2.3 Machine Tool Basics — Mill Workholding — SMITHY GRANITE 3-in-1
http://www.smithy.com (see transcription of video below)
Learn about the basics of metal lathe operations using our Smithy Granite combo lathe/mill/drill machines. You can visit us at www.smithy.com for more information or send us any questions about your project. Our trained technicians will be glad to help you with your project.
“The selection of a work holding tool is a very important part of milling. If there is a failure in a milling operation, nine chances out of ten, the failure was due to the work being pushed out of it’s position by the force of the cutting tool, or the work piece flexed because it was not properly supported. All of the work holding tools installed on the milling table are held in position with the help of the table’s t-slots. It’s important to keep the table and the t-slots clean and free from any burrs, nicks, or rust.
A machine vise is by far the easiest way to hold small parts for milling and drilling. There are many different styles of vises. This is a plane-milling vise. Parts should be set as deep into the jaws as possible. If the part has to be high on the jaws, to give clearance for machining, it should have full support. Here we are using a set of parallels to raise the work and provide support against the downward force of the cutting tool. Adjustable vises are helpful in holding parts that have to be machined at an angle. Work that is mounted directly on the milling table can be held in place with t-nuts, threaded studs, and strap clamps. The strap clamp should always be parallel to the table, with the stud and nut as close to the work piece as possible. The outer ends of these clamps are supported with step blocks. There are many other tools used in conjunction with strap clamps to hold work. Here, V-blocks and strap clamps are being used to hold round stock on the table.
Slotted angle plates are used in setups when the piece being machined needs to be held at a true ninety degree angle to the table. These plates are heavy and are made in a number of sizes. Work can be clamped or bolted onto the angle plate.
The Smithy step block is another form of angle plate and can be used for a number of milling and lathe operations. Here we are using it to bring a thin work piece closer to the milling spindle. Work can also be mounted on the side, as you would with any angle plate.
Another tool that is extremely useful on a Smithy machine is an adjustable angle plate. This tool is used to hold work that has to be milled at an angle other than ninety degrees. It can hold work flat, or at an angle, to the left or right, up to forty-five degrees. It’s very useful for holding thin plates or castings that might be difficult to hold and totally support in a vise. If you want to mill in an arc, you need a tool that will hold and precisely turn the work piece. The tool used for this type of machining is the rotary table. Graduations around the tables’ circumference, and on the hand wheel, allow the operator to manually adjust the location of the work piece anywhere within the 360 degree movement of the table. The rotary table is an extremely versatile tool that can be used to mill complex angles and patterns, as well as do indexing operations. It’s also used extensively to drill accurate hole circles.”