Does your knurling look bad ?

[darkzero]

Very cool, nice work!

I get double knurls all the time. i have a mac so I can't download. The formulas look very complex. I'll just keep double knurling as at least it provides a nice gripping surface

The formula is not complex at all. I used to use the online calculator LMS has on their site & then just made my own spreadsheet.

Stock Diameters for Even Knurls

On that page aside from the calculator, it explains how to calculate the formula as well as the formula to use in Excel.

View attachment Stock Diameter for Even Knurls.xlsx

Using that same formula I had it added to my machining app for Android that my brother made for me & is what I use now since my phone is always with me.

I don't even know if the lathe should be moving longitudinally on the x axis as it's knurling or if the carriage should be locked

For traverse knurling it's best to use convex knurling wheels. I use the ones from Accutrak & the results are better than the other wheels I have tried especially now that they use a new coating on them. I mostly knurl Ti and these actually last a while & give great results.

You can also get away with traverse knurling using beveled edge wheels depending on how tough the metal is that you are knurling.

 

[Ray C]

Love the spread sheet. I like the fact that you can change the knurl pitch values. I have a set that are 21tpi, counted it 4 times. Going a little cross-eyed from it.

To get a nice pattern , If I have a 21 tpi knurl, should I set the carriage feed on 21tpi also? OR is it strictly a function of the diameter of the work piece and it should track correctly, regardless of carriage feed speed, as long as the correct diameter of work is matched up with the knurl?

It's based entirely on TPI of the knurl wheels and diameter of stock. I use a clamp-type knurl tool and my procedure (when knurling shafts between 1/2 to 1" dia) is to set the RPM to around 60 and set the feed rate to about 0.003 IPR. I start the rotation (with power-feed disabled) and quickly establish a full-depth cut. I may stop the lathe initially to verify that I have enough pressure to form a proper pattern with good points then, I engage the power-feed. I've never knurled any more than a few inch segment and that takes a few minutes this way. Soak it with cutting oil -enough to keep the grindings suspended and not get packed in the knurl grooves.

You really need to get the cutting pressure right the first time. I've never had luck trying to go over a knurl once it's been cut. Too much pressure and it chews-up the sides of the pattern. Not enough pressure and you won't get good points on the diamonds. -Takes a little practice to know how much to tighten the clamp tool...


Ray

 

[schor]

I run at about 70rpm and .005 feed rate. Get enough pressure to make a single pass. This is brass and fairly easy to knurl but like Ray said, lots of cutting fluid.

 

[fretsman]

Very cool, nice work!




The formula is not complex at all. I used to use the online calculator LMS has on their site & then just made my own spreadsheet.

Stock Diameters for Even Knurls

On that page aside from the calculator, it explains how to calculate the formula as well as the formula to use in Excel.

View attachment 68795


Using that same formula I had it added to my machining app for Android that my brother made for me & is what I use now since my phone is always with me.







For traverse knurling it's best to use convex knurling wheels. I use the ones from Accutrak & the results are better than the other wheels I have tried especially now that they use a new coating on them. I mostly knurl Ti and these actually last a while & give great results.

You can also get away with traverse knurling using beveled edge wheels depending on how tough the metal is that you are knurling.

Is your brothers app available somewhere? Seems it would be quite handy-

Thanks,
Dave

 

[Ray C]

Just mentioning once again that those Accu-Trak convex wheels are the cat's meow and have been using them at the suggestion of fellow member "Darkzero". With a proper knurl tool (clamp or scissor type) they make knurling positively easy.

BTW: No affiliation with the company, just a happy customer. http://accu-trak.com/knurls_convex.html Most folks here will need either the KNV or KPV size wheels and unless you're doing straight lines, you will need two wheels (one left hand, one right hand) at a cost of about $28 each. -Worth every penny.


Ray

 

[SE18]

Hi guys, great stuff! So Ray's lathe allows axial feeding. .003 and .005 are pretty deep bites!

When I first got my SB9A 1942 lathe in 2012, the first thing I did was tear it completely down and clean everything. It was my first time doing metal work.

For my first project, I needed a replacement peg for my miter saw box. The cheapo plastic one snapped off at the bottom and I only had one so instead of just making a replacement, I made 2 of them.

As part of the project, I knurled it, thinking it was perfect until someone rained on my picnic and told me it was double knurled and I'd have to do some complex formulas (which are actually quite easy to do for genius math whizes who know how to add and subtract)

Here's a couple pix from that first ever project. I still use them btw so in response to the title of this thread "Does your knurling look bad?" I'd have to say in hindsight YES, INDEED!

 

[Ray C]

SE18,

If you visit that website and look at the knurl wheels closely, you'll notice the edges are contoured and spiral. That's what allows axial feeding. Any lathe can do axial feeding, it's whether or not the knurl wheels can do it gracefully. The feed rate is a real trade-off. If you feed too slow, all the suspended grit gets ground into the cuts over and over -and that gives un-sharp looking knurl diamonds. If you feed too fast, it puts way too much stress on the knurl wheels and knurl tool itself...

Anyhow, those wheels are the only brand I've ever seen with that unique edge contour that makes axial feeding very simple. I have done axial feeding with the flat-sided wheels and yes, then you can only feed at about 0.001 IPR. Again, I don't try to make multiple passes either and the depth of cut if on the order of about 40 thou or so (I'm guessing)...



Ray

 

[SE18]

Guess axial would be good if you need to turn stuff out fast like for production

Anyway, I think the 2 uses for knurling are for aiding in gripping (my weightlift barbell has it) and also to upset a rod that needs a tight fit in an overbored hole

 

[darkzero]

Axial knurling is not really for production. Form knurling can be a slow process. Cut knurlers are mainly used for production. Cut knurlers actually cut the knurl pattern as opposed to form knurling that displaces the material to form the knurl pattern.

Like Ray said, pretty much any lathe can axial knurl but the rigidity, knurling tool, & material will limit what can be traverse knurled.

As I mentioned I mostly knurl titanium 6Al4V & it's not easy to do a fully formed axial knurl. I have a Knurlcraft K1-44 HD scissor knurl that costs $389 at MSC, I scored it for $80 on ebay & it was practically new. Again, I use Accutrak convex wheels & I also use solid carbide roll pins. When I traverse a fully formed knurl, sometimes it requires so much force that my tool post will spin no matter how tight I crank down on the nut. When that happens, luckily I have a Dorian SQCTP so I can pin my tool post.




Like Ray mentioned, I like to knurl in the least amount of passes if possible. Sometimes I can get away with 2-3 passes max if needed & depending how fully formed the knurl is. But I always shoot for just one pass. Multiple passes with give me flaking. Here's a fully formed knurl on Ti 6Al-4V with 3 passes. Here you can see some flaking.







Here's some more Ti 6Al4V done in one pass which of course gives me the best results.







Now partial form knurling is MUCH easier on your equipment but it's more for asthetics than functionality.





Double tracking is usually bad, well for looks but not always. Sometimes I induce double tracking but only for single diagonal knurls. The two pieces below were done with the same pitch wheels, Ti 6al4V.




The piece on the top I turned into an ice pick that I gave Matt @ Quality Machine Tools (Precision Matthews)





Here's another combo of the single diagonal knurl & induced double tracking. It's a 2 piece 32" long titanium spear. These are the longest pieces I have ever knurled. Had to have the tool post pinned & the lathe made so many scrazy noises that I have never heard from it before. Guess the lathe didn't like that & I haven't done another one like this since.









Ever form knurl delrin/acetal before? Someone was curious & got me curious. Didn't know what to expect & I tried it. First pic was just a partial knurl. Second pic I retracked the knurl then attempted a fully formed knurl but I ran it dry just for the hell of it. Third pic was with flooding it with lube as I usually do. The day was coming to an end so I didn't want to try any further.










Sorry for the long ass post, I tried to break it up into 3 posts but the update thread mod is installed here (quite annoying IMO)

Is your brothers app available somewhere? Seems it would be quite handy-

Thanks,
Dave

Unfortunately not at this time. I have only gave it to a few friends to play with. I still want to have more stuff added & verified.

 

[fretsman]

Thanks for the reply, darkzero, and may I say, you do wonderful work- )

Dave