Reply To: Sumitomo insert help

[CabengParticipant @cabeng]

Well MAC, it might be worth thinking about buying a new toolholder as well! I suggest that for three reasons:

1) If you happen to buy a box of 8mm tips just before the holder wears out (and they do, unfortunately), you could be left with a load of expensive bits of carbide that you won't be able to use because you won't be able to replace the toolholder.

2) There's another holder available for the CCGT tips, one that uses the other two corners, the ones with the obtuse angles, so you get twice the number of cutting edges for the same cost! It's designation is SCRCR for the right hand cutting version. Unfortunately, the toolholder is no longer available for 8mm tips.

3) Nobody other than Sumitomo makes 8mm tips, so there wouldn't be any opportunity to use alternatives, should the urge or need come upon you. 6mm & 9mm are standard sizes from many (if not all) manufacturers.

HB Cutting Tools can supply German manufactured holders at about half the price of the Sumitomo items – I just changed to 6mm tips and bought 4 of these holders (Right hand, left hand, right hand obtuse and neutral) from them, £28 each plus VAT, although I think the obtuse one was a bit more pricey. I've only just got them, so it will be several years (I hope!) before I know how long they'll last, but HB assured me that these were items that they sold into industry, and that I wouldn't notice any difference.

Maybe of interest – I've used the Sumitomos for many years on a Myford S7B PCF machine with VFD drive – it loves 'em, and shifts metal at an amazing rate. 2300 rpm on 1" FCMS is fine, the lathe hasn't been on the slow speed range since I got them. But watch out for the chips, they go ballistic!

Oh, and if anyone tells you that they don't like interrupted cuts…. don't believe them. The trick to making the tips survive interupted cuts is to cut DEEPER, e.g. 1.25" FCMS hex bar down to round in one cut.