This tool parting steel is at    • $25 eBay parting tool vs Steel. Small...  
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It was suggested to me that a $25 parting tool including 10 inserts from eBay was quite good. I am not a great believer in cheap tools being cost effective, but I bought one anyway so I could make a comparison video. My main parting tools for my small cnc lathe are a Sumitomo 2.0 wide insert with a maximum parting diameter of 20mm and a Kennametal 1.6 wide 41mm maximum parting diameter. I don't attempt to part any diameter larger than that. These tools cost up to $125 each and the inserts are around $15 each double ended. But for me they work and that is what counts. Many thousands of parts and they have never let me down. Parting takes place when the rest of the process is finished, it is not the time to have things go wrong and ruin the part. That is definitely not cost effective.
With small parts, I typically part non ferrous parts at 3000 rpm with feeds of 0.02 to0.07 mm/rev. For steel the spindle rpm gets lower, but they still work great. In the video each tool takes a facing cut, a turning cut and 2 parting cuts. Material is 20ø alloy 2011 machining grade aluminium. Speed is 3000rpm, and the feed is 0.05mm /rev. Insert codes are as follows: Ebay parting tool 1.5 wide insert MGMN150-G Kennametal 1.6 wide insert A2016N00CF01 Sumitomo 2.0 wide GF type insert GCMN2002-GF Cutting speeds as for GF Non Ferrous 150/300, actually used 190m/min After trying this cheap carbide insert parting tool from eBay, I am pretty sure it must be far better than using a High Speed Steel parting blade.