How to use a boring bar on a lathe

Last updated on November 18th, 2022 at 11:57 am

What is a lathe boring bar

A boring bar is a tool you can use on a metal lathe. The machine operates a tool that rotates while moving a cutting tool. As it removes material, this works to enlarge the inside diameter of a workpiece. This is a standard routine you can do with a micro lathe. Choosing the best boring bar will depend on the level of accuracy you require. Choosing the stiffest option will dictate the precision. Choosing a boring bar with the largest diameter and shortest extension length is the most balanced option.

There are three types of boring bars on the market that come with their specifications and benefits.

High-Speed Steel (HSS)

HSS is a type of bar that is often cheaper and tougher. It’s fast because it’s easy to re-tip the bar on a standard grinder and honing stone. It means you can reuse it if the cutting edges wear.

Brazed Carbide Boring Bar

This option is much sharper than most boring bars. It can cut 2.5-5 times faster than the HSS bar. The reason why it’s faster is that it can tolerate much more heat. You will find that Brazed carbide is 2.5 times more rigid than steel. The only challenge is that the bar must be reground or discarded when its cutting edges wear.

Indexable Carbide Boring Bar

This option has similar qualities as the HSS bar, but it provides a smoother finish because of the minor cutting edge. You should achieve a more accurate bore size even when performing rough boring.

How to set up boring bar in the lathe

Orientation

It is rare to find a boring bar that comes with alignment flats. This missing feature means that orienting the top surface of the cutting edge parallel to the XZ plane of the lathe is required for greater precision.

The three main orientations of a boring bar are- negative rake, neutral, and positive rake. When looking at all these options, you will find that neutral is the safest. Trying out other orientations will require setting the tooltip on the vertical spindle centerline.

Check to ensure that cutting tip clearance is sufficient. The top option is positive rakes when dealing with smaller, weaker materials like aluminum and plastics. If the materials are much stronger than these, then use negative racks.

Height

Height is an essential factor to consider when setting up a boring tool. You will need to select a boring bar with a height that users can adjust. You will need to try and get as close to the vertical spindle centerline as you can without straining.

If the boring bar is not on the vertical centerline, it will significantly reduce your precision. The bar could also sustain damage permanently.

Deep boring on a lathe

1. Start by removing the tailstock center. This item will have to be interchanged with a ‘hollow center.’ You can distinguish this center from others because it has a hole through it. When in motion, this hole will allow a drill to pass through. 
2. Apply a minuscule amount of grease to the end of the center. This task will assist the wood in rotating without any restrictions.
3. The drill is pushed through the tailstock and hollow center as you start using this. This allows wood chippings to be removed and avoids the auger becoming jammed and consequently spinning with the rotting wood. 
4. You will need to be steady as you bore deeply and then withdraw it from the tailstock.

Using a boring bar on a mini-lathe

If you intend to use a boring bar on a mini lathe, then you will have to measure the boring bar accurately. You can do this by using Dial or Digital Calipers, Small Hole Gage, or a Gage Pin.

How do you use a boring bar on a lathe?

How do you touch off a boring bar on a lathe?

For this, we will be using a digital angle finder. You can place the angle finder flush against the angle finder seat, then attach the seat to the x-axis of the lathe. The core is magnetized, so it should be held in place. Turn the angle finder on and then press zero. This should work to zero out the angle finder. When the angle finder is calibrated to the lathe, you can attach it to the boring bar. If you can match the bolts on the head of the bar, you’ll see a flat that the angle finder seat will magnetize to with the angle finder. This item will be attached to the boring bar and needs to be rotated. Rotate it until the bar until the angle finder reads zero degrees. The final task is to tighten the bar in place, and now you should be ready to go.

How does a boring head work?

They are tools used that are used to enlarge an existing hole.

How do you grind a boring bar tool?

This can be applied to boring and grooving without too many modifications. If you intend to reshape the tool, then use a diamond whetstone.

How many types of boring bars are there?

There are three types of boring bars

1. Brazed Carbide Boring Bar
2. Indexable Carbide Boring Bar
3. High-Speed Steel (HSS)

How do you use a boring bar set?

Can you use a boring bar on a mill?

You can use the boring bar on a mill. 

What is a horizontal boring machine used for?

To drill holes horizontally. You should be able to handle more extensive parts with this method. 

What is a heavy metal boring bar?

It is suitable for boring low carbons, stainless steel, and ferrous metals.