knurling tools

[gavuk]

Need to get a knurling tool for my harrison L5 9" lathe,only ever used the self centreing style ,I see the clamping style and realise they reduce load on the bearings etc ,i can see that being a big issue on a small lathe emco/clarke but is it something i need to worry about?also the clamp style tools have size limits which i don't think would be an issue with a self centre 2 wheel job,anybody got the style which rotates and carries fine/med/coarse wheels on the same tool as I'm feeling drawn to it ...

 

[brightspark]

Need to get a knurling tool for my harrison L5 9" lathe,only ever used the self centreing style ,I see the clamping style and realise they reduce load on the bearings etc ,i can see that being a big issue on a small lathe emco/clarke but is it something i need to worry about?also the clamp style tools have size limits which i don't think would be an issue with a self centre 2 wheel job,anybody got the style which rotates and carries fine/med/coarse wheels on the same tool as I'm feeling drawn to it ...

ive just been using the self centering 2 wheel one on my L5. its not a problem on the bearings the lathe can handle it no bother

 

[gavuk]

Cheers BS, thought as much, as the lathe is heavy duty in comparrison to some of the modern stuff,

 

[scott0031]

Most machines will handle the traditional self centering type (probably other than the modern toy machines for home markets) but in real terms of knurling they are not a lot of good. They generate pressure on the job in turn causes deflection, this in turn means a non constant pressure on the work piece. The end result is more often something people pass off as knurling and not knurling as it should be. Most often double cutting is a consequence, the knurl is not defined and often really horrible. You can get good results but for the general user is a lot more luck than judgment. The quality of the knurl wheel itself has a lot to do with it. The cheap knurling tools you get are just that low quality wheels generally bad to just partially acceptable results.

They are ok for short stubby work pieces, longer more slender pieces are very problematic, often the double cut you get is caused my the generated pressure making the work piece move in the chuck, often that pressure you have to apply to attempt to get a clean cut, can not be (always) be offset but wrenching the chuck up dead tight. Which incidentally which will not do the chuck or the machine any good at all in the long run.


The clamp style is not only about reducing pressure on the chuck and the headstock bearings. The big difference is they way they load that pressure. they give as near neutral pressure as you can get as the wheels are opposite each other, so that pressure is canceled out compared with loading from one side. The results you will get from a clamp style are far superior to a single sided pressure, a clamp style with give you a proper knurl with repeatable results time and time again, providing you know what your doing, as with all machine work.


I hope you find this helpful.


Kind regards,


Scott (ward engineering)

 

[gavuk]

Thanks for replying Scott,think in the end,i need to decide if i will ever need to knurl anything over 38-50mm? prob not, I only have a 5" chuck at the moment,need to buy a bigger 4 jaw soon methinks ....

 

[scott0031]

Thanks for replying Scott,think in the end,i need to decide if i will ever need to knurl anything over 38-50mm? prob not, I only have a 5" chuck at the moment,need to buy a bigger 4 jaw soon methinks ....

Indeed, it's a hoses for courses situation. Clamp style can easily do a lot less than those sizes, very small in fact. I do down to 3mm comfortable on lengthy pieces at times, they will do smaller they are again far superior for smaller work than a self centering type for reasons mentioned. They are the way to go really, without getting to in depth and involved but that style of neutral pressure is how you see these fine results with knurling from say a shop bought item. Even in a production environment the principle is the same, so if you can use a production principle in the home workshop at cheap cost i would always use it over the common more home grown method, just because its known a bit better in the laymen's machine shop.

Here is a link to a pic of a industrial version used on automatic, capstan/turret, multi-spindle, and various other lathe types including sometimes cnc. As you can see the principle remains the same.


http://www.tangi-flow.com/tooling_knurlrecessingalignment.odl

A decent independent 4 jaw chuck is a wise move, much better for heavier work for the lathe size with more stubborn materials. They offer much more rigidity than a 3 jaw and nearly always underestimated and underused by most, again horses for courses.


Kind regards,



Scott