Think here an extreme. Say you only had five indents on a full turn of your item. It would make a different set of indents the next time around if the 'wrong'diameter, but there are incremental diameters where the knurl would superimpose 5, 6, 7, 8, etc knurls per turn. So ideally the diameters need to match the knurling wheel in use. Often knurling a little deeper will make the small amount of difference imperceptible.

Try it and see.

It does happen that the pattern does not perfectly fit your chosen diameter but a slight skim wil get thing working properly.

Mike

The pressure of the knurls extrudes material up from the original plain diameter. The material has to come from somewhere so the knurling wheel points sink below the original plain surface. Effectively the knurl pattern comes into balance with some above and some below the original surface. The process inherently has some leeway as to exactly what diameter the balance occurs at so the starting diameter doesn't have to be exact. In practice its rare to take a knurl right to sharp points so errors can be hidden in slightly sharper or slightly blunter points.

In practice for medium knurls on typical sizes of material, say half to one inch diameter, one more or one less knurl point translates to around 10 to 20 thou variation in stock diameter so extrusion variation can take up most errors. As its a symmetrical process which can go either up or down the actual range will be ±5 to ±10. If the workpiece is small or the knurl coarse you may get thin slivers of metal cut off the sides of the knurl points when the error is a bit excessive.

I rarely worry about stock diameter unless below 0.375". Just have at it until things look right works fine.

Clive.

if the depth of knurl is approximately the same as the width of the pattern, then between the top and bottom of the knurl pattern there are typically three integer numbers of knurls that could be made around the work for any given diameter.

Now knurls are not kept in fixed engagement with the work like gear cutters, and the simple truth (as Clive has explained) is that they will self-adjust by slipping into whatever number of knurls is a close match to the setting of the diameter.

It is possible to get a double pattern if you use VERY light pressure so only the tips of the knurls engage the work, but if you always start with a good engagement and plenty of pressure you should never have a problem with a 'bastard knurl'.

Neil

One of the most hand knurling tools I have for small parts uses the flint wheel from a Bic disposable lighter, the idea came from one of Stan Bray's books. You can make this i an hour or so, cost zero.  Ian S C

Edited By Ian S C on 23/05/2017 12:28:27