How To Fabricate With a Metal Square Rod

Cut square metal to a round shape in a lathe.

Cutting square metal in a milling machine is common because it can sit well in a vise or fixture. On a lathe, it is a whole different story because the chuck jaws are made to hold round stock. You can make a specific fixture to hold round stock on common jobs or you could cut new jaws that will accommodate the square metal. The machining aspects are similar on a milling machine, but again differ on a lathe because you must watch the cut carefully. Cutting square material can cause tool or material movement due to excessive force, so take small cuts.

Things You'll Need

• Band or chop saw
• Indicator
• Chuck jaws
• Vise or fixture
• Face mill
• End mills
• Carbide insert cutter
• Measuring tools

Instructions

1. Analyze the blueprint to determine the size of square stock you will need for the raw material. Increase the needed size to the next available raw square stock size. Square stock can be made of aluminum, brass or steel and comes in long and short lengths for various jobs. Order the proper length and quantity for the job by calculating the amount you need and comparing it to the lengths available from your metal supplier.

2. Cut the material to size for the production run or cut one or two pieces for a prototype. Add about 1/4 inch to the finished length for the raw material to account for uneven cuts and facing operations. Use a band saw for harder material such as steel and a chop saw for aluminum and brass because it is quicker and more accurate.

3. Place the material in a vise for a mill or a square fixture, or specialized jaws for a lathe. Chucks can hold square material with specialized fixtures. Indicate the material and set your tools in the machine. Indicating is the process of ensuring the straightness of the work holding device, vise or jaws. Set all of the tools when working with a CNC machine or start with the first tool needed for manual machines.

4. Take your first face cuts to remove the front or top of the material. Reset your Z dimensions using this newly created smooth surface. Facing gives you an even starting point for the accurate cutting operations that follow. Bring your facing tool in manually or program it as the first step on a CNC control. Check the surface to make sure all of the rough cut has been removed. Lower the Z axis, which is the front of the piece on a lathe and the top on a mill, if not, and rerun the facing operation.

5. Cut the square shape down to a cylinder using a manual or CNC lathe. Start from the outside and take slow passes with a carbide insert cutter until the material is round on one end. Only take about 1/10 inch at a time so the edges do not dislodge or damage the tool. Cut around the edges or use an end mill on a mill, CNC or otherwise to cut the square shape away where necessary.

6. Continue the rest of the cutting operations until the piece is complete. Compare the important dimensions to the blue print before removing it from the fixture. Square material can be tricky, but if left in the vise or fixture, can be rerun to make accurate.

References

• American Machine Tools: How to Use a Lathe
• American Machine Tools: How to Use a Milling Machine