topic Re: Trying to loft at a tangent to the profile face? in Fusion Support Forum

Trying to loft at a tangent to the profile face?

Anonymous — Wed, 24 Jul 2019 11:25:28 GMT

I'm making custom rounded corner profiles for skirting/baseboard. The first time I did it, it worked perfectly. Unfortunately the company has changed the profile slightly, so I needed to remake my model. I can't for the life of me figure out why it's gone crazy. Below is the result I'm after:

Which was achieved by selecting to two profiles and using a tangent arc as the rail.

This creates the components I'm after, a nice 46 degree slice that I glue in and paint. Which ends up looking like this: https://www.instagram.com/p/BhNsEQGnubY/

Now what the profile has changed I had to create a new model. I'm pretty sure I followed exactly the same process, except for some reason (probably because I'm doing things a bit 'nicer' than I used to), I don't have any of the lines on the decoration of the skirting (which become loft points), so when I loft, it comes out like this...

A complete random higglety pigglety mess! I think I have identified the issue, just unsure how to rectify it.

This is how I come up with the original sketch, I cut a thin bit of skirting, scan it, calibrate it, trace it, and use a Fit Point Spline to match the decoration.

This doesn't seem to be the way I did it originally, as the spline seems to be made up of sections in the original sketch, where this is one continuous spline. Which I think is where my issue has arisen from.

Any assistance would be greatly appreciated, I don't have much hair left to pull out!

Thanks.

Re: Trying to loft at a tangent to the profile face?

davebYYPCU — Wed, 24 Jul 2019 11:41:52 GMT

Three ways to fix it, come to mind

more horizontal sketches and tangent arcs, to stop the irregularity,

or, construct an axis line through the existing radius curve’s centre point, to Revolve the profile.

But you can Sweep that profile right round the room, then split body for the piece/s you need.

Might help...

Re: Trying to loft at a tangent to the profile face?

Anonymous — Wed, 24 Jul 2019 12:06:06 GMT

For a bit more clarity here's an image of the underside, a sweep won't work due to the allowances that have to be made for plaster corner beads (which have a 1mm radius).

I really just want to turn every tangent handle into a loft point. Or split the single curve at every tangent handle?

Re: Trying to loft at a tangent to the profile face?

davebYYPCU — Wed, 24 Jul 2019 12:15:00 GMT

Then ditch the spline and trace with tangent arcs, probably what you did first time.

Sweep with Guide Rail will do it, but I see that the Revolve is gone unless you go to a 90 degree segment.

Might help....

Re: Trying to loft at a tangent to the profile face?

Anonymous — Sat, 27 Jul 2019 08:00:35 GMT

Well I really thought I had it... I just redid the trace with a fit point spline, but started and stopped each section. Then grabbed the curvature points and constrained them to 'equal' and 'collinear' with their adjacent segment.

Everything looked like it was going to work, but when I tried to make the segment, I'm told the rail can not be tangent to the profiles! That's the whole point of the bloody thing 😛 I really can't figure out how I did it last time, maybe I've learnt too much and am trying to do things a little more properly. When before I was bumbling around like an idiot (which I'm still doing to an extent as I haven't used it in a while). Ugh, over it for now 😛

Re: Trying to loft at a tangent to the profile face?

davebYYPCU — Sat, 27 Jul 2019 09:26:56 GMT

Yeah, seen that too, but your rails are not tangent to the profiles,

however, this is 3 Sweeps of the spline, no distortion,

Might help....

Re: Trying to loft at a tangent to the profile face?

Anonymous — Sat, 27 Jul 2019 09:36:26 GMT

I get the same error when I try to sweep... to make the path, I start a new sketch and then project the two leading edges of the bodies through, and connect them with a tangent arc. So that would make them at a tangent to the profile right? I dunno... If I unhide the original models and create the loft, it works, just won't play ball with this one.

Re: Trying to loft at a tangent to the profile face?

davebYYPCU — Sat, 27 Jul 2019 09:44:56 GMT

Have you read my timeline, the middle Sweep uses the Guide rail, the other two don't,

Settings in each are slightly different.

Might help.....

Re: Trying to loft at a tangent to the profile face?

Anonymous — Sun, 28 Jul 2019 23:23:07 GMT

Yeah sorry I don't get exactly what you mean, this segment needs to fit into a very specific geometry in the real world. Two pieces of skirting, cut at 22.5 degrees on my mitre saw, then installed with a 1 degree spring, so they're essentially at 91 degrees to each other, and the segment I print ends up being 46 degrees, with the curves being tangent to the face of the skirting. It's almost like the behaviour of the loft has changed in an update, I don't know...

I retraced the profile with the breaks in the spline, and tried to loft it again (I removed the rotated 22.5 degree sections so the path wasn't tangent to the profile) and it worked, but ignored all the additional loft points. Doing... my... head... in 😛

This is as far as I've gotten:

Where it originally did this, which is exactly what I want. I still can't see the difference. I think I'm going to start again with a fresh model and go from there! I'll look at your solution again, just can't really figure it out. I'm just a humble carpenter here 🙂

Re: Trying to loft at a tangent to the profile face?

davebYYPCU — Sun, 28 Jul 2019 23:44:19 GMT

Fusion made your part in my file, from the coloured photo, so size is unknown but done.

Down load my file from the link in the forum post just above.

In Fusion, Open from your saved location. Take the timeline back to after the 3rd Sweep icon.

In the Browser, Use lightbulbs to Hide the straight sections.

Your part, with spline and tangent rails, 46 degrees, but with Sweep not Loft.

Transfer my selections and Settings from that Sweep, (Edit Feature), into your file.

If stuck, File > Export an example file with your data, can check it out if you wish.

Might help....

Re: Trying to loft at a tangent to the profile face?

Anonymous — Mon, 29 Jul 2019 00:01:05 GMT

If attached the file with the two profiles... Body 1 and 2 is the exact position of the elements in the real world. Sketch 3 is the tangent arc. I have all the elements in the right locations, just can't make it behave! Going to have a coffee or 10

Re: Trying to loft at a tangent to the profile face?

davebYYPCU — Mon, 29 Jul 2019 02:39:03 GMT

I could not make a nice Loft, due to insufficient rails, to stop the contour shrink wrapping.

To edit your model, I have added sketch 5, for the two curves of the Sweep with Guide rail.

Might help.....

Re: Trying to loft at a tangent to the profile face?

Anonymous — Mon, 29 Jul 2019 03:37:59 GMT

Awesome! That's exactly what I'm after, no idea how you did it, or where you put sketch 5, but I like it! 😄

Re: Trying to loft at a tangent to the profile face?

davebYYPCU — Mon, 29 Jul 2019 05:34:26 GMT

Well because you were using Sketch 4 to make / cut the extrudes,

Sketch 5 is on the same plane, with projected lines, and the 2 radius curves needed for the Sweep.

For the sweep I clicked on the extruded face, path on one curve, Guide rail for the other curve,

Because those 2 curves are only crossing the gap, they would interfere with the sketch 4, so follow my own advice and one sketch per feature, away we go.

Happy to help....

Re: Trying to loft at a tangent to the profile face?

Anonymous — Tue, 30 Jul 2019 07:55:42 GMT

Ok, I made sketch 5, projected the two curves, tried to create the sweep, I get this abomination. I'm obviously not picking up what you're putting down. I'm still at a loss as to why it worked perfectly last time and every other time I've done it for multiple projects! Cheers 🙂

Re: Trying to loft at a tangent to the profile face?

TrippyLighting — Tue, 30 Jul 2019 11:52:09 GMT

Before you actually get into lofting you need to step back to the basics and improve your sketching skills.

This profile was created using several short spline segments that are connected at the ends, but do not have any form of tangency constraint applied. That would not be really a fix, however.

This should really be only one spline.

First yours:

Here's mine:

Overlay:

Re: Trying to loft at a tangent to the profile face?

davebYYPCU — Tue, 30 Jul 2019 11:53:47 GMT

Yeah, something out of order,

This is my dialogue settings for that piece we are after,

The profile is the face of the body, not a sketch profile,

Might help....

Re: Trying to loft at a tangent to the profile face?

TrippyLighting — Tue, 30 Jul 2019 12:03:04 GMT

Here's one way to loft this without any rails.

Re: Trying to loft at a tangent to the profile face?

Anonymous — Wed, 31 Jul 2019 00:30:23 GMT

@TrippyLighting wrote:
Before you actually get into lofting you need to step back to the basics and improve your sketching skills.
This profile was created using several short spline segments that are connected at the ends, but do not have any form of tangency constraint applied.

If you read above that's what I started with, but then added the extra points with tangency constraints to hopefully force extra loft points like my original model had. I have no idea why it's not playing ball this time. There have been a few updates since I last used it, but that doesn't explain why it works on my old model still.

Re: Trying to loft at a tangent to the profile face?

Anonymous — Wed, 31 Jul 2019 01:05:07 GMT

@davebYYPCU wrote:
Yeah, something out of order,
This is my dialogue settings for that piece we are after,
The profile is the face of the body, not a sketch profile,

Might help....

Perfect! It was the profile scaling. I had the right profile/path/rail selected, just not the right options. I've got no idea why that would have changed... Cheers! I'm going back to the original paths I had where it was one spline and giving that a crack.