Couplers for Food Grinder • Video

Wooden coupler on auger
Wooden Coupler
Coupler on Grinder
Wooden Coupler on Grinder

Metal coupler on auger
Metal Coupler
Coupler on Grinder
Metal Coupler on Grinder
Couplers for Gearbox Video


G-Code, DXF and Printable Templates

The template can be printed on 8½ by 11 inch paper. It is sized on a one to one scale.
The scaling can be checked with the dimensions of the bounding box on the template.
The gcodes and dxf files work on my systems but they may not be compatible with others.

Video Transcript

This video is about two DIY couplers that can connect a hand crank food grinder or grain mill to a motor or gearbox.

One coupler is made of metal and the other is wood.
Using a bolt in the crank attachment hole as a coupler did not serve well. The small bolt sheared too easily. The coupling has to transition from an oddly shaped crank axle to a common shape.

The wooden coupler makes this transition in layers.
Each disk is drilled and cut for its single function. The entire set is screwed and glued together.

The originals were made from disks that were cut with a hole saw. Forstner bits work well for drilling the rough holes for the different shapes. A Dremel, rasp and/or knife can trim the work. The ones shown here were CNC cut. This is the 18 x 24 machine working.
The first layer is cut to fit the grinder's crank hub. Different mills and grinders have differently shaped hubs. This plate system allows for customization without the need to redesign the entire system.
The second layer also matches the hub, and has a recess for a washer that is screwed to the hub. The washer is placed inside the disks before they are glued together.
The third layer gives clearance for the attachment screw. The fourth layer has a slot for a pinned axle.
The fifth layer has a smaller slot that holds the pinned axle in place.

The matching axle is a half inch bolt or rod with a hole for a pin drilled through it.
The pin slides through the last slotted plate and locks into the inside slotted plate.
The plates hold the pin in both forward and reverse.
The entire set is glued and screwed together once the shapes are cut and aligned.
Make sure that the screw holes are on the leading side of the pin so the pin will press toward the screws.

The metal coupling was CNC cut from 5/8 by 1 ¼ inch aluminum flat bar because this was the size of stock at hand. Wider stock will work because the gcode is for a circle as shown with this wooden prototype.

A rod couper was pressed and pounded into the disk. This unit uses a half inch coupler that fits an eleven sixteenth inch wrench.

The recess for the crank required final trim work with a Dremel to match the crank hub. The hub's casting is somewhat crude.
The stop for the attachment screw is an 1/8 inch section of ½ inch threaded rod or bolt that was drilled and cut.
It was threaded into the rod coupler and secured with thread locker.

The gearbox's drive shaft is a half inch bolt. Part of the threads were cut off and a nut was tightened till it stopped where the bolt's threads. The nut keeps the axle from bottoming onto the connecting screw's head and crushing the screw-driver slot. The nut also make removal easier. It gives a purchase for a wrench so the axle can be loosened.
Both couplers have served well.

This video is part two of a series on driving a hand cranked grinder or mill with a drill. The remaining videos are of the gearbox and the stand.
There is more info on my site Solsylva dot com.
Thanks for watching!


There are four YouTube videos in the food chopper series. The Peanut Butter Grinder (YouTube) is the first one. It does not have a webpage.
The Coupler is the second. Its information is listed above.

The third video is of the gearboxes. Here is the Gearboxes page with the construction info.
The stand is the fourth video and the info is on the food grinder stand page.