Wednesday, October 19, 2016

Drawbore, not so boring!

For my next project, which is going to be a big outdoor table, I've decided to try something new; drawboring. I've wanted to try this for quite some time now and I'm finally biting the bullet and going for it.

What is Drawboring?

Drawboring is done in a mortise and tenon joint and is similar to a pegged mortise and tenon joint, but instead of simply drilling a hole through the mortise and tenon, and inserting a peg, the hole drilled in the tenon is offset by about a 1/16 of an inch. This is done so that, when the peg is hammered through the joint, it draws the joint together very firm and creates a very strong mechanical joint. In fact, some people don't even use glue with a drawbore joint because it is so strong, but I think glue is still a great idea, you know, just in case.

What do I need?

In order to create a drawbore joint, you don't necessarily need anything special, but I will recommend getting getting a set of drawbore pins. I ordered a 3/8" pin from Lee Valley to match the size of the drawbore pegs, or dowels, I am going to use. A drawbore pin is a tapered piece of smooth steel that, once you have the joint prepared, you push the drawbore pin into the joint to "loosen" the joint a bit so the peg or dowel will be able to make its way into the joint without completely breaking the peg.

How to?

So, how do you make a drawbore joint? Christopher Schwarz has a really good article on drawbores that I suggest you check out for some great details. If you are, like me, more of a visual person, Paul Sellers has a good YouTube video on his channel. There are several others that have examples of how to make a drawbore joint as well.

The basic premise of the drawbore is actually pretty simple. First, make a standard mortise and tenon join, nice clean joint, firm fit, etc. Next, disassemble the joint and drill a 1/4" or 3/8" hole through the side of your mortise joint. I suggest clamping a scrap piece to the back of the mortise so you don't have a blowout on the back side; always start drilling on the show side so it stays nice and clean.

Next, put the joint back together and insert a brad point drill bit the same size as the hole you drilled. I prefer a brad point because it has a nice sharp tip on it that will give you a crisp center mark. Insert the bit into the hole that was drilled in the mortise and give it a light tap to make a mark on the tenon. Do this for all joints.

Once you have done that, take the joint back apart and locate that tick mark you just made. Now, make another tick mark about 1/16" towards the shoulder of the tenon; that is key. If you go the wrong way, you will actually loosen your joint. Next, drill a hole through the tenon on that mark closest to the tenon shoulder. Once all those are drilled, reassemble the joint and use your drawbore pin and carefully push it into the joint to make way for the peg, then remove the pin.

The last thing to do is to take your peg or dowel and taper one end of it so that it can get into the joint without getting hung up. Put glue on your mortise and tenon joint, put some glue on the tapered end of your peg, and carefully drive the peg into the hole until it comes out the backside of the joint. You now have both a mechanical and a chemical bond in your joint with virtually no way to get it apart and should last a lifetime.

Final Thoughts...

So, that is the quick and dirty of the drawbore joint, I will provide a little more visual elements when I get to make the joints for this table. In the meantime, check out the resources above or just do a Google search for "drawbore joint" and you will get a lot of material. I suggest giving the joint a try; it is a very strong joint and also adds a nice design element to your piece. You can use all different types of shapes, sizes and colors of pegs that help your joint standout. Experiment and have fun with it!

Monday, October 17, 2016

Office Desk Build (Final)

In Part 2 of the Office Desk build, I covered the joinery process for the base, which was all mortise and tenons. In the final part, we sort of put a lid on this project by putting the top on and going through the finish.

Top Construction

The tops finish thickness will be 3/4" so I started with 4/4 rough cherry and milled it down. As you may recall in the Part 1 post, I had already laid out what pieces the top would come from. I do find though, that you really don't make that final decision on which pieces go where until you've run the pieces through the jointer and planer and see the true grain patterns. 

The milling process is pretty standard stuff; start with the jointer, get one face flat, then use that face against the jointer fence to get one edge straight and square to the face. Then, over to the planer to get the pieces to their final thickness. Once that is all done, I lay the pieces back out to get the best "show faces" and grain patterns that are most appealing to me.

This pattern was the one I liked the best, so once I have it the way I like it, I put a witness pattern across the pieces so I know which board goes where during the glueing process. Once the glue-up is done, I use my Lee Valley bevel up smoother to get rid of mill marks and any glue residue on the top.

Shaping the Top

While thinking through the design of this desk, I really didn't want to just have a plane square top. I wanted the top to be a little different, a bit more inviting and have a nice look to it. What I came up with was to make the front edge have a concave curve to it. I felt that, this way, you could really get your chair up close to the desk, and have a natural place for your arms to rest nicely. Here is that edge:

Once I formed this edge (on the bandsaw by the way), I used my Lee Valley spoke shaves to create a rounded under bevel on the bottom edge of this curve, which you will see in the finished pictures below. I thought this would be a nice details and trick of the eye and, honestly, I was just playing around with ideas at this point and, since the piece is for me, I can do that.

Finish and Finished Product

The finish on this piece follows the principles I try to usually follow, keep it simple and natural looking. So, for this piece I opted for a Tung oil finish, about 3 coats then a wipe-on polyurethane over that (after letting the oil set for a couple weeks to fully cure). The wipe-on is an oil based, cut 50/50 on the first two coats then about 75/25 on the last two coats. Very light sanding in between coats to remove dust and nibs. I then used 00 steel wool with some furniture wax to rub it out and then buff it to a nice smooth finish. 

Here are a couple photos of the finished product, the first one shows that under bevel on the front edge of the top.

Finished product:

Lessons Learned - What's Next?

As with anything, I like to learn something from a project, whether it is a technique or design element. On this project, I hand chopped my first mortises, which was fun, but a lot of work. I don't think I could have reliably done it with a machine so I was "forced" to learn this method. Second, if I re-think the design, I think I would curve the front apron on the base to look similar to the curve on the top; I think that would have been a nice design element and made the desk even more inviting; maybe next time.

My next project is going to be an outdoor dining table for a friend of mine who recently bought a house. This table will be made from white oak, which is very reliable for outdoor furniture. Check back in, or subscribe to the blog to get updates on this beast of a table!