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We’ve all seen this popular little clasp. It’s the go-to closure on everything from casual backpacks to high-end handbags. As with anything that includes moving parts, and may involve tools to install, it can seem intimidating. You might opt instead for a simple button closure, a snap, or simply hope a flap stays put on its own. Here’s the secret about this two-part lock: it’s actually quite easy to put in. The key is confirming the placement of both halves, but that’s just a matter of careful measuring and double-checking. So what are you waiting for? On the next project that features a flap or strap to secure – go pro with a tuck lock.

This tutorial shows you the basic steps of installation. As we mentioned above, the other hugely important component is marking. Most patterns/tutorials will include directions for where and when to insert the closure. It is traditionally installed toward the end of the project’s steps along the finished edge of a flap designed to lay flat against a base unit.

As with all specialty locks and clasps, be extra careful with your measuring and marking for the two halves of the closure. As you’ll see below, we recommend inserting the top first (the actual pushing mechanism), then clicking the top into the base to double-check the placement for the opposite half.

If the placement is not accurate, the flap (or strap or whatever you hope to attach) will not lay flat. The other reason for extra confirmation is the fact that both halves of the lock require cutting small holes in your finished project! It’s pretty hard to cover up holes in the wrong place; it usually means a complete re-do.

Do you love the bag you can catch a glimpse of in our sample photos? It’s our Slim Mustang Messenger Bag – casual and fun for anyone!

The parts of a tuck/push lock

A complete tuck lock has four parts: two for the base and two for the top.

The base consists of a washer and a base plate. The top consists of a spring button and a pronged bar.

The top edge of the spring button has a gap, which is how it slips onto the edge of the finished flap or strap. The pronged bar (careful, those prongs are sharp) slips through side holes on both the front and black plates. Bending over the prongs onto the back of the flap/strap secures the unit in place.

The base plate also has sharp prongs to pierce the fabric against which it will sit, usually the body of the bag/purse. The washer than slips over the prongs, and as above, the prongs are bent down to hold the base in place. You’ll notice the washer has a center “trough” – the prongs are designed to lay in this trough. When crimped properly, this allows the back of the base to be flush.

Even with all their matching elements, one of which is a moving part, these locks are surprisingly inexpensive. Most of the online and in-store options we looked at started at just $3.00 – $5.00. For a few extra dollars, you can give your project a super pro look.

Dritz® recentely expanded their line of locks, which makes this closure option much easier to find at local sewing and craft stores (in-store and online). We also spotted a nice selection online, including several decorative styles, from Tandy Leather. When searching online, be aware that different sources refer to this notion by different names. The most common are: Tuck Lock, Push Lock, Press Lock, and Thumb Catch.


Gather your materials. In addition to the lock itself, you’ll also need a pair of sharp scissors or a seam ripper or an awl, a marking pen or pencil, a small flat head screwdriver, and a soft hammer.

Tuck locks are heavy and are therefore meant for thicker, heavier materials. There are not the right choice for a lightweight project. The layers of fabric into which the lock is being inserted should be substantial on their own, such as layers of canvas, interfaced cotton or even leather. But, if you’re concerned, you can also add one or more squares of a mid-weight fusible interfacing behind each half of the lock to provide extra stability.


  1. As mentioned above, most patterns will include directions for when and where to place the closure. Measure accordingly to find your insertion point(s).
  2. Slip the spring button into place and mark the two side holes. In the photos below, the base half is simply sitting on the fabric; it hasn’t yet been inserted.
  3. You can certainly insert your marking pen or pencil into the holes to create a mark, but it’s actually easier to use the pronged bar to make indents. Place the prongs of the bar into the side holes and push down hard enough to create an indent.
  4. Pull away the top half to reveal the marks. Use your awl, sharp scissors or seam ripper to open up the holes. We prefer an awl.
  5. Slide the spring button back into place, lining up the holes, and insert the pronged bar from front to back.
  6. Using the top of a screwdriver, bend both prongs towards the center. Use a soft hammer to further flatten them into place.
  7. Slide the two halves of the lock together. Place the flap/strap into position onto the base portion of the project. Pin the flap/strap to secure it. You should already have some basic measurements for the base of the lock. But to confirm placement, with the flap/strap secured, press the base prongs into the fabric. As above, your goal is to push hard enough to create indentation marks in the fabric.
  8. Not to be a nag, but this is the second point at which you should double and triple check your placement. Make sure the flap/strap is still laying completely flat and and perfectly straight.
  9. Pull away the lock to reveal the marks, and open the holes with your favorite tool.
  10. Insert the prongs of the base plate through the holes from the front to the back. Flip over the project. Slip the washer over the prongs. With a flat head screwdriver, fold both prongs down towards the center so they lay completely flat within the little center trough. Hammer down to further secure with the soft hammer.
  11. You could also crimp with pliers, but you should cover the closure with a cloth to avoid marking or bending the metal.
  12. Your tuck lock insertion is now complete.

If you like this closure, you may also enjoy our tutorials on How To Insert a Magnetic Snap and How To Insert a Twist Lock.

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Patricia Yardley Dearden
Patricia Yardley Dearden
2 years ago

Is anyone else concerned about the back side of the flap where the pronged bar is inserted and bent? The prongs, even though bent fully could catch on something. I have been trying to figure out how to hide this part in the back

Liz Johnson
Liz Johnson
2 years ago

Hi Patricia – This tutorial is focused mostly on the steps for inserting in general – where the locks go will depend on the project on which they are being used. In the sample above, we show putting them on the bottom of a long flap as the final step in the construction process, so – yes – the prongs do show on the back. They can be crimped quite flat and smooth, so on this project we didn’t run into any issues with snagging. In a “bottom of the flap” situation, this is quite common – and for this… Read more »

6 years ago

Another great tutorial. Thank

Another great tutorial. Thank you!

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