Yes the lathe tool should be in line with centre of the work. Its easy to make a "stand " so that the lathe tool fits exactly underneath when at centre height. No harm done by asking RDG if you can exchange for the correct size, I've always found them helpful, after all there is no better advert than a satisfied customer and you might buy again.

Change wheels I'm not familiar with your lathe but when some comes up with the details of the gears, try HPC in Chesterfield or Davall of Hatfield. I have bought gears from HPC and they have a very useful catalogue. You could also try Chester, place an advert here or ebay. John

12mm tooling might eventually be useful for some jobs. They just need that extra 4-6 mm thick ‘shim’ to get them to centre height. So no great deal if they cannot be refunded/exchanged. Learning on smaller cutters is cheaper than making mistakes with more expensive ones!

A good introduction to lathe cutting tools (just to confuse you further) might be the vid on this subject by ‘this old tony’ on u-toob. You might then understand that you need to start simple and progress at a rate that suits you. There are several explanations on the net for uses of the different inserts and tables explaining the codes for the letters.

What material you are going to be cutting might help sort out a few simple general purpose inserts, if you intend going this way.

Have fun making chips.

12mm tools are perfectly adequate as you are not meant to use the absolute biggest you can cram into the holder. You should always leave room to shim up to height . Most of the time 1/4" or 3/8" HSS are the best to use and available on ebay as a bunch of used ie ready ground to some weird shape for a quid each.

+1 for making a Tool Centre Height Gauge. It will save you hours of frustration and wasted time, and probably material.

ANY chance that Chester (or Warco) could supply the missing changewheels?

Failing that, if you can't get them via the "Wanted" section on here, maybe you could find some kind soul who would make them for you, (you would learn as the work was done together). If you could, at least, get dimensions, DP / Mod no, it would be a start.

Whereabouts are you?

Can you find a Model Engineering Club nearby, where you may be able to get help?

Howard

John, before you buy gear cutters have a look at the following webpage – link – the cutters there are 20deg pressure angle so would run happily with your existing gears. I've found that meshing 14.5 deg pa with 20 deg pa the running characteristic feels very "notchy" as the gears do stick and then clear due to interference between the teeth. It could give you chatter problems.

It could also be worth contacting Chester Machine Tools if you haven't already as in the past they have had a box of miscellaneous gears, at their sales open days and at the occasional shows that they've done, for you have a rummage through. I don't know what those gears have come from but change wheels for your lathe might just be amongst them

I've not used gear cutters from CTC but other tooling (ER collets) have been excellent for my needs – just a happy customer.