Thursday, July 8, 2010

Sticking Together

Glue Ups
Glue ups are the easily the most stressful time of any project. Everything needs to fit firmly without the slightest gap. You need to glue all the joints (often on both sides) and apply all your clamps. And depending on your glue you have 10-20min to do it. If you get stuck half way it might mean pulling the joints about, scraping off the glue, and restarting. Glue ups also seem to be the time I hit my head on machinery, trip on a clamp or any other assortment of stressful moments.

The Myrtle Table
The first step is assembling your four square nicely jointed boards for a dry fit. For this project I used titebond III glue.

I like to work small sections at a time. So I began by gluing boards into pairs.

Now with only 3 sections I glued the fiddleback boards together with sash clamps and F clamps to hold the boards level.

The final stage was adding the 40mm edging pieces.

Added stress:
This glue up was complicated by some unforeseen problems. The lid on my glue pot (an old mayo bottle) came off twice. First dumping ~70ml of glue onto my project. Then ~150ml onto the floor. Stress. Then one of my joints didn't work and it feel apart. This was probably related to not extending the period of clamping in light of the cold weather. Possibly (hopefully not) related to old glue.

Gluing Tips
  1. Always do a dry a fit. Always. Put everything together without glue and make sure it fits firmly with out a slight tap or pressure.
  2. Have all your clamps, cawls, and protective scraps at the ready.
  3. You can always use more clamps (usually you'll need a clamp at least every 30cm.)
  4. Understand your glue. Wood glues (eg. PVA) absorb into the wood and cross link. Zero gap is good for these glues. Epoxies can bridge small gaps and act as space fillers. Hide glue is warm water soluble which has advantages and disadvantages.
  5. Glue up in stages. By gluing small sections together, and then joining those sections, you'll reduce the amount of wet glue surface at any one time and reduce the number of clamps needed.

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