Mostly 0.2mm for me with 0.4 kept for roughing steel and iron castings. The 0.8mm only come out if I want a decent corner fillet for things that I want to look cast. I find the smaller radius deflects long slender work less so good for valves and crankshafts, etc.

Without knowing about your lathe, it's impossible to offer useful advice. My experience is that 0.8mm tip dia. inserts don't suit a Myford Super 7 – it's just not rigid enough to work the insert at depths of cut and feed rates that justify the larger tip radius. However, an Emco Maximat Super 11 takes them in its stride – even 'blunt' inserts, designed for hogging off metal, rather than fine finishing – and with a very good surface finish. Not bashing Myfords, it's just horses for courses…

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Turning tool set for indexable inserts 7 pieces with key Each turning tool with indexable insert of carbide metal quality the indexable inserts have 4 cutting edges Insert shape CCMT 1 x left hand turning tool - for straight turning 1 x right hand turning tool - for straight turning 1 x right hand facing tool - for face turning 1 x right hand straight turning tool - for straight turning 1 x pointed turning tool - for outside thread turning and straight turning 1 x offset pointed turning tool - for outside thread turning and straight turning 1 x boring bar for right hand cutting - for turning out internal bores

I use 0.2mm, 0.4mm and 0.8mm radius inserts. The 0.4mm inserts get used most for general turning and the radius is a good compromise when a really sharp internal corner is not needed. I use the 0.2mm inserts for smaller diameter work and where a sharp internal corner is needed. The 0.8mm inserts are used for heavy roughing, especially in steel and cast iron, and where I want a nice fillet.

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I saw the following on their website 'We suggest the use of 0.8mm corner radius inserts for general cutting, and 0.4mm corner radius inserts for finishing.' From personal experience you can get chatter from using too large a tip radius

If you have a hobby size lathe I would stick to 0.4 radius as a good compromise. I must admit I like the 0.2 ones for a lot of what I do but the cutting point of the insert can be easily damaged if not careful.

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I seem to have always gone for what I got origionally when I bought the tool holder, 0.4 however I notice Arc also sell 0.8 and just wondering what the advantage/dissadvantage of the two sizes

Home › Forums › General Questions › Carbide inserts. 0.4 or 0.8 This topic has 12 replies, 10 voices, and was last updated 22 February 2020 at 07:00 by petro1head. Viewing 13 posts - 1 through 13 (of 13 total) Author Posts 21 February 2020 at 10:31 #27164 petro1headParticipant @petro1head Advert 21 February 2020 at 10:31 #453324 petro1headParticipant @petro1head Time for some new inserts. I am after ferrous and non ferrous. I seem to have always gone for what I got origionally when I bought the tool holder, 0.4 however I notice Arc also sell 0.8 and just wondering what the advantage/dissadvantage of the two sizes Edited By petro1head on 21/02/2020 10:31:20 21 February 2020 at 10:39 #453325 Tony Pratt 1Participant @tonypratt1 I saw the following on their website 'We suggest the use of 0.8mm corner radius inserts for general cutting, and 0.4mm corner radius inserts for finishing.' From personal experience you can get chatter from using too large a tip radius Tony 21 February 2020 at 10:55 #453329 petro1headParticipant @petro1head So prob best just to stick with what i Know, 0.4mm 21 February 2020 at 11:20 #453333 Anonymous I use 0.2mm, 0.4mm and 0.8mm radius inserts. The 0.4mm inserts get used most for general turning and the radius is a good compromise when a really sharp internal corner is not needed. I use the 0.2mm inserts for smaller diameter work and where a sharp internal corner is needed. The 0.8mm inserts are used for heavy roughing, especially in steel and cast iron, and where I want a nice fillet. To some extent the smaller the insert radius the smaller the final depth of cut can be and still maintain a decent finish, although many other factors also need to be considered. Similarly the larger the radius the higher the feedrate can be for a given finish, which may help with chatter problems. Speaking of which I've never had a chatter problem due to the 0.8mm radius inserts, but I do drive them fairly hard. While I find it useful to have all three options available the 0.4mm insert is a good compromise. Andrew 21 February 2020 at 11:35 #453334 Douglas JohnstonParticipant @douglasjohnston98463 If you have a hobby size lathe I would stick to 0.4 radius as a good compromise. I must admit I like the 0.2 ones for a lot of what I do but the cutting point of the insert can be easily damaged if not careful. Doug 21 February 2020 at 12:30 #453342 CirclipParticipant @circlip Bench grinder and a lick on the tip with a fine stone for us non NASA types.

To some extent the smaller the insert radius the smaller the final depth of cut can be and still maintain a decent finish, although many other factors also need to be considered. Similarly the larger the radius the higher the feedrate can be for a given finish, which may help with chatter problems. Speaking of which I've never had a chatter problem due to the 0.8mm radius inserts, but I do drive them fairly hard.

Without knowing about your lathe, it's impossible to offer useful advice. My experience is that 0.8mm tip dia. inserts don't suit a Myford Super 7 – it's just not rigid enough to work the insert at depths of cut and feed rates that justify the larger tip radius. However, an Emco Maximat Super 11 takes them in its stride – even 'blunt' inserts, designed for hogging off metal, rather than fine finishing – and with a very good surface finish. Not bashing Myfords, it's just horses for courses…

Like Jason I mainly use the .2mm rad inserts as they are more suitable for the type of parts I make but do use the .4 for some work as facing cuts with a .2 rad have to be less than tip rad to cut cleanly.

Tapered gib problem Screw cutting chart ML4 When locking the head after tramming puts the mill seriously out of tram How to reduce head diameter of countersunk wood screw? MEW 344 cover-feature 5 inch battery loco speed controller Butch stuck regulator, on going. BT Upgrade to Digital Phone Line “Failed” ammeter shunt Machining cams on the mill