Knurl Wheels

[kiwi2]

I have bought a couple of 1.5mm straight knurl wheels from China, mainly because I couldn't find anyone local who could supply them. I was intending on using them to create a good strong straight knurl on some 6 mm brass rod which I would then press into aluminium to act as bushes. They turned up and I had a go at knurling the rod and only succeeded in mashing the surface - no sign of any discrete lines. I've had a look at them under the microscope and there appears to be flats on the top of the triangular elements (see photos). The surface is badly crazed, probably due to the heat treatment. Does anyone know whether knurl wheels need to be sharp at the tip of the triangles? I may also be too optimistic in trying to knurl a 6mm rod with such a coarse knurl - any comments.
I need to supply feedback on these but I thought I'd run it past people who know what they are talking about before I do this.
Thanks,
Alan C.

 

[canadianhorsepower]

I almost stop using set up on a shaft
you need so much pressure for it to work you end you
bending everything.:wall:


the only time I had some success with them was giving
it a small angle about 3 degree
good luck

 

[GailInNM]

If you use a scissor type knurling tool you will probably be OK. The knurls oppose each other and take most of the pressure so only a small amount of side pressure is needed on the stock.
Gail in NM

 

[tornitore45]

Brass is not very ductile it tend to crumble rather than cold flow.
That said, 6mm is pretty weak for aggressive knurling but the secret on getting a knurl started is to be aggressive at the start.
In this case a scissor knurler is the only vay and you must be dead on center otherwise the shaft will bend ans slip out of the dies.

 

[canadianhorsepower]

Brass is not very ductile it tend to crumble rather than cold flow.
That said, 6mm is pretty weak for aggressive knurling but the secret on getting a knurl started is to be aggressive at the start.
In this case a scissor knurler is the only vay and you must be dead on center otherwise the shaft will bend ans slip out of the dies.

straight knurl wheels are made to be use one wheel only not two wheel

 

[GailInNM]

Single wheel straight knurls work very well on larger diameter stock, but scissor straight knurls are frequently used on smaller diameter stock, Single wheels are easier to set up as only the tool position has to be on center while the knurls have to be adjusted to the stock size and depth of knurl also.
Gail in NM

 

[kiwi2]

Thanks guys. I am using a scissor arrangent which has worked well with diamond pattern wheels in the past. I'm not too fussed if I can't get them to work as they only cost about US$5 each (shipping was free). I might give them a go on a bigger diameter (say 1") piece of stock.

 

[canadianhorsepower]

instruction on straight knurl of wikipedia

Process[edit source | editbeta]


A single wheel knurling tool



A diamond knurling tool with two of the interchangeable rollers shown above it


More common than knurl cutting, knurl rolling is usually accomplished using one or more very hard rollers that contain the reverse of the pattern to be imposed. It is possible for a "straight" knurl (not criss-crossed) to be pressed with a single roller, however the material needs to be supported adequately to avoid deformation. A criss-cross pattern can be accomplished using any of:

• A single roller that contains the reverse of the complete desired pattern. These are available to form either "male" or "female" patterns,
• A left-handed straight roller followed by a right-handed straight roller (or vice-versa), or
• One or more left-handed rollers used simultaneously with one or more right-handed rollers.

Rolled knurls are somewhat more complicated to design than cut knurls because the outer diameter of the work piece must be chosen to allow the roller to roll an integral number of patterns around the workpiece. By comparison, for cut knurls, the spacing of the cuts is not preset and can be adjusted to allow an integral number of patterns around the workpiece no matter what the diameter of the workpiece.
Hand knurling tools are available. These resemble pipecutters but contain knurling wheels rather than cutting wheels. Usually, three wheels are carried by the tool: two left-handed wheels and one right-handed wheel or vice-versa.
On the lathe, knurl cutting is usually accomplished using the same automatic-feed mechanisms that are used to cut screw threads; knurling can be thought of as simply a series of threads cut at extremely coarse pitch and in both the left-hand and right-hand directions.[http://en.wikipedia.org/wiki/Wikipedia:Citation_needed