The cutting frame is similar to a circular saw in the way it works. It has a spinning cutter which is engaged with the wood to cut into it.
For use, it is held in a quick change tool post (QCTP), and the QCTP bolted to an cross slide (much like a metal lathe's tooling is held in the compound rest).
There are a number varieties of cutting frames, but the first 4 are the most used today :
If you wish to make your own HCF, Bill Ooms has provided great directions. Additional notes from my own experiences making an HCF are on this page.
The video below shows an HCF in use.
If you wish to make your own VCF, Bill Ooms has provided great directions.
In the pictures of the horizontal and universal cutting frames to the right, the brass part at the end of the arms is the cutter head. The pointed part in the cutter head is the cutter.
Cutters for ICFs take various shapes, and some examples from Holtzapffel's Turning and Mechanical Manipulation, vol. 5 - The Principles and Practice of Ornamental or Complex Turning are shown below.
| Key Note : Cutting Frames are where the quality of ornamental cutting comes to life. If there is vibration in the cutting frame it will be transmitted to the cuts, and the quality of the work will be poor. |
When you are using the ornamental lathe, listen for noise in the cutting frame.
There are two types of cutters :
Advantages of using carbide cutters are :
The insert recommended is from Circle Machine Co., part number is 2828732 (the industry number for them is TDAB-505-C25). It is grade C25 carbide, and has a 0.007" corner radius. This radius is recommended over those cutters with 0.002" radii (or smaller).
A larger corner radius "blurs" the definition, and that may be what you want as an artist. However, a corner radius smaller than 0.007" will not necessarily give better definition. Those will amplify each and every striation in your cuts, making them look like someone dragged a rake over your workpiece.
Advantages of using fly cutters are :
Traditionally, fly cutters were flat pieces of metal with various shapes, and there are some ornamental turners who use these still today. Many of these are used with vertical cutting frames, but they work on other cutting frames : It just really mattes what the turner is trying to achieve.
Some examples are shown to the left.
The smaller cutters shown above would be used in internal, eccentric, elliptical, and epicycloidal cutting frames, whilst the larger would be used in vertical, horizontal, and universal cutting frames. (There much more information about these, and pictures, in Holtzapffel's Turning and Mechanical Manipulation, vol. 5 - The Principles and Practice of Ornamental or Complex Turning.)
This is a YouTube video showing a fly cutter in use :
And this YouTube video shows how I make and sharpen a rod-based fly cutter:
Eddie Bell gave a presentation about variations on the Gorst du Plessis finials at the 2018 Ornamental Turners International Symposium. This is a nice presentation about the effect fly cutter shapes can have on the object shape.
At the 2018 Ornamental Turners International Symposium, Steve White introduced the idea of using slitting saws in a cutting frame. These are the same saws that get used in milling machines for cutting slits in an object.
Steve's use of this was to cut a slit of a certain size (say, 1/16") along the Z axis in an object at various locations (e.g., every 90° around the circumference), and then insert a piece of contrasting wood into the slit. This is different from segments glued together with thin contrasting woods. In this case, the slits did not traverse the entire length of the piece, only a part of it. (I realize a picture would be great, and I'm working on getting one.) It is a great way to produce a uniformity and beauty that couldn't be easily done via other methods.
The cutting head is traditionally rotated using an overhead drive, but direct drive approaches are also used.
Cutting frames can be purchased from a number of vendors (see also, Buying a Rose Engine Lathe), or you can make your own. Directions for making a cutting frame are nicely described by Bill Ooms. There are additional notes about this at making a Cutting Frame.
If you make your own, you will need belting for it (that is the orange stuff in the universal cutting frame picture, above). I used the same cable belting for this as I used on my overhead drive.