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Knurling 101?

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Janderso

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#1
I just found a steady rest for my old South Bend lathe.
The adjusting knobs are missing. I would like to make them, I have one knurling device/tool.
I purchased the Phase II QCTP kit and it camewith a knurling tool.
I was watching some YouTube videos and found out there are several types of these tools.
TPI, specific OD, beveled, scissor, etc.
Please take the confusion out of this question.
I just want to make two simple bands per knob.
Thank you,
Jeff
 

ttabbal

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#2
As I understand it, that one that comes with the tool post is a bump knurler. They put a heavier load on the spindle bearings, chuck, etc.. They work, but can be touchy. The scissor type seem more commonly recommended.

To use it, I would make sure the work is tightly held in the chuck and use a live center on the other end.

I'm a noob that hasn't knurled anything, I've just been reading about it. I am planning on waiting to get a scissor type.
 

benmychree

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#3
The scissor type is definitely easier on the machine than the bump type; if you have a small lathe, the scissor type is what you want. Most knurls are of the diametral pitch type, and work best on even fractional diameters; if used on odd diameters, they are liable to double track; for odd diameters, circular pitch knurls work better. One important thing in knurling is to not "pussy foot" around, adjust the tool for a lot of initial pressure on the work, this will help to avoid double tracking; when I start a knurl, I do not use the full width of the knurl, maybe half, and when the knurl is established, I then travel to the length required.
 

Cooter Brown

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#4
Take that Knurling tool you have cut the Knurl rollers off with an angle grinder they are a waste of time. Find a scissor type knurling tool.
 

magicniner

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#5
I use a bump knurling tool for very fine knurls, Clamp knurling tools are excellent for anything chunkier, I use an old Brown and Sharpe and a new Integi for most formed knurls.

John Stevenson once knurled a tapered bar to demonstrate that OD/pitch calculation is optional for those with adequate skills, Joe Pie tests the calculated pitch diameters theory in this video and towards the end surprises himself by demonstrating that good technique in applying firm initial pressure produces good knurls on diameters that don't "Match" the pitch of the knurls.


Cut Knurling does benefit from correct diameters but still allows more leeway than you'd think.
 

Janderso

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#7
I think this bump knurled is going in the recycling, paperweight.
Scissor seems the best.
Thank you
 

Liljoebrshooter

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#9
I found an app for determining the correct diameter for the knurl pitch. It works very good.
I have only used a bump style with some good name brand knurls I bought used on the bay.
This knob is made of 304ss.
It can be tough to get a perfect looking knurl.
Joe Hynes
 

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dlane

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#10
I use a scissor type “eagle rock I think” if I see double tracking I tighten it up more and get good knurles .
Knurling kinda moves material more than removing it.
If you remove the knurl wheels off the bump knurler and mount bearings on the end works good to force a part to run truer
In lathe 3jaw
 
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pacifica

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#11
Good video showing process of scissors knurling. I would practice first , knurling too deep is a common error.wd-40 or kerosense lubricant.
 

benmychree

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#12
There is another type of knurling tool that does actually cut the knurl, has types for straight and diamond knurl; I think they are Swiss made; very little pressure involved, they are fed to depth at the start and fed axially for the cut.
 

P. Waller

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#13
This is not rocket surgery.

Place stock in work holding device, chuck, collet or between centers. Place tool in holder and knurl.
If cross pattern knurling run the tool into the work as fast as possible with the required force to make the knurl in one shot, do not be shy here.

A cross pattern requires 2 tools so a scissor type holder makes much sense. In 30 years of knurling I have never once considered diameter/knurl pitch to be important, as mentioned above a tapered part should knurl just fine, have never done it but may give it a try this week just for fun.

I have never used a cut knurl but we do have one so may try that as well.
 

chips&more

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#14
Some folks get all excited about using math to determine the proper material OD for doing the knurl. Well, maybe yes and maybe no on the math. I do get the math concern, but for me, I have NEVER done any math and my knurl jobs come out just fine. I use the Aloris scissor type. I come in onto the edge with full depth. I make the knurl as quick as I can, I do not hang around. Hanging around imbeds crap into the knurl. I get in and get out quickly…Dave
 

darkzero

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#15
Try to knurl harder materials or anything that work hardens easily & you'll quickly learn that you need the math. With soft materials, like most everyone has experienced, just mash on it more & usually you'll fix any double tracking. And with cut knurlers, math is important if you want repeatable results.
 

petertha

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#16
I found this link & made a simple spreadsheet based on their guidelines.
https://accu-trak.com/technicalinfo/blank_diameter_selection.html

Just a few inputs (red numbers) & it spits out optimal starting diameter, boom done. This dramatically improved my prior hit & miss results, especially finer pitch & larger diameter combos. For sure there are still variables in the process like material & squeeze depth which is a feel thing, but this eliminated the inconsistency. I think some combinations 'work' just because of lucky combinations. But change one or the other or both & that will be the crappy knurl that will refuse to look good. I liken this to intermeshing gears where gear pitch & center distances are... well... kind of important. Good luck & happy knurling!
 

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magicniner

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#17
John Stevenson once form knurled a taper to demonstrate how much bull is talked about diameter having to match pitch.
Joe Pie's video shows that the assumption that OD must relate to pitch is wrong for formed knurling, if you know how to knurl.
I've never had a formed knurl track incorrectly since I learned that straight in hard with plenty of lube works every time and pussy-footing around leads to belief in calculated diameters. :D
 

petertha

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#18
I'm just a hobbyist so what do I know. My hunch is what's happening behind the scenes is the stock diameter is being altered by relative feel. Light pressure deforms the stock less (but can show up as incomplete knurl). Heavy over-pressure distorts the stock more (but can show up as galled knurls). As long as the material + knurl type + setup rigidity ++ is amenable to this variation then some sort of pattern will emerge. Some people view knurling as 'if it didn't double track then its awesome'. But under any magnification it may well look like sh*t.

Every time you pick up a micrometer you are doing 'math' unless the line happens to coincide with zero every time, so I guess I don't see the big deal. Why not stack the cards in your favour by turning it to a specific diameter? If it doesn't work you haven't lost anything over 'straight in hard' to whatever diameter presents itself. I mean you're going to be turning it down to 'some' diameter anyways just to ensure its circular right? The bottom line is if you're happy, then so am I. :)
 
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magicniner

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#19
Why not stack the cards in your favour by turning it to a specific diameter? :)
Why? Because it's unnecessary?
OTOH if you have so much time and so little you want to do with it that you can waste time at every opportunity Why Not? It saves you learning how to engage the tooling in a way which just works regardless of OD ;-)

If you want high quality, predictable, reproducible production quality knurling you would use Cut Knurling, try it. If you can bring yourself to fork out for the tooling.
With Cut Knurling you can produce a light knurl on plastic (10% area or less cut) with sharp edges which give a comfortable feel and excellent grip, furthermore it looks like a product you'd buy. :D
 

Boris Ludwig

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#20
Interesting thread.

Does anyone know where I can buy narrow knurling wheels with fine patterns? The wheels I need are to be a 1/16" wide. I have found Youtubes of how to make them with a mill but I don't have a mill and I'm still at the beginning of my learning to use a lathe.

Any suggestions welcome.
 

savarin

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#21
Why so narrow?
Could you turn the base material down to leave 1/16" wide lands that could then be knurled?
 

Boris Ludwig

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#22
Why so narrow?
Could you turn the base material down to leave 1/16" wide lands that could then be knurled?
It needs to be narrow because the nickel silver cup is small but needs a narrow band at the end of the cup with a knurl for aesthetics and for grip on the matching ring.

I guess I could leave a land. I hadn't though of doing it that way. I thought the knurl is done first then the part is trimmed around the knurl. But now that I think about it I could do it that way. But still a fine narrower wheel would be better.
 

Janderso

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#25
Thank you for the responses. I gave Knurling a try over the weekend. I used the only one I had. I used the bump Phase II.
I did everything wrong. I was trying to knurl cold rolled steel for some jacks. No I am not going to take a pic!
I pussyfooted
I did not want to put that much pressure/force on the spindle.
I printed out the spread sheet.
Maybe I should try the scissor version of knurling tools.
 
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