Lathe cutter geometry (HSS)

Lathe cutter geometry
(HSS)

Learning target: I can teach lathe cutter geometry and its importance.

You will learn how to grind your lathe cutter in 3 steps and the reasons for each step.

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How and why on grinding

Grinding the End Relief

Use the coarse wheel of your bench grinder (rougher) and hold the tool blank angled downwards from the tip to the rear and with the tip pointing to the left about 10-15 degrees.

The tip of the tool blank should be a little below the center line of the wheel. DO NOT let the cutter move in your hand when grinding, this will cause "rounding" of the surface of the tool.

Grinding causes the tool blank to get quite hot so you will need to dip the end of the tool into a water bath every 15 seconds or so during the grinding operation. When you see the tip of the tool start to discolor from the heat its a good time to make a cooling dip.

Grinding the End Relief

This is referring to the very end of your cutter.

You should pick a corner of your HSS and that will be your cutting point.

That corner should always be angled up and away from the wheel so that there is clearance ground on that side.

Multiple Choice

The cutter should be BLANK centerline of the wheel.

• Below

• Above

• In line with

Multiple Choice

Allowing the cutter to move in you hand while grinding will cause BLANK

• The cutter to be dull

• Squaring

• Rounding

• You to get an injury

Multiple Choice

You should dip your cutter into a water bath or coolant every BLANK seconds

• 30

• 15

• 5

• 10

​The top picture where it shows front angle clearance is the first place you grind.

Notice there is a single corner point at the top and that is what will cut.

Grinding the left side relief

The procedure is essentially the same except that we hold the tool with the side at about a 10 degree angle to the grinding wheel.

This side is the side that when in the tool holder it will be on the left side.

Same concept of keeping the point of your cutter up and towards yourself when grinding. The cutting edge should ALWAYS be the LAST part of the cutter to contact the wheel.

Grinding the left side relief

This is also a compound angle.

Meaning it has TWO angles. Just take one angle at a time.

First grind it with straight with the point up and towards yourself.

Multiple Choice

You cutting edge should always be the BLANK side to make contact with the wheel.

• First

• Middle

• Last

• Never

Multiple Choice

A compound angle means..

• Two angles

• One angle

• No angles

• Certain degree of an angle

​In this imagine you should be looking at the side clearance angle.

Grinding the top relief (rake)

The rake is the top of the cutter.

This angle is what helps form the metal chips being cut off the workpiece fall off nicely.

This side will be ground the same way as the left side relief. Remember that the cutting edge should be the last part to make contact with the grinding wheel.

Should be a compound angle that has a nice angle to help the chips break and fall off.

Multiple Choice

The rake is..

• The bottom of the cutter

• The side of the cutter

• A tool to remove yard debris

• The top of the cutter

Multiple Choice

The rake angle helps BLANK to fall off

• Lays chips

• Metal chips

• Chocolate chips

• Coolant

​In this image you should be focused on the rake.

Rounding the nose

You don't typically want a super sharp cutting edge.

To knock off burrs and take just a little bit of the sharpness away, you can take a stone and lightly stone the cutting edge.

It is more likely to chip of you leave it too sharp.

Multiple Choice

To round the nose you can take a BLANK to it.

• Stone

• File

• Grinder

• Sponge

Now you have a functional HSS lathe tool!

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You're done!

Information can be found at this link from this lesson.