[livefreeordie]

I've been using form knurls in 6061 with off and on results. Looking into cut knurls but don't know if I need a single or double wheel. Most parts I run will require radial transversing of the material. Can a single wheel cut knurl do this clean?

[handlewanker]

Hi, all my knurls have been made with a single wheel for straight knurls or a double wheel knurl tool for the diamond pattern, both from one side of the job on a manual lathe.

The only time I differed was on a production job where I made up a three knurl fixed knurler that pushed onto the bar material from the end in the turret of my capstan lathe......material diam being pre tested to get the knurl pattern.

It will be tricky if not extremely difficult to determine the exact diam of the finished job with a fixed knurler as the material is being displaced and reformed to give the finished diam and even knurl structure.

There is a balanced knurl tool in the market that has a set of 2 knurls in a frame with two adjustable arms, and these arms are used to take the pressure off the job by being applied from both sides simultaneously.

If you knurl with a manual lathe, speed about 100 rpm, and the twin or single wheel type knurl tool, you must start from the very end of the job, approx 2mm from the end, NOT MORE, with the knurls/knurl evenly centralised to your bar material, and just make an indentation in the material end about .1mm deep at the start, and traverse the knurler slowly along the job, reversing back to the beginning.......then apply a bit more pressure to establish the knurl pattern as the material is forced up.

The knurl will make it's own pitch spacing and it is complete when the points are pointed.....any more pressure once the points are formed and the knurls will override the knurl pitch and deform it.

There is no exact formula for the diam of the work piece for a decent knurl.....it's finished when the knurl form is pointed, and the diam is what you get.

ALWAYS, as in every time, finish the knurl form with a VERY LIGHT TOUCH across the top of the knurl with a very fine file or wet and dry paper on a metal backing, having first cleaned the swarf out of the knurled grooves with an old tooth brush or fine wire brush.

Coolant can be used for a lubricant whilst knurling is in process.

I can guarantee perfect knurls every time using a single straight knurl or a twin diamond pattern knurler with the preformed knurling wheels if you follow what I have just posted.
Ian.

[livefreeordie]

I'm running on an Okuma 370MW. Production running knobs for high end camera equipment. With the form knurls I've been using, I've had to use a scissor holder, but I'm not happy with the results. I've never worked with cut knurls. Will a single wheel holder produce a visibly acceptable pattern, while transversing the material?

[handlewanker]

Hi, I've never used a cut type knurl, just the press against the material type or normal knurling method.....single rolls work OK with a straight type knurl, whereas you need two rolls for the diamond pattern.

The diamond pattern type comes as a pair on a holder or with three sets of rolls......fine, medium and coarse pattern on a holder that you rotate for the desired pattern.

All the "press against the job" types put pressure on the workpiece, so this must be firm in the chuck or still attached to the bar being cut.......preferably knurling first close to the chuck or collet and turning down the shank afterwards.

The other type I think you said was the scissor type, by that I think you mean the one where you have the knurl rolls on two arms and a screw between them to apply the pressure.....this takes away the force against the workpiece as it's equalised, but I have found that the arms tend to move sideways and mess the knurl pattern up a bit.

In all knurling exercises where you press the knurl against the material, it is vital to start the knurl at the very end of the material with a shallow depth of .2mm approx and about 2mm depth.......this allows the knurl to bite into the material and exert little pressure on the workpiece.

When the knurl pattern has formed, after a couple of revolutions, you can traverse along and back again slowly, then increasing the depth another .2mm and repeating the exercise........just make sure not to go deeper than when the knurl pattern has fully formed.

You might find that the cut knurling tool works quicker and more cleanly........I can't comment as I've never used it.
Ian.

[exospex]

The biggest factor in combating knurl problems is making sure that your circumference is close to a multiple of your knurl pitch. If it isn't you will fight it all day long.

[handlewanker]

Hi, Knurl problem?.....there is no knurl problem.......I can cut a knurl on ANY diam using plain straight knurls with a single wheeel or the diamond pattern with double wheels, and both with a press on type knurler or the balanced type that presses the knurl wheels from both sides.

The secret is to start your knurl from 1/4 of the width of the knurl wheel on the end and just press it into the metal a small amount to make an impression.......feed it slowly across and back and repeat until the knurl patter is fully formed.

The secret is that the metal displaced will form the raised points and self generate the exact knurl pattern.

There is no calculation with regards to the knurl pattern or diam reqd.....been in the trade for over 50 years.

Did you read my previous post?
Ian.

[exospex]

50 years. wow. that must mean you know everything. Now don't I feel foolish for trying to help the OP with his problem.

[handlewanker]

Hiiiiyyyy, Nobody can know everything, but a lot of people know a lot about every thing, some know a lot about nothing, and some know nothing about anything at all......50 years does not make you a know all, but if you haven't learned anything in 50 years there's no teaching you anything.

Take my advice as I posted it or go and get someone else with some experience to do the job for you.
Ian.

[Farmers Machine]

Dorian Tool International in East Bernard Texas makes a cutting knurl tool. used it on 2" dia 316 stainless steel on a CNC Milltronics lathe. the cut was 12" long and could do 20 parts before turning the wheels over. it is a one pass operation at about 0.018 to 0.020" inch per rev with heavy coolant flood.
Good Luck
The Farmer