Need Help on Knurling Tools

[jroma1]

[SUB]One of my problems is knurling, first I tryed using one of the older rocker types then I went on to using the knurling accessory that came with my QCTP. In either case the problems are the same,they are: 1-adjusting the height of the tool so that both rollers rotate [/SUB]simultaneously on tth workpiece and with even pressure. 2-From what I understand there are those that favor the tool to be exactly at 90 degrees to the work piece and there are some who believe the knurling tool should be sligthly off a few degrees. 3- Aside from these two items there is the question of RPM or how fast the work piece should be turning and how important is it to apply cutting oil?

Someone once commented that using the type of tools mentioned above places undo pressure on the lathes spindel bearings,to me this sounds reasonable. This is why I would feel that the sissor type knurling tool is ideal.

Any comments suggestions greatly appreciated

John

 

[Ray C]

Hi...

If you look at this thread, Nelson did a fine job of showing about knurl pitch. http://www.hobby-machinist.com/show...g-by-Conrad-Hoffman?highlight=knurling+conrad I added to that post and gave a link to a video that demonstrates the theory.

One thing to keep in mind, is that the word pitch is used in a lot of ways. In regard to threads, it's supposed to be the reciprocal of threads-per-inch but, historically, people call knurl pitch in terms of threads-per-inch which, is technically incorrect terminology... Oh well.

Yes, lateral pressure type knurls put strain on the bearing but worse yet, a bizillion more times pressure on the compound and ways (and everything in-between) and I'm of the opinion that the bearings can take it but, all those other surfaces fare worse. Others may certainly have different opinions and I accept them too. I keep knurling to a minimum and always talk my customers into doing fine knurl when they want it. It's easier on the lathe. ...Been meaning to get a scissor-type for some time now -just haven't gotten around to it. Maybe I'll retire the 4-5 others that I have, make my own scissor frame and re-use the wheels. -Easy project!

Cutting oil is necessary (for steel)! Not regular oil but, high sulfur cutting oil. At a moledular level, sulfur helps break the bonds of steel and it truly makes a difference. -There's a reason that metal workers have been using hi sulfur oil for cutting for a century or two -because it works. One of the common ingredients in a blacksmith shop is raw sulfur. Why? because they use it to spot-soften metal when punching holes. Sulfur softens steel -not a theory -a fact.

Oh, there is SO much on the internet about this simple task but, it is not rocket science (but just as fun and rewarding though). Once it finally sinks-in that the lines have to go around the surface an even multiple of times, the light bulb goes on (it did for me anyhow). Then, you learn that the workpiece diameter needs to be adjusted to the pitch of your wheel. -And finally, not all wheels are created equal (unless you buy good ones). I have a knurl wheel that drove me nuts. Turns-out, it's center hole was off just a bit and the pitch was not as stated. Doing the exercise that Nelson pointed out puts it all in perspective.

And one thing that I should have stated up front... Keep your fingers and anything you care about away from those rollers.

 

[Ray C]

I'd like to amend/clarify my thought about the pressure on the tool post, compound, ways etc... The forces being applied on that assembly is exactly equal and opposite to what the bearings feel (1st law of physics). However, I feel that any decent roller bearing can take it but, feel the effects on those other components is considerably more deleterious.

Ray

 

[Tony Wells]

Compare the usually 1/4" pin style plain bearing of the knurling tool with the much, much larger surface area of even an older plain bearing lathe or the tapered or ball bearings of a modern lathe.

That said, I prefer either the scissor style knurling tool, or a cut knurling tool even more. Very little side pressure to push the work around, so I don't worry about the bearings so much as the quality of the work.

 

[Ray C]

Tony,

Last night, I looked-up cut knurling and all I can say is Yowzah! Really nifty but man, they're expensive ...between 600-1200 bucks. Cool little devils but at that price (and given that I knurl about 10-12 times a year) I'll stick with form knurling.

Ray

Compare the usually 1/4" pin style plain bearing of the knurling tool with the much, much larger surface area of even an older plain bearing lathe or the tapered or ball bearings of a modern lathe.

That said, I prefer either the scissor style knurling tool, or a cut knurling tool even more. Very little side pressure to push the work around, so I don't worry about the bearings so much as the quality of the work.

 

[OakRidgeGuy]

I have not been able to find a price, but I already know that I want one of those Zeus RF3's!

 

[Ray C]

About $900 -minus the wheels. They're 35 each.

I have not been able to find a price, but I already know that I want one of those Zeus RF3's!

 

[DMS]

There were plans in HSM about a year.. year and a half ago maybe, for a cut knurler.

 

[darkzero]

I use an Eagle Rock Knurlcraft K1-44 HD scissor knurler with Accu-Trak wheels. Here some examples of knurling I have done all on Ti 6Al4V.

















I also have a small Dorian straddle type knurler but I have not used it yet.

 

[ScrapMetal]

There were plans in HSM about a year.. year and a half ago maybe, for a cut knurler.

I have that set of magazines/plans for that cutting knurler on the top of my "to make" list. FWIW - You can still get the back issues (spread over three or four issues) straight from HSM.

I use an Eagle Rock Knurlcraft K1-44 HD scissor knurler with Accu-Trak wheels. Here some examples of knurling I have done all on Ti 6Al4V.

I also have a small Dorian straddle type knurler but I have not used it yet.

Beautiful job on the knurling. Any special technique to get such a clean cut/pattern?

Thanks,

-Ron