Knurling ,How do you do it right

[dalem9]

I have a bunch of different size and design knurling cutters. I would like to learn how to use them. I would like to know the way to figure out the proper diameter; to be able to have the design come out right . Is there some kind of formula to do this? Many thanks, Dale

[sshire]

Dale
The best explanation I've seen is on Tom's Techniques here (the knurling starts at 5:00)

<a href="https://www.youtube.com/watch?v=3WbBCLF0Go8" target="_blank">http://www.youtube.com/watch?v=3WbBCLF0Go8</a>

I'm sure there are many, many more, but Tom's explanation of how to calculate the diameter based on knurl pitch is very good. His other videos are just as informative.

[Arbalest]

Just as important is a decent holder. Some of the far eastern clamp type are poorly made. I ended up making my own in the end.

[tangler]

With respect, I think one can over analyse knurling.  In my experience the knurling tool will sort itself out without calculation.  It helps not to try to knurl to the full width of the knurl wheel. Start at one end, get the tool knurling till you have a good pattern and then feed the tool along the axis using the lathe carriage.  You will get swarf when knurling - this is how the technique sorts out it's own diameter.  It is useful to have a fine brass brush handy to clean out the pattern.

We discussed this back in April in Jo's R&B thread.

Cheers,

Rod

[mklotz]

I'm with Rod on this one but, if you want to do the calculation, there's a program on my page for calculating the diameter. 

Basically, you want the circumference of the workpiece to be an integral multiple of the tooth spacing on the knurl...

dk = knurl diameter
nk = number of teeth on knurl
pk = pi*dk/nk = circumferential distance between knurl teeth

dw = workpiece diameter
cw = pi*dw = workpiece circumference

x = cw/pk

In general 'x' will not be an integer.  Truncate it to the largest integer less than x (in math this is called the floor function) and call this value 'N'.

Now, the desired workpiece diameter is:

dd = N*pk/pi

[Graham Meek]

Whilst I was taught the calculation route during my apprenticeship it is something I seldom do, I usually turn to the diameter I require and use the tool in the photograph. I never try to knurl plain bar stock without first taking a light skim over the diameter. Over the years I have found with the set of knurls in the holder shown that I just need to apply a 1/4 turn on the adjuster nut once I have set the knurls to touch on the diameter. I never start the knurls on the job, a 45 degree chamfer on the end will automatically align this particular tool once the self act is engaged.

My best regards
Gray,

[dalem9]

Thanks Guy's That is just what I wanted to know ,the right way to do it. Thanks again Dale