Starting a difficult knurl

savarin

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I just thought I would sling this up just in case its of help to anyone else.
The knurls on the stainless knobs for my binocular are very very difficult to get to full depth with no double tracking.
https://www.hobby-machinist.com/threads/the-giant-binocular.55688/page-4
What I have resorted to is starting them at the beginning of the shaft but only one third to one half the width of the wheels actually making contact and cutting.
This seems to let me get the full depth of cut easier with no double tracking then slowly move along the bar for the length of knurl required.
If you peruse the knurls in the link above closely you can see some of the double track still visible.
This method of starting appears to have solved this.
 
I've done it that way for many years and it works. I mainly use Circular Pitch knurls so the exact diameter is not critical but adequate pressure is, especially in SS because you have to get about a 90% pattern on the first run or you risk work hardening. I've taken to only using knurls with a beveled edge for axial running but convex cobalt knurls would be even better and carbide pins would be icing on the cake if doing a lot of SS knurls.

Haven't seen @darkzero around lately but he is good with SS and Ti knurls.

Good tip, Savarin!
 
I just thought I would sling this up just in case its of help to anyone else.
The knurls on the stainless knobs for my binocular are very very difficult to get to full depth with no double tracking.
https://www.hobby-machinist.com/threads/the-giant-binocular.55688/page-4
What I have resorted to is starting them at the beginning of the shaft but only one third to one half the width of the wheels actually making contact and cutting.
This seems to let me get the full depth of cut easier with no double tracking then slowly move along the bar for the length of knurl required.
If you peruse the knurls in the link above closely you can see some of the double track still visible.
This method of starting appears to have solved this.
I always do it that way, and have for many years.
 
Hi Guys,

It helps to have the circumference of what ever you are knurling a multiple of the knurl pattern pitch.
 
Hi Guys,

It helps to have the circumference of what ever you are knurling a multiple of the knurl pattern pitch.
The diameter/circumference as you are first making contact with the work radially, or the diameter/circumference where the knurl is fully formed, or somewhere in between? Unfortunately, there are multiple circumferences of a knurling job. I understand the theory, and I usually follow it, but I cannot say that my odds of getting a good knurl are increased by doing anything other than starting at the end of the work, which does not work when the knurl is somewhere in the center of the part only. The only other thing that seems to help me (sometimes) is cranking in quickly to engage the part fully. Still, I approach every knurling job with trepidation, more so at the end of a long, fussy job... :oops:
 
Hi Bob,

As an example, suppose the knurling wheel has a pitch of 1.5 mm. Any circumference that this pitch will divide into should produce a knurl without any overlaps in the pattern.

If you take a wheel and run it over some paper you will be able to measure its pitch. The rest is just a few sums !
 
Hi Bob,

As an example, suppose the knurling wheel has a pitch of 1.5 mm. Any circumference that this pitch will divide into should produce a knurl without any overlaps in the pattern.

If you take a wheel and run it over some paper you will be able to measure its pitch. The rest is just a few sums !

This is possibly true if using Diametral Pitch knurls. With Circular Pitch knurls, it is more about pressure.
 
In all honesty I have found no difference with using the diameter to pitch method to just going for it hard.
 
This is possibly true if using Diametral Pitch knurls. With Circular Pitch knurls, it is more about pressure.
I must admit that most of my knurls came to me from another owner, and though they are high quality, I have no idea of which type they are. I do have some knurls that are known to be diametral pitch, I bought them. Still, though I am using the formula correctly I still get variable results, it is like rolling the dice, in this case I get about 50/50 good and poor results. That is with using horizontal bump pressure, which I well know is an issue. I did purchase a scissors type knurling tool some time ago, but still have not had an occasion to use it yet. I expect it will help, but I am still gun shy...
 
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