looks like not enough pressure and also the pressure not applied quick enough so the knurls time themselves together. Your knurl has the knurls mistimed. I find that better knurls are to be had by being quite agressive with the pressure applied and a mid range spindle speed with oil. This is an aquired skill similar to parting off.

As an Appretice was told to set the knurls to “cut” about 0.010″ deep.

With plenty of oil and a slow speed and feed (gradually traversing the workpiece from front edge to full engagement to the end of the required length ) The results are always acceptable to good.

Scissors knurling tools are better than single wheel ones, since the spindle bearings are not subjected to the sideways forces (Quite large) when using a single wheel knurling tool.

I chamfer after knurling, since materail is always displaced sideways.

Howard

They look very good indeed, Bernard.

I share your preference for straight knurling, though if you can’t get your fingers on the knob very easily because you’re coming at it from a strange angle a diamond knurl may be easier to use.

What is the tooth count and diameter of the knurls you used in this case?

CNC makes great knurls!

How does everyone go with using a scissor-type knurler with two straight knurl wheels? I have trouble getting the two straight wheels “timed” to avoid getting an overly fine double knurl. So I have reverted to using a single wheel plunged straight in for straight knurling.

Using a tailstock centre and putting the fixed steady on the job between the knurling and the chuck helps take the load off the headstock bearings.

With diagonal “diamond” knurling I dont have this problem and use my shop-made scissor type tool.

One tip to offer: Bring your knurls to a sharp point then run a fine file over the job in the lathe to knock the sharp edges off the points, leaving a small flat instead. That way the knurl does not peel the skin off your hand like a cheese grater when you use it. Look at commercial knurls on good quality tap wrench handles and die stocks. Nowhere near pointy, for this reason. Imagine yourself using that tool or dial etc for 8 hours a day on a production line and ask how it would feel by the end of the day.

If you don’t bring the knurls to a point first before filing smooth, there will be a burr of thrown up metal that is also rough on hands in use.

Your hands are your most important tools. Look after them.

On 13 March 2024 at 11:30 Howard Lewis Said:

Scissors knurling tools are better than single wheel ones, since the spindle bearings are not subjected to the sideways forces (Quite large) when using a single wheel knurling tool.

 

I don’t do a lot of knurling, mainly because I prefer fluted knobs(and killed my wheels on a bit of stainless, but we won’t talk about that), but I find the concern about the spindle bearings when using single wheels a bit odd. Surely, in the diameters most of us seem to do, bending the part is likely to happen much earlier?

On 14 March 2024 at 09:56 Graham Meek Said:

In my engineering career straight knurls were never used in pairs only as a single wheel.

 

That’s good to know I am not the only one to have trouble with straight pairs. I only ever used common diamond knurls at work back in the day, and then they were plunged straight in on large industrial lathes, in the old type tool with two wheels held close together in a pivoting head. Didn’t come across the straight wheels until recent model engineering work in my second childhood.

https://www.model-engineer.co.uk/forums/topic/cnc-knurling/page/2/

I started this thread on the “old” site last time knurling came up.  You can make lengths of knurled stock and slice them up as required.

Try the Hemingway one it has slim knurls of industrial quality and are very good.

This is my own design Knurling tool. It has offset wheel so so I can get nearer to the chuck and three sets of knurls Rough, medium  and fine. It is able to go from very small to about 2inch diamiter.

The screw has been changed to a Knurled nut since photos taken.

David

David, how did you put the colour on that?

You tube (and now, common sense) tells me knurling tools have a pitch and so work best on certain diameters. Small diameter changes might make a difference? I can’t knurl.