How to choose your spindle or router head
How to choose your spindle
Choosing a Spindle
The spindle on your CNC router is the motor that does the cutting, with a cutting tool helping it out of course. You could say that it is the actual router of your CNC router. Like most of the other parts you use on your machine there are multiple types of spindles you can choose from. Some are made for cutting wood, some are made for cutting metal, etc. Generally spindles made for wood, plastics or other soft materials move at a speed of 8,000 to 30,000 RPM (revolutions per minute). Metal cutting spindles tend to operate at 2,000 to 10,000 RPM. Most spindles that can cut wood can cut metal as well but this is usually limited to non-ferrous metals like aluminum. Cutting metal or carbon-based composites at speeds usually requires a coolant system for cooling the material you are cutting and the cutting tool itself. Spindles are classified by power rating, using horsepower in English units and watts in SI units. Some spindles can be controlled with the CNC controller, allowing you to regulate the RPM based on your material and the feed rate of the machine. Other options can also be installed such as an automatic tool change, a tool sensor and a touch probe. There are many factors you should consider when choosing a spindle for either a pre-made or homemade CNC router.
When you are buying a machine you should be well informed to the capabilities of the spindle before you make your purchase. Most companies that sell CNC routers do a good job of giving you the information on the capabilities of the spindle. The information is easy to understand and often appeals to customers so that information is made readily available by sellers. For example, the average hobbyist will have an easier time understanding what the figures for the spindle mean than they would understanding what the exact capabilities of the linear bearings or leadscrews are on the machine they are looking at. While the spindle is important keep in mind that there are still other factors to consider such as load ratings, RPM and power requirements.
If you are building your own CNC router you will still be making an important decision when you are selecting your spindle. For many hobbyists you have to consider a budget when making your selection but there will be multiple choices within the same price range, whatever your price range may be. One of the key factors to consider as a hobbyist is the noise level. If you are near neighbors you probably do not want to run an extremely loud machine for hours on end, unless you want angry neighbors. As a hobbyist you will likely need to budget well for this part of your machine. A hand-held router can be a prime replacement for a spindle if you are looking for ways to trim down your budget.
The first difference between a router and a spindle will be the horsepower (or watts). If you need to convert the units, horsepower is the kilowatt rating times 1.34. Routers sometimes advertise a “peak” horsepower and you should be wary of this. “Peak” could mean that with perfect voltage, perfect temperature and other ideal conditions they were able to get that speed for a few seconds so do your research before buying. A spindle will usually last at least ten times as long as a router before being worn down, often lasting twice or even three times as long as that. In the long-run your cost will be about the same per hour of use. At a glance a router seems cheaper, and it certainly is in the short-term, but when you factor in the extra time a router needs since you have to make multiple passes and how many more bits you will go through you really are not saving money. A $30-$40 bit you could get seven or eight sheets out of a router as opposed to getting close to thirty out of a spindle. As a hobbyist, buy whichever part you can afford. If you ever start making a living from your CNC router then a spindle is for you.