Fireball Tool DIY Mini Go-Kart Belt Grinder
The Go-Kart Belt Grinder has become synonymous with Fireball Tool. In early 2019, Jason raided his scrap pile and junk shelf with the idea of building a belt grinder that could stand up to his demanding fabrication work. Seven years later, with more than 4 million views, the Go-Kart Belt Grinder has helped put Fireball Tool on the map.
One of the most common requests we’ve received is for plans—or even a production version—of the original Go-Kart Belt Grinder. While we’re excited to see what the future holds, we also wanted to create something that more people could realistically build in a DIY environment.
Jason’s original design made zero compromises when it came to speed, power, and rigidity. However, the construction methods and materials required aren’t easily accessible to the average person. With that in mind, we set out to design a Go-Kart Belt Grinder that can be built with basic shop tools such as, an angle grinder, power drill, a Fireball square, and a welder. While still only using materials readily available from your local steel supplier, wrecking yard, or even Amazon; no fancy laser cut parts or precision machining. All while trying to keep to a budget of under $1500 USD.
We’re excited to announce that the complete DIY plans are now available on the Fireball Tool website. Go-kart Grinder Plans
Choosing the Belt and Wheel Size
The first major design decision was determining the belt and wheel size.
The original Go-Kart Belt Grinder uses a 6-inch-wide × 89-inch-long belt running on a 6-inch × 11.75-inch tire. That combination performs exceptionally well thanks to the incredibly rigid frame, but when we simplified and scaled down the design, the forces generated by that much rotating mass introduced too much vibration to make it practical.
After evaluating the most common belt sizes available, we concluded that a 6-inch belt simply wasn’t a realistic option for this project. Instead, we stepped down to a 4-inch-wide belt.
The most common tire for a 4-inch-wide setup is a 10-inch diameter tire, which reduces the rotating mass by roughly 50%.
While 4 × 48-inch belts are widely available, pairing one with our wheel size resulted in a grinder that looked more like a Venn diagram than the classic two-wheel layout we were after. Moving up to a 4 × 60-inch belt gave us the proportions and functionality we wanted.
That led us to our final configuration:
-
4-inch × 60-inch belt
-
4.5/10.0-5 tire
-
5 × 5 wheel
Belt Tracking and Tensioning
The next challenge was designing the grinder’s mechanical functions—specifically belt tracking and tensioning.
On the original grinder, Jason accomplished both functions with a pivoting flexure plate that also served as the motor mount.
For this design, we wanted to simplify the mechanics by separating those functions. Instead of one complex component performing two jobs, we created two simple components that each perform a single task.
We retained the flexure concept from the original grinder but incorporated it directly into the frame. Belt tracking is adjusted using a simple heim joint linkage.
The entire motor frame pivots to provide belt tension and is tensioned by a hydraulic strut. This pivoting assembly also serves as the motor mount.
Keeping the Iconic 8-Ball Shifter
One feature we absolutely wanted to keep was the iconic 8-ball shifter from the original Go-Kart Grinder.
To accomplish this, we designed a simple offset cam connected to the shifter handle. Pulling the handle forward pushes against the motor frame, releasing belt tension for quick belt changes. Let go of the handle, and the hydraulic strut automatically re-tensions the belt, leaving you ready to get back to work.
Motor Selection
After upgrading the original Go-Kart Grinder earlier this year, we confirmed a simple rule of thumb:
Plan on at least 1 horsepower per inch of belt width.
While you can get by with about ¾ HP per inch, a full 1 HP per inch delivers noticeably better performance.
Using the 184T motor frame size we selected, you can typically find 1,750 RPM motors in 3 HP, 5 HP, and 7.5 HP configurations. We recommend the 5 HP version because it’s widely available and is generally the largest horsepower motor you can run on single-phase power.
If you’re looking for even more performance, pairing a 3-phase motor with a VFD is an excellent upgrade.
Frame Design
With the drivetrain, belt size, and mechanical layout finalized, the next step was designing a compact frame that could be built using common steel shapes and basic fabrication techniques.
We also incorporated everything needed to make the grinder practical in daily use, including:
-
Adjustable work table
-
Platen assembly
-
Belt guard
-
Motor control mounting location
Parts List
To make sourcing parts as easy as possible, we’ve put together a spreadsheet containing Amazon links for the majority of the required components.
Building the Grinder
The grinder goes together surprisingly easily, and we’ve included a complete set of fixture maps to make fabrication and assembly as straightforward as possible if you have a fixture table.
We’ve also included optional upgrades and alternate versions of several components for builders who want to squeeze every bit of performance out of the machine.
As always, don’t be afraid to customize the design and make it your own.
Performance
Don’t let the size fool you—the Mini Go-Kart Grinder removes material surprisingly fast.
In our ½-inch steel rod test, it consistently achieved 6.5 inches per minute (IPM). For comparison, the original Go-Kart Grinder completed the same test at 10.5 IPM.
That’s impressive performance from such a compact machine.
Stay tuned for the full build video coming soon.
If you build one, we’d love to see it. Share your photos and experiences here on the Fireball Tool Forum, and if you have any questions during your build, don’t hesitate to ask. We’re always happy to help.
). On a side note, I actually purchased a 7.5 HP 3 phase motor to try and replicate the original build; it was a take-off from something that the customer wanted a bigger motor on, so it’s brand new.