House of Hacks

Monday, May 5, 2014

How to drill holes for cam lock connectors


Description
Discover the spacing and sizes of the holes in order to use cam lock connectors in your next project. Cam connectors provide a clean and secure, but easy to disassemble, joint for boards. In this video, I provide the drill bit sizes and hole spacing for commonly found cam locks.

For a written transcript, go to How to drill holes for cam lock connectors

Music under Creative Commons License By Attribution 3.0.
Intro/Exit: "Hot Swing" by Kevin MacLeod at http://incompetech.com

Transcript

Want to learn how to drill the holes to use cam locks? I'll show how here today at the House of Hacks.

[Intro]

Hi Makers, Builders and Do-it-yourselfers. Harley here.

On a recent desk project I thought it'd be interesting to use cam locks for part of the assembly. It was in a couple areas where I didn't need huge amounts of strength and I wanted clean lines and easy disassembly. Cam locks seemed like a good solution.

If you're not familiar with them, cam lock connectors are a two part fastener that looks like this. They're used to connect two flat pieces together at a 90 degree angle. Things like the sides of book cases, or, in my case, a side support to a table top. There is a post that screws into the flat side of the first surface and slides into a hole on the end of the second surface. A cam lock slides into a hole in the surface of the second piece and locks onto the top of the post, pulling the joint together as the cam locks into place.

I have only seen them used in pre-cut furniture that's designed for home assembly, but I knew I could get them at my local home center. So I went down and picked some up. I did the next logical thing and searched around the internet to find out the hole pattern. Obviously I knew I needed several holes. I just didn't know the spacing and the sizes. Surprisingly, I didn't find anything on the internet. So I sat down to figure it out.

The home center had two types of posts: one had wood screw threads and the other had machine screw threads. I used the ones designed for wood. Both thread types came in only one size and it seemed about the same as all the other's I've seen in furniture kits. I don't know if the connectors come in different sizes or if there's pretty much only one standard. In any case, the bags for the ones I had were marked with "M6 x 45.5" for the connector bolts and "15mm x 16mm" for the cam connector. The details I present here are for these sizes.

All my bits are in imperial measurements, but the tolerances are close enough they worked just fine in spite of the metric hardware. I used a drill press for all my holes to help ensure straight holes and a good fit. If you don't use a drill press, do your best to get the holes as straight as possible.

For this project, three bits are needed: 3/16" and 5/16" in a twist or brad pointed bit and a 5/8" Forstner bit.

Use the 3/16" bit to drill holes for the posts to screw into. The depth isn't terribly important as long as it's deep enough for the post to screw in securely up to the shoulder of the thread. I found 7/16" deep worked well.

Before putting the posts into the hole, I transferred a mark to the other piece. It is fairly critical to get these holes correctly aligned as the post has to go into both of them. I didn't have any dowel centers small enough so I found a self-tapping screw in the surplus screw box with an outside thread diameter the same as my hole size. I cut it to a little over 1/2" long and set it in the hole, pointy side up. I used it to mark the center of the matching hole in the other wood. Then the post could be screwed in.

Next I drilled the holes in the end piece using the 5/16" bit. The holes need to be a bit over 1" deep. Again the depth isn't critical as long as it's long enough to go into the area where the third hole will be drilled.

Finally I drilled the hole in the side for the cam nut. Here I used the 5/8" Forstner bit. This hole is the most critical of the three. The center positioning needs to be pretty precise for the cam to engage properly. Its center is the same as the one on the edge and it's 1-5/16" from the edge. This puts the edge of the hole right underneath the top of the post. If it's too far from the edge, the cam won't engage and if it's too close to the edge the cam won't tighten against the wood.

Its depth will vary depending on the thickness of the material and where the post is relative to the surface. It needs to be about 4mm deeper than the distance the centerline of the post's hole is from the edge.

Once the holes are all drilled it's ready for assembly. The post is screwed into the first piece. Make sure to get it in straight and don't over tighten it, but get it snugged up to the shoulder. Now, the two parts just slide together. Finally, the cam is put in with the open side towards the top of the post and given a 180 degree turn with a screwdriver. If everything is done properly, it should lock down tight.

I'd recommend getting two pieces of scrap material to practice on. Once you've done it a time or two, it's easier to proceed with confidence on the main project pieces.

I'm pretty pleased with the way this worked. It took a bit to drill all the holes but it provides a nice clean joint that's secure and easy to take apart for storage or moving.

Thanks for watching and until next time, go make something. It doesn't have to be perfect, just have fun!