Knurling problems

[TheBilletGuy]

Hopefully I'm posting this in the right place...

So I'm making some oil caps and I've put a straight knurl on the outside face, but thr knurl isn't as nice as I'd hope and for future caps I'd like to improve on it! I've done a bit of research but can't fathom my head round it! The piece of aluminium (yes I know not ideal for knurling) is 60mm od, the knurling wheel I have is a 36tooth wheel, 15.8mm diameter. I'm not sure how you work out what the tpi of that wheel is and if it is correct for knurling a piece that large, or do I need a coarser wheel? The knurl almost looks like it's skipping between the knurl it's already formed. Which leads me onto my next question

Should you feed into the metal then go along? Or start in front of the piece at the set depth and then feed along?

Hopefully someone out there is more knowledgeable than me on knurling...

Sean

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[Jim Dawson]

I do one part that has a straight knurl about 25mm long. 6061 aluminum, about 30mm diameter. Not sure what size the tool is, maybe 20mm or so. I just set the depth and feed in from the front at about 0.2 mm / revolution, turning about 300 RPM. Flood coolant. Seems to come out fine each time. I'm doing this in a CNC lathe, but have used the same procedure on a manual lathe.

[Dualkit]

Should you feed into the metal then go along? Or start in front of the piece at the set depth and then feed along?

Sean

You can do it either way. A straddle or scissor type knurl holder is the easiest to get set correctly, but single knurls aren't that hard to set once you get used to it. High feed rate and low rpm work best and it is very important to get the depth set correctly. Do not go any deeper than the valleys on the knurl. Also when knurling aluminum stay away from poor quality 6061, that includes all Chinese made and USA recyclers like Service Center metals, the stuff they sell is usually too soft and tears easily. Hydro and Kaiser are good brands sold where I am at.

[hfjbuis]

Have a look at this video

[Dualkit]

Have a look at this video

I have data capped internet I only get 15 GB a month so I can't watch the video to critic it. Just from the picture I see non fill on the middle and right band.

[hfjbuis]

What you see is the result of different knurling methods using the same tool.

Basically, as I see it, his most important message is to start knurling at the final depth you want.

[Dualkit]

What you see is the result of different knurling methods using the same tool.

Basically, as I see it, his most important message is to start knurling at the final depth you want.

Got it. What kind of tool is he using? Straddle, scissor or single? I think the OP was making a straight knurl, not a diamond. If it was just for grip I think the easiest solution for someone new to knurling would to buy a scissor tool with diamond knurls. I have seen them go used in decent shape for as little as $20.

[Dualkit]

Also if the OP comes back he needs to tell us what type of machine he is using and the type of tool.

[hfjbuis]

Got it. What kind of tool is he using? Straddle, scissor or single? I think the OP was making a straight knurl, not a diamond. If it was just for grip I think the easiest solution for someone new to knurling would to buy a scissor tool with diamond knurls. I have seen them go used in decent shape for as little as $20.

He is using a scissor tool than can swivel and 16 TPI diamond wheels without bevel (sharp corners)

For knurling, I use a stepper on the spindle and a HSS 4 mm round tool with a grounded sharp pin. The CNC does the knurling (cutting), always a good result.