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Aloris AT-19: Knurl Questions

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Splat

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Hey guys. I picked up an Aloris AT-19 lathe knurl tool for a decent price. I have a few projects I've been wanting to knurl but good knurlers are $$. Was going to fab one up, like Hawkeye's Camjack knurler, but I got a good deal on the Aloris....just had to wait for the guy to decide if he wanted to sell it. :dunno: So if I wanted to do length-wise (lateral) knurling on my lathe do I need specific knurls for that? I think I read I do somewhere but can't find it. Also, any style or pattern you recommend for general knurling? Thanks.
 

mikey

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You will probably do best with convex knurls for axial running. The best known maker is Accu-Trak: https://accu-trak.com/knurls_convex.html. You can also use knurls with a bevel on the edges and accomplish the same thing but you have to have the maker grind them for you that way.

I have that knurler, too. Its neat because you just close down slightly on the work piece and the tool will self-adjust on the tool post; then you just lock it down to get the correct height. It takes 3/4OD x 3/8W x 1/4ID knurls if I recall correctly. That would be the KPV series of Accu-Trak knurls. Note that they sell both Circular Pitch and Diametral Pitch knurls. The difference is that the DP knurls are used with fractional sized stock from 3/32 to 1". They use a pitch classification and there are only four pitches used: 64,96,128,160. The idea is that you don't need to calculate the diameter of the work before you knurl it. It is meant to work with nominal sized stock, which works for production situations.

CP knurls will fit any diameter and use a tooth per inch (TPI) classification. The smaller the number, the coarser the pattern. There are formulas for use with CP wheels that allow you to turn your work piece to a diameter that will make mistracking less likely. I've seen all sorts of arguments about whether you should calculate the diameter or not. Obviously, as hobby guys, many opt to calculate diameters and then turn the work to that diameter within tight tolerances, only to find that wheels often mistrack anyway.

For general work, you will usually be using male knurling wheels that come in either a straight pattern that form parallel lines like that on the edge of a coin or diagonal pattern that forms a diamond-shaped knurl. Diagonal knurls require that you use a RH and LH knurl in each set of wheels. For straight, you use two of the same pitch and there is no handedness.

I use mainly CP knurls and don't calculate diameters because quite often I am knurling something that is just the way I want it so I just clamp down on it with enough pressure so the knurls don't mistrack. In fact, Form-Rol, a maker of good knurls, suggest that you use enough initial pressure to "ram the die into the blank" on the first revolution to immediately form a pattern that the wheel will follow. They also recommend that you form the knurl about 90% of full depth; they consider going to full depth to be abusive and will shorten knurl life. So, I move the knurls onto the work so that half the wheel is in contact and then crank up the pressure until I hit somewhere near 90% of full depth. Once I get that, I lube it up and run the pattern in one go. You want to feed as fast as the pattern allows and try not to dwell. Once you reach the end, back it out at about twice the feed rate as you went in. This reduces the chances of flaking. Run a file over the top of the knurls to reduce the sharp edges, then a wire brush to remove any loose debris and you're done.

So, to be sure I answered your questions, you will be well served using convex knurls for running a long pattern down the axis of the blank; this is called axial running. You will do well with two types of knurls - straight and diagonal - that will form straight lines or diamonds. How coarse or fine is up to you. I prefer finer patterns, myself. A "medium" pattern is something in the range of 16 tpi. You will have to try it and see what looks best to you.
 

Splat

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Mike, you always amaze me with your knowledge and generosity. Thank you. Again. :) OK, I'll have to see what condition the wheels are I have. They look OK but I haven't actually used the knurler yet. I'll check out Accutrak since I've heard a lot of guys mention them.

As for procedure, I get what you're saying except "They also recommend that you form the knurl about 90% of full depth; they consider going to full depth to be abusive and will shorten knurl life. So, I move the knurls onto the work so that half the wheel is in contact and then crank up the pressure until I hit somewhere near 90% of full depth." I assume you mean how far into the work the wheels are pressing down/in, right? What do you mean by "half the wheel is in contact"? I assume you mean both wheels are brought over the work only half of their diameter before cranking down? Thanks.
 

mikey

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Thanks, Splat. Just trying to help.

Most of what I said applies to CP knurls.

Yeah, move half the width of the wheels onto the end of the work piece. I forgot to mention that I usually put a small chamfer on the end of the work. This makes it easier to get the wheels onto the work. Anyway, move half the width of the wheels onto the end and start to apply pressure. Turn the work by hand as you do this and slowly start to increase pressure; you'll see the pattern form. If it mistracks (creates multiple tracks), keep increasing pressure and it will start to form enough of an impression that the wheels will track. Once you get the wheels to track, look at the pattern. You want almost a full depth pattern but the tips will have a very slight flat. Slowly increase pressure and when you see that, run the knurl.

Some guys prefer to do this in stages. I used to do that but it takes longer and doesn't really create a better knurl. Plus you get more flaking when you make multiple passes.

Also forgot to tell you that knurling is an extreme pressure operation. You will have best results with sulfur-bearing cutting oil on most stuff.
 

Splat

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Got it. I remember guys saying u need formulas, exact diameters, yada, yada, yada...and I'm sure there's truth and sound reasoning for it. It seems lately I seeing guys, like Joe Pi, saying basically to go all in, and usually in one pass, and to heck with formulas, etc. I was never good in math! o_O Man Mike, I can't wait to try this thing out. Btw, the Aloris I got has the arm on it so it fits into a standard tool qctp holder. The one you have fits the qctpost dovetails. I hope mine works as good as yours. :cool 3:
 

mikey

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You're right, yours is different from mine. I didn't look good at it. Still, should work fine. If not, then you can either build another scissors knurler or get an Eagle Rock.

Keep in mind that the "bypass the formulas and crank it up" thing applies to CP knurls primarily. Knurling isn't hard to do; like most things, we just have to figure it out.

You do know that we need pics, right? :)
 

Splat

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Guys, what's a good general purpose pitch/TPI (gonna go with circular pitch wheels) for surface knurls like on a flashlight body, screw heads, etc..... so mainly for good gripping purchase without ripping your skin off? ATT I don't have plans for anything that needs to be knurled to specific diameter(s). I was thinking 30TPI or 33TPI? Thanks.
 
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mikey

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I think a 30 tpi CP knurl would look nice on a flashlight barrel. We all have different tastes as to what looks good to us so you'll have to try it and see.
 

ddickey

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I agree with 30 too. That is why I suggested 128 DP knurls. Close to a 30 tpi
 

Splat

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Thanks Mike and ddickey.
 

darkzero

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Got it. I remember guys saying u need formulas, exact diameters, yada, yada, yada...and I'm sure there's truth and sound reasoning for it. It seems lately I seeing guys, like Joe Pi, saying basically to go all in, and usually in one pass, and to heck with formulas, etc. I was never good in math! o_O Man Mike, I can't wait to try this thing out. Btw, the Aloris I got has the arm on it so it fits into a standard tool qctp holder. The one you have fits the qctpost dovetails. I hope mine works as good as yours. :cool 3:
You really only need to calculate for knurls if knurling flat knurls (partially formed), hard materials, or if using a cut knurler. That is why I calculate for knurls. I don't like to form a knurl with multiple passes, I get better results, & with material that work hardens easily you don't want to take multpile passes. But usually when I knurl cosmetics is more important than functionality.
 

mikey

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What ever works for you.
Okay, from this comment I am assuming (dangerous, I know) that you recommend we should always calculate diameters for use with CP knurls? If we don't then what, the knurls will mistrack?
 

shelly142

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Mikey,
I don’t believe I was recommending anything. This thread had a number of opinions/ recommendations for what is required to produce an acceptable knurled shaft. One was for the need for a specific diameter based on pitch for CP type knurls. I just offered a chart with that information. The user will ultimately determine to utilize the data provided or not. In either case it is his or her choice to make.
Shelly142
 

mikey

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Okay, thanks for clearing that up.

Darkzero and I have had this discussion before, the one about having to calculate or not. He is in the "calculate" camp and I'm in the "no need to calculate with CP knurls" camp. Your comment came right after his and my impression was perhaps wrong. Darkzero has demonstrated multiple times that he is extremely adept at making high quality knurls. In fact, many members aspire to match his work so this guy knows what he's talking about. I'm actually not defending him; his work speaks for itself, far better than Will can himself.

I've only been knurling for maybe 28 years or so and probably still have a lot to learn but like most hobby guys, I've been down the "calculate" road and have found them to be cumbersome and unnecessary in most cases. In the early calculating days, I struggled with this knurling thing and calculated probably hundreds of times, only to find that when a calculated diameter worked it was because I applied adequate pressure. It was the pressure, not the diameter, that made the difference. I've since proven to myself that this is so many, many times.

So, you're right ... whatever works for you. My apologies for misconstruing your intent.
 

shelly142

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Sometimes the sequencing of the thread responses can be a bit confusing. No damage done, I think we all contribute for the benefit of the group.
 
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