Yes, I'm new to fusion so sorry if things seem unclear, most likely don't have the best of practices implemented.

Re: How to loft a scythe blade

laughingcreek — Sun, 04 Mar 2018 04:17:44 GMT

Can't really tell what your looking for at the bevel transitions. Your going to have trouble with the way it's drawn. But I wonder if our working to hard? how does this approach look to you?

Re: How to loft a scythe blade

davebYYPCU — Sun, 04 Mar 2018 04:34:02 GMT

To follow the canvass,

I have made two more profiles, and then two Lofts, with the same rail, from the point,

Looks close to what you asked for, file attached.

Re: How to loft a scythe blade

ws376 — Sun, 04 Mar 2018 05:41:45 GMT

Alright so let me double run over it to make sure I got the idea down.

1. You made 2 planes so you could add the sketches for the blade angles.

2. You lofted the shorter part using the two plane sketches you did as the profiles and the outer diameter of the blade is the rail that is used for both lofts.

3. You lofted the longer part using the adjacent face and tip as profiles and again used the outer diameter of the blade as its rail.

This looks like its as close as I am about to get, which I do find a bit unfortunate, I do get that the drawing is complex, but If I have lines on in sketches why cant it use the inner line as a rail as you done for the outer line, is it because that line continues all the way along the bottom instead of stopping at the face? If that is the case is there a way I can't section up that line so that I can say "from this point on loft". I just feel like there has to be a way to follow it exactly, and its not so much that I need it to be 100% exact it's just, I feel like if its there, it should be possible.

I feel like laughingcreek is correct with saying I'm going to have trouble with the ways its drawn, but that's just the shape, Im redrawing it from reference, and planning to recreate this in the real world via 3D printing and needing mechanisms in it for it to actually function and not just be a prop. So I cant just change it for ease of recreating it.

Ill try to work with it some more using both suggestions and see if I can't come up with a compromise, just sucks that I'm spending more time fiddling with the software trying to get the blade to form properly than I am working on the actual engineering that needs to be done.

I do thank the people that take the time to help, I already have more knowledge, just hope I can pull it all together.

Re: How to loft a scythe blade

davebYYPCU — Sun, 04 Mar 2018 07:14:29 GMT

Yes, 1, 2, 3, are as you determined.

Loft has a few unwritten rules to follow,

Rails have to touch all the profiles, (one loft would be ok)

AND, must be smooth or tangent connections with multi segments in any rail. (Unable with this one)

Therefore, seeing what the canvass was requiring, the blade could not be made with one loft, because of the sharp intersection, with the shank.

Using one long rail for both lofts, meant that developing other rails was not going to make it any better.

Wasn't sure about the shank profile,

Let us know if you're stuck.

Re: How to loft a scythe blade

ws376 — Sun, 04 Mar 2018 21:11:14 GMT

Yea, I am wondering if I shouldn't start from the beginning on the blade here and redraw some sketches. I spent an additional few hours trying to patch and stitch the blade together and trying to learn exactly what it wants to do that. It was strange because I had to use the existing body, the spine of the blade as its guide, if I were to try to pick the 4 sections on the blade itself for a patch it would give a calculation error, regardless if I had chain link on for fusion to pick the lines or not and me pick them. Especially since it would preview the patch and look fine but hit OK and it just give me an error.

I also have to extrude the the other pieces along the blade and realizing that I cant extrude them into the bade due to its curved nature, I need to make the sketch continue in more and join the bodies.

As well as I need to section the blade (I attached a picture of the original version to show what it has to be like). Right now I'm just trying to revise the curvature of the blade to match the reference canvas. I could stick with the first one, but I fine that to be lazy and not staying true to the project.

I want to figure this out as best as I can and hone these skills, because I do like Fusion's Environment, but if it can't accomplish these shapes then I can't use it for my needs.

Re: How to loft a scythe blade

ws376 — Mon, 05 Mar 2018 23:51:51 GMT

I've Decided to just go ahead and move to Free Form modeling. I feel this geometry is is too complex for fusion to handle with lofts. I'm starting to look into Fusion's Form tools and see if I can make everything I need in there.