Coronet Major reduction drive, anyone know the ratio?

[justinpeer]

My Coronet Major is the 3 pulley version with the motor running at 2800rpm which gives me speeds of 2k, 3k and 4k rpm. It has the reduction gear fitted, as shown in the photo, but there's no indication as to what the ratio is, and I couldn't find it referenced online anywhere.

I leave the lathe in it's slowest setting most of the time but as I'd like to start turning bowls, I'll be using the reduction gear but would be interested to know what speed it's actually going at so I can tell what sort of size bowl is reasonable to attempt.

 

[ChaiLatte]

Take the fan cover off. Mark one of the blades. Mark the output pulley. Rotate fan ten revolutions. Count revolutions of output pulley.

Stick reflective tape to output pulley. Use tachometer application on jphone to tell you.

Remove cover plate to reduction gearbox. Count teeth on gears.

 

[justinpeer]

Take the fan cover off. Mark one of the blades. Mark the output pulley. Rotate fan ten revolutions. Count revolutions of output pulley.

Stick reflective tape to output pulley. Use tachometer application on jphone to tell you.

Remove cover plate to reduction gearbox. Count teeth on gears.

that tachometer app looks a great option, I'll have a go with it tomorrow and see how I get on, thanks very much for the suggestion.

 

[ChaiLatte]

The relevant page at lathes.co.uk lists some speeds which might cross-check anything you measure yourself. It would also be wise to confirm the 2000, 3000, 4000 you mention as they might be rounded numbers.

You might have to read the page to decipher which of the listed ones are relevant to your motor and gearbox setup (as it talks of a 'student' version that was slowed down).

There is a dedicated tachometer on Amazon for £17 if you want to take regular measurements.

 

[Robbo3]

The Major Gearbox, (GM501A) & the Minor Gearbox (M5A) both have a 4 to 1 reduction ratio.
Page 17 of the attached leaflet.

 

[joethedrummer]

The Major Gearbox, (GM501A) & the Minor Gearbox (M5A) both have a 4 to 1 reduction ratio.
Page 17 of the attached leaflet.

,,when you,ve got to know ,,, ask Robbo !!

 

[justinpeer]

@Robbo3 Thanks very much, that's perfect. I'll check with the app but it's good to know that I should be able to get down to around 500rpm which is pretty workable for most bowls I'm likely to attempt.

 

[justinpeer]

Ok, so I went and put the strobe app on it. Discovered that, of course, it doesn't give you a single reading, it could be any multiple of the actual speed. Knowing the config of pulleys it's in, it should be at 2000rpm, the app shows 2080, but also 1040 and 4160. With the gearbox engaged it's about 520, but also multiples upwards of that. So think everything looks good but no way to be absolutely sure.