You most likely have the wrong inserts for cutting brass. A lot of carbide inserts are not sharp like a ground hss, but are often very blunt/ dull. This is intentional as the tool relies on high surface speed to plasticise the material and induce chipping and very high metal removal rates. For home machines, like on my myford, I use the positive geometry and often coated inserts. These are sharp like a hss tool. They will give a very good finish on a variety of materials and don't need a lot of power to be cutting effectively. I like the Korloy from Korea and also the Kyocera from Japan. They make very high quality inserts and between them, make a selection for everything. The Kyocera ceramic inserts are fantastic for turning hard materials.

Neil

Those are CCMT inserts and really meant for steel. You can use silver coloured CCGT tips for brass and bronze.

Both these styles of tip work well with a mini lathe, they should give reasonable results with your lathe. use dead on centre height and run the machine three times as fast as you would with HSS.

Neil

Following advice from this forum about that supplier I visited their stand at Doncaster. They spent ages explaining tip technology, writing down notes on what to order next time & i came away spending far more than I intended. However, it was money well spent

I can't really see the geometry from the link but I have a different style of finishing tip and on a mini lathe the depth of cut makes a big difference to the finish. 1mm DEEP is fine but much beyond that and vibrations can set it. As Neil mentioned higher speed may help – oddly also an increased feed rate.

The tips I am using have a lot of positive rake and I suspect it's down to that. I have used different coatings on them and all have been ok on brass, steel and aluminium, until coating wear spoils things.

John

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https://www.kyocera-unimerco.co.uk/Kyocera/metal/turning-tools/turning-inserts/cc/UpdateFacets/

This is the UK site, The inserts I use are these, Kyocera CCGT060202MP-CK PR1425

Product code TKD01307 PR1425

A better picture is here,

https://www.kyocera-unimerco.co.uk/kyocera/metal/turning-tools/turning-inserts/cc/tkd01307/

Strictly speaking, these are a stainless steel grade insert. I used these inserts for cutting the modified outer bearing races to make my home made Magneto style bearing.They are not real cheap, but unbelievably good. You get a very good surface finish with hard steels, P20 type steels, and mild steels, as well as Aluminium alloys and brass, bronze and copper. I don't run my lathe any faster than the top pulley on the low selection, about 700 rpm or so. Run at a feed rate at between the lowest on the feed box to 6 thou per rev, or just by feel. Mostly I turn by feel and look at the chips coming off. For depths of cut, it will easily cut 0.5 to 1.0 mm 1mm to 2mm on diameter. I have not tried taking a 3mm diameter cut, but the packet says up to 3mm on diameter.

I generally get my tips from this range. Micro polished in particular.

**LINK**

I did buy coated finishing tips for stainless initially but aluminium soon removes the coating. I don't think that the geometry of the micro polished ones is significantly different.

For deep cuts in normal materials I feel that HSS still has the edge as it can be ground in a way that allows a lot of metal removal via deep cuts on smaller lathes.

John

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Look again Raymond, it shows a DCMT tip in a CCMT or SCMT shaped recess

I do have a holder that used the spare two corners of a CC** tip that leaves a 75" shoulder an SCRCR that is better for turning and have seen facing holders that do the same. There is also a good video showing the making of a holder that will use these same two corners for facing and giving a 45deg chamfer

Brian, there is a place in town that sell inserts, Cica Spares on Little Spence St down Portsmith way. He might be able to set you up with some good quality inserts. The Indian inserts have a poor reputation as has been mentioned above. Or if buying inserts off the net, try to get Sumitomo or Kyocera, Mitsubishi or Sandvik or similar brands. I found cheap no-name inserts to be pretty useless.

Jason – just had a look at the universal holder, the tip in the add clearly doesn't fir the holder, or is this something new?

Thats why I put a at the end of my link, definately does not fit.

I did ask Ketan if he was going to stock them but he declined, something about only bodgers would use something like that

Some botched up picture of a tip that is not designed to fit the holder shown… SCMC holder + DC** tip… I don't think so… unknown brand … & look at the price… warning bells chaps

George.