Worm meshing with a spur gear

[akpalican]

My textbook says that a low cost method of creating a wormgear set is to use a worm with a spur gear. However, it doesn't say how to do this. I'm assuming it must have the same pitch but other than that, I'm not sure. Dutton-Lainson makes a worm gear winch which looks like it uses this concept (see the 2nd image and the dimensional drawing: but I noticed that the worm is at an angle...not sure if this helps the two mesh?

11011_addl_1.jpg

DD_WG1500HEX.PDF


Can anyone please help?

[Kelly_Bramble]

low cost method of creating a wormgear set is to use a worm with a spur gear

Worm gear/spur gear as opposed to what gear arrangement?

My textbook

What is the name of the textbook? ISBN?

[akpalican]

Textbook: Machine Elements in Mechanical Design 4th ed. by Robert Mott, ISBN: 0-13-061885-3
Section 8-9 explains 3 types of wormgear drives: 1.) cylindrical worm with throated wormgear 2.) special cylindrical worm with standard spur or helical gear 3.) hourglass worm with enveloping-type worm gear.

Seems like the standard arrangement is cylindrical worm with throated wormgear, however, it will be cheaper to buy a standard spur gear if I could figure out what geometry I need to match.

Any ideas as to why the link I attached in my initial post has the worm at an angle?

[jboggs]

The worm is at an angle so that its teeth mesh with the spur gear teeth. Its teeth are in the form of a screw helix. You are seeing the back side of the screw form in your PDF view. The main difference between a worm gear and a spur gear is that worm gear teeth are cut at an angle to match the helix angle of the worm. This arrangement accomplishes a similar effect by just mounting the worm and the spur at an angle to each other.