"Knurling Made Simple" Article

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"Knurling Made Simple" Article

Post by machineprojects » Thu Jan 17, 2008 5:08 pm

Here's a preview of the article "Knurling Made Simple" posted on the

new 'Articles' section of the site. If you wish to view it complete

with images go to www.proshoppublishing.com/articles.html.

Happy reading!

(By the way, the machinist tips & projects sections are looking great

on the new ProShop Pub. website. Our newsletter announcing all the

updates can be viewed at www.proshoppublishing.com/newsletter.html.)

* * *

"Knurling Made Simple" (preview)

Knurled surfaces are commonly seen on cylindrical parts such as

handles, knobs and rollers. Knurling is a process that creates a

pleasing, easy-to-grip geometric pattern on a part's surface.

When knurling, machinists apply a tool with two freely rotating

rollers that deform, or push, the material rather than cut it.

Creating a crisp, clean knurl on a lathe is easy if you follow these


- Understand the relationship between a knurling tool and the diameter

of the part to be knurled.

Some machinists get into trouble when they try to start a knurl over

an arbitrary diameter and find that the knurl doesn't track properly

by repeating itself in the previously laid grooves.

A proper diameter to knurl is any diameter that is a multiple of the

spacing, or distance, between the teeth of a knurling tool divided by

pi(3.14159). The relationship is the same whether the knurl is diamond

or a straight knurl. However, you must measure the spacing of a

diamond knurl's teeth along the axis of the part or roller for the

relationship to hold true.

Suppose you want to impress a diamond knurl on a 1"-dia. shaft and the

distance between each tooth of the knurling tool measured, with

calipers, along the roller's axis is 0.060". The measurement is not

extremely critical in that ultimately you will determine the final

diameter by trial and error. However, the measurement will give you a

decent starting point.

Following the formula stated previously, 0.060 divided by 3.14159 is

0.019. Therefore, any multiple of 0.019 should provide a diameter for

a perfect knurl. For example, 0.019 times an arbitrary number such as

40 equals 0.760. In theory, then, if you turned a shaft to 0.760", you

should be able to create a perfect knurl.

However, because you want to knurl a 1"-dia. shaft, you have to find a

multiple of 0.019 that gets you close to 1", such as 52 ( 0.019 × 52 =

0.988). Based on experience, though, the chances of producing a

perfect knurl on the 0.988"-dia. shaft are not great. An error occurs

as a result of an imperfect measurement between the teeth of the

knurling tool, which isn't a big deal because ultimately you are going

to sneak up on a usable diameter. Therefore, begin by machining the

part about 0.010" larger than the calculated diameter.

- Lay a short test knurl by hand. ...

Check out the rest of this article at




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