March 14, 2010

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Failure of finger joints on a closet rod

March 9, 2010 By Al Navas 4 Comments

The setting: A nice, quiet dinner with a little music in the background. A wonderful meal on the table, fresh out of the oven. And then, a terrible sound, as if a small avalanche of snow is falling off the roof to the deck, and onto the ground below.

Sandy and I looked at each other, nodded as if saying to each other “…could be the cat in the living room…” Sandy actually said it. We continued eating our nice meal. Forward three hours, time for bed, time to put some clothes in the hamper in the closet. The entire left wall of clothes is on the floor, the result of a failed oak rack – the failure occurred at the finger joints:

Failed finger joint.

Here is the interesting part: Once opened, the joint showed no evidence of glue ever having been applied on any surface:

Failed joint exposed.

How could this joint have survived the weight of two huge, fully-loaded shoe racks, plus the weight of heavy clothes? Even more amazing: This part of the rack, about a 3-foot span, was held in place by less than 1/2-inch of a very small screw actually in the wood. I remember putting up the rack in a hurry, as a permanent installation at least seven years ago, and not even wondering about this deficiency…wow!

The repair: I ripped a 1-1/2 inch wide strip, 1-inch thick piece of white oak, rounded all four corners, and installed it using T-straps with three screws to the top part of the rack. The screws securing the new rack are just over an inch into the white oak. I think this repair is likely to last a good while longer than the original.

— Al Navas

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Filed Under Blog, Finger joints, Joinery Tagged With failure, finger joint, joiner, rack

I cheated on my knife

March 5, 2010 By Al Navas Leave a Comment

I cheated today (by the time you read this, it will be tomorrow). I cheated on my knife. And I don’t regret it…Shouldn’t I feel guilty? Or should I feel sad? As a matter of fact, I am happy.

If I have but a few pins to make to pull a joint tight using the drawboring technique, I use a good, sharp knife, or a sharp chisel, to create the tip. It is this tip that allows the pin to snake through the offset holes in the tenons:

I use either chisel or knife to prepare the pins.

Now, the cheating part: Faced with preparing upwards of 20 pins, including a few spares, I scoured the shop until I found an obvious solution – an electric pencil sharpener:

Pencil sharpening technology to the rescue!

I found out that oak is very hard on electric pencil sharpeners. The electric version would not run at all after doing about 12 pins. I scoured the shop again, looking for something that might work. Back to very old technology, the trusty mechanical sharpener – I felt like I was in grade school again:

Older technology proves more reliable...

Using old and modern pencil sharpening technology I was able to finish preparing the pins in a fraction of the time I allotted. The electric model gets a reprieve from the trash can, as it worked fine again after the motor cooled off; who knew these actually have thermal protection?

Is this more than two flinks of pins?

I now have a nice bunch of pins, ready to do their drawboring thing on some mortise & tenon joinery. Whew! Thank-you, pencil sharpeners! Now I have a new question: What is a group of pins called? Is it a gaggle of pins? Or would a group of 12 pins be called a flink?

This is the last time I cheat on the knife – honest! Why am I taking such drastic measures? Because I found a much better way to prepare the pins!

— Al Navas

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Filed Under Blog, Drawboring, Joinery Tagged With drawboring, Joinery, pins

Readying the drawboring pins, and applying finish to the dust cover

March 4, 2010 By Al Navas 4 Comments

As I stepped out of the shop, I noticed the temperature gauge in the shade, on the wall of the wooden shed:

The thermometer caught my eye.

I had to look. Confirmed! I might be able to get away with spraying some lacquer today. The temperature was just above 40°F:

The first time over 40°F in weeks!

In the shop, on the outer wall to the finishing room, the thermometer has held between 66°F and 68°F for the last several weeks:

Master thermo-hygrometer, on finishing room wall.

The remote unit, near the West wall, and on the lumber rack, showed a slightly lower temperature, but still acceptable to spray the finish:

Remote thermo-hygro, at lumber rack.

In the finishing room, with all the equipment set up and ready to go, I started adjustments on the spray pattern, and air and liquid flow – I like to use craft paper as the target to make the adjustments:

Adjusting air and liquid flow, for optimum spray pattern.

During the Winter months I use a small ceramic heater in the finishing room; I use it to keep the temperature at 73°-74°F. It is powerful enough to keep the temperature in the room at 73°F with the 2,200 CFM exhaust fan running. In Winter I am typically limited to about 12-15 minutes of spray time before the temperature in the open part of the shop drops several degrees as the make up air comes in through a window. I should have waited until tomorrow, or the day after, to spray, as the outdoor temperatures will be in the high 40s; but why not today? Aw, heck, just get it done!

Following a short session spraying the lacquer, I moved on to preparing the pins I will use in drawboring the joints. I found a huge amount of oak dowels at the local home center, and proceeded to select those with the straightest grain (I don’t own a plate, to make my own pins). To minimize measurement errors, I decided to use one piece of dowel, pre cut to 2-3/4 inches, to measure all the others:

Measuring drawbore pins.

I have been readying the band saw for a presentation on resawing lumber to our Guild next week; as a result, the guides and blade are off the 17-inch machine. Why not use the Kenyon replica dovetail saw (made by Mike Wenzloff) to cut the pins to size? Of course! That made sense:

Cutting pins, using dovetail saw.

Some people prefer to cut with the dowel vertical to the workbench:

Another way to cut the pins.

I had a great day in the shop. The outside temperatures and the sunshine have been a welcome addition to the time spent in the shop. Have you:

  • Been able to do much work in your shop, or is it too cold?
  • Applied any finishes during the cold Winter months, or are some projects waiting for warmer weather?

Drop me a note to let me know about your time in the shop during the last several cold weeks.

— Al Navas

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Filed Under Blog, Finishing, Joinery, Mortise, Tenon Tagged With dovetail saw, drawbore pin, finish, technique