Worm gear

[Franco ConvertiniParticipant @francoconvertini28916]

Hello, I want to make a worm gear for this gear. Could you tell me what pitch I need to set? Thanks, Franco.

[DC31kParticipant @dc31k]

The gear specification is given in GHT’s book, in connection with the headstock dividing attachment. See:

https://www.hemingwaykits.com/HK149X

If you wish to learn fishing instead of just being thrown a fish finger, you can upskill to answer the question yourself.

Gears have three specifying parameters: no. of teeth, diametral pitch and pressure angle. You do not need any further skills to identify the first of these. If you read Ivan Law’s excellent book, you will learn how to calculate the second of these.

Download GearDXF software and print out on paper gears using those two parameters and guessing at the pressure angle. You only have two choices. Offer the print out up to the gear  and see which of the two fits best.

[old martParticipant @oldmart]

The gear showed is not intended to mesh with a worm gear, however it can be done although not able to carry power as the meshing is not exactly correct. You need to measure the diameter of the bull gear and count the number of teeth to use an online gear module calculator which will give you the tooth pitch. The worm will have to be tilted to mesh with the straight teeth on the wheel. You will also have to choose the number of starts on the wheel you make.

We were given an Atlas 12 x 24 lathe which did not have its threading dial which works like a worm wheel on the leadscrew which is simply a straight worm of infinite diameter. I knew the number of teeth that the worm wheel should have and the TPI of the leadscrew and bought a gear that meshed correctly. The axis of the gear had to be tilted to match the leadscrew thread and the housing made to suit. The threading indicator works perfectly since it does not transmit more power than needed to turn it.

[JasonBModerator @jasonb]

Circumference of a 1″ circle is 1 x pi = 3.142″

Divide 3.142″ by the DP of the gear which I think is 20DP on a Myford

3.142/20 = 0.1571″ pitch

If you want tpi then 1/0.1571 = 6.365tpi

But may be easier to select 4mm pitch as that is very close

[John PParticipant @johnp77052]

The bull gear on a Myford   is 16 DP   ,well it is on mine  checked against  16 DP hob   fits

perfect ,  Ivan law’s  book list the pitch as.1963 inch    5 mm = .1968 inch  so that would

do .Depth of cut =.135 inch.

20 deg  PA.

John

[Author]

Posts