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Carbide question

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Adam Pinson

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The copper work i create is best turned with carbide but even then the inserts blunt fairly fast, i've been buying them in packs of 3, round, square and diamond for approx 15 quid which i feel is a too expensive, does anyone know where i could get them in higher quantities or just cheaper? thanks.....
 

dannyr

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How long/how much work do these last for?

The tungsten carbide will be far harder than the copper - maybe there's a chem reaction taking place - are you using a coolant? is this on a machine tool or a wood-type lathe?

Most inserts also have 4, 6 or 8 cutting edges (or more with a circular insert).

Although they may have a golden coating of titanium nitride (only microns thick) the whole of the rest of the insert should be solid tungsten carbide (with cobalt or nickel binder) so sharpenable to any depth (but some insert geometries have a difficult groove). (the point of inserts is generally not to have to sharpen).
 

Adam Pinson

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How long/how much work do these last for?

The tungsten carbide will be far harder than the copper - maybe there's a chem reaction taking place - are you using a coolant? is this on a machine tool or a wood-type lathe?

Most inserts also have 4, 6 or 8 cutting edges (or more with a circular insert).

Although they may have a golden coating of titanium nitride (only microns thick) the whole of the rest of the insert should be solid tungsten carbide (with cobalt or nickel binder) so sharpenable to any depth (but some insert geometries have a difficult groove). (the point of inserts is generally not to have to sharpen).
They do get blunt, i know this from experience, it's a wood lathe and the copper is chopped wire cast in epoxy. I am aware of different quality tips, all carbide is not equal etc..... i can use steel, gouges etc, but that means constant sharpening.....
 

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I only use HSS on copper and or the Ozzy diamond cutting tip.....
it's not a diamond it's just a special steel in the shape of a diamond....
it's not cheap but works real well......on most materials.....it wont replace carbide tho.....
it's ment more for the home machinist who's lathe isn't fast enough or stong enough to get the best outta carbide....
 

TheTiddles

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Carbide should last ages on soft copper and resin, the problem I’d expect to happen is the cutter getting gummed up very easily, which is less to do with the tool and more the coolant flow/removal
 

SVB

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i’ve used standard HSS on aluminium, copper and silver will good results. Something else may be going on here if you’re dulling tools quickly. also I’m not sure carbide is best choice depending on cutter geometry as it may not be as ‘sharp‘ to begin with and therefore more prone to galling up. I’m not sure, just some thoughts if it helps.
simon
 

Tanglefoot20

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Just an bout from a skilled turner...i always used HSS on softer metals...with a good top rake and radiused tip... using tungsten tools creates a welding effect so the copper work hardens an tends to stick to the tip. soft metals all act the same way....aluminium is aweful with tungsten.
Always try and use HSS and experiment with rake angles
Regards

Steve
 

TheTiddles

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Just an bout from a skilled turner...i always used HSS on softer metals...with a good top rake and radiused tip... using tungsten tools creates a welding effect so the copper work hardens an tends to stick to the tip. soft metals all act the same way....aluminium is aweful with tungsten.
Always try and use HSS and experiment with rake angles
Regards

Steve
Welding copper to tungsten carbide?
 
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TheTiddles

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Why not? - tungsten carbide tips on saws, drills etc are usually held on by a braze (ie copper based) - and 'tungsten carbide' is actually tiny particles of tungsten carbide in a matrix of cobalt or nickel
Because copper melts around 1000c and tungsten carbide at 2900c, even the cobalt binder at 1500c.

Brazing isn’t welding, it’s an adhesive process, there’s no melting of the parent material. Even a diffusion weld would need to be up above 50% of the melt temperature at least and require the correct surface preparation and a lot of pressure for a protracted period. You can weld carbides by laser and electron beam to steel of certain grades and invar, MIG and TIG have also been demonstrated as well as friction welds.

Brazing remains the most common method, but it’s not a weld.
 

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