How to sew an easy backpack with adjustable straps
Step 1 Cut out the fabric pieces for the bag
You need two front pieces from the outer fabric and lining in the dimensions – 19 inches wide and 17 1/2 inches long from the lining fabric and 19 inches wide and 18 1/2 inches long from the outer fabric.
You also need two back pieces from the outer fabric and lining in the dimensions – 12 inches wide and 17 1/2 inches long from the lining fabric and 12 inches wide and 18 1/2 inches long from the outer fabric.
And interfacing for all the pieces, which goes without saying.
Mark two oval shapes on the outer fabric and the lining fabric for the bottom of the bag. Fold the fabric and mark as given below. Cut it out.
You also need to cut two flap fabric pieces – one from the outer fabric and another from the lining. (Instead of the lining fabric you may want to use outer fabric for this as this fabric is visible)
You also need 4 straps
For the straps cut fabric in these dimensions
2 straps – 36 inches by 3 inches
2 straps – 5 inches by 3 inches
And one extra fabric piece of the outer fabric – 3 inches by 12 inches for attaching the flap and the straps
Hardware needed – 2 sliders, 2 rectangle rings, a pair of magnetic snaps or Velcro.
Step 2 Make the adjustable straps.
Keep the long side edges of the strap pieces (right sides) together and sew with a 1/4 inch seam allowance, forming a tube.
Turn the tube right side out with whatever means you usually use. With long tubes I simply use a needle and thread method.
Turn it rightside out.
Adjust the seam to the back and press in place.
Top stitch the edges of the straps to make them firm.
Step 3 Assemble the straps.
You need to get 2 sliders, 2 square rings for making the adjustable straps.
Thread the rectangular rings with the short straps.
Insert one end of the long strap through the slider as in the picture below.
Thread the lower end of the strap with the rectangular strap.
Now turn the strap upside down; Thread the lower edge of the strap through the bar of the slider from top to bottom to the inside – see the picture to be clear.
Sew the edge across.
This is what you get.
Step 4 Prepare the flap.
Take the two flap pieces and keep them right sides together.
Sew along the edge with a 1/4 inch allowance.
Clip all alomg the seam allowance.
Turn it right side out. You need to attach a magnetic snap or velcro to close your back pack at the lining part of the flap.
Attach it from the inside of the lining – so that it will not be visible from the outside. (Actually if you are attaching velcro you should do this before assembling the flap)
Keep a washer as well as a small piece of fabric in the back where you attach the snap to give it more strength .
Top stitch along the outer edge of the flap to beautify it.
Step 5 Assemble the back piece with straps.
Keep the straps and the flap on the back piece (outer fabric piece) as in the picture below.
Keep 3 inch wide and 12 inch long outer fabric piece on top of the joint near the flap and top stitch in place. Sew along the bottom edge also keeping the straps all together for the time being.
Step 6 Make the bag body.
Sew the fabric pieces for the lining together to make a tube.
The 17 1/2 inch sides are joined for the lining bag and the 18 1/2 inch sides are joined for the outer bag.
Now attach the oval piece to the tube as the bottom edge.
Do these steps for the outer fabric as well.
This is how the outer bag looks on the back with the adjustable straps.
You now have two bag pieces – one of outer fabric and one of lining.The lining is a little shorter than the outer bag.
Step 6 Assemble the bag body.
Keep the outer bag rightside out. Keep the lining bag inner side out.
Insert the lining bag body inside the outer bag.
Now just turn the outer bag top edge to the inside and sew in place with your sewing machine.
Step 7 Attach the other part of the magnetic snap on the front of the bag.
Keep the flap closed and see where the snap should be attached.