Lessons in calculating fabric use & pattern engineering

This isn’t what I intended to be writing about but it ended up that way. This entry was supposed to be about making men’s ties -along with a nifty construction process I think is better than the way that other people on the web show you how to do it. No no, it ended up being about calculating fabric usage by way of marker making because the trickiest thing about making men’s ties -presumably in a production environment since that’s what we do around here- is figuring out how to cut the things out. Ties are an extreme and in some respects, simplistic example but I think it’s still useful for illustrative purposes.

The trickiest thing about making ties isn’t sewing them. It’s cutting them in such a way you don’t sacrifice product quality but optimize your yield. A reason why ties are such a great example of this is because they are definitely generated according to the fabric width. In the book, I talk about how and why a pattern maker will -ideally- need to know the width of your fabric before they start working (don’t hire one who doesn’t ask). A pattern maker has to keep a macro view of fabric usage as they work. Ties are the best example of this as I’ve ever found. Before I forget. In keeping with the original intent of the series, I have a tie pattern for you if someone can tell me how to output it. I thought I could save as anything (DXF etc) but those options aren’t popping up for me.

When you’re planning a line of products, anticipated material usage should be right at the top of the list. Making bias dresses is going to take quite a bit more fabric than ones cut on grain. Therefore, you’re probably looking at higher price points. Same thing with ties. Can you afford to make them? Fabrics designed for ties can be expensive. If your ties will have an obvious pattern such as a large graphic on the tip of the fatter end, it’ll cost even more. If you want to use fabric like that, not only will you have to tell the pattern maker the width, you’ll have to provide a fabric sample containing more than one repeat.

For the sake of simplicity, let’s assume you want ties without an obvious pattern such as a large central graphic. Most of these fabrics are 44-45 wide silks. Below is a view of one pattern laid out (larger view 24kb).

In making one tie, fabric usage is about 23″ with 30% efficiency. That means 70% of the available square inches of fabric are wasted. If we assume our tie fabric is $100 a yard or $2.78 per inch (although pricey, most aren’t this costly but let’s make the math easy), the fabric cost for this tie is $64. At 30% efficiency, that means $44.76 will end up in the trash. [By the way, this is yet another reason why samples are expensive, more on this later.].

Adding a second tie takes a total of 24.5″ for both, reducing fabric usage to 12.25″ each but efficiency jumps to 57% (below, larger view 37kb).

This time, the fabric cost per tie is $34 in materials but of this, due to the 43% waste, $29.26 goes in the trash. By the way, if you ever wonder why a contractor resents attempts to negotiate the sewing fees lower, it could have a lot to do with the efficiency of your patterns. On each item of this example, the $29+ worth of fabric going in the trash is equivalent to over three hours of labor per piece. You’re throwing out more in the trash than you’re paying them. They resent negotiating attempts because you’re asking them to take a pay cut so you can continue to waste money on fabric. Like I always say, if you have your heart set on blowing that kind of money, it’s better to give it to people than the trash can.

I got a question about allocation costs this morning. The DE wanted to know how and when she should calculate fabric allocation for samples. As you can see from this example, it would be very handy to know that you’re better off ordering ties in multiples of two because one costs as much as two in material and since the biggest cost of ties is fabric (returning to the third paragraph of this entry) this matters a great deal. The only way you’ll know allocation, is by either getting the figure from the pattern maker or if that’s you, you’ll have to mock up a marker (pg 114-120 of the book).

In the end, of course two ties isn’t efficient. Below is a mock up of a marker showing ten ties. By the way, this marker was made using the “Quick” auto-“nesting” feature of my marker making software. [I put “nesting” in quotation marks because this isn’t technically nesting but that’s the term they use for it. A nest shows on overlay of all sizes as one pattern piece. Auto-plot might be a better term for it but then you wouldn’t know old school pattern makers like me rarely avoid the opportunity to find fault with the terminology that software programs use :). Doesn’t seem like a big deal unless you’re hunting and pecking through menus to find functions. Then it matters.] They have another marker making option that analyzes at a higher level that you can add on; it costs a bit more but people swear by it (I don’t have it). In this example below the auto-“nesting” marker maker rendered this result (larger view 144kb),

Increasing the marker to make ten ties (using the auto-“nesting” feature) increases efficiency to 60.66%, a substantial yield improvement. That still seems awful. So, not having made many markers, I thought I’d make one manually to see if I could improve over the auto function of the computer. You don’t know this but there’s a lot of marker makers who really dislike automatic marker making and claim they can do it better. The research backs them up. It’s estimated that manual marker making can improve efficiency from 3% to 7%. As it happens, I get a yield of nearly 70% efficiency (69.93%) with the manual marker. That improvement in efficiency is about a 15%. I’m sure a pro could easily beat even that. Here’s what my manually made marker looks like (larger view 130kb).

Material usage at this point stands at 10 1/8″ per tie (.3yd, chart from pg.81), actual cost being nearly $28 per tie. Compared to cutting one ($64) or two ties ($34), this is substantial savings. However, there’s still 30% of your fabric ending up in the trash, amounting to $8.46 per unit (waste for one $45, two was $14.65). This is where you might want to go back and re-read the second paragraph of this entry. Oh never mind, for the sake of reading continuity, I’ll repeat it for you:

The trickiest thing about making ties isn’t sewing them. It’s cutting them in such a way you don’t sacrifice product quality but optimize your yield. A reason why ties are such a great example of this is because they are definitely generated according to the fabric width. In the book, I talk about that how and why a pattern maker will -ideally- need to know the width of your fabric before they start working (don’t hire one who doesn’t ask). A pattern maker has to keep a macro view of fabric usage as they work. Ties are the best example of this as I’ve ever found.

Knowing fabric width and mocking up a marker, a pattern maker will know roughly how much fabric you’ll need and how much waste will be left over well before you’ve ever had one prototype sewn up. Take a look at the tie below. On the left side, you’ll see an example of pattern engineering. The tie has been split into three pieces rather than two.

I’m pleased to show this example because one of our DE‘s family owned the Wembley Tie Company for many years.

By the way, this is why a “really simple” pattern can cost more than you imagine it should. Anybody can take a tie apart and make a pattern for it like I did; it’s the matter of engineering the pattern to fit on a marker with less waste that is the time consuming factor in this pattern’s design. It helps if they have a CAD program to make it easier and faster but it can be done by hand too. The point is, making the tie into a three piece, rather than a two piece pattern like the Wembly tie above, can significantly increase the yield, more than paying for the cost of the pattern engineering. It’s activity and investment at the front end of the process that generates the most savings. Most of you worry more about sewing costs when you should be worrying more about pattern and fabric efficiencies instead. I rarely find a pattern in which I can’t find at least 50 cents to a dollar in reduced sewing costs through better pattern engineering.

Returning to a related matter of fabric width and pattern engineering, again see the repeat of the automatic marker below:

You can see that’s there’s waste at the top of the marker. What this means is that if your fabric is narrower than the 45″ I’m using for this example, you may not get a better yield if you break up the tie into three pieces. You may do well enough as is. This is also another example of why you may need a separate pattern for the same product if you’re using different fabrics. You can’t always use the pattern designed for one width of goods on all of them. This is also why, if you’re using different widths of goods, your costs will vary for the same exact product. I know that’s obvious to many of you but it’s not for everyone. Therefore, your product costs will differ even if the fabrics cost the “same”.

In such cases of making the same product out of different width goods, you worry about pricing. If the items are identical except for fabric but you want uniform pricing, I recommend averaging the costs between the two and selling each for the same price. Now just because they have the same price doesn’t mean they should have the same style number. These are two entirely different patterns (two vs three piece), you don’t want them mixed up accidentally. There’s no reason you can’t price them the same. You could argue the three piece costs more in pattern making and charge more for it but it’s also saving you fabric money that the two piece isn’t.

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  1. Esther says:

    I love playing with the marker making software. To me it is a lot like putting jigsaw puzzles together. And yes, it is true, I never let the software auto-nest for me. I can improve efficiency by manually laying the pieces. Great blog entry on ties!

  2. /anne... says:

    “old school pattern makers like me rarely avoid the opportunity to find fault with the terminology that software programs use :).”

    Part of my job as a technical writer is to find out what terminology the enduser already uses and understands, and beat the programmers over the head with a blunt stick until they use it ;-).

    So often, they hire me at the last minute to perform miracles, and when I ask them to change things so the users will Actually Understand what the programmer is going on about, I get told ‘It’s too late – and anyway, they don’t care’.

    So, I’m in there batting for you guys, but you need to complain too.

  3. Babette says:

    They just don’t teach this in fashion schools. I once enquired in cutting class as to what point do you take account of the rate you pay your cutter (eg single lays for accuracy in plaid matching) vs fabric cost vs price point of the finished goods vs wastage vs %factor skewing off grain and was told that “you should leave that to the bean counters”.

    I’m glad to see you advocate capturing this information right at the beginning of the process.

  4. daisy janie says:

    Love this post. I had a customer ask about custom ties recently for a special occasion. Having never made a tie or even thought about it, I took one apart to measure fabric amounts needed. I was shocked by the volume of fabric hiding under those sneaky folds. I also had someone who makes ties bid on that portion of the job, and her first question was the width of the fabric. Shocked again by the amount of fabric needed to make 10 ties!

  5. Christy B. says:

    Perfect timing… I’m making 7 ties for my wedding and have already made my 3 piece pattern, but not the marker yet. The fabric is hand-dyed so laying out the pieces becomes trickier… I want the prettiest parts of the fabric for the front of the ties without getting a horrible yield!

  6. beverly says:

    Katherine, tho you have improved the yeild,from a cutters point of view, your version would be harder to cut. Making a marker is not always about improving yeild,it is also about lining up the cut lines on each piece so that the cutter can easily cut from one piece to another in a smooth flowing line. Those knives are tricky to manuever around awkwardly shaped markers. The computer’s “nest” actually would be much easier for cutting.

  7. esther says:

    Only partly true on the difficulty of cutting. If cut with a traditional saw by hand, then it would be more difficult. The ties could be cut by machine and a tighter placement could be used. Pattern pieces on a machine cut marker have a buffer and are cut with a smaller knife or or rotary blade.

  8. Kathleen says:

    Beverly does bring up a very good point tho, the cost of cutting and I should have mentioned its importance in the entry.

    I didn’t mention it in the entry because the difference in the cost of cutting the two markers was negligible. My CAD program (StyleCAD) has an awesome feature. It will provide a report on cutting costs per marker. Since the costs were essentially the same, I didn’t mention it altho cutting cost is a factor in marker design generally.

  9. Sue Whelan says:

    I’m in awe of what I learn here! Like Kipling’s Elephant’s Child, I’m full of “insatiable curtiosity” about how things are made. Kathleen always provides me with terrific answers before I even know I wanted to ask the question! Never again will I complain about the price of my husband’s ties and the next DH complains (and he will, lol) I will refer him to what I’ve learned here. Fascinating. Thank you.

  10. Kerryn says:

    Hi Kathleen,

    As far as outputting to DXF etc… see if your program has an Export feature rather than using Save or Save as?

    Most CAD programs will export to .DXF

  11. fitriansyah says:

    Hi, I am very intersted to learn/study about auto marker, I from indonesia. I am working as Aplication engineer. I have experience with Lectra, Gerber, and optitec. Please help me to choose the best one software for auto marker and auto patern gradding.

  12. Paul says:

    This reply is 2-years after the article. The diagonal seam in the tie is supposed to be in a certain location as a guide to tying the knot at the neck. If there are two seams to reduce fabric waste then one needs to be marked in some fashion to indicate it is the one used to indicate where you begin to form the knot/tie the two parts together. I did not know this until I saw a video on neck tie tying.

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