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CONVERTIBLE SLING BAG

Go out in style with this fashionable sling bag! This triangle-shaped sling bag sports a dual pocket front and the versatile zippered shoulder strap converts to either a one-shoulder or two-shoulder carrying strap. The bag comes with two zippered storage compartments and the aforementioned mobile phone pouch pocket.

Dimensions: approximately 15″ high / 14″ wide / 6″ deep with a 40″ [1 m] separating shoulder strap; an 8” [20 cm] zip front pocket and an 11″ [28 cm] deep front pouch. [38 cm x 35.5 cm x 15 cm]

Construction Method: Turned finish – this method may be recognized by noting the lack of machine-stitching that is visible at points of assembly on the exterior side of the bag except for topstitching. This is possible by placing the material, or parts, face to face, machining and turning right-side out. It is the most commonly used assembly process. The back section has a turned-edge finish. Skiving the seam allowance pares down the thickness of leather, along the outer edge to reduce bulk and/or allow for turning. A pocket lining is used to cover the interior of the front pouch for added support and a neat appearance.

Material Used: tanned cowhide leather with corded piping; 100% cotton pocket lining.

Design Tip: Other kinds of leathers may be used for this bag design as long as you select a fairly light-weight (think 2 to 3 ounce average, 1/16 inch thick) choice such as goatskin or pigskin. There are also many synthetic choices as well as durable woven fabrics in the marketplace that may be “easier” to handle other than genuine leather. In all cases, you may have to check that your sewing machine will be able to sew through several layers of the fabric before you proceed with making up this bag.

You will need:

  • 1 pair of metal square buckles, 1” dia. [25 mm]
  • 1 pair of metal grommets, ” dia. [10 mm]
  • 1 nylon coil separating zipper, 28” long [71 cm]
  • 1 nylon coil closed zipper, 14” long [35 cm]
  • 1 nylon coil closed zipper, 8” long [20 cm]
  • 1 cowhide or garment leather skin, 4-10 oz. (approx. 8 sq.ft)
  • yd. [0.3 m] of pocket lining, 24” wide [60 cm]
  • 2½ yds. [2.4 m] of pre-cut fusible interfacing, 1” wide [25 mm]
  • 1½ yds. [1.4 m] of cable cord, ¼” dia. [5 mm]
  • 1 spool of polyester heavy-duty thread
  • Double-sided mounting tape, 10 mm. wide
  • Leather punch
  • Leather brayer
  • Leather skiving knife
  • X-acto knife
  • Kraft paper

PATTERN

Draw a rectangle and label it, A-B-C-D.

A-B = 21″ [53.5 cm].

A-C = 14″ [35.5 cm].

Square down from C and square across from B to locate D.

D-E = 6″ [15 cm].

Square across to locate F.

B-D-E-F is the base of the bag.

Find the mid-point of line A-C; label point G.

Square down from G to locate H.

A-G-H-F represents the front section of the bag.

1 from G = 4″ [10 cm].

Join F to 1 with a straight line.

2 from G = 3″ [7.5 cm].

Square 3 from 2 = 4-1/2″ [11.5 cm].

Square 4 from 3 = 3/8″ [1 cm].

Join F and 4 with a straight line.

5 from 2 = 2″ [5 cm].

6 from 5 = 4″ [10 cm] or half the desired zipper length (optional)

7 from 6 = 3/8″ [1 cm].

This is the front pocket with inset zipper.

Square down from 7 to locate 8 on base.

9 from 8 = 1″ [2.5 cm].

This is the buckle placement.

1-G-H-F is the bag front.

G-C-E-H represents  the back section of the bag.

10 from G = line G-1.

Join E to point 10 with a straight line.

Draw a 45º angle line from E; on this tangent line measure 1″ [2.5 cm] from E.

Arc a curve to pass through this point and lie on lines E-10 and E-H.

Measure the length of 10-E + half of B-D.

Measure this distance from 10 to curve at E to H (and beyond) to locate point 11.

Join G to 11 with a straight line. Square from this line (12) to blend smoothly into curve at E.

Square from G a curve to meet point 10.

13 from G = 2″ [5 cm].

square 14 from 13 = 1″ [2.5 cm] for the grommet placement.

G-10-E-12 is the bag back.

Draw a rectangle and label, H-I-J-K.

H-I = 1-F.

Square down from J and square across from I to locate K.

H-J = half of B-F.

M is the midpoint of line H-J.

Join M to K with a straight line.

For the front portion of the gusset, round off the point at K with a curved arc (as shown).

Square at M on line M-K to line H-M to locate N.

N-M-K-I is the gusset of the bag.

Draw a square and label O-P-Q-R.

O-P and O-Q = 6″ [15 cm].

This is the collar ring (neck) for the bag.

Trace off the following sections on pattern paper:

BASE = F-E-D-B.

COLLAR = O-Q-R-P.

SIDE GUSSET = N-M-K-I.

BACK = G-10-E(rounded)-12.

Fold pattern paper in half and align centerline (G-H) on foldline:

FRONT = 1-G-H-F.

FRONT POCKET = 3-2-H-F-4

Add seam allowance to all pattern pieces except for top of gusset pieces and cut out pattern.

CUTTING

Tip: Use a rotary cutter or X-acto knife, along with a metal ruler to cut leather.

         Remember to “flip” pattern pieces to mirror image.

FRONT – cut 1X leather

FRONT POCKET – cut 1X leather

BACK – cut 2X leather (mirrored)

FRONT GUSSET – cut 2X leather (mirrored)

BACK GUSSET – cut 2X leather (mirrored)

NECK COLLAR – cut 1X leather

SHOULDER STRAP – cut 2X leather ( 40” long x 3” wide) [100 cm x 7.5 cm]

BUCKLE STRAP – cut 2X leather (10” long x 3” wide) [25.5 cm x 7.5 cm]

POCKET LINING – cut 1X pocketing

PIPING TRIM – cut 2X leather (approx. 24” [61 cm] long x 1½” [4 cm] wide

ASSEMBLY

For all pieces: Bevel the seam allowance with the leather skiving knife on each leather piece to reduce any bulk when turning.

a) Small Parts Preparation

Making Leather Piping with a Cord Filler – To make up, cut 2 strips of leather to desired length and twice the width of your filler, plus seam allowance. (I used a 1/4″ cable cord inside the piping as a filler).

Take advantage of double-sided seam tape. One piece on the edge, and one piece on the center. Remove the release paper and stick the cording on center without any twists. Here again, this is the real trick to making up piping trim successfully (try to do this some other way and see what happens). Then, fold the leather straight over and press the edges together.

Now lets sew it together. A cording foot is one of my favourite tools for this job when I make it in leather but you may use a roller foot as well. The leather and filler are controlled by the seam tape as they feed between the foot and the guide for a straight tight seam. Set piping aside.

Making Buckle Strap – To make up, cut 2 strips of leather to desired length and twice the width of the inner diameter of your buckle, plus seam allowance. (I used a 1” diameter metal buckle with a prong).

Once again, make use of the double-sided seam tape. One piece of tape on each long edge, and fold each side towards center. Remove the release paper and stick the wrong sides of the leather strip on center without any twists. Press the folded edges with a nylon hand brayer to set the fold.

Topstitch around the perimeter of the strap. A roller foot is my favourite tool for this job when I make it in leather. Use a leather punch to make a hole in the leather for the buckle’s prong. Attach buckle into place and secure it by stitching across the ends of the strap. Repeat for second buckle and set aside.

Make Shoulder Strap – To make up, cut 2 strips of leather to desired length and twice the finished width of inner diameter of the buckle, plus seam allowance. Bevel the seam allowances with the skiving knife on each leather strips to reduce any bulk when turning.

Cut 2 lengths of narrow Knit-fuse® interfacing (I used pre-cut tape sold by the roll) equal to the length of the leather straps. Iron on fusible interfacing to back of leather strips on one side of center.

I know this is contrary to what you have heard of leather care yet you CAN heat press leather. Now, this may seem like the exact opposite of good care treatment, but “fusible knit interfacing” that tailors and seamstresses use, will add body to thin layers without stiffening the leather. It has an extremely thin layer of dried adhesive on one side of it which you activate with heat without much pressure.
Now here’s the part that the leatherworks will get up in arms about — fuse some of the Knit-fuse
® to the leather, meaning you stick it under a press (like a 30″ long iron, with the option of using steam), sandwiched in-between layers of brown paper (I used brown kraft paper aka parcel wrap). So the sandwiched layers are: bottom of the press, then brown paper, then leather (FACE SIDE DOWN), then fusible interfacing, then the top layer of the brown paper, then the top of the press. The sandwich is heat-pressed for say 10 seconds (you might want to trial-test your timing on a scrap piece). You can also do this operation using a hand-iron but you will need to pin the leather to an ironing board to prevent it from shifting, and use a low-setting on your steam iron. Ok, that said, I wonder if anybody out there wants to scream at me that applying heat to leather is not advisable? Do remember that the grain side of the leather is not ever touching a hot surface — just the back side gets the heat. Although this leather isn’t thick, do not rest your iron for more than 10 seconds at a time, keep it moving in a up-and-down direction. (That is why the 30” press is a better option; the leather will not move). Most importantly, allow the fixed leather to cool down completely before going to the sewing machine.
This operation is done frequently in mass-production, and it does not damage the leather, and the fusible interfacing adheres marvellously to the wrong side/suede side of the leather, lending just the amount of body that one would want to stabilize the shoulder straps to apply the long zipper.

Make use of the double-sided seam tape to attach the long separating zipper, with one piece of tape on each long edge of the zipper tape. Allow approximately 10 inches from the end of each leather strip and align zipper to edge of leather. Remove the release paper and stick the zipper, FACE SIDE UP, to the FACE SIDE of the leather strips which has the applied interfacing. Sew in place, using a zipper foot attachment. Turn in the sewn edge and press the seam with a nylon brayer to set the fold. Use more double-side seam tape to hold the rolled seam down.

Next, turn in the seam allowance on the opposite edge of the leather strap and press it down using the hand roller and double-sided tape.

Fold the leather in half lengthwise, with wrong sides together, and align the turned-edge along the zipper teeth. Use double-sided seam tape to keep the layers together. Press with hand roller to neaten the turning.

Topstitch around the perimeter of the shoulder strap, using the roller foot attachment for this job when making it in leather. Use a leather punch to make several evenly-spaced holes in the leather, on the free end of the shoulder strap, for the buckle. Repeat this method for other side of the separating zipper and set aside.

b) Front Pocket Construction

Cut 2 strips of fusible interfacing tape equal to the width of the front pocket piece. Using the same procedure described above for heat pressing leather, iron 1 strip of fusible interfacing to the top edge of the front pocket; and the second, over the zipper opening on the back of the leather.

Mark the placement of the zipper opening onto the back side, using tailor’s chalk. Carefully cut out the outline of the opening, with the aid of a metal ruler and sharp X-acto knife.

Align the zipper, FACE SIDE UP, from the back of the leather so that the zipper is centered in the cut-out window. Use double-sided seam tape to secure the position.

Topstitch around the outline of the opening to attach the zipper, using the roller foot attachment.

Layer the front pocket and the pocket lining, with FACE SIDES together, matching the top edge of the pocket. Stitch lining in place. From FACE SIDE of lining, understitch lining to leather.

On the wrong side of the leather, lightly score a line parallel to this seam, 1-inch away [2.5 cm]. Fold leather on the scored line and turn under facing. With FACE SIDE UP, edgestitch along top of folded edge of pocket. Machine-baste sides of front pocket with lining. Set aside.

c) Gusset Construction

Take 1 front and 1 back of the gusset pieces and lay them with FACE SIDES together. Stitch center seam and press seam open with hand roller. Grade one of the seam allowances and fold the wider seam allowance over the graded one. With FACE SIDE UP, edgestitch along the center seam to catch the seam allowances underneath the layers. Set aside.

Take the remaining pair of gusset pieces and attach closed zipper in the center seam. Do this by, taping the zipper, FACE SIDE DOWN to the center seam on the FACE SIDE of the leather and from the bottom of the seam. Sew in place, using a zipper foot attachment. Turn in the sewn edge and press the seam with a nylon brayer to set the fold. Use more double-side seam tape to hold the rolled seam down. With FACE SIDES UP, topstitch on both sides of the zipper to secure, using the roller foot attachment to prevent drag on the leather. Set aside.

d) Back Construction

Take the pair of back pieces and lay them with FACE SIDES together. Stitch center seam and press seam open with hand roller. With FACE SIDE UP, edgestitch along both sides of the center seam to catch the seam allowances underneath.

On the back of the leather, mark the placement points for the grommets. Iron on a small square of fusible interfacing at these 2 points, as directed above, to stabilize the area.

Using a leather punch, make a hole at each location (if the hole is too small for the stem of the grommet, carefully clip into the outline of the hole to release it slightly). From the FACE SIDE, push a grommet into each hole and secure, following manufacturer’s directions.

e) Body Construction

Lay the Front Pocket, FACE UP onto the Front section of the bag. Match the bottom corners of the Front Pocket to the bottom corners of the Front (at point F) and align the raw edges at the sides to create a slight ease at the top of the pocket (the top edge of the pouch will bow slightly). Machine-stitch the Front Pocket to the Front piece.

With FACE SIDES together, layer the Base piece on top of the Front section and match the long seam.

Machine-stitch the seam and press seam open with hand roller. Grade the seam allowance of the Base piece and fold the wider seam allowance over the graded one. With FACE SIDE UP, edgestitch along the seam on the Base piece to catch the seam allowances underneath the layers.

With FACE SIDE UP, align and match piping trim to outer edges (sides) of the Front-Base section.

Machine-baste in place.

With FACE SIDES together, align and match a gusset to each side of the Front-Base section. The gusset with the zipper is located on the right-hand side of the bag. Sew each seam following the stitch line of the piping trim. Clip into the seam allowance if necessary to release any puckering of the seam

At top of each gusset, fold the gusset, with FACE SIDES together, and sew across top with a slant 1/4-inch seam allowance (this seam will be hidden inside the bag).

Three sides of the bag are complete. Once again, making use of the double-sided seam tape, tape the open edge of the partially completed bag. Remove the release paper and stick the wrong sides of the leather edge (seam allowance) toward the inside of the body, without stretching the leather (you may clip the seam allowance if needed). Press the folded edges with the hand brayer to set the fold.

Repeat this step on the back section. You will definitely need to clip the curved seam allowance at the top of this section and at the corners. (I often find it easier to use shorter lengths of tape on curved seams for more control when turning the leather).

Now, carefully match and butt the folded edges together (FACE UP), align the seam along the outer edge of the back section (I find paper clips or clothespins are ideal for holding the layers together).

Before edgestitching the layers together, slip the shoulder strap between the 2 grommet holes, and center-align the shoulder strap over the centerback seam with the zipper FACE SIDE UP. Machine-stitch the curved seam to the Front section, tucking in the gusset tops on each side.

Along the bottom edge of the back section, locate the placement positions for the buckles. Slip the bucket strap between the 2 layer at each location (the buckle prong should face up). Edgestitch the outer edge of the bag along the sides and bottom.

f) Finishing

Make up the Neck Collar – Start by, taping 2 opposite edges on the wrong side of the Neck Collar piece. Remove the releasing paper and turn under the edges (seam allowance). Press the folded edges with the hand brayer to set the fold.

With FACE SIDES together, fold the Collar piece in half lengthwise and sew up the raw edges. Press the seam open with the hand roller. Turn Collar piece right-side-out.

Now, fold the Collar piece width-wise, with FACE SIDES OUT, and align the folded edges together. Tape open side close, if desired. Edgestitch along the turned edge to create a collar ring.

Slide the Neck Collar onto the Shoulder Strap and pull it down to the end of the Shoulder Strap (as shown in the front view of the bag) to cinch up the top of the bag. Alternatively, you may leave the Collar off and allow the top of the bag to lie flat (as shown in back view of the bag).

Make a Grip Handle – Construct a leather “cord” by folding a scrap piece of leather over a cord filler and stitch it as a leather cord. Thread each end of the leather through the grommet holes. Knot each end of the leather cord to prevent the grip from sliding out (do this by going into the cavity of the bag via the side zipper opening).

Attach the loose ends of the Shoulder Strap to each of the buckles. (if you plan to adjust the Shoulder Straps often, you might want to reinforce the holes in the strapping with metal eyelets).

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