Knurling Titanium

[gsrworks]

darkzero,

Thanks for the information your posts are always above and beyond what I expect. I'll just have to order some new wheels from accutrak of the same direction, just curious what TPI are you using for the single diagonal knurling shown in the flashlight and ice pick photos? I also noticed the accutrak are only sold in the convex shape, is that better for any material? or specific for just hard materials, I plan on mostly knurling aluminum and some low carbon steel, eventually might need to do some stainless.

I also have a PM1236 (your thread about the PM1236 really sold me on buying it, thanks again). You seem to knurl a lot of titanium, but have you found a sweet spot for RPM and feedrate for all knurling using the scissor type holder or do you have to constantly vary it for material and diameter?

One last question you mentioned you can induce double tracking to create the finer looking knurl, could you please elaborate on how this is done with a scissor knurl?

Best Regards,
John

 

[darkzero]

darkzero,

Thanks for the information your posts are always above and beyond what I expect. I'll just have to order some new wheels from accutrak of the same direction, just curious what TPI are you using for the single diagonal knurling shown in the flashlight and ice pick photos? I also noticed the accutrak are only sold in the convex shape, is that better for any material? or specific for just hard materials, I plan on mostly knurling aluminum and some low carbon steel, eventually might need to do some stainless.

I also have a PM1236 (your thread about the PM1236 really sold me on buying it, thanks again). You seem to knurl a lot of titanium, but have you found a sweet spot for RPM and feedrate for all knurling using the scissor type holder or do you have to constantly vary it for material and diameter?

One last question you mentioned you can induce double tracking to create the finer looking knurl, could you please elaborate on how this is done with a scissor knurl?

Best Regards,
John

No problem John & thanks.

Accutrack sells "standard" wheels also, they normally come unbeveled but you can order them with bevels also. The convex wheels are made for traversing which is essential for traverse form knurling harder materials. I believe I was using 21 TPI for those pieces but the pitch is dependent on the diameter & how fine/coarse you want the knurl.

Spindle speed & feedrate differs on the dia & material as well as how deep of knurl you are knurling. Like for a fully formed knurl I run slower then a partial flat knurl. With Ti (& harder materials) & form knurling it's best to knurl with the least amount of passes as possible. The more passes you make, the more chance of flaking you will get.

For double tracking when knurling the proper size pitch/dia, it's kind of hard to explain but when I do it slightly have the wheels contact, run the spindle, then apply pressure (depth) with the scissor tool. Most of the time I can get it double track this way as if I was double the pitch wheels. Normally I apply pressure with the spindle off, roll with my hand to check the knurl, then traverse under power.


Here's an example of Ti flaking.





Ti fully formed with no flaking.



Partial formed (flat) knurling in Ti. The black piece is delrin which was an experiment.





And another example of normal & double tracking with the same pitch wheels.

 

[Jewelmaker]

Not trying to nit pick here but as far as I ever knew, the correct term for "spiral knurling" is simply LH/RH single diagonal knurling. Some people may not know what "spiral knurling" is without seeing a pic of it.

Anyways, I also use EagleRock Knurlcraft scissor knurlers, the K1-44 heavy duty scissor to be exact. To get a single diagonal knurl with a scissor tool, simply use two wheels with the same direction rather than a LH & RH diagonal wheels to get a diamond pattern.

I use the HD version cause I knurl Ti with it but I also use solid carbide roll pins & convex wheels for traversing. Generally with knurling you want to avoid double tracking but I sometimes induce double tracking when doing a single diagonal knurl to get a finer pattern without having to change wheel pitch.


And again the same pitch with induced double tracking, a Ti ice pick that I made for Matt at Precision Matthews.

Hi darkzero

Your knurling looks excellent! I am really keen to achieve this type of result on titanium, stainless steel and tantalum for jewelry (textured rings). I only have a small lathe (equivalent to a south bend 9 inch). Do you think I would have any luck using the set up you describe with the K1-44 HD and convex accu trak wheels on this lathe? I trained as a jewelry maker at art school, so most of my machining knowledge is self taught or from friends. I've looked up the eagle rock scissor type knurl holders - does left hand, right hand and center refer to the orientation in the tool post? If I'm travelling towards the left, which one do I need?

Finally, how did you achieve the blue finish on the Ti ice pick? It is heat treated? Anodized?

Thanks again,

 

[darkzero]

Hi darkzero

Your knurling looks excellent! I am really keen to achieve this type of result on titanium, stainless steel and tantalum for jewelry (textured rings). I only have a small lathe (equivalent to a south bend 9 inch). Do you think I would have any luck using the set up you describe with the K1-44 HD and convex accu trak wheels on this lathe? I trained as a jewelry maker at art school, so most of my machining knowledge is self taught or from friends. I've looked up the eagle rock scissor type knurl holders - does left hand, right hand and center refer to the orientation in the tool post? If I'm travelling towards the left, which one do I need?

Finally, how did you achieve the blue finish on the Ti ice pick? It is heat treated? Anodized?

Thanks again,

Thank you

I can't really say. For a partial knurl on Ti I would think yes. For a fully formed knurl on Ti it requires a lot of force so if the lathe is not that rigid it might be tough. Sometimes I have to pin my tool post so it doesn't move. Also with my K1-44 I use solid carbide roll pins. It is possible to use solid carbide pins on the non-HD model but they have to be pressed in. I didn't think it was possible but I have seen someone do it.

The LH & RH models indicate where the knurling wheels sit on the tool for knurling close to shoulder. I have the center model which in theory should be stronger cause the knurls are supported on both sides. I would say give it a try, only way to find out. If the forces are too great for what you want to achieve, you could go with a cut knurler, less strain but also much more expensive.

The colors I do on Ti is anodizing (electrolyte bath). You could also heat anodize Ti but it's not as consistent or controllable but gives a different type of cool look. Colors are also very limited with heat anodizing. The blue on the ice pick was done after I did a deep etch on it. Normally anodizing over a machined finish gives a brighter appearance.

This is how blue looks without etching (the ice pick I anodized at a slightly lighter tone but you get the idea).

 

[Jewelmaker]

Also with my K1-44 I use solid carbide roll pins. It is possible to use solid carbide pins on the non-HD model but they have to be pressed in. I didn't think it was possible but I have seen someone do it.

Thanks for all the excellent info. Can you get the K1-44 supplied with the carbide roll pins, or do they need to be purchased separately and fitted?

An update here - you can get the K1-44 Scissor type knurling tool supplied with the carbide pins - they are $11.60 each.

 

[wquiles]

Latest combo: diamond knurling and swirl (or twist) knurling: