Toolholders Can Make or Break Your Day

My metalworking career began in my dad’s machine shop. It was a typical small machine shop with a few lathes, mills and surface grinder. Everything was manual. We made a lot of different parts but always in small quantities and nothing that required CNC machines.

That all changed with a phone call from a long-time customer who was trying to source a production part. The customer used about 3,000 of these parts per year, and making them in the needed quantities was going to require CNC equipment. So, we started shopping for a vertical machining center (VMC).

We researched several manufacturers from high-end Japanese makers with names you would recognize to low-end machines that you probably would not recognize. While researching the machines we found out quickly there was a significant difference in machine construction, spindle power, available RPM and features like thermal compensation. As you are already aware, the more you spend the more you get. We ended up making a compromise between price and performance and chose a machine that, on paper, was not as robust as the competition.

Off we went on the great CNC journey. We broke tools, scrapped parts, crashed into things, drilled a few holes in the table and learned other hard lessons about programming and running a CNC machine. We were not reaping the benefits of a CNC controlled machine; quality was a problem, and labor costs were too high. It was frustrating.

One of the most important realizations we came away with is that, in general, the quality of the tooling you put in a machine is more critical than the quality of the machine. Junk tools will impede the capability of high-end machines and high-quality tools will improve the performance of a budget machine.

Several problems plagued our machining process and chatter was a frequent issue. Our first big job was machining aluminum extrusions, which should have been super easy, but we kept getting a terrible surface finish and had to throw out the parts. Eventually, one of our cutting tool representatives suggested we ditch the side lock endmill holder we were using and buy something sturdier. So we purchased a hydraulic endmill chuck. These chucks use hydraulic pressure to collapse the toolholder around the entire shank of the tool, providing a firm grip on the shank. The old-style side lock holders have some clearance between the tool shank and toolholder that can open the door to chatter at the high RPM needed to efficiently machine aluminum. Once we started using the endmill chuck, the chatter problems disappeared.