Choosing a Belt Grinder For Knife Making
Finding useful, reliable information all in one place is a common problem when starting out in knife making. It can be difficult and costly to determine which tools, materials, and supplies will best suit you for the type of work you want to pursue. In this and future articles, we will do our best to provide you with a good starting point for blacksmithing and knife making!
What You Should Know About Grinder Specs!
Dimensions of the Belt Grinder
Belt grinders are classified according to the width and length of their belt. A 1×30 grinder, for example, has a 1-inch wide belt that is 30 inches in circumference, whereas a 2×72 grinder has a 2-inch wide belt that is 72 inches in circumference.
A wider belt creates more friction on a machine’s flat platen, necessitating more power, whereas a longer belt allows for less time between belt changes but necessitates more power.
The size of the belt has a significant impact on the use of the grinder; as a general rule, the larger the belt, the more useful it is for heavy stock removal.
Size of the Motor
To grind steel with abrasive belts, you must have a high belt speed and the ability to apply a lot of pressure. Your engine must keep up! The more powerful the grinder, the larger the motor. For a 72″ long belt, a rule of thumb is 1 horsepower (hp) of motor power per 1″ of belt width.
A 2×72 grinder, for example, works best with a 2hp motor. A 1×72″: grinder, on the other hand, would grind well with only 1hp. When you shorten the belt, you reduce the demand on the motor, which is why our 2×48″ machines come with a 1.5hp motor.
Speed of the Belt
The third critical factor in steel grinding is the speed at which your belt travels. To grind effectively, it must move much faster than a woodsander. Our shop’s 2×48″ machines run at 4100 surface feet per minute (sfpm).
You can make do with less, but your stock removal rate will suffer as a result.
Determine the belt speed as follows: sfpm = (x drive wheel diameter) x motor rpm
Because typical wood sanding only requires 2500-3200sfpm, keep in mind that a woodworking-oriented grinder will have a slower stock removal rate on steel.
Fixed Speed or Variable?
Variable speed can be a great addition to a grinder, allowing you to do heavy steel hogging at full speeds and fine handle sanding at low speeds. The machine’s speed is controlled by a Variable Frequency Drive (vfd) connected to a three-phase motor. It can be costly, but we find them to be extremely useful in our shop.
How much should I pay for a Belt Grinder?
When deciding on the best grinder for you, it’s critical to consider your budget as well as the type of work you’ll be doing. We’ve compiled a list of common grinder sizes and why you’d use them.
Sizes of Knife Making Grinder
When deciding on the best grinder for you, it’s critical to consider your budget as well as the type of work you’ll be doing. We’ve compiled a list of common grinder sizes and why you’d use them.
A 1×30 belt grinder is the most affordable belt grinder to begin knife making with. They’re not as versatile as the more expensive machines, but for less than $60, they’re a fantastic tool and a great place to start. The first “For grinding bevels and profiling knives, a wide belt is sufficient.
The main disadvantage of the 1×30 is that the belt isn’t wide enough to effectively flatten off material, which is a big job in any knife shop. A 6 is one of the more expensive models “However, a disc sander on the side can help with this. The 30” long belt also doesn’t provide much abrasive surface area, which means you’ll have to change belts more frequently, and the motor isn’t the most powerful in the world.
Overall, a 1×30 is an excellent low-cost entry point into knife making. If you decide to use this size of grinder, keep in mind that good ceramic-based abrasives are required; otherwise, the grinder will not perform to its full potential. Plenty of incredible knife makers (including Will Stelter) began with this machine, and it is a sure-fire way to help ignite your knife making passion, but if you’re serious about knife making, you’ll outgrow it.
Option at a Low Cost
1×42 Belt Grinders
The 1×42 is very similar to the 1×30, but it has a smaller selection of abrasives; we would not recommend it. A 1×42 isn’t entirely worth it when a 2×42 is a similar price and has a wider belt for more stability.
2x42Belt Grinders
The 2×42 belt grinders are made by a few different companies and typically come with a 6 inch belt “They have a disc sander on the side and are intended for the woodworking market. Most major abrasive companies offer a wide range of appropriate belts. Because of the wider belt, they are also easier to use than the 1×30.
They do, however, have some drawbacks, such as the lack of a suitable slack-belt option or usable contact wheels. Because they typically only have a 1/3hp motor, they will slow and “bog down” as you grind, limiting your grinding ability. Its configuration is also limited in that it cannot be easily tilted 90 degrees to the side. This can be a worthwhile option for a beginner without breaking the bank but you will be dreaming for more power as your career develops.
4x36Belt Grinders
The 4×36″ belt sander is one we get a lot of questions about, as it’s a common sander a lot of people already have, found at most hardware stores around the world
Unfortunately, it is not ideal for most knife making/blacksmithing applications. It is designed for woodwork and the way it’s built doesn’t allow for the use of the edge of the belt to be utilized, which is an essential part of a belt sander in knife making applications.
Due to the weak motor and wide belt, it will bog down easier than other machines. Most people will be better off buying a 1×30” or 1×42” when starting into knife making.
2x48Belt Grinders
The 2×48″ grinder size is an interesting one, it’s the smallest belt size that can come in a “square wheel configuration” body, but most commercially available grinders of this size come in an upright style. These grinders also have an excellent array of belts for them, virtually the same selection that is available for 2×72. You’ll find an increasing number of accessories available, from small wheels, to contact wheels to surface grinding attachments and they often have a larger motor than the smaller grinders. If you are a serious hobbyist or a professional short on space, a 2×48” is an excellent option.
We love how easily this size of grinder can fit into a small workshop and how versatile it can be with a variable frequency drive speed controller. It has prices ranging from $330-$1495 depending on motor power and the particular configuration.
2×72
The 2×72 belt grinder is the industry standard for professional knife making. Partially due to the vast array of belts available for the grinder, as well as being a generally powerful and still reasonably compact machine. There are a wide variety of options available, ranging from building one yourself to buying a top of the line professional grade grinder, designed to suit a Bladesmith perfectly.
Along with great abrasive options, the number of accessories that are available for a 2×72” machine is also second to none. Wheel attachments from 1/4″ to 16″ and just about every size in between are available for getting into tight spots, profiling, fullering, and wide hollow grinds. Surface grinding attachments, slack belt rotary platens, and other attachments are becoming more available for them as well.
A Knife Makers 2×72 (and some 2×48’s) commonly come in the “square wheel” configuration, with a 4-7″ drive wheel in the back, a tensioning and tracking wheel on the top, and a flat platen with two contact wheels facing the user. This style is the grinder of choice due to its adaptability and versatility. Most of them out of the box have a flat platen, two contact wheels, and a slack belt without changing any tooling. When the need arises for different specialty tooling, the switch is easy. A turn of a handle for the tooling arm to come free, and you’re able to replace it quickly with another.
A more budget friendly option is the vertical style that has a large drive/contact wheel on the bottom, a flat platen halfway up, and tension and tracking wheel at the top. The vertically configured style takes up less space than the square-wheel style. Still, it is far less versatile, as it usually doesn’t have the option for changing tooling the same way the square wheel does and the flat platen is less useful.
The vertically configured 2×72’s are an excellent grinder for the money and will out-perform most smaller grinders. They’re an excellent option for hobbyists or for those just finding out if knife making is something they’d like to pursue.
We recommend a square wheel configuration 2×72” or 2×48” if it’s within the budget, adding attachments as you can afford them is an excellent way to build up your shop slowly.