Dishing tools differ even though they all do the same job in the same way–a bar that spans a diameter of the wheel, arching over the hub axle, with a means to touch the axle end cap. All adjust for different hub widths and can be used on a range of rim diameters.
Their superficial resemblance hides that fact that these tools are really quite different to use. Serious wheel builders have no shortage of personal preferences.
Slotted Center Posts
One difference amongst tools is the center post. Park and Unior offer slotted plates that adjust to reach the hub.
Sliding Cylinder Center Posts
Others have a sliding cylinder, secured, in the case of Var, by a knob.
The EVT and Wheel Fanatyk tools secure their center posts with spring loaded triggers.
Threaded Center Posts
The other option is a threaded center post, such as Campagnolo’s discontinued dishing tool.
Our favorite threaded post tool is by Cyclus. A meaty, rigid, deep green classic with nickel plated center post.
You might worry that it’s slower to adjust to a particular wheel but you’d miss the way they are best used. As in the image above, hold one foot of the tool against the rim, then thread the post down until it touches the axle. Tighten just a bit more to lift the second foot off the rim. Tap the foot and listen.
If there is no “tap” sound, the foot is either solidly on the rim or in the air. Adjust the center post until you can hear a faint tap. This becomes quick with practice. That faint tap sound only occurs when the second foot is within about ~0.1mm of the rim. It’s a sure signal you’re there, much easier and more accurate than trying to see if the center post is close to the hub. No bending down, squinting, or lifting the assembly up to eye level.
This way to judge dishing with a threaded center post was my only method for decades. It is comforting to hear the faint tap even if it’s coming from across the workshop. It’s the sound of accuracy!