The use of backgear on the Cowells was necessary to get the torque and I do wonder if it would be possible to do the work on one of these small Seig C0 lathes which use electronic speed control. I don't know what kind of torque is available at low speeds on these small lathes. We have one at our clubroom and I might take a bit of mild steel up to see if it is possible.
Well since I run online support groups for the C0 and have one sitting in the middle of my kitchen, I'll have a go too, but not necessarily before the AGM. I'm reluctant to promote the C0 these days - things have got so bad that its main champion, Arc Euro Trade, have been obliged to discontinue it, (still do the accessories though) and Axminster have ramped the price up dramatically to pay for the heavy-duty support that purchasers need.
If anyone cares, a C0 outfit with all three chucks mentioned is now £600.
Having said that, if somebody already has a C0, or is prepared to treat it as a 'lathe kit' needing serious reworking to do what it says on the tin, or (like me) is prepared to forget slide-rest turning and use it for hand-rest turning, then I reckon it's up to the job, given ingenuity.
To answer your question on torque, at the lowest speeds (control knob pointing to 9 o'clock), roughly 100rpm, I can stall the spindle with my bare fingers. It will still peel off a shaving, but not a very big one, and the current-trip often pulls out. Meanwhile, the DC motor is very stressed because, with the motor virtually stationary, the Back EMF is zero so the brief current pulses are huge, and the cooling fan is useless.
The forté of the C0 is its high speed, but anyone with a C0 they don't mind cutting up could re-motor it for high torque / low speed.
In terms of Economy Lathe Tactics:
The first step is to ditch those handy offcuts of BDMS (Bright Drawn Mild Steel) bar.
It's not only seriously work-hardened, but in bar form it has higher carbon content than BMS (Black Mild Steel), both factors making it harder to machine. (Opposite might apply if you want to hack washers out of plate though.)
Better still is a free-machining steel like EN1a or Leaded EN1a.
The next step is to optimise tool efficiency.
A sharp HSS tool with the right rake for the job is a joy. (The best tool grinding teacher is a treadle lathe - your leg tells you instantly whether you've got it right.) My own preference is for hand gravers, which respond instantly to the slightest tweak of rake.
What gravers can't do, of course, is get a series of tyres identical first time round. So that needs dealing with at some stage.
But don't write gravers off as mere 'ticklers'. To start with, a tickle is all we need when modifying wheels, but also a decent graver in a long handle on a big lathe can peel off angry smoking blue swarf just as effectively as a slide-rest tool (leather gloves and a face mask help!).
Then there's chucking, which I'll pontificate on when I've done more wheels.
Finally Feeds and Speeds.
- Your back-geared lathe is having slow success with high-torque / low speed.
- My Pulse Width speed controlled lathe is having slow success with high-speed / low torque.
I'm probably making even finer swarf than you, but it's coming off in quantity!
David