2009 February — Sandal Woods

February 23, 2009 By Al Navas

The full-size table: Time for dry fit of the base

I took off a little time, to investigate the best ratio of liquid resin to catalyst when using Unibond 800 glue (the liquid part). It turns out that 10:1 by weight worked best; and, best of all, this was confirmed by Darryl Keil, at VacuPress. The normal working range for Unibond 800 is 7:1 for a “fast” reaction (translation: shortest open time and quickest set times); a ratio of 12:1 results in a “slow” reaction time (longest open time before applying clamping pressure). As I understand it, the “ideal” ratio is 10:1.

Using a 12:1 Unibond 800 liquid-to-catalyst ratio, with 2-inch thick machined walnut boards containing 7 – 9% moisture, and ambient temperature of 75°F, I managed to create some glue-ups that failed (that is, open up slightly on one edge). Since it was the week-end, and I could not access the folks at VacuPress, I decided to try laminations using 10:1 Unibond 800-to-catalyst ratio.

In the context of my work, all this means that in this case the 12:1 ratio was not the optimal ratio. Based on my results, I suggest that readers try the mixing ratios that give them the best results. I cannot tell why a ratio of 12:1 did not work 100%; but I know that in this case the 10:1 ratio worked great.

I am happy to report that no failures have resulted when using the 10:1 Unibond-to-catalyst ratio. Therefore, I decided to proceed to machine the mortises in the legs.

In this photo I use the tall stand I made some time ago, to allow machining the tenons on longer boards, such as required for this table; it worked great, with minimal vibration, by simply clamping the stand to the workbench:

I will use this stand on the workbench when I make the stand-up desk; that piece will require aprons close to 60 inches long.

Once the initial setup is complete, machining the mortises is trivial. But it is important to keep track of which leg goes in which position:

I prefer to always check for square during dry fit. It is much easier to make corrections at this stage, prior to gluing up; it is also a good preparation for clamping strategy:

The longest parallel clamps I own are 48-inch Besseys. As a result, I had to purchase some Bessey K body clamp extenders:

In case something goes wrong – and sometimes things happen – I like to have a spare leg. It is time well spent:

Next: Since the table top is already finished, I will glue up this base, and prep it for the finish.

Filed Under: Blog, FMT Pro, Leigh jig

February 15, 2009 By Al Navas

Announcing the February 2009 drawing from Sommerfeld Tools

I am pleased to announce the February drawing / giveaway from Sommerfeld Tools. This month we will give away the Special Profile 4-inch mitered molding router bit:

One lucky winner in North America (sorry – cannot ship outside N. America at this time). From Page 18 of the Sommerfeld Catalog:

Before now you had to pay high, custom-tooling dollars to get this elegant look on a mitered raised panel. After you’ve made your first set of doors with your new mitered molding bit, your work will be the admiration of all your woodworking friends.

We advise using Sommerfeld’s Tongue and Groove Cabinetmaking Set with this bit to make your mitered doors. For those of you that don’t have our tongue and groove set, we have the new pro set shown on page 17, which includes all 4 bits needed to create your mitered raised panel door.
The center-point turning of all our bits ensures that this extra long bit (4“) is perfectly balanced with no run out to produce professional quality cuts.
We advise cutting 3” wide stiles and rails for building your mitered raised panel doors.
Detailed instructions for making mitered raised panel doors (are) included in the Cabinetmaking Made Easy DVD.

To register for the drawings, send me an e-mail to sandal_woods@bbwi.net with your name and full address; I cannot accept your entry if it does not have all the information. And please remember that if you have registered for the monthly drawings before, you do not have to register again.

Good luck to everyone!

Filed Under: Blog, Shop tools

February 12, 2009 By Al Navas

The full-size table: Walnut legs

The table top is done, and now my attention turns to the base: Milling and glue-up of the walnut legs, and milling the quarter-sawn white oak for the aprons. In this post I illustrate how I go about gluing up the legs once the walnut is milled to rough dimensions.

Preparation for this glue-up is essential, as the following are mandatory for success:

A glue that will not creep, and also provides a rigid, gap-filling glue line – I prefer to use Unibond 800, a two-part urea resin glue.
Have a good clamping strategy – and plenty of clamps on-hand, as they will be needed in order to get a good glue line. I am glad I did not use the vacuum bag, as a lot of glue is squeezed out during the glue-up, as you will see.
All materials should be stored in an area kept above 70°F, to ensure proper curing of the Unibond 800. In my case, this means the finishing room; I can keep it at temperature with a small ceramic heater.
Although the two parts of this glue system can be measured by volume, the better method is do it by weight – therefore, a good, accurate balance is needed for this. I have a little electronic balance accurate to 0.1 grams, which is adequately accurate for this job – and it cost about $100 a couple of years ago.
Proper mixing of the part-part system is required, until it is smooth and all clumps of the powder catalyst are dissolved/dispersed in the liquid resin.
I like to use a rubber roller to spread the glue evenly on all surfaces. This is a brayer, which is typically used to apply printing ink or paint to a printing plate; it is available at craft supply stores.
Take your time! One of the nice features about Unibond 800 is its long open time. So, relax, prepare a sufficient amount of glue for the job at hand, and proceed methodically.

Now, a few photos to illustrate some of the things I mentioned above.

Once everything is ready (clamps, milled boards, plastic sheets under everything, etc.), I proceed to weigh the Unibond 8700 components, and to mix thoroughly in a plastic beaker/measuring cup:

I pour an amount onto the surfaces, and proceed to spread the mixed glue evenly on the boards – notice I have applied blue painter’s tape to the bar on the clamps, to make removal of any glue squeeze-out easier:

Methodically I apply glue and spread it on all the surfaces I will be gluing up – remember, you have plenty of open time with this glue system:

Now I proceed to tighten the clamps, lightly at first on all of them, and then as tight as I can get things – and I use as many clamps as I can. Clamping blocks are a great help to do this:

After glue-up, I prefer to wait at least overnight, to let the glue cure properly. Then I do some clean-up using a scraper – this glue is tough, hard, and brittle:

Once I have one edge reasonably flat, I use the band saw to remove a little wood on the opposite side – and at the same time remove all the glue that squeezed out. This results in savings in time, and in muscle power:

Immediately after coming off the band saw I look at the glue line. The resulting glue line is small, thin, and even throughout, a great pay-off to the work: