Thread: Knurling on the lathe

Originally Posted by 19brendan81

Hi all,

Whats the go with knurling on a lathe? I notice that knurling tools are available in 2 head, 2 clamp head, 6 head, 12mm, 14mm etc. What application does each of these tools have?

Cheers.

Brendan

ALL of them make a knurl, it's what your preference is, to which tool you use.

Just remember that making a Knurl, is DEFORMING the surface of the metal, it takes some balls to do it, so if you got a wimp of a lathe, then use the two roller clamping action knurling tool, just keep screwing it down as you go, until you get the knurl you want.

The 6 headed ones, have 3 different types of knurling patterns, you use two heads at a time for each different knurl pattern, just rotate the whole assembly, till you get the knurl pattern you want.

The two head variety, have only one knurl pattern, if you want any more, then buy different patterned rollers and change out as required.

12mm or 14mm, how wide you want the knurl, you can even get skinny ones too. Lots of different patterns available, go do a google.

regards radish

The previous post covers most of the story, but one point is not clearly spelt out.

All systems except the clamp style exert a significant side load on the work piece and hence the machine. Radish refers to this in the section about a wimp of a lathe, but it is equally applicable to a wimpy work piece (long and slender) which requires support from a travelling steady or the use of a clamp style tool.

With a properly set clamp tool, the wheels are located over the centre line of the work and only apply a compressive force to it, so no side load problems trying to bend the work and producing an uneven knurl .

19brendan81,

If you go back to my post of 19th May 2009, you will find some additional info that may help you.

Mini lathe/mill project No.3 Knurling tool

Ken

Also knurls size also need to correspond to the diameter of the work piece otherwise the pattern does not come out right... I find it hard to get a correct knurl 90% of the time..

RC. I find that the most common mistake people make when knurling is they don't go deep enuf. Until you reach the proper depth of knurl you won't get the full formation of the diamond peaks. Keeping the tool engaged with the workpiece until you are done helps too. Often people try to get a fine or medium knurl with a coarse knurling tool by not going to depth which results in less than perfect knurls. Oh be sure to use a cutting fluid too for a better finish!

al

Thanks everyone. It sounds like the clamping action will be the way to go. i have a 1hp 3 phase 10x20 lathe. I am interested in putting knurls on handles and knobs for grip.

To give me an idea, what size is the knurl on a socket wrench? 12 or 14?

Depends on what brand of spanner you got your scratches on, a diamond pattern is the best for gripping, but others prefer a straight knurl.

Now if your going to give it a whirl, a few things you should know about it.

First, as somebody else said, you got to go deep enough with the knurling rollers, or the finished knurl looks kind of stupid and WILL NOT grip your hand very well at all.

Second, when your actually doing a knurl and you got the rollers putting some real heavy pressure on the job, just think about the stationary pins that are holding those rollers. Pressure plus movement creates lots of heat, make sure you cool the rollers and pins, or you aren't going to have them for very long.

Thirdly, you want a long knurl as on a handle of something, you can drive the knurling tool with the carriage, it creates a better knurl than if you just keep stabbing the knurling tool at the job lots of times.

Fourth, if doing a long knurl, DO NOT try and take too heavy a cut first up, make a reasonable indent with the first pass, come back to the start again and into it again, this time a bit heavier. The knurling rollers will find the previous pattern very easily. Keep repeating this, until you have achieved the depth, that you reckon you want.

Fifth, watch out you don't bend the item if it's a long bit, centre pop and use the tailstock to support the long flappy end, if you don't, then just watch it turn to excreta.

regards radish

Cheers Radish!

I'm not sure if my dad taught me or if I learnt it at work, but I remember being told a trick for knurling.
With the lathe out of gear/turned off, wind the knurling tool onto the job. Turn the chuck by hand to start the knurl on 2/3rds of the diameter. Add more pressure until you almost have a full impression, (only on 2/3rds to 3/4rs)then quickly turn it around to complete the diameter. This should give you a proper knurl...they look horrid if they get doubled up.

Originally Posted by BEE55T

they look horrid if they get doubled up.

That is always my problem, a double knurl....

I've found that jamming the knurling tool in very abruptly and deeply with the lathe spindle going at very low speed to be effective in avoiding the dreaded double knurl.

Bee55t's approach sounds good. I'll have to give that a whirl next time I'm doing some knurling.

For me, I place the knurling tool at a slight angle to the job. Run low rpm like (depending on the diameter, after a slow surface speed). Run the stream of coolant on the tool, and not the job. I agree with bee55t but I would not try to cut it in one pass, more two or three. Depending on how much the job will bend. Chamfer the ends on the knurl after you are done and not before.

Hi as stated by others a lot of side load with knurling stay close to chuck if you have plenty to do put the four chuck on it will save your 3 jaw from getting bell mouthed.I used to wire brush after knurling and lightly emery cloth just to take the peaks off. cheers john c