Originally Posted by MountainGuardian
P.S.. Okay actually I do have another question, the wife and I watched videos of lathing on youtube until about 5 am this morning and I heard the term negative rake tip quite a few times on numerous different videos. It appears that a "negative rake" keeps you from gouging too much material too quickly, is this correct? What exactly does the term "negative" refer to in this scenario?
The term "negative rake tip" normally refers to carbide tipped turning tools.
There are various kinds of turning tools available. Gouges, skew chisels, and scrapers are examples. In the old days, you sharpened those tools yourself, and there are many ways to sharpen them. Current versions of those tools are made with harder high speed steel (HSS), but they still require frequent sharpening.
A newer category of turning tool is one that takes replaceable carbide tips. Carbide is very hard and very durable, so carbide tips last longer than standard HSS tools when turning. The idea is that when the carbide is not cutting well enough, you can rotate it around to expose a fresh edge. When all the edges are used up, you replace the carbide tip with a new sharp one.
Carbide tips come in various shapes, such as round, square, rounded-square, and diamond (pointed tip). Usually the tool is designed to support the back of a specific tip, so you can't put a square carbide tip in a round tool, for example. In general, most woodturners use carbide tipped tools as scrapers. You keep the tool flat on the tool rest, and gently press the edge of the carbide tip against the center of the rotating turning, thus scraping away the wood.
HSS vs. Carbide
Some people prefer HSS turning tools, some prefer carbide tipped turning tools, and many people use both, like me. Which tool (or tip) you choose depends on what you are turning, plus a lot of personal preference and experience. Just because carbide tipped turning tools are newer does not mean that they are better. Each type of tool has its own advantages and disadvantages, and the way you use them can be quite different. As I work, I switch tools often, and have no compunction about going back and forth between HSS and carbide. Whatever works, right?
HSS and carbide tools are different in how they are used. It is probably safe to say that carbide tools make it easier to get decent results for beginners, but they can be limiting compared to the more traditional HSS tools. HSS tools require more learning and practice (including sharpening skills!) but you can learn to do a wide variety of cuts with them.
Important Note: Some spindle tools should never
be used for faceplate turning, like bowls. See my comment about safety, below.
Negative Rake Carbide Tips
A typical carbide tip has a flat top, with a beveled (angled) edge underneath. That flat-topped sharp edge can cut rather aggressively, and it can "catch" on the wood.
A negative rake carbide tip has a bevel on top with a slight downward angle. That downward angled bevel meets the normal underside bevel around the edge. When you present the tool to the wood, the downward angle makes for a less aggressive cut. The edge is still sharp, but it touches the wood at an angle instead of flat on.
Note that the sum of the top angle (negative rake) and bottom bevel angle is different than a traditional carbide tip with a flat top. That makes a negative rake carbide tip different than simply presenting a standard tip at a downward angle.
I have not tried a negative rake carbide tip for myself. I get by with raising the tool rest slightly, lifting the tool handle, and presenting a standard carbide tip angled slightly down. It is not the same as a true negative rake tip, but it works well enough for me.
One VERY IMPORTANT Final Note:
Some people fail to appreciate the dangers of a woodturning lathe. A lathe can severely injure you just as fast as a table saw or other power tool. Be sure you have a full understanding of lathe safety practices before you start turning anything.