Gearboxes for Food Chopper • Video

Metal Gearbox with Grinder
Wooden Gearbox with Grinder

Metal and Wood Gearboxes
Parts of Wooden Gearbox

Gearbox Video


G-Code, DXF and Printable Templates

These templates can be printed on 8½ by 11 inch paper. All except the gearbox_overview.pdf are sized on a one to one scale. The gearbox_overview.pdf shows how the parts fit on a piece of stock.
The scaling can be checked with the dimensions of the bounding boxes on the templates.

The gcode and dxf files work on my systems but they may not be compatible with others.

Video Transcript

This is the third video of a four part series on powering a hand cranked food grinder or mill with a power drill. This video is about the gearboxes.
Drills generally lack the low speed torque to turn a food grinder, so speed reduction is needed.

Gears from garage door openers are the heart of these two gearboxes. The gears are on EBay for around ten dollars. They are for half horsepower Craftsman-Chamberlain openers, so the gears' durability is in line with the hand held power drills.

The worm gear has two starts; that is, it has two sets of threads running together. The driven gear has thirty two teeth, so the driven gear turns once for every sixteen turns of the worm gear.
The box is made of ¼ inch hardboard. Machine screws tie it together. Its ends are adjustable so the gears can be properly aligned.

Half inch bore flanged sleeve bearings pressed into the sides hold the driven gear's axle bolt or rod. The axle is drilled for pins that secure the gear. Sections of HVPC plumbing fitting can be pressed over the hubs of the driven gear if the pins are loose. The sides with the sleeve bearings sandwich the driven gear; washers keep the gear centered.

The worm gear's axle in this box is a 5/6 inch threaded rod. This is so it will fit a 3/8 inch drill chuck. Nuts fit inside the hex recesses in the worm gear.
A rounded locking nut fits inside the worm gear and centers it. Tightening nuts on the gear's ends secures it.

Skate bearings fit 5/16 inch rod well enough to be used as the axle's bearings. The bearings are pressed into the recesses in the end plates. Nuts on the outside of the bearings secure them.

The boxes' ends are put between the boxes' sides. The bottom is installed. It keep the box from racking. The machine screws are tightened as the position of the worm gear is checked. The box is now ready for work.

The aluminum box was made fro a section of 2x3x 1/8 inch wall rectangular tube, because that is what I had on hand. There are not gcodes for this box
The driven gear does not quite fit in the aluminum, so a hole was milled in the side. This hole could be drilled and filed.

Both axles on this box are ½ inch and ride in flanged sleeve bearings. Both axles are drilled for pins that hold the gears in place. The bearing's holes' position's in the aluminum need to be on the mark because they can only be adjusted by elongating the bearings' support holes in the aluminum.

These gear boxes are simple and inexpensive to build, and have been useful in other applications. The next video in the series is of the stand for the setup. Drawings and gcodes are available on my site
Thanks for watching!

Construction Notes

The four holes around the bearings' holes are optional. They give clearance for the bearings should the larger holes not be perfectly round.

The machine screws that tie the wooden box together are #8 or #10. They are 2½ inches long.
The router bit for the gcode is a ¼ inch straight bit.

Related Video Notes

There are four YouTube videos in the food chopper series. The Peanut Butter Grinder (YouTube) is the first one.
The Coupler is the second. Here is the Coupler page with the construction information.

The third video is of the gearboxes. Its construction info is listed above.
The stand is the fourth video and the info is on the food grinder stand page.