When it comes to making butcher block almost every wood worker has at one time or another had to glue up multiple butcher blocks together. In edge glue lamination there are several factors to consider that all affect the integrity of the glue joint and lamination process. Whether you are using large industrial equipment or standard woodworking tools, we all have to follow some of the basic principles that I will touch on below:
WOOD SELECTION AND PREPARATION:
Moisture: A Known Nuisance
We all know as wood workers that moisture content is not your friend and can cause havoc on any wood-working project. The main focus of this article is going to be focusing on the glue up process with Radio Frequency equipment. However, the same theories and fundamentals apply to any glue up process. In a perfect world, the wood you start with will have a moisture content ranging from 7% to no more than 10% moisture content. Typical wood you buy from the kiln dry operations will be in the 6-8% range.
Pro Tip: if you have some wood that has been laying around the shop for a while and want to glue that up, you may want to check with a wood moisture meter first to ensure proper moisture level.
Joints and Grit
The next important step is to ensure that your edge glue or flat panel glue job is done precisely and properly. It’s imperative that the joints are straight and free of any saw or cutting marks. For abrasive planning preparation; a grit of 50-70 is recommended for the sand paper to properly prepare the wood joint. Anything below 50 grit sand paper and you risk fracturing the wood surface and the fibers resulting in a very weak or failed glue joint.
Pro Tip: If the surface is too smooth the fibers are crushed and the glue and not penetrate the wood. If a drop of water placed on the surface to be glued requires an extended period of time to absorb the glue will act the same way.
We like to think of it like baking a cake. A good baker always uses fresh ingredients when we surface or prepare or wood for glue up so we always glue up within 24 to 36 hour period of when the wood is surfaced. This way all the fibers of the wood are properly prepared for the best glue adhesion. Making sure that your wood is fresh and properly prepared for glue up is key.
When It’s Done Right: When your joints are glued properly, the bond can actually be stronger than the wood itself. In most cases, the wood is more prone to “break” than glue joint.
GLUE UP AND APPLICATION
This is where the advantage of some commercial equipment comes into play mostly with the open glue time. Typical for standard glue open time is 10 to 15 minutes. This is where using a hand roller and some manual clamps especially for big jobs it is very important you work fast. Some larger shops have glue spreaders and Clamp carrier’s big wheels of clamps to speed up the time to get the glue applied to the panels and under pressure.
The amount of glue and type of glue used is also important if you use an RF radio frequency glue press as we do it requires a different type of glue that will conduct electricity. Standard wood glue do not conduct electricity in the RF press, therefore, we use Franklin 2015 Glue products. If you are using a clamp or carrier, this doesn’t apply to you.
Commercial glue rollers are much more accurate not only in the time to apply the glue but making sure you have a consistent volume of glue. Recommended by most RF glue manufactures would be 7-10 mils of glue application. We use a glue with a 10 minute open time and we have the press for the thicker boards set on a 6 minute cycle. So when one shuffleboard top is in the press getting the RF to dry and cure the glue we are laying up the next top on the glue roll up prep table.
If you don’t have a RF Press: RF presses are expensive pieces of equipment. A skilled woodworker can achieve the same results using a clamp rack or carrier to minimize the time between the glue up and press cycles.
Some interesting facts about RF glue press
So what is an RF press and what are the main advantages? The first and largest advantage is the speed in which the glue is cured and when combined with a glue spreader or roller and commercial layup table. You can make sure your glue open time and prep time is to a minimum. The simply explanation is think of it as a huge microwave oven. The RF gluers alternate current between the top and bottom. The switching of the frequency is what creates heat friction in the glue, which will then drive the moisture from the glue line (think of a microwave oven).
When using a RF Press, you have several different factors like the thickness of the material, the type of material, moisture content all effect the settings and time that is required for the glue cycle to cure. When a board comes out of the press it is cured 50-60% and 24 hours later it is 100% cured.
Although there are a lot of different types of glue and methods for edge glue or manufacture butcher block nothing compares with the use of an RF cure machine for speed, ease of use and consistency and integrity of the glue joint.
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