Worm Gearbox Design Revealed

A worm gearbox is assembled to show the key design elements. The gearbox only needs one precision hole for the main wormgear shaft. A slot and a pinned worm shaft assembly avoids the need for a very precise center hole..... https://bit.ly/3onfQon

distance in the casting. At the same time the cover provides for adjustment with two allen set screws. Other assemblies and features make it a dividing head. But the gearbox itself is a chunk of material with one precision hole and a slot/pin at 90°. Think through the ways to hold it in the manufacturing phase and you have a very efficient case.

Chapters
0:00 Intro
0:12 Preview
0:51 Examinatin of Worm and Wormgear
2:04 Wormgear and Worm Specs measured
4:30 Re-Assembly
5:00 The Secrets are in the Gearbox!
8:47 Mock-up of the wormgear
12:17 Pressing Wormgear onto shaft (aligned)
15:54 Adjustments on the shaft for end-play
18:08 Worm assembly on a rotating tapered pin
20:13 Lubrication and adjustment of backlash
21:05 Backlash fine adjustment with setscrews
24:26 Brake
24:50 Dividing head specific pieces
26:25 Outro














There are many ways to make a Worm Gearbox:
1) Use a chunk of Aluminum and core out and drill/bore the main wormgear shaft hole in a CNC mill
2) 3D print and concept gearbox, press in some sort of bushing for smooth running, do some light milling and maybe drilling and tapping as required
3) Make the box as a weldment, then bore the main hole and add the worm mounting feature
4) Design it in 3D, get a casting made...
5) There is always someone out there thinking up something new.

During the filming of this video, I grabbed my handy pitch gage set - the closest match was 16DP and 14.5PA. But a super close inspection - after publication - shows this to be a 5-TPI gearset. Here are all the various pitch measurements that are equal to 5-TPI:
Inputs
Threads per Inch: 5.000 1/in
Outputs
Module: 1.617 mm
Diametral Pitch: 15.708 1/in
Circular Pitch: 0.200 in
Threads per Inch: 5.000 1/in
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Tooling and machines usually limit worm gear/worm design quite a bit. Most US lathes can cut TPI and metric threads, a rarer few can cut DP/Module.

Looks like the 16DP is pretty close to 15.708 but not an exact match required for gearing.

The history of gears is surprisingly interesting - the process of milling, generating and hobbing gears plus the transmission of torque and movement all find a place here. Follow along as we expand our gear shop and practice "The Gear Art"
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