Thread: Metric threading on Imperial 9"AR Hercus

I have a imperial 9" Hercus AR.
And a gear set for metric and maybe other stuff I bought through AMH a few years ago.
The transition gears (Right Name ?) are not the 100 to 127 bushed pair but the 60 to 63 bushed pair.
My other loose gears are 46 44 42 36 33 30 27 24

The chart for the imperial to metric conversion below just describes the MM pitch range using the 100 /127 transition gears on the compound position.
If that's the correct description again .

Hercus (2).JPG

So with my 60 to 63 bushed gear . Do I just use this chart and use the 60 / 63 where it says to use the 100 to 127 ?

Or is there another chart describing the gear set up for the 60 to 63 that is different from the one above ?

I have scoured AMH looking for it but had no luck .

Or is it in the Hercus TBOT? I only have the later 260 lathe edition of that atm . Waiting on an early copy atm .

Thanks . Rob

Using a 60/63 pair will be the same as using 120/126, so don't use the 100/127 settings. See if there are 120/127 settings as they should be equivalent-ish.

Michael

I found these for the 260 lathe in my TBOT.

Is using these for my AR lathe with same 8TPI lead screw OK ?

IMG_7940a.jpg IMG_7941a.jpg

I don't understand the gear lever positions either from the chart on right .

This is what you need.
PM me if you need a higher res copy. I can email it. Cheers, Tony

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Thanks Tony I will send a PM . Ill print it out .

That left chart, whats the lever positions , they go up to 80 ?

Rob

Originally Posted by auscab

Thanks Tony I will send a PM . Ill print it out .

That left chart, whats the lever positions , they go up to 80 ?

Rob

Hi Rob

The gear lever positions are what you set the gearbox to cut so if it says for example 16 on the chart then you would set the gearbox to cut a 16TPI thread, the attached photos may make it clearer for you, the gearboxes on the 9" will cut up to 224 TPI.

Regards Steve

Originally Posted by auscab

Or is it in the Hercus TBOT? I only have the later 260 lathe edition of that atm . Waiting on an early copy atm .

I have a PDF copy of the early version if you want it?

Steve, spot on. I sent Rob a high res pdf of much the same. I reckon the chart stops at 80 because that would give you an M2 thread, and you'd being doing really well to single point cut that...I'd be reaching for a die. Cheers, Tony

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Originally Posted by Tinkerer77

Hi Rob

The gear lever positions are what you set the gearbox to cut so if it says for example 16 on the chart then you would set the gearbox to cut a TPI thread, the attached photos may make it clearer for you, the gearboxes on the 9" will cut up to 224 TPI.

Regards Steve

Thanks Steve . Tony sent me the same, explanations from a couple of angles is a great help.

Rob

Originally Posted by Silversprings

Steve, spot on. I sent Rob a high res pdf of much the same. I reckon the chart stops at 80 because that would give you an M2 thread, and you'd being doing really well to single point cut that...I'd be reaching for a die. Cheers, Tony

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Thank you Tony .
I will store that info you sent and do a print out for the workshop.

Rob