change wheels

[noel shelleyParticipant @noelshelley55608]

change wheels ?

[noel shelleyParticipant @noelshelley55608]

I have 3 sets of change wheels ! One set is myford at 20DP. Another set is drummond I believe, with 2 1/8" driving pins and 7/16" bore. What DP are they ? 24? Then there is the mystery set. The bore is 18mm, the width is15mm and a 5mm keyway. The tooth count goes up by 5s. They mesh with myford gears but are slightly smaller, eg 60t 20DP = 3.100"OD, 60t ?=3.055"OD. A) What pitch ? 1.25Mod ? B) What do they belong to? They look old. Many thanks Noel.

[HopperParticipant @hopper]

Drummond change gears are 14DP. And 14.5 degree pressure angle

The ones that mesh with the Myford could be 20 DP but a different pressure angle from the Myfords, which I think were also 14.5 degree but opinions vary on that. Or they could possibly be 20DP and just cut to a slightly different spec using undersize blanks for clearance etc. Maybe.

Plenty of online charts for module gear specs will tell you if they are module whatever based on diameter in mm and number of teeth.

[Keith LongParticipant @keithlong89920]

Noel the gears with the 2 pins are NOT Drummond if they have 7/16 in. bore, Drummond are 5/8 in. and as Hopper has said Drummond gear will be 14dp and 14.5 deg.pa. Myford change gears are 20dp and 14.5 deg.pa, but the tumbler reverse gears on a Myford could well be 20 deg.pa, I know they are on some models.

The only lathe that I've seen on the lathes.co.uk website with 7/16 in. bore gears is the Exe, and I believe that that make used a 2 pin drive system as well.

Have you recently acquired these via EBay by any chance?

[DC31kParticipant @dc31k]

Posted by noel shelley on 08/03/2020 22:06:53:

A) What pitch ? 1.25Mod ? B) What do they belong to? They look old.

The numbers you give match up with 1.25MOD.

Oldness does not necessarily mean they are imperial spec. Europe, with its metric system, has existed for a long time…

Are you familiar with the method of identifying gears? Measure OD in millimetres and divide by (number of teeth +2) for metric. For imperial, divide (number of teeth +2) by OD in inches. This will help you work out the ones you think are Drummond.

[Author]

Posts