Making a 2×72 belt grinder (knife grinder) at Home


NOTE: This article is for information purposes only! Making your own belt grinder can be dangerous, please do not attempt to do this unless you are experienced! It’s much safer to purchase a well-built 2×72 belt grinder from a known & trusted supplier (we’ll be adding a recommended supplier of 2×72 belt grinders in the UK soon!)

As they are usually the best option for knife making, we’ll concentrate on 2×72 knife grinders. There have been a few mentions of small strip sanders, handheld belt sander conversions, and home built belt sanders with belts shorter than 72′′. We’ll also go over how to find used motors, make your own homemade belt grinder wheels, and a variety of other ways to save money while building your own belt sander.

A high-quality new 2×72 belt grinder can cost between £600 and £2,000, even if built from a belt grinder kit. Some home builders make their own sanders for next to nothing, while others spend hundreds of pounds on new wheels, a new motor, and other accessories. A good homebuilt 2×72 belt sander, on the other hand, can be had for about a tenth of the retail price – around £250. If you can find some spare parts and components cheaply (most notably the motor), you can easily cut that cost in half, to around £125.

The original builders are fully credited for all of the builds featured herein.

Belt sander elements
A belt sander can be reasonably disassembled into the five constituent parts listed below. If you want to build a belt sander but aren’t sure where to begin, think about each component separately.

  1. The framework. This is usually made of steel, but it can also be made of wood. The metal frame is usually welded together, but it can also be bolted together. Get a free weight bench on Craigslist and cut it up to use as a frame.
  2. the casters Beaumont Metal Works sells pre-made belt sander wheels, but they are quite expensive. You can make your own wheels if you have machining skills. You can obtain wheels (skateboard wheels are a favorite). You can also make your own wheels out of wood or several layers of MDF. Idler wheels can be removed from engines. For proper tracking, the wheels must be crowned. Crowning can be done with a machine or even with masking tape. The backing on the 2×72 belts, on the other hand, can wear down the crowning.
  3. The power supply. Almost always, this will be an electric motor. You can purchase a brand-new engine. You can save money by removing a motor from an existing tool or appliance.

Get a free treadmill from Craigslist with a nice motor and controls that will allow you to vary the speed of your belt sander. Examine the treadmill belt and how worn the more common buttons or controls are to get a rough idea of the treadmill motor’s condition. A treadmill motor is usually in excellent condition; you’re unlikely to get a well-used treadmill from an Olympic athlete.

Consider searching with misspellings when sourcing from Craigslist; in this case, the most common misspelling of treadmill is “treadmil.” It’s also sometimes spelled as two words: “tread mill.”

Here are some videos that demonstrate how to identify and wire treadmill motors for use in homemade tools.

Treadmill motor wiring with off-the-shelf parts. By buffcleb.

DC treadmill motor controller wiring for a belt grinder. By mikemanmade.

You can also convert an existing tool, such as a bench grinder, into a belt sander. Smaller belt sanders can be powered by an electric drill or even a rotary tool such as a Dremel.

Dust and debris will be kept at bay by a sealed motor. You can also construct your own protective enclosure. You won’t know how bad the vibration is until you use the sander for the first time. For the time being, just think about mounting options that minimise vibration.

You might want to change the speed of the motor, and a step pulley is a good way to do so. After accounting for speed adjustments, whether with a variable frequency drive, a step pulley, or another method, some builders find that they rarely use the different speeds anyway.

  1. The mechanism for tracking. The belt must be properly tracked in order to ride properly on the wheels. For many first-time belt sander builders, this is an afterthought that becomes a major headache when the belt sander is tested. Fortunately, tracking is simple and is usually accomplished with an eye bolt. When the speed of the vehicle changes, the tracking must be adjusted.
  2. The mechanism for tensioning. To operate, the belt on the belt sander must be tensioned, and then relaxed to remove the belt. One method is to attach the motor to a hinged plate, which then serves as the tensioning device. Another excellent method is to salvage the incline motor from a treadmill, which is used to vary the incline of the treadmill so that a person can walk or run “uphill” on the treadmill. This incline motor can also be used as a tensioner.

In addition to the five components listed above, there are several add-ons to consider in the future, including:

-Various types of grinding rests.
-Additional disc sander or buffing wheel.
-Portability wheels or casters (one trick is to use an inexpensive Harbor Freight rolling engine stand).
-A bin for collecting sparks.

Once the belt sander is built, these add-ons will be relatively simple to build and customise for your specific needs. It’s usually better to build your belt sander, get it up and running, and then customise it as you see fit. Most home tool builders never completely finish a project; they prefer to add to and adjust it over time. Your belt sander will almost certainly never be finished – you’re making a tool, not a sandwich.

Belt sander articles and forum discussions

Here’s our curated selection of articles and forum discussions of standard belt sander builds (videos, plans, and miscellaneous other belt sander builds are further below). Click on each photo below for the full build.

Made from metal plate, with scrap aluminum for the rollers and pulley. By Vyacheslav.Nevolya.

Made from scrap metal and a 2800 rpm motor. By rendoman.

2×72 with stand, 1/2 HP motor, and wheels from eBay. By chiasson.

Tiltable sander with metal tubing frame and MDF wheels. By Roger Xue.

Detailed build with multiple photos and videos. Switches between vertical and horizontal operation; built with CNC machining. By HelicopterJohn.

Commercial-quality build of belt grinder for knife making. Includes many 3D renderings. By Vladislav.

Beautiful high-end belt sander. By Vernon.

2×60 knife grinder. Made out of aluminum, with plywood idler wheels, for under $200. By Dave Wood.

Small 1×30 strip sander made from plywood. Many photos, build details, and video. By Dave Wirth.

Belt sander videos

Here are a couple of videos of homemade belt sanders

YouTube videos are best viewed with the speed controls turned on. We recommend watching the build at 1.5x or 2x speed first for many builds. You can easily change this on YouTube by clicking the cog icon in the lower-right corner of any video. On the other hand, you might want to watch a video in slow motion. To do so, pause the video and then advance frame by frame by using the period key to move forward one frame and the comma key to move back one frame. You can also move forward 10 seconds by pressing the L key, and backward 10 seconds by pressing the J key.

There are hundreds of YouTube videos on how to build belt sanders; you could spend weeks watching them. We removed the ones with poor lighting or audio, and we concentrated on shorter videos. Some of the better videos we included are longer (20+ minutes) or part of a series. You can also use the 2x speed trick mentioned above to cut a 30-minute video down to 15 minutes.
2×72 sander constructed from a treadmill and a weightlifting bench. Submitted by mikemanmade.

2×72 sander made from square tube and plate. Includes turned pulleys from cast aluminum stock. By Black Beard Projects.

2×72 sander build that documents construction process. Used a tractor to stretch out an extension spring into a compression spring. By Making Stuff.

Comprehensive build with bill of materials, photos, and construction tips. By Michael Clerc.

Sander with used motor and VFD. Includes plans for belt sander, and separate plans for machining wheels. By Dan Comeau.

30″/48″ sander with turned aluminum pulleys and tilting table. Includes many technical drawings. By digr.

2×72 sander powered by a 2HP motor with speed control. Includes technical drawings. By Mike Conner.

Simple smaller sander with plywood frame and commercial wheels. Includes 1 basic technical drawing. By Robert Frink.

Converting existing tools to belt sanders

The most straightforward way to construct a benchtop belt sander is to solidly mount a portable belt sander. This isn’t a do-it-yourself 2×72 belt grinder, but the cost is minimal, if not free. Firmly mounting a portable tool for use as a fixed tool is a common homemade tool builder trick that applies to a wide range of tools. Here are some builds that include mounted portable belt sanders. To see the entire build, click on any of the photos below.

A basic workbench mount for a portable belt sander. By 1dmaxpwr.

Clamping a portable belt sander in a vise. By Boyntonstu.

A simple wooden jig for benchtop mounting of a portable belt sander. By Sandor Nagyszalanczy.

Wooden box mount for an antique Rockwell handheld belt sander. By BrooklynBay.

A hand drill/driver or rotary Dremel tool will never be strong enough to power a 2×72 belt grinder. Nonetheless, using these tools to power a belt sander is clever and worth mentioning, albeit briefly. Here are some drill-powered and Dremel-powered belt sander examples. To see the entire build, click on any of the photos below.

Dremel belt sander attachment. By Tuomas.

Portable, Dremel-powered mini belt grinder. By barberorp.

Drill-powered strip sander from plywood. Shows entire build process, plus measurements of all components. By Gökmen ALTUNTAŞ.

Yet another strategy is to construct a belt sander from a bench grinder. Here are some examples of belt sanders made from bench grinders. Click on each photo below for the full build.

Twin belt sander, powered by bench grinder, with frames cast in aluminum. By Carlos B.

Twin belt sander based on bench grinder. By garycullen.

A basic belt sander made from a bench grinder, with machined pulleys. By naughtyboy.