How to sharpen metal lathe tool bits

how to sharpen metal lathe tool bits

The relief angles are needed to stop the tool rubbing. Chatter was a problem on both machines during deep cuts with high feed rate until I limited the feed rate by reducing the side relief see below and reduced the width of the cutting section.

Toolbit Development 1

With some thought you may well build on, and improve, the ideas covered here. I've found I'm using these bits more, especially for roughing, as time goes on.

To grind a new bit, it is oriented so the angle on its end has the longest part uppermost to minimize material removal. OK, tell me again why we need this level of control over the edges?

how to sharpen metal lathe tool bits

The diagram below shows the terminology used to describe cutting tools click for a larger image. Place the cutting edge side of the bit down on the tool rest.

Lathe Bit Sharpening

This flat area is easy to hone to a polished finish on carbide paper. The relief angle is the critical one. The tool in action.

how to sharpen metal lathe tool bits

This is effectively a dual tool with a roughing section followed by a finishing section. Ensure that the surface is dry before proceeding. The tool rest angle is giving us our side rake. Patience and nerve heat-death are machinist virtues. Modern shop practice tends towards zero or even negative rake tools, but these are rarely suited to the home shop.

How to Sharpen Metal Lathe Tools

How long you can go between dunks is the measure of true grit. When they catch the light they should look like perfect planes, with no rounding near the edges.

how to sharpen metal lathe tool bits

The end of the tool in my hand should be angled forward, towards the back of the grinding wheel. Other than those high end tools, few brazed tools perform their best right out of the box, and you can't fix this using only a green carbide wheel. First, set up your bench grinder. Easy, problem solved.

Sharpening HSS Lathe Tool Bits

Tool height should be set to put the finishing point on center. You should be lapping the minimum amount of material necessary to the function of the tool.

how to sharpen metal lathe tool bits

This is even more of a time saver with carbide.