YOU CAN BUILD THE 2X72 BELT GRINDER KNIFE MAKERS USE FOR UNDER 200 DOLLARS — THE KEY PART IS IN EVERY DEAD TREADMILL
The 2x72 belt grinder knife makers love, built for under 200 dollars around the motor from a dead treadmill.
by Making Stuff
Workshop
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- ●●●●○
- time
- a long weekend
- license
- license not specified
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●●●●○ · a long weekend · license not specified · 0 stars · repo
WHAT YOU’LL NEED
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COMPAREE VERDICT
This is a documented path to a real 2x72 variable-speed belt grinder for under 200 dollars in total by the creator's own account, assuming you can weld and already have access to basic metalworking tools. Commercial 2x72 grinders have a hefty price; here the motor and controller from a dead treadmill (2.5 HP, 130 V DC) give you variable speed for the cost of a used MC-60 controller and a potentiometer. The build guide tells the story of the build and gives the parts list, but it is not a paint-by-numbers tutorial. You need to be comfortable welding a steel frame, sourcing or cutting a flat platen, and wiring a mains-powered DC motor controller. The things most likely to go wrong: a treadmill with the wrong motor, steel costing more than the creator paid, and belt tracking problems if the pulleys are not square or the base lacks clearance. The free BOM gives you the steel sizes, and the builder's 3D drawing is available to his Patreon supporters, but you still have to fabricate it. If you have the tools and the skills, this is a legitimately cost-effective route to a workshop-grade grinder. If you have never welded or worked with mains voltage, start with something smaller.
IN THE REPO
GOOD TO KNOW
- —The frame drawing (SketchUp) is available only to Making Stuff's paying Patreon supporters; the free guide gives the steel sizes in the BOM.
- —Build guide at makingstuff.info/Projects/Belt_Grinder tells the build story and has a BOM with steel sizes and parts
- —No wiring diagram for the MC-60 is published; the guide only says you add a 10k potentiometer for speed, plus a power switch and an enclosure for the electronics.
- —The platen is cut from 3/8 inch steel plate; the creator paid his local welding shop to CNC plasma cut it rather than making it with hand tools and a drill press.
- —No open licence is stated for the design; the guide is informal documentation, not a step-by-step manual.
- —The treadmill motor is free only if you source a broken treadmill locally — prices vary if you buy used
Parts to buy
8 itemsFrom our check of the build. Exact quantities and part numbers are in the creator’s BOM.
Can I build this?
This build involves mains voltage — for adults comfortable with electrical work only.
Build at your own risk. Projects involve tools, electronics and sometimes mains voltage — follow the creator’s safety notes.
Videos
Making a DIY 2x72" Belt Grinder from Treadmill Parts
587,000 views, shows the finished grinder running and some of the fabrication process, but this is a progress/demo video not a step-by-step tutorial
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Start here
Navigation into the creator’s own docs — we don’t rewrite the guide, we route you to the source.
- 1.Read the build guide at makingstuff.info/Projects/Belt_Grinder and its BOM to understand the frame geometry and part list (The guide has photos and a BOM but assumes you know how to weld and wire a DC motor controller)
- 2.Source a dead treadmill with a 130 V DC motor, ideally around 2.5 HP like the creator's — check local classifieds, gyms clearing old equipment, or appliance recyclers(Some treadmills use AC motors or lower-power DC motors that will not have enough torque; confirm the motor specs before you haul it home)
- 3.Order the MC-60 controller from eBay (~30 dollars) and the belt grinder wheels (34 dollars from the supplier in the guide)(The MC-60 is a generic PWM controller for DC motors; it will ship with basic wiring notes but not a schematic for this specific project)
- 4.Cut or order the 3/8 inch steel platen and frame tubing per the BOM — the original builder had his local welding shop cut the platen on a CNC plasma cutter(The platen must be flat and rigid or the belt will not track properly and you will burn through sandpaper)
Resources
Documentation, files and community threads for this build — we link straight to the original sources and never rehost the creator’s files.
KNOWN ISSUES
- Buying a treadmill with the wrong motor — some are AC induction motors that will not give you variable speed, and some older or cheaper treadmills use underpowered DC motors that will stall under load
- Underestimating the cost of steel — the creator paid about 100 dollars for the steel and the CNC-cut platen and notes that off-the-shelf steel cost more than the discounted offcuts he usually buys; prices vary by region.
- Wiring the MC-60 controller incorrectly — it is a treadmill controller and the guide has no wiring diagram, so a mistake can destroy the controller or create a mains-voltage short.
- Building a frame that is not square or rigid enough — any flex in the frame will cause the belt to wander off the wheels, and you will spend hours trying to track it down
- Skipping a belt guard or face shield — 2×72 belts run fast enough to throw sparks, metal shavings, and broken abrasive across the room, and a snapped belt can whip back with enough force to injure you
- Expecting a step-by-step build manual — the guide documents what was built and shows photos, but it assumes you already know how to weld, read a technical drawing, and wire a motor controller
Can I use a different motor controller instead of the MC-60?
The guide only documents the MC-60, the treadmill motor controller that is common used on eBay and new with warranty on Amazon. Another controller rated for your motor's voltage and current may work, but you would be on your own.
Do I need a CNC to cut the platen, or can I do it by hand?
The platen is a flat piece of 3/8 inch steel — the original builder had a local welding shop plasma-cut it, or you can cut it by hand with an angle grinder and files, but it will take longer and flatness matters for belt tracking.
How do I know if a treadmill motor is powerful enough?
Read the motor nameplate. The creator's motor was a 2.5 HP, 130 V DC treadmill motor, which ran the grinder well under 3000 RPM. A motor that is AC, or much weaker than that, will not match his results with the MC-60 controller.
Is this as good as a commercial grinder?
It takes standard 2x72 belts, and the creator says it works well running under 3000 RPM; the MC-60 controller even boosts power when you press a workpiece hard into the belt. He also notes a flaw to avoid: his base has too little clearance, so the belt can rub if it is not adjusted correctly.
Community builds
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Discussion1
FROM THE COMPAREE TEAM
The creator built a 2x72 grinder from a free treadmill motor and a used MC-60 controller, for under 200 dollars in total by his own account. What is the first thing you would grind if you built one?
Making Stuff
The build guide and video come from Making Stuff, a maker who documents metalworking and shop builds from salvaged parts. The written guide and BOM are free on his site; his SketchUp drawing of the frame is a Patreon perk for paying supporters.
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DISCLAIMER
- Comparee is not the author of the projects featured here. All rights to each project belong to its creator — every page links to the original source, and we never host creators’ files.
- Information is provided without warranty and may become outdated as projects evolve. Prices are indicative bands only — always check the creator’s parts list for current costs.
- Building and operating any project is at your own responsibility. Protective equipment, safe workshop practice and compliance with local regulations are the builder’s responsibility.
CompareeTEAM1mo agoedited
Practical notes from our verification: the build video at youtube.com/watch?v=6GoEXR5NuHo has over 580,000 views and shows the grinder being made and running, but it is a build video, not a step-by-step tutorial. The written guide at makingstuff.info/Projects/Belt_Grinder has the full parts list and the story of the build, and assumes you can weld and wire a DC motor controller. The 3D drawing for this design is a SketchUp file available to the creator's Maker+ patrons on Patreon; no open licence is stated for the design. Cost depends on your local steel: the creator paid about 100 dollars for the steel plus CNC plasma cutting of the platen at a local welding shop, and says the whole project came in under 200 dollars. The MC-60 controller came out of treadmills and is common used on eBay; you add a 10k potentiometer for speed. The photos on this page show a similar treadmill-motor grinder built by MarkSand on Instructables, credited on each image; they are not of the Making Stuff build. Correction (4 October 2026): we re-checked this page line by line against the project's own repository, documentation and videos, and fixed errors in earlier versions.