The Leg Blocks

Both Leg Blocks Start Here

You might think you'll never have to deal with leggings when it comes to swimwear, but you'd be wrong. One third of the Australian coastline, for example, has seasonal jelly fish that can cause serious injury if you're not wearing a stinger suit (a swimsuit with leggings). Some surfers and divers wear Lycra wet suits instead of neoprene in warmer waters. There is a huge movement towards full coverage sun protection swimwear for children. And of course there's always the massive dancewear arena.


The one piece block with legs added (and sometimes arms) is called a catsuit. There are two styles of leg blocks. Each is distinctly different and each serves a specific function. All catsuit or leggings patterns, no matter how different, are based on one of these block styles.


The first block is very much like a pair of close fit jeans (see image below). It is characterized by a centre front seam and centre back seam. Final patterns based on this block may or may not have side seams. It may have a separate gusset added. If it's part of a full catsuit, it may have a full length centre front or centre back zipper.


This style of block is the easiest to construct and the most forgiving to fit. Due to the way the seams come together under the crotch, there will usually be a gap between the crotch and the garment. The panels also join at a point which some people consider aesthetically and anatomically incorrect. This gap is, however, necessary to allow the wearer to walk without cutting themselves in half!

The great advantage of having no vertical reduction in your blocks and patterns is being able to insert a centre front or centre back zipper. Keep in mind that non-metal zips tend to be bulky and look even more bulky when pulled tightly to the body with thin swimwear fabrics.


The second block is much like adding sleeves to the leg holes of a one piece block (see image below). It maintains all of the gusset area of the one piece and so is much closer fitting and offers a significantly better range of movement. It's certainly a better looking garment, and offers the potential to move the "leg line" pretty much anywhere because it will always stay located in the garment. On the other hand, it's much more difficult to construct the block and certainly involves more sewing to put it together.


This block is referred to as the gymnast block because it looks like a gymnast wearing a leotard over the top of tights. Ironically, most tights are centre seam blocks with a gusset added!

Thigh and calf measurements vary a great deal within each size, more so than waist and hips. I have no idea why this is. It seems slightly related to height and weight, but still varies for similar values. I'm guessing it's more an issue of lifestyle. For this reason, if you want to test the block (as opposed to just learning how to do it), I suggest measuring the person you're going to test it on and use those measurements rather than the set in my size tables. That way if you've made a mistake somewhere along the line you'll be more able to identify it. Also you'll more clearly see the advantages and disadvantages of each type of leg block.


Both blocks are initially constructed the same way. Follow steps 1 to 6 to create the leg base block and then click on one of the links at the end to choose which style you want to complete. Using either a CAD package or drafting paper, simply follow the drafting instructions. At the end of each step your drawing should match the illustration. If it doesn't go back to the start of that step and work your way through again. This example block has been drafted for a size 10B/C using 12% horizontal negative ease and 0% vertical ease.

Step One

Transfer your one piece block from the waist down, maintaining the distance of half hip measurement between the centre front and the centre back.

1-2: Draw down waist to floor without any reduction. Draw down the same distance on the centre front. Square across at floor line.

1-3: Measure down waist to knee without any reduction. Square across to centre front.

Step Two

1-4: Measure down 1/3 of waist to floor measurement and square across. This line corresponds to the widest point of the thigh and more often than not seems to line up with the half gusset line (base line) on the one piece block.

4-5: Measure down another 1/3 of waist to floor measurement and square across. This line corresponds to the widest point of the calf.

2-6: Floor to cuff and square across. This is an arbitrary measurement based on style. It represents the smallest part of the leg just above the ankle. 11cm seems to be about right for most sizes, but measure if you have that opportunity.

Step Three

1-4: Measure down 1/3 of waist to floor measurement and square across. This line corresponds to the widest point of the thigh and more often than not seems to line up with the half gusset line (base line) on the one piece block.

4-5: Measure down another 1/3 of waist to floor measurement and square across. This line corresponds to the widest point of the calf.

2-6: Floor to cuff and square across. This is an arbitrary measurement based on style. It represents the smallest part of the leg just above the ankle. 11cm seems to be about right for most sizes, but measure if you have that opportunity.

7: Divide hip line in half and mark it as point 7. Square down to floor. Extend both front and back side seams to point 7 on the hip line.

8, 9: Divide hip line in half again and mark back as point 8 and front as point 9. Square down to floor from both 8 and 9. These vertical lines are referred to as the quarter lines which mark the centre of the leg.

Step Four

10-11: Point 10 is centred on the thigh line directly below point 7. Square out either side half the thigh measurement with no reduction to points 11 and 12.

13-14: Half calf measurement with only half the reduction. eg; if you are normally using 12% reduction for this fabric then only use 6% to allow for more movement. Centre this distance on both the front and back quarter lines as illustrated. The calf measurement is used for both the knee and the calf.

15-16: Half calf measurement with only half the reduction. Centre this distance on both the front and back quarter lines as illustrated.

17-18: Half ankle measurement with only half the reduction. Centre this distance on both the front and back quarter lines as illustrated.

Step Five

Join all the points on the front and back leg panels as illustrated.

Step Six

Carefully smooth off the side seams all the way up to the waist line. Do the same with the front and back inseams. All front and back seams should mirror each other perfectly at this stage. All curves should be long and gradual.


To summarize the tensions, so far we have 12% reduction at the waist, 0% at the hips and thigh and then 6% from the knee down. There should be no vertical reduction anywhere. If you recall the one piece block we didn't apply reduction because the hip line was cut by the leg hole. Now there are leggings it's reasonable to apply reduction again, however consider how much movement occurs in this part of the garment. Applying the whole 12% would be too restrictive to movement. If you feel you really must, apply up to half reduction to the hips and thigh but no more. You apply it at this step and not earlier in order to keep the quarter lines in the right place. The dotted orange line represents 6% reduction at the thigh and hips.

At this point you need to decide which type of block you are going to construct.

 

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