Thompson Direct Drive


Includes special narrow band clamp and standoffs for X or Y

I attached my name to this drive because I love simple and this is, perhaps, the most simple drive mount possible. I started with the gear drive and didn’t think of direct drive until later and it proved to be quiet and fast and simple. They stick out a lot is the largest drawback. Also, the handle mounts on the rear shaft of the motor so the motor takes the full brunt of manual forces. If you wanted to build your own, this is as simple as it gets. I have a number of couplers for sale separately. Drives can be with or without motors.

The Thompson Direct Drive (TDD) slides over the leadscrew shaft and engages the 3 jaw coupler just like the handle. Anti-rotation braces are clamped around the leadscrew bearing boss to hold the drive in place while it turns the screw. This is probably the simplest way to drive a shaft with a motor.

The main advantage is there is no need for a support structure. Most direct drive installations start with a new fully machined bearing block or at least four nice standoffs and the mounting holes that go with them. There is also no need for a flexible coupler. The drive is mounted on the leadscrew and is manufactured to be very concentric with the motor shaft. Any misalignment that does exist is taken up by compliance in the brace. A simple hose clamp secures the unit in place and the unit can be installed or removed with a twist of the wrist.

With no gear reduction, the motor must be the 115mm long, 425 oz-in NEMA23 to drive the Rong Fu at a good speed. These motors have an 8mm shaft as opposed to ¼”. A 3-jaw driver has a 17mm bore on one end and an 8mm bore with set screws on the other. This drive is quiet and fast.

On the negative side, the motor does stick out quite a bit. In cramped spaces that can make it difficult to move around freely. The Z-axis usually requires a gear drive for compactness but a motor could slide on the axle shaft for a direct drive version.

Comes with the coupler, two standoffs with feet and a band clamp


The motor and coupler slide over the beefy lead screw shaft giving it full support
These long standoffs are needed to keep the motor from spinning around. They do not support the motor
These are both ends of the drive coupler used with direct drive. These are for sale upon request

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