Member postings for Peter Howell 1

Thanks that helps.

Up to now I've only cut cycloid clock wheels using commercial cutters. But my interests have moved on from clocks and most other mechanisms use involute, so I thought I'd have a go at making my own cutter. I have Ivan Law's book and had started making the Eureka tool, so I'm interested to read what Martin Gearing has to say.

Right.

So if I'm going to make a gear how to I know what pressure angle to use for the job in hand?

Is it all down to experience or are there some specified design criteria ?

Reading, with interest, the series Tempering and Gear Cutting.

What I've never really understood is why have the different gear pressure angles?

I understand their effect on tooth shape, but why have the different angles in the first place.

I must sing the praises of Polly Engineering.

I am building their Trojan loco in kit form supplied in modules 1 per month.

On Monday I'd had an email advising that they were trying to stay open and my next module was more or less complete so did I want it. I replied yes.

On Tuesday I had a phone call from them to say that after the government announcement they would be closing there and then but not only had they got that module they had also got my boiler so did I want that too. Of course I said yes pleased. They managed to pack both modules and dispatch them in what must have been a very hectic day. UPS delivered yesterday, so at least I've something to help pass the time

Peter Howell