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elginrunner
04-13-2012, 10:08 PM
Well I finally got a successful knurl tonight.

http://img577.imageshack.us/img577/9725/008yve.jpg (http://imageshack.us/photo/my-images/577/008yve.jpg/)

Uploaded with ImageShack.us (http://imageshack.us)

And I had to change a thing or two, and came back and tried again on another piece, and it changed to this...

http://img268.imageshack.us/img268/2576/009kbg.jpg (http://imageshack.us/photo/my-images/268/009kbg.jpg/)

Uploaded with ImageShack.us (http://imageshack.us)

Now what made the pattern finer?? I have since tried different speeds of feeds but everything is a fine pattern now... So what adjustments to be made for coarser diamonds???

sasquatch
04-13-2012, 10:13 PM
Not sure, but those appear to be very nicely defined knurls.

KiddZimaHater
04-13-2012, 10:19 PM
HHAHA.. Welcome to the world of knurling.
It's a royal pain in the arse.
I use floating head knurlers, rigid knurlers, and scissor type knurlers... all with mixed results.
One part will be beautiful, and the next will double-track. Then a knurl will seize and ruin the part.
It's all fun.:mad:
I still haven't found out why 2 parts, with the same diameters, same rpm, same feedrate, etc. will give two different results.:confused:

RussZHC
04-13-2012, 10:20 PM
First, those are pretty good looking knurls.


And I had to change a thing or two
and those changes did not involve changing the knurling wheels themselves? AFAIK (not much) to see that major a change (the knurls are both deeper and what, 3x the size? in the first sample compared to the second?), to see that major a change its different knurling rollers. Or maybe one of several removed? (grasping here)

could you mention a bit more about the tooling, IIRC from your earlier posts, you were sort of searching...

Edit: a place to look though...bottom of first photo is quite clear as to spacing etc....this portion is not shown in the second photo

Edit II: different materials? My stock is so unknown and random, if it were me, I would almost expect it...

elginrunner
04-13-2012, 10:50 PM
I used a cheap grizzly floating head (http://www.grizzly.com/products/2-pc-Knurling-Tool-Holder-Set/H5936) knurling tool that I got a couple of weeks ago....

I havn't changed anything. It's in a quick change tool post holder, and while I got a great pattern on the first, I was sure to lock the height adjustment so It would be centered for the next job....

The material on both items are just cold rolled steel, one may be a different grade, than the other, the larger diamond pattern is 1018 I know.

Joel
04-13-2012, 11:23 PM
The knurls double-tracked. As you progressed, the pressure of the knurl was imparted between the previous (coarser/correct pitch) pattern. Thus, you end up with a knurl twice as 'fine' as the knurl wheels intended pitch.
Perhaps, you could think of the knurled surface somewhat as a gear. You can change the number of 'teeth' by cranking in the knurling tool and displacing more material. Your goal is to have the teeth mesh up when the two sides of the knurl meet. otherwise, you have xx and a HALF a tooth - the double knurl.

I hate to open up the can of knurling worms here, since most of us well know that knurling is represented as both incredibly easy and utterly impossible.
For those new to knurling, my suggestion is to start off with a lot of pressure (which is why scissors type knurlers are much preferred). Begin the knurl by rotating the chuck back and forth by hand through part of a rotation. Establish a definite pattern BEFORE going any farther. One you have a solid start and significant depth, go ahead and go all the way around. The pattern should 'mesh up'. Once all is well, fire up the lathe and increase the depth a bit more, engage the feed, and proceed with the knurl.

livesteam
04-13-2012, 11:29 PM
This method has always worked pretty much first time.
The knurl wheels must be the beveled edge type.
I use a clamp type (same action as a scissors type) 2 wheel knurler.
To start, touch the wheels to the work piece then move the carriage off the work.
Apply a heavy feed setting. You will have to experiment to find what
it takes. Now start the lathe at very low RPM. Move the carriage back to
the work and force the wheels to climb on the work a short distance.
Stop the lathe and inspect the pattern. If the knurl depth was sufficient
the pattern will have picked up perfectly right off. Calculating for pitch
diameters is not neccessary. If the tracking is good you have the initial
feed heavy enough. Continue to run the lathe across as needed.
Roll the knurler back off the work, apply a little more feed and roll back on.
Repeat until the depth is what you need. Don't overdo it.
The cleanest work comes from knurling in as few passes and revolutions as
possible with lubrication. Brass tends to make flakes that get mashed into
the pattern, so be quick and brush off the flakes if need be.
The whole operation can be setup and done way faster than the the time it
takes to read this.
Good luck, RichD

elginrunner
04-14-2012, 06:44 AM
Joel,

I'm unable to apply enough pressure to form the diamond shape on a single pass. I have to reverse direction a few times, increasing the depth each time. The feed is never disengaged, I only shut the machine down and reverse the direction of feed (if that made sense).

If I understand correctly, it's not taking the same "path" thus producing a smaller pattern.... Looks like I get to play a bit more with this thing to figure how to produce the coarse pattern that I like.

JoeLee
04-14-2012, 08:36 AM
Those are both nice looking knurls. If you double tracked it worked out perfectly, usually by accident. Typically the only way to get a finer pattern is to change to a finer set of knurls, or perhaps a shallower impression. To get a deeper impression in a single pass try comming in with the edge of the knurl, angle your tool post, if they are the sharp edge type instead of keeping the knurl flat against the work.

JL...............

Paul Alciatore
04-14-2012, 01:46 PM
If you search this forum for "knurl" you will get more information and opinions on this subject than will fit in a dozen books.

Search. Read. Learn!

And be confused on this subject like the rest of us.

Joel
04-14-2012, 03:44 PM
You shouldn't need the full form in one pass, but you do need a good solid impression.

I used to do lots of these (30" of knurl per part):
http://img.photobucket.com/albums/v186/JoelinTX/Knurl.jpg

And you are correct about the wheels not taking the 'same path'. On the second revolution, the knurl wheel went in between the impression made in the first rotation (that tooth and a half problem I was talking about), and back and forth it goes.
Not that you asked, but I would really recommend a scissors knurler for a whole variety of reasons. The cheap ones work just fine IMHO.

Jaakko Fagerlund
04-15-2012, 02:39 AM
And just to give Tool Envy Syndrome, there was recently a discussion of a cut knurling tool which allows easy to do knurling even on a small power lathe or long and slender workpieces (like thin pipe).

goose
04-15-2012, 08:23 AM
My guesses;

A: The knurl wheels are made of low grade steel, they cut in good for the first sample, then were dulled to the point of skipping and double tracking.

B: The material used were different in hardness.

C: In sample one, it appears you established the pattern while entering the diameter of the work piece? , as opposed to trying to establish across the full width of the knurl wheels in later samples.