Cheap chinese Involute gear cutters

What does the Module signify in these gear cutters. I understand the DP and pressure angles but they all seem to specify various module numbers ?

Thanks

Matt

Specification:

• Brand new

• Module: M1

• Material: HSS

• Bore: approx. 22mm

• Color: as picture shows

• Pressure Angle: 20 degree

• Quantity: 8pcs per set

Each of Gear is different:

• 1#: 12-13 Gear

• 2#: 14-16 Gear

• 3#: 17-20 Gear

• 4#: 21-25 Gear

• 5#: 26-34 Gear

• 6#: 34-54 Gear

• 7#: 55-134 Gear

• 8#: ≥135 Gear

Module is the metric system of measuring gears, DP is the old imperial way.

MOD 1 is equivalent to 25.4DP

Edited By JasonB on 29/08/2018 15:02:18

Module is the "metric" way of specifing the size of gears. In simplified terms it's the inverse of DP. The precise definition is that the module is the length of the circular pitch in millimetres, so the bigger the number the larger the gear teeth.

Confusingly the numbering of module gear cutters is the reverse of DP cutters. So a #8 DP cutter is for the same number of teeth as a #1 module cutter, and so on.

Andrew

Hi Matt,

The Module system is used for metric gears, see here. Diametral Pitch = 25.4/Module, more formulas for metric gears here.

Thor

Thanks Guys...understand....I have been watching too many US you tubers.

Hi Matt,

Module is the metric way of specifying gears. There is a direct equivalent to DP sizes, just divide 25.4 by the Module. Thus M1 is 25.4DP and M.4 is (25.4/0.4) is 63.5. The tooth form is still involute but if you use Module gears you will need to change the design to cope with the size of gears you will cut although, e.g. 0.8M at 31.75DP is probably close enough to 32DP not to be a problem. You will note also that the cutter number is the other way round from the DP (Brown and Sharpe) notation where a #1 cutter >135.

HTH,

Rod

Way, way too slow - sorry to reiterate the good advice above.

Edited By Roderick Jenkins on 29/08/2018 15:13:15

The other significant point is that module involute cutters are 20°PA and DP involute cutters are 14.5°DP unless marked differently

No disagreement with Mark, but the 20° pressure angle was common when I started my apprenticeship in 1968. The 14-1/2° is to match the older machines that many of us have. Just a comment to reinforce the need to check.

Bill

Are those gear cutters any good ? Has anyone ever used them ? Might be interested in a set for myself

All replies welcome.

If you are substituting MOD gears for DP then however close the tooth size may be you will need to check the centre to centre dimensions to ensure correct meshing.

Emgee

I used some cheap, presumably Chinese, DP rather than module, involute cutters from a well known ME supplier when I was machining helical gears to check that I understood the mathematics. I knew I'd never use the cutters again which is why I bought cheap.

If I was cutting gears that mattered I wouldn't use them. My impression was they were rather more eccentric than they should be, and one had a visible wobble.

Andrew

I've had a couple of sets of small Module gear cutters from CTC and have been perfectly happy with them.

Rod

I've used a few of teh RDG ones and they have done for the slow reving IC and steam engines. Also bought some even cheaper ones from the far east and at £5 a pop can be treated as disposable and they did seem to start loosing their edge after about 80 teeth (spaces) but the ones I did look OK to me. Expect they would last longer if use don brass rather than the steel I was cutting.

I've also used RDG's import cutters. In my case it was putting the teeth back on the feed gears for my shaper after machining all the broken ones off and building the remains up with 98% nickel welding rod. They worked perfectly well for the purpose.

Edited By Mark Rand on 29/08/2018 21:34:02

I make my own single point cutters, slower but they do the job

I've also used a homebrew rack form hob with success, which is as fast as using an involute cutter.

Neil

Module 1 is very easy to remember when you are creating the blank gearwheel also if you want to make 50 teeth gearwheel, then add 2 extra to 50 teeth will be 52 mm blank gear wheel (formula: (2+Z) x Module) and height of tooth is 2,25 mm. Module 1 is same as 3,1416 mm (PI) .  

Edited By Jens Eirik Skogstad on 30/08/2018 16:33:32