Wood routers are a great tool, but many woodworkers are afraid of them. This happens when tool technique is not understood, or the tool is used without any knowledge of how to use it and the end results are poor and but knowing how to use them can elevate your woodworking techniques.
Watch it on Youtube: https://youtu.be/ZMmv152lzco
Woodworking encompasses many unique processes because of the nature of how wood grain grows and the kinds of things that we do in making woodworking projects, and one of these seldom know or used techniques are quite valuable to know
Known as the climbing cut and used with wood routers, this technique is a way of cutting against the wood grain by approaching the cut from the back of the grain and easing the bit into the cut which helps to reduce or even eliminate wood tear-out or wood chipping out which often happens when bits and blades are used in cross-grain wood.
Anyone who works with wood is keenly aware that wood has grain and when cutting with the grain of the wood we can make nice even and smooth cuts without too much difficulty but cutting against the grain is a whole other story. To make a nice clean cut with either a blade or a bit when cutting against the grain and still getting a nice clean cut without the wood either chipping out or tearing, can be quite a chore. The first thing that is imperative in cutting against any grain is the bit or blade needs to be precisely sharp, like a razer sharp, but even that doesn't solve the problems many times.
It's important to understand how bits work and for climbing cuts the best bits to use are those with bearings because you will want to have a surface for the bearing to ride on to get the best results AND to help control the router bit depth, which always wants to be a very small shallow cut. Never try to cut too much with any router bit, shallow, multiple cuts are ALWAYS the best in terms of safety and for the best quality of cut.
Using a router like this requires a certain amount of knowledge because the direction of the bit will want to pull the router along the wood so you need to grip the wood router firmly and know ahead of time that the bit is going to want to pull the router along. All router bits spin in a clockwise manner. Many routers will have an arrow somewhere on the base of the tool as a quick reminder to the operator as to which direction the bit will be spinning. Under normal circumstances, we always want the router bit cutting edge to be moving into the wood so the cutting bit is always moving into the wood.
One of the techniques that were developed many, many years ago is the climbing cut. What this means is that rather than using the wood router to cut the wood where the bit is being eased into the wood, like we would do normally when routing wood, instead, we use it backward. By that I mean we start at the opposite end of the but and ease the router back through the wood.
I selected a piece of wood that had a very good, visible grain pattern and cut an arc into it to help demonstrate how the grain of the wood can vary. Remember that you do not have to cut and arc as I did, if you are routing tapered legs, for example, the grain of the wood in a tapered leg could also be slanted which would be another case where a climbing cut might work better than a standard cut and give you better results with less wood tear-out.
The picture below is a visual representation of what is going on under the router.
The Freud round-over bit I commonly use is the Freud 3/16" Roundover, it seems to fit most of what I make, you can see it here or check out others on the woodworkweb Amazon link page for router bit listings.
As shown in the picture below the router bit travels clockwise, so pushing the router into the direction the blade is spinning would be the normal way to use a router. A climbing cut would mean starting at the end of the cut and moving the router backwards through the wood, known as the climbing cut because the bit starts at the back of the wood and climbs its way through the wood and as such helps to reduce tear-out which is a cause or rough cuts and is always hard to sand out, and if the cuts are really bad and torn out, they can be impossible to fix without making another cut.
Taking small cuts and moving slowly is the key to this technique and this is how you get good results. The reason this process works is that the wood is cut away from the back of the grain first which means there is nothing there to "bind" the cut which is what causes chipping and tear-out when trying to route into cross grain or even leading grain such as in the curved piece of wood used for the demo.
A similar technique can be used for trimming veneers or other very thin wood, where the grain of the wood is reverse or wavy. Cutting from the back of the wood first helps to ensure the very thin wood is not torn apart by the aggressive cut of a router bit cutting into the grain and basically splitting it apart.
The Flush Trim Bit that I have is an older version Freud bit, below is the later version with the red coating that resists glue and sap build-ups and is available through the woodworkweb Amazon site, see it here
The technique of the wood router climbing cut is not often used and is poorly understood, but once you see the advantages of using it on reverse grain, you will soon rely on it for better router cuts and much smoother cutting ...
Copyright Colin Knecht