March 23, 2022

How to knurl on a lathe

What is meant by knurling?

Knurling is a metal modification process of creating small ridges along a metal object’s surface to improve handling, making it easy. The knurled object can be physically handled, lifted, or gripped.

Knurling is also known as the process of modification and the machine attachment component used to create grooves along a substrate’s surface. It comprises durable finish standards, optimally finished, and corrosion resistance.

There are ways to mold a substrate with the knurled workpiece to copy the knurl pattern onto the surface. The components of this activity involve a molded object, a method of forming a structured abrasive, and an abrasive surface.

How do you knurl on a lathe machine?        

  1. Clamp your work for knurling, and set up for knurling can be made between centres or mounted in a solid chunk. Do not attempt to knurl by holding the knurling work in a rubber or metal collet chuck because the pressures of knurling can damage these devices. If mounting the knurling work between centres, make the centre holes. If using a chuck to hold the work, use the tailstock centre to support the end of the work, and doing a long knurl, use a steady rest to support the work.
  2. Set the knurling tool in place. There are two types of knurling tools. These are the knuckle joint and revolving head type of knurling tools. The knuckle joint type features a single pair of rollers that revolve around the work as it is knurled. The revolving head type of tool is fitted with three rollers to change the pitch to a different knurl without changing the setup. There are two knurl patterns, diamond and straight.
  3. You can now jump into the knurling operation. It starts by determining the location and length of the knurl and then setting the machine for knurling. Use a slow speed with a medium feed. The standard knurling speed is set from 60 to 80 RPM, while the knurling feed is best from 0.04 mm to 0.08 mm revolution of the spindle. The knurling tool has to be set in the tool post with the axis of the knurling head at centre height, and the face of the knurls parallel with the work surface. 
  4. Check that the rollers move freely and are in good cutting condition. If the face of the roller is in this manner. The pressure required to start the knurl will be lessened. That is how the knurl cuts smoother.
  5. Oil the knurling cutting wheels where they contact the workpiece. Bring the cutting wheels up to the surface of the work with almost 1/2 of the face of the roller. It has to be in contact with the work. Apply oil over the area to be knurled. 
  6. Start the lathe while forcing the knurls into the work about 0.05 mm. As the impression starts to form, engage the carriage feed lever. Observe the knurl for a few revolutions and shut off the machine. 
  7. Check to see that the knurl is tracking and not double-tracking.

        What is a knurling tool for lathe?

A knurling tool is a manufacturing and repair tool on lathes that produce straight, diagonal, or diamond patterns. It is presented as teeth of uniform pitch on the exterior of the workpiece. The diamond pattern is also called the cross pattern, and angular patterns are either left hand or right hand.

Face knurling on the lathe

Face knurling is ideal for manual use and CNC lathes where adjustment is unnecessary. It is for use with adjustable or fixed-end rolling holders.

Knurling instructions

  1. Press a pattern onto a round section. The knurling pattern works as a grip for a handle. 
  2. Set the lathe so that the chuck revolves at a low speed. 
  3. Press the knurling tool against the rotating steel and apply pressure. It has to be done slowly and increased until the knurling tool produces a pattern on the steel.
  4. The automatic control lever is engaged, which starts the automatic traverse of the saddle. As the saddle moves along the bed of the lathe, the knurled pattern is pressed into the steel along its length.
  5. If the traverse of the lathe is stopped and then reversed, a diamond pattern is produced.
  6. Multiple, knurled patterns are produced depending on the knurling tool selected, knurling speeds, and feeds

How to knurl metal without a lathe

Knurling is also by hand. Hand knurling uses a rolling roll that creates the desired pattern on the workpiece. Buy hand knurlers. These look like pipe cutters but have knurling wheels, and you can also use a drill press as a vertical wood and metal lathe. That is only for the metal. 

What RPM should you knurl at?        

Knurl at a maximum surface speed of about 150 SFPM (Feet/Min) or 50 m/min.

        How do you Knurl on a CNC lathe?

  1. Install the workpiece.
  2. Install the knurling tool.
  3. Clamp the tool firmly.
  4. Select low cutting speed and large feed.
  5. Start the spindle of the machine tool.
  6. Apply sufficient coolant to the knurled cutter.
  7. Move the knurled tooling to cut into the workpiece and apply pressure until a diamond pattern is made.
  8. Adjust the knurling tool visually to deflect it by a small angle.

        Can you Knurl aluminium?

Yes, and Aluminum knurls beautifully.

        How do you find the diameter of knurling?

Use the Knurling calculator. This tool calculates an appropriate diameter for knurling. That is if you know the circular pitch of your knurl.

How do you straight A knurl on a lathe?        

Knurl at the slowest speed your lathe offers, and use a straight knurl.

        How do I get a perfect knurl?

  • Increase your feed rate to about .025″/rev.
  • Make sure your knurling tool is set and square with your work.
  • Use a good quality knurling tool. 
  • Use some cutting fluid such as Tap Magic or flood coolant to keep the knurling tool, and the part flushed.

        How do you knurl a flat surface?

Flat knurls are on a shaper or planer. Use a coining-type knurling tool in a machine tool spindle as the forces involved are different from a standard cutter and would likely damage your spindle train. Cut it with a pointed center-cutting lathe for a small area to knurl.

        Can you hand knurl?

Yes, you can.

        How is knurl pitch calculated?

Circular pitch is based on the distance between the teeth per inch (TPI). It is measured along with the wheel from one tooth point to the next, and diametral pitch is on the number of teeth per inch of the wheel’s diameter.

        How do you use a clamp-type knurling tool?

Install and clamp it tightly after it is situated squarely on the workpiece. Do not move it onto the workpiece.

David D. Hughes
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