My original posts on exploring automating shell shapes were written in my 910 electronic days using mylar sheets in early 2013: 1, 2. The repeat produced a visually successful fabric. I received a question on FB about executing the shells on a punchcard machine, and another on how I “come up with these things”, so here I am going to attempt to share some of my present thought processes.
Since the time I wrote my original posts my approach to my explanations has changed. I have become increasingly familiar with the software I acquired since then, and now have cable connections that allow for download to 2 different model Brother electronic machines. iPhone cameras make it far easier to “shoot and share”. Initially, I used to often start at step 10 of any technique, now I explore the basics and logic in more detail.
My original mylar repeat entered as separate programs in days when each mylar sheet was precious. 
The 910 in my default setting produced the “image’ as drawn on the knit side of the resulting fabric. The post was written prior to my tiling the repeats as a matter of routine to check their alignments. Doing so would have shown a couple of missing pixels, and pointed to any other errors in filling in mylar squares.
All transfers were made in the same direction, which now leads me to wonder whether biasing might result in a long piece of knitting. My leaf lace post illustrates modules created manually by holding with the direction of knitting reversed after the completion of each row of leaves. The start of the same concept being applied to the shell shapes with errors later observed and resolved: 
As always, ideas need error-proofing and refining, easier done in a chart if possible prior to any actual knitting. This type of design would be required to achieve a continuous, uninterrupted repeat on the electronic, whether all in a single direction or reversing every other row of shapes. It is applicable to joining several punchcards, but only on single 24 stitch widths.
There are a number of changes to make if it is necessary to get the pattern to reverse direction in alternate rows of completed shapes. My first tests were planned with knitting moving only from left to right. To execute such a pattern on a punchcard KM, the repeat needs to be altered from 14X2 to 12X2 in width. This is the start of sorting that out:
Attempts to visualize holding can happen in spreadsheets, documents, image processing canvases, or even simply on graph paper, moving/ “drawing” back and forth across the cells mimicking carriage movements and marking them accordingly. Large staggered repeats can be programmed in electronics. All shapes are limited in terms of the width of the repeat occurring across the number of available needles on any machine. Some previous posts on electronic knitting such repeats: 2014/02/24/holdingshort-rows-hand-tech-to-chart-to-automating-with-slip-stitch-1/, 2018/05/20/ayab-short-rows-automated-with-slipstitch/, 2019/08/03/a-return-to-short-row-shapings-bumps-and-slits/
As mentioned, my long-ago swatches were knit on a 910, which by default produced the knit image as programmed on the knit side. On the punchcard machines, the image-as-drawn effect is achieved on the purl side. Lettering is likely the most familiar instance where mirroring is required for punchcard machines to produce it correctly, a consideration here as well. 
For the moment I will work drawing the shapes in the direction I wish to have them appear on the knit side. The beginning goal was to establish a continuous 24 stitch repeat, with the same technique applicable to electronics thus avoiding programming 2 different repeats. This proved to be a fail.
If the color changer were to be used for changes every 2 rows the complete number of rows would need to be a multiple of 4 in height for each segment. With larger gaps between changes, the yarn may be changed every X rows manually, making an easy fix to breaking that rule. The next step is working out 12 stitch repeats with patterning needles to be brought in and out of holding position as well. The options on a punchcard would include 8, 12, and 24 stitch motif widths. The machines will be set to slip in both directions throughout, end needle selection must be canceled. This method is not executable easily on km models that do not offer that option, electronics use KC II. Note that machines sold in Europe in some models may have different names for the same functions, ie. SM in some instances is the equivalent of KC II, whereas ours is for a single motif. Punchcard settings: 
I do not have any blank punchcards to test a repeat on at the moment. I do have a 930 that essentially behaves the same way by producing the entered pattern on the purl side, so I planned on that fact. Adding arrows to my tentative chart reflect the direction of the next movement of the knit carriage 
the starting 24 stitch brick repeat,
reduced to black pixels/punched holes and mirrored horizontally to have the result planned above on the knit side 
The bottom, curved edge fo each of the shapes is created first. That said, the above used as a continuous repeat is not executable to achieve 2 rows of different consecutive shapes.
Other shapes have previously been explored using slip stitch, and later, slip stitch combined with holding. A brief return to previous turns at holding and slip stitch used to create alternating color shapes: in 2013/02/12/an-entrelac-pretender/, a continuous slip stitch only card was used. The result on the knit side,
while on the reverse floats between alternating shapes are the norm 
Results with no floats are found in the swatches in the posts: 2013/02/21/entrelac-pretender-2/
and a larger motif: 2013/04/11/entrelac-pretender-3/
Both were knit using pairs of punchcards for each.
Returning to the goal of the moment: to knit the shells in a floatless way, using a technique executable on a punchcard machine as well. The repeat in question so far is 28 rows high. If the punchcard or the electronic advance every row with each pass of the carriage, the alternating shifting blocks of the repeat will be selected in full with every 28 passes. In this instance, one returns to the start of the same repeat every 28 rows. Identical shell full shapes are created across the knitting rather than the shifting shapes desired in alternating full row repeats.
Separating the 28-row repeat into 2-14 row ones. The 12 stitch repeat is tiled X2 horizontally. If programming two separate repeats were the only solution, the bottom shapes, 14 rows high, would need to be punched X 4 in one card. In electronics half of each repeat would be adequate to program only once and entered as an all-over, repeating pattern.
Here the repeat for all full-size shells is planned, the black squares would also need to be punched X 4 on a second punchcard, to be programmed separately.
Marking up the needle bed with water-soluble markers or pencils helps track placements of repeats across the desired number of needles in work: dark lines indicate placement beginning with the mark for half a repeat to maintain straight side edges on the finished piece. Red lines mark the placement of the stitches when they are moved to the left in order to knit the full shells across the bed. 
On a 930, the image will be knit in the direction of the pattern as drawn on the knit side, as it would be on a punchcard machine. I intend to begin knitting the shells with COR. Since the pattern is fixed on the needle bed, one option is to move the work in one direction or the other on the needle bed using a garter bar, so that the knitting is in the proper place for the desired anticipated needle selection. This was easier in my own mind than reprogramming the pattern repeat for each full row of shells whether by entering a new download or altering placement using the position option at the start of each row. One of my first working repeats amended later in several steps is shown here mirrored in black and white
Visualizing the process on the needle bed
Scaling the image to render it a bit more legible:
The machine will be set for both slip stitch in both directions and holding. End needle selection is canceled.
The first preselection row is from left to right. Every needle will be preselected and will knit every stitch for the first 2 rows in the desired shell color.
Color changes are made manually.
At the completion of a row of shells, its corresponding color ends on the left side, a free pass is made, returning to the right. Knitting with the new color for the alternate groups of shells begins again on the right side.
After the first 2 all knit rows, as the carriage works its way back to the right on the following pass, preselecting will occur for a decreasing number of stitches. This is the first-row holding selection when using the above repeat:
Beginning piece with half a shell on each side: all but the first 6 stitches are brought out to hold. When more than the single needle is selected at the top of the first half-shell (6 sts to start, 1 at the end), COR: bring the next group of 12 stitches to the left into work, knit to left.
COL: bring original 6 needles out to hold. Bring into work any needles not selected in the group of 12 into work as well.
Continue knitting, repeating the process across the bed.
On design row 14 of the last half-shell remove work on a garter bar.
To execute full shells across the next row of shapes: move the work 6 stitches to the left.
Return emptied needles to A position (out of work, OOW).
With all remaining needles in B preselect the next row (1) from left to right. Cam settings need not be changed.
Change color if desired, knitting 2 rows across all the stitches.
Bring all needles out to hold except for the first group of 12 sts between red marks, and repeat the process previously described across the bed.
When the last shell is completed, design row 14, remove the work on the garter bar again, shift it 6 stitches to the right.
Push back the now emptied needles back to A (OOW).
With all stitches in the B position, make a free pass to the right, row 1 of the half shell row will be preselected, change color, continue across the pattern row as described. This yarn is far too thin but makes stitch formation easy to identify.
The last tweak eliminating having to bring any needles into work by hand when working at the start of each shape is reached. Punchcard knitters will need to punch the black squares, repeating the 24 stitch pattern 4 times in height, to a total of 56 rows.
I used two repeats side by side on the electronic as well to eliminate having to consider and choose the position option on the 930 needle bed, resulting in having the pattern centered in each 24 stitch fixed segment of needle selection. I am in the habit of using a needle tape for punchcard machines on my electronic models since I so often transition usings designs for the former in the latter. It is possible to add all knit rows or even patterned ones between shell rows. On an electronic KM with 2 carriages available, adding a FI band would be simpler than trying to manage to change cam buttons in addition to the other number of steps already involved with the slip stitch and holding combination along with moving the knit on the needle bed. Contrasting color row stripes can be programmed by adding 2 or more/ even number rows of all black squares (or punched holes) at the top of each 14-row segment of the final repeat. Reverse shaping of shells appears to not be necessary to avoid biasing on my limited tests. The proof of concept swatch:
I was too aggressive with clipping yarn ends on the left side, especially while in the process of changing colors, not ever a good idea. Automating the pattern fully on electronic models using only slip stitch patterning is possible. The length of such patterns grows exponentially in proportion to the size of the repeats. Reviewing errors in the beginning concept 
An attempt to visualize the placement of the shape variations in the finished piece using the shell motifs beginning with the shapes created in order to create a straight side edge
Redrawing the pattern for a 36 stitch test. On the left is the drawn image of the pattern, on the right the mirrored image for downloading to my machine to produce it in the desired direction. Much of the time is invested in developing and testing the final and correct image for download, the knitting that follows that is fairly quick. My repeat is 36 stitches wide, 98 rows high
COR: knit a base row in color one from right to left
COL: KCII (no end needle selection) to right, the only needles preselected will be those corresponding to the programmed black squares, the remaining will be in B position. Knit to the right.
COR: set the machine to slip in both directions. Knit slowly and evenly. All needles in work on the bed must be cleared with each pass of the carriage.
Continue in pattern across the bed, checking that all stitches are knitting off properly.
When all needles are preselected, change colors for the next set of shells. These rows create the base for the next group of shapes. If a stripe or other pattern is wanted regularly, those rows are best added to the programmed pattern itself.
The automated test swatch: 
Preserving the 3D texture relies on using yarns with “memory”, ie wool and avoiding aggressive blocking. Using thinner yarns makes the stitch formation more evident. Hard pressing, in this case, knit using acrylic yarns, flattens the fabric considerably, and often, permanently. Both the hold/slip (top) and fully automated swatches (bottom) are shown.
Isolating like modules and looking for any differences in each to prepare for a larger number of repeats in each row of shapes across the needle bed
There are several methods for securing yarn ends both during and after knitting in the final pieces using these techniques. Testing such methods on swatches is the best way to determine what works for yarn and colors used as well as our own personal preference. The pattern width may be adjusted to create considerably larger shells if desired. Punchcard knitters are limited to 8, 12, and 24 stitch repeats. For them, this would be the maximum size, including an added number of rows for contrasting color stripes, in this instance 4. 
A return to the original 14 stitch repeat, illustrating a way to begin editing for an extra row in width at the bottom of the shape and ending on 2 stitches rather than a single stitch at the top
Imagining adding increases and or decreases for shaping at sides, which in turn could lead to an evaluation of switching to entrelac approaches when creating large shell shapes for similar effects. The 3D qualities and distortions are obviously missing from these illustrations.
A Prada sweater using similar shapes 
If you are interested in any large size clamshells, and intarsia appeals to you whether in hand or machine knitting, Cheryl Brunette has thorough directions for many such shapes, including 2 videos on shell shapes Part 1, and Part 2
More online inspiration using large shapes:
from a Russian blog
a hand-knit blanket from Garnstudio 
the common illustration for shaping triangular shawls using such motifs 
Similar pattern repeats are at times also referred to as scallops, fans, or scales. A “scallop” design 
a “fan”
The “striped” repeat produces essentially the same fabric. The knit carriage may be set to slip in both directions when using it since the row of all punched holes or black pixels will knit every stitch on every needle selected while in the previous samples the cam button set to knit in one direction performed that function regardless of any markings on the design repeat. The ribber is set to knit in one direction, slip in the other. Reversing sides for cam button settings produces the same fabric 
The 
The repeat I chose is designated as suitable for the Garter Carriage. It is 24 stitches wide by 48 rows high, shown below as provided, charted in Gimp as .png for download, and tiled to help visualize how continuous repeats might line up. The image .png was downloaded with img2track to my 930, with a stretch factor of 1.0, retaining the original repeat size
Open stitches may also be joined using this method, but they would have to be hooked onto the second piece every row rather than every other, and caution should be taken in terms of skipping any stitch, as any such stitch will unravel at the end of the process unless it has been secured.
This is a long-ago demo swatch. The chevrons are shaped by holding, could be knit on any machine in any width. After the first strip is knit to the desired length, the second is joined to it as it is being knit. I generally prefer the joins with the carriage on the right and the completed strip hooked onto its left side. If the color changer is to be used, then the strip being created to join to the finished piece should always be knit on the left side of the bed in order to allow for traveling to and from the color changer every 2 rows. The image here is turned sideways, the chevrons could be used either vertically or horizontally depending on the design plans. 
The above method may be used to join fair isle patterns in order to achieve significantly wider final panels. Some artists, when no electronic models were available, would join cards in continued lengths and plan their repeats side by side to achieve large, non-repetitive images. The punchcard width markings on your Brother needle tape can serve as guides. I use punchcard repeats so often I replaced the needle tape in my 910 early on with one for punchcard models. Markings may also be seen on them for every 8 stitches 
Here a slip-stitch ruffle was joined on the left to one of my completed shawl bodies. 
and continued until I reached the point where I wanted to experiment with increases, keeping the shape symmetrical. I picked up a loop from both added pieces and hooked them onto the first empty needle on each side of the strip, essentially casting on an added stitch on each side each time, following with 2 knit rows. 
After working on my “desired shape” I tested decreases:
COR: after hooking up the next row, knit one row to the left 
The cleanest joins happen when the edges are straight to start with, above there was a movement of the edges happening because of the distortion of the fabric created by the eyelets. A light pressing if possible may also set the edge stitches, help them lie flat, and make them more visible. When working with slanted edges on the first piece this is one way to join it, taking into consideration whether any adjustment in the frequency of hooking up needs to be made. 
from the Brother Ribber techniques book 
Patterns from manufacturers: Superba manual 
on page 38 a repeat and instructions are offered for a spiral tube sock. The latter has no heel shaping, but traditional toe shaping can be added. 
Lastly, it is possible to knit socks sideways (as well as gloves), usually in garter stitch and in hand knitting. This is a crochet illustration that points to the general construction method.
I asked on Ravelry for advice or shared experiences. A possible culprit was suggested to me, and I was pointed toward the
When I tried to turn the screws marked in red I found they were loose. After I took apart the racking handle, braving far more disassembly than turned out to be needed, housing little screws and washers in separate small plastic containers along with their comrade larger parts, I found perhaps I could have reduced the effort considerably. I did not take photos during the process, as I was not brimming with confidence in the result. Enlarging a portion of the above helped me understand how parts related to each other a bit better. 
It really may not have been necessary to even remove the bracket lever. The #10 piece of metal was loose inside the machine, might simply have fallen out if I had turned the bed on its side and given it a mild shake after removing #57. This is with the piece in question in its housing where it belongs (white arrow), shown in relation to the needle retainer bar (black arrow) and screws marked with red arrows that hold it in place. 
The piece is obviously thinner than the space it lives in, so for screws to anchor it properly, a flathead screwdriver or other improvised tool needs to be inserted under it, lifting it into position and holding it in place with its holes lined up with outside of bed so screws can grip it and be tightened properly. 
a rearview with ends woven in
When the end of the first row that row is reached, as contrast color is added, stitches need to be cast on on the far left in order to keep the work on the bed a constant number of stitches. The usual method suggested is e wrapping, this is picking up from the row below. I found either method produced looser, longer stitches on the far edge 
reaching the far right: 
Such weights are made of lead. That is a concern, there are products on the market that may be used to coat them. This one is easily found in home improvement stores and online
It does a good job of weighing down those straight edges along the bumps, making the stitches easier to pick up. When rehanging those stitches, uniformly hanging the loops, not the knots along the edges involved will give a smoother join. Here a paper clip is used as the “hanger”
Lastly, a swatch ending in all knit rows. The only remaining issue is the fact that those side triangles are formed by stitches that are looser than across the rest of the piece. This yarn is thin and a poor choice, but fine for getting the technique down and beginning to understand what happens to stitches, how one needs to move from one side to the other, and what happens along the edges of each individual shape 
to consider the number of stitches required and whether the fact that other than garter stitch knit stitches are not square,
Weaving cast-on only works on machines with weaving brushes ie Brother. I tend to knit with weaving brushes down no matter what the fabric is unless using them results in problems ie the particular yarn being used has a tendency to get caught up in them.
A crochet hook could be used in place of the latch tool.
For mock rib executed on the single bed, for double rib as well, see 
Reviewing approaches to binding off with needle and yarn: working single bed is sometimes performed on the machine and is illustrated below working from left to right. It is referred to as back or stem stitch and “sew off” method, and is shared in many of the old machine knitting manuals. It is easier to achieve if after knitting the last row one knits at least 2 or 3 more rows in waste yarn to make the stitches more accessible. The knit side shows single loops in view upon completion. Dropping small groups of stitches off as one makes progress across the row may make the technique easier, helping with the placement of the other hand to hold the work. On the machine, the fixed distances between needles and gate pegs help to keep the tension even. The backstitching may be done off the machine, but maintaining even tension there may be a bit harder.
or the needle and yarn sewing method may be used. There is a limit as to the length of yarn used so as not to pose problems. Very wide pieces may prove to be a challenge, requiring more than a single yarn end to complete the bind-off. My own yarn end max limit for sewing up or off is about 18 inches
I prefer an alternative method for waste yarn scrap off, ending in place of circular or U knitting: knit the last row in garment yarn. Thread up waste yarn, and knit it at single-bed tension. Knit 4 rows on one bed, with a separate strand or even a second contrasting color of equal weight, and knit 4 rows on the opposite bed. Repeat alternating until there are more than 12 rows on each bed and scrap off. This will allow you to press the waste knitting only, and the flaps are opened up to reveal the tops of the stitches created on each bed. Finishing can then be executed as below.
