Try JB Cutting Tools, or Cutwel.

(Not “JB Tools”, unless you are in America – but I don’t know if that firm stocks such items anyway.)

I think you’ll find the inserts themselves are all to industry standards, described by their convoluted letters-and-numbers codes, so needn’t necessarily be made by Sandvik to fit Sandvik holders.

So ask by the holder designation, which Sandvik stamps on its side.

Parting-off to 3/4″ depth (the bar radius) in free-cutting mild-steel should not be a problem provided the lathe and setting are sufficiently rigid, and crucially, the tool is set correctly to height and perpendicularly to the axis.

I set mine by ensuring the holder is fully engaged with the tool-post, then gently using the saddle handwheel to pushing its flank lightly against the chuck jaws or tailstock barrel face so they act as a square, while tightening the tool-post clamp-nut.

Richard,

The forum looked into this problem a couple of years ago.  Greenwood tools used to supply these inserts individually but since they ceased trading the tips only seemed to be available in boxes of ten – rather more than most people need at £15 odd each.

However, a quick search shows that Cromwell now seem to sell them individually Cromwell tools

for about £20 each delivered.

ARC Eurotrade sell a similar but much more pocket friendly system that works well ARC Eurotrade

with replacement tips at a couple of quid each ARC GTN 2 tips.

HTH,

Rod

The illustration of the ARC GTN 2 tips gives the impression that they are rather blunt. If this is indeed the case has anyone tried using a suitable hone (e.g. diamond) on the top surface to produce a keen edge suitable for use with lightly constricted lathes ?

I find the GTN-2 work OK on my lightweight Chinese machine on steel and cast iron. I don’t bother with a rear toolpost and even hang it off the side of my QCTP.

Did part of some 115mm thick wall tube today but just went with a cheap import 1.5mm HSS tool as it saved a bit more material that I may have a use for. Quite happy at 200rpm.

The fillets left in the corners are important, as you say, but are their radii ever so critical?

When I turned my steam-lorry crankshaft I used an HSS tool and simply free-hand rounded its corners- I forget if by grinder or oil-stone. The existence of the fillet being more important than its size.

The pin length is slightly over the journal width, but I also chamfered the journal ends.

If you using a parting-tool to profile a crankshaft, an HSS one would be better because you need traverse it as well as feeding inwards, and indexable parting-tools are not designed for side-loading.