Down cut bits require a slightly slower feed rate. Though a router always turns in the same direction, from the operators perspective, that rotation appears to reverse depending on if the router is bit down in the common hand-held mode or bit up, as when mounted in a router table. Straight Router Bits. The number of email questions on this subject instigated this up down spiral router bits kit. You must be logged in to write a comment. Learn More.

A Up Down Spiral Router Bits Youtube down-cut bit will leave a clean top edge, but it sends the chips downward, into the dado where they have no place to go. You can make this cut, but you have to take it slower than usual to give the chips a chance to clear.

For woodworkers who work with A-grade veneers on both sides of the stock and must have a clean edge top, bottom, and middle, the compression bit is a good choice. It has an up-cut configuration on the tip of the bit and a down-cut spiral ground on the shank.

By lining up the bit just right, you can get a superior edge across the entire thickness of the wood. Router-bit manufacturers have difficulty making solid-carbide spiral bits with cutting diameters larger than their shanks.

Straight bits, on the other hand, go through dozens of fractional sizes, all the way up to 2-in. Depending on the job you have in mind for your router bit, straight bits also come in a variety of cutter lengths.

So you can buy close to exactly the length of cutter you need. Straight bits also have a huge advantage over spiral bits when it comes to template routing, because you can buy them with guide bearings.

And those bearings can be mounted on the tip of the cutter or on the shank of the cutter, depending on your needs and your template. The bearings are made for a variety of cutter diameters and lengths. With their superior edge cut, spirals make great template cutters when used with collar guides.

But when it comes to bearing-guided bits, spirals seem to be available only with bearings mounted on the end of the bit. Shank-shod, bearing-guided, solid-carbide bits spiral bits with the bearings on the shaft end of the bit , which would permit template routing with the template on top of the work and trim cutting through only part of the work face, are not available. Some woodworkers like to sharpen their straight bits, although I find it difficult to get it right and always send out my bits for sharpening.

Carbide-tipped straight bits usually have enough carbide thickness to be reground four or five times, and the tech- nology to do so is common. A few services claim to be able to sharpen spiral bits. To me, this translates into a substantial loss.

Spiral bits might stay sharp longer than straight bits, but even so, the cost of using spiral bits will always be higher. Spiral bits work incredibly well in the production environment and especially in CNC computer numerically controlled router industrial applications. But in a hand router, their use sometimes imposes unusual risks not associated with the equivalent or bigger straight bits.

The down-cut spiral bit's screw-driven forces are sufficient enough to pick the router up and twist it out of your hands—with no warning. I know, because it has happened to me. On end grain the spiral bit is getting even more traction, so the risk is even greater—a pity, too, because a sweet end-grain finish is attractive.

The up-cut spiral bit can have the opposite effect. It wants to pick up the work. So you must secure the work in some kind of fixture or hold it by a clamp. I never rout anything that is not secured or clamped, but some people do. I do keep a few solid-carbide spiral bits because, when I want a beautiful face cut or I am cutting narrow mortises, and I have the money, there is just nothing better.

But my cabinet is mostly full of a wide variety of straight bits. For general-purpose work, for template and pattern routing, and for those times when need a large-diameter bit, I still reach for one of my straight bits. Quick View. Add to Cart. You must be logged in to write a comment. Log Cnc Router Drill Bits Kit In. Find a Store. My Account.

My Cart. Go to Home Page. Mobile Navigation. Same Day Shipping Find a Store. Search Go. Topics Cabinetry. Choosing Hardware. Dust Collection. While both of these Infinity bits are very effective, knowing when to use an up cut left or a down cut right can make a substantial difference in your project. Click image to enlarge Up Cut vs. The number of email questions on this subject instigated this story. Though the flutes run in opposite directions, telling an up cut from a down cut bit can be difficult if you cannot imagine their rotation in the router.

Though a router always turns in the same direction, from the operators perspective, that rotation appears to reverse depending on if the router is bit down in the common hand-held mode or bit up, as when mounted in a router table.

With the bit down, the rotation is clockwise. That means the side of the bit farthest from the operator is turning left to right, the near side right to left. This is very important for feed direction, as we always want the cutting edges turning against the feed direction, not with it.

When the router is oriented with the bit up, as when mounted in a router table, the side of the bit closest to the operator is turning left to right and the back side right to left.

Because the wood is fed against the rotation of the cutting edges, we almost always work against the front side of the bit. If the wood is fed into a router bit on the wrong side, the feed direction matches the bits rotation, making a dangerous kick out all but certain. Feeding the wood with rather than against bit rotation allows the cutting edges to become highly efficient feed dogs that grab the wood, accelerate it and shoot it off the table at dangerous speeds.

Up cut bits are very efficient at evacuating chips from the hole or slot it is cutting. Deep holes or grooves still have to be cut using multiple light cuts, but the upward direction of the flutes while rotating prevent the debris from building up in the hole and binding or even breaking the bit.

The problem with up cut bits is that the same action of the flutes that brings the chips up can also lift or fray the wood fibers around the edges of the cut. While this damage is usually minor, Up Down Spiral Router Bits Zero especially with good quality bits, it can be noticeable if those edges will be visible when the project is assembled. Up cut bits are frequently used for cutting mortises because of their depth. Since the edges of a mortise are eventually hidden by the shoulders of the tenon that will be fit to it, this chipping or fraying will be hidden after assembly and have no impact on the finished project.

The downward slicing action of a down cut bit leaves a very clean, crisp edge around the hole or groove it cuts. While chips still are evacuated from the hole, a down cut bit is far less efficient in this respect than is an up cut design.

This chip ejection deficiency of down cut bits is minimized by the relatively shallow cuts they most commonly are used to make. Down cut spiral bits are a good choice for cutting dados or shallow grooves, especially when the edges will be visible when the project is assembled.

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