Correct, except that it was usually done beforehand in the factory. The process is described in "The Last Years of Mill Engine Building" by Arnold Throp. The assembled flywheel was bolted in bearings on the floor over a deep pit. It was turned using a worm drive from the factory lineshafting onto the internal barring gear teeth in the flywheel. Grooving was done with large (3" square) carbon steel tools while labourers toiled in the pit removing wheelbarrow loads of swarf and grit.

Andrew

I didn't have a lathe big enough to allow me to turn the flywheel for my steam launch engine so I did the final trueing up with the flywheel mounted on the engine and running on air. I had done the roughing out on an old Herbert turret lathe but the lack of suitable chucks or boring tools meant that I could not bore it and turn the outside at the same setting. I bolted down a compound table on the bench next to the engine and mounted bit of toolsteel on that. Certainly ensures that the flywheel runs true. I suspect the old timers would have mostly used a stub shaft rather than the actual engine.

It is an idea worth bearing in mind, since for a stationary engine, often the only part that needs a larger lathe is the flywheel.

John

**LINK**

I haven't worked on a VTL this big, but did put a control system on a Craven used to turn the bearing ring surface on the underside of Callenger tank turret castings at the old ROF Barnbow factory near Leeds. The company that rebuilt the machine did a promotional video with their works Escort van on the table with it rotating under the cross rail.

Also worked on a Crawford Swift roll turning lathe, a bit like this one:

**LINK**

As part of a rebuild & CNC conversion, 12" rising blocks were fitted under the headstock & tailstock to increase the swing to around 60" & IIRC it was 40' between centres with a 125 hp main drive. If the operator started a cut at the start of his shift, the cut had not finished when he went off shift. The operator's boiler suit was polished down one side, where he leaned on the roll as it rotated so he could watch the tool – prompt action being required if the insert failed to prevent damage to the holder. The swarf came off like car coil springs, slowly coiling up above the tool until it got too heavy & then dropped with a "clang" through ramps cast in the bed to a conveyor below. I can't recall exact speeds & feeds, but the inserts were about 2" square, run at full depth at around 1/8"/rev and probably 10 rpm or less IIRC

Large machine tools are interesting things to work on.

A rather similar method was adopted at Saltburn on Sea on the east coast which has an inclined water powered cliff lift down to the beach level.

​The original top wheel over which the wire ropes run finally succumbed to the weather after about 80 years and was replaced by a similar size of pit head wheel salvaged from a local coal mine closure. The grooves for the ropes needed to be widened slightly and the cars provided the motive power to drive the wheel, one groove at a time, while the machining was done using a temporary tool holder and slide borrowed from a lathe.
​The lower wheel is below the pumping building at the bottom and protected from the ravages of the weather

​The old header wheel is now displayed lying on its side at the top of the lift.

Regards
Brian

I machined my 2 hp hot bulb Blackstones single flywheel in a similar way to Waynes ,using a Greeves trials bike sprocket mounted on the crankshaft and a villiers gearbox sprocket mounted in my Colchester lathe chuck,connected with ten feet of sprocket chain, 2 ft 6in flywheel rotated at about 7 to 10 rpm ,I used the lathe top slide to machine the rim ,it took far longer to set it up than carry out the machining,