Slash & Spread Part II

[wildspidee]

In January of 2013, Clive was kind enough to answer an inquiry I had regarding a "slash and spread" technique that is common with paper sewing patterns. He taught me how to create blocks that could then be rotated to spread a pattern out.

Now I need to take this technique a little further and spread the pattern to a specific distance. Each segment of the pattern needs to be equally spaced apart. For example, the pattern edge to be spread is initially 6" long.

Slash1.jpg (19.35 KiB) Viewed 11194 times

I then need to spread it out so that the resulting arc is 10" long from tip to tip. (I'm just using arbitrary numbers here, it will differ). When rotating the pieces it is very difficult to end up with the exact spread amount. Ideally, I would draw an arc the correct length and divide it up into markers to use during the rotation process. The problem is I have no idea what the angle of the arc will be. You'll see that even the non-spread side of the pattern will be an arc after rotation.

Slash2.jpg (32.32 KiB) Viewed 11194 times

I've tried drawing a straight line and segmenting it for reference, but that doesn't work. I've also tried drawing little tiny lines off one side of a piece as markers, but that is flawed, too. Any suggestions would be appreciated.

I have attached a QCAD File with all the entities drawn, so it can be manipulated.

[andrew]

You could use the new 'Paste along Entity' tool to create markers along the spline at regular intervals:

1. Draw the marker you want to use (a point, cross, circle, etc.).
2. Select the marker
3. Edit > Copy
4. Edit > Paste along Entity
5. Enter desired number or distance in tool bar (here we choose three positions, excluding start and end point)
6. Click the entity along which to paste the marker

Note that I've changed the top end point of the spline, assuming it should lead to the same corner as the other parts of the spline.

Screen Shot 2015-02-16 at 14.21.52.png (224.08 KiB) Viewed 11177 times

[wildspidee]

Thank you Andrew.

I didn't know that feature was in QCAD. It works very well and I will use the technique quite a bit. Unfortunately, I still have a problem. How do I get the spline to mark? I can guess as to the general shape needed, but I can't control the length. Once a spline is drawn, the length can't be adjusted. Even exploded to a polyline, the length can't be changed. I also can't use the lengthen/shorten command on a spline.

Using a line as reference is too straight and an arc is too curved. I need to be able to draw a gentle curve, a spline is perfect, with a specific length. Am I missing something here?

Lori

[andrew]

Spline lengths cannot be easily adjusted because enlarging the spline would be undefined (a spline that is 10 units long can be extended into a spline that is 20 units long in an infinite number of ways).

To shorten a spline to a given length, you may proceed as follows:
Modify > Divide
Click spline
Snap > Distance
Enter length of spline in options tool bar
Click division point

[wildspidee]

That's a nice work around that did the job perfectly.

Thank you Andrew.

[Husky]

Hallo Lori,

Using a line as reference is too straight and an arc is too curved. I need to be able to draw a gentle curve, a spline is perfect, with a specific length.

Just curious: May I ask you what the purpose is for this "particular gentle 10" (?) curve at the open end?

What's about the other side? Could something like this work too?

[wildspidee]

Husky,

There is no real purpose to the curve, other than providing the basis to spread the pattern 'parts' equally to the correct finished spread length. If I could accomplish this using your technique, it would be amazing. The issue is the angle. How did you come up with 10 ? Was it just random for the demonstration?

Perhaps if I explain this in context, it will make more sense. When you want to add fullness (gathers, pleats, etc) to a sewing pattern, you slash it into even segments and then spread them to the desired width. In the dxf example I provided, the original edge of the pattern piece was 6". I wanted the new edge to be 10". I needed to cut the pattern into segments and spread them evenly so that end-to-end my new edge is 10". Then I can draw the final spline using all the segments as guides for the correct shape.

I was using the curve only as a guideline to spread the segments. Logically, this is flawed. I can't anticipate the exact final curve after spreading, so my guideline won't be that precise. My husband and I were trying to come up with a way to determine how to draw a precise guide prior to the spreading. We spent several hours, but neither of us are that good with math or geometry, so my spline guide was the best I could do. I'm still convinced that you could use rays extending from an origin to do this. The problem is, where would the origin be? It would have to be X distance from the finished edge, but we couldn't figure out the X. Here's a simple little image to illustrate:

Rays.jpg (26.65 KiB) Viewed 11159 times

I hope I explained this clearly. Do you have any suggestions?

Thank you for taking the time to provide the excellent demonstration.

Lori

[Husky]

Lori,

I hope I explained this clearly.

Yes - absolutely. Now I know what we are talking about. Thank you!

Do you have any suggestions?

Yes - right now I think about to use small (D=1") circles as a distance entity and "Tangent to point" lines to pick up angles for the rotation.



Is it self-explaining?

[wildspidee]

Husky,

I really appreciate all the time you spent on this tutorial. It simply couldn't have been done any better. I can definitely use the technique and it brought other things to my attention as well. I have to create guidelines and determining their length is tricky. I've never used rays, but your tutorial showed how incredibly useful they are. This alone will save me a lot of time.

Also, your tutorial displays your QCAD keystrokes in the video. What did you use to do this? This would also be very beneficial to me.

All your time was well spent. I learned so many things.

Thank you,
Lori

[Husky]

Hello Lori,

... and it brought other things to my attention as well. I have to create guidelines and determining their length is tricky. I've never used rays, but your tutorial showed how incredibly useful they are. This alone will save me a lot of time.

Let us call this: Kill two birds with one stone!

Also, your tutorial displays your QCAD keystrokes in the video. What did you use to do this? This would also be very beneficial to me.

It's a customized Version of a keystroke displayer program and has nothing to do with the QCAD Program. I'm right now waiting for a "bug" response of the Author and then I'll be back to you with more infos, ok?

I learned so many things.

Me too - believe me - I never spent before a thought about "Slash and spread sewing techniques" ....
Flat pattern layouts for all kinds of metal shapes - yes, no problem but textiles .... that's new.

[wildspidee]

Few people appreciate the complexities of garment sewing / pattern drafting. You have to take a flat 2-D shape (fabric, no depth per se) and turn it into a 3-D object that completely conforms to the body. Then once you have that figured out, you have to manipulate it (make it fancy) so it actually looks good.

I'm building an add-on for pattern drafting, with Andrew's amazing help, to work with QCAD and then I'm giving it away. You may find yourself answering some questions in the future from those users.

At least now you have a touch of experience!

Thanks again,

Lori

[Husky]

Lori,

I'm building an add-on for pattern drafting, with Andrew's amazing help, to work with QCAD and then I'm giving it away.

That is what I already thought .....

May I bring two QCad forum section to your attention:
For testing and feedbacks purposes we provide the "QCAD 3 ' Script Add-On & Plug-in challenge ' - Work in Progress" forum.

It's always nice to have a feedback on a new script (+tutorial?) before it is introduced to the "Big world".
This forum will be open for everybody for testing, bug reports, performance issues, feature request etc. etc. etc..
viewforum.php?f=107


If everything is working as expected - you can place the script and the tutorials into the "Finished 'Ready to go' Scripts/Plug-in's" forum.
viewforum.php?f=109

This one will be locked for User discussions to keep it overseeable.

Thank you!

[wildspidee]

Husky,

Thank you for the great information. I will release it in the Work In Progress forum for feedback. My concern is that few people in the QCAD world are interested in garment patterns and aren't necessarily going to know if my scripts are working or not. I'm going to release it to my YouTube audience at the same time, but they will be forewarned that it is a Beta release.

After some time, and I'm sure many fixes, I'll put it in the Finished Ready / Plug-ins forum. I think that most of my downloads will be initiated by my own marketing efforts, but over time could be substantial.

My plug-in is not only for those that sew in the real world, but those that sew in the virtual one. People who model 3D clothing need to know how to make patterns and they have enlisted my help.

It's going to be fun!

Lori