Milling a surface Knurl on a flat part

legoboy · Dec 7, 2018

I would like to machine a surface knurl on a flat part using an old Deckel with Sinumerik control. The control has a very small memory with no capacity to DNC so I am looking for examples of a macro one could use to create the repetitive pattern. I basically just want to make a diagonal cross hatch with a 90 deg spot drill, maybe 0.05" depth. So it would be like if you rolled out a diamond knurl you would turn in the lathe.
Any insights would be appreciated,
Thanks

D.D.Machine · Dec 7, 2018

Macro is going to be harder to write than a subroutine.. I dont know that control but most controls are easy to write subs for ... it would just be a simple move and run sub. at the end of the sub it goes back to the next line in the main program and you move and call the sub .. you can even stack subs so one sub can call the other sub and run it a set number of times. that is how I knurled handgun slides. full program was like 20 lines of code

npolanosky · Dec 7, 2018

If you're not terribly picky about the pattern, you can do it with a facemill/flycutter at a low rpm and high feed. I've used TPG inserts of varying radii to do this in the past, and it's pretty straightforward to calculate the correct speed/feed for the knurl pitch you're looking for. If you've gotta have straight lines I'd definitely go the sub route as suggested above.

aj · Dec 7, 2018

We had a similar job several years ago where we had to "mill" a knurl on a flat piece of stainless 22" long. I wrote this (for a Fanuc) to accomplish the task.

#100=-0.250(X START POSITION)
#101=#100+0.2742(X END AT 30 DEG.)
#102=22.0(LENGTH OF KNURL)

G40 G80
G57 G90 T2 M6
G0 X0.0 Y0.050 S6000 M3
G43 Z0.1 H2 M8

WHILE[#100LE#102]DO1
G0 X#100 Y0.050
G1 Z-.01 F100.
X#101 Y-0.425 F20.0
G0 Z0.1
#100=#100+0.050
#101=#101+0.050
END1

#100=-0.250(RESET X START POSITION)
#101=#100+0.2742(RESET X END)
G0 X#101 Y-0.475

WHILE[#100LE#102]DO2
G0 X#100 Y-0.475
G1 Z-.01 F100.
X#101 Y0.050 F20.0
G0 Z0.1
#100=#100+0.050
#101=#101+0.050
END2
G0 G28 Z0 M9
G28 Y0 M5
G0 X0.

Hope this does you some good.

legoboy · Dec 7, 2018

Thank you for the helpful responses.

Alberic · Dec 8, 2018

legoboy said:
I would like to machine a surface knurl on a flat part using an old Deckel with Sinumerik control. The control has a very small memory with no capacity to DNC so I am looking for examples of a macro one could use to create the repetitive pattern. I basically just want to make a diagonal cross hatch with a 90 deg spot drill, maybe 0.05" depth. So it would be like if you rolled out a diamond knurl you would turn in the lathe.
Any insights would be appreciated,
Thanks

I was researching some custom knurls a month or two back, and came across a "flat knurl" rig for a CNC mill. Apparently, it was intended to be pressed into the (flat) surface by the spindle, and then traversed sideways. The rolls would form the stripes in, just like normal, only flat.

I just looked for them again, and it turns out Dorian makes them, and MSC has 'em. I've never used them, but it seemed like something that should get mentioned. ( Milling Machine Flat-Surface Knurlers - MSCDirect.com )

FWIW,
Brian

legoboy · Dec 8, 2018

That looks like it would simplify things. I wonder how hard it is to match the knurl on step over.

jrmach · Dec 8, 2018

Not a real knurl ,a cut that simulates the look of a knurl
could shoot you some g-code if that looks appealing

aj · Dec 8, 2018

Alberic said:
I was researching some custom knurls a month or two back, and came across a "flat knurl" rig for a CNC mill.

We tried one of those on the above mentioned job. We couldn't get good results with it...

legoboy · Dec 9, 2018

That looks really good, that would work nice. Thanks

rick-b · Dec 11, 2018

jrmach said:
Not a real knurl ,a cut that simulates the look of a knurl
could shoot you some g-code if that looks appealingView attachment 243975

I like that finish. But I would have no idea how to do it.

mhajicek · Dec 11, 2018

Looks like a crosshatch done with a ball endmill.

MattiJ · Dec 11, 2018

Not what op asked but has anyone attempted to create the knurl with non-rotating tool?
CNC shaper if you will.

No feed rate limitations like with spot drill. Need to be able to index the spindle and obviously you cant do crazy deep knurls in single pass.

jrmach · Dec 11, 2018

rick-b said:
I like that finish. But I would have no idea how to do it.

Have not done in a while,but it goes like this
First figure out the angle you want on the sides of the cut ,,,for instance 60,82,90 degree cutter,,etc.
Now a bit more trickier is draw the pattern,but keep in mind the depth of cut plays a big part on how far away to space your pattern lines
This is where simulation software is invaluable
As far as CAM,just use a profile,no compensation tool path with depth of cut on what you saw to your liking simulating the part
it is easy,but playing with the above variables you can get all kinds of results

BUT,I think I may have done that particular example in BobArt and 3D Planar it
been a long time,but I have done both ways with great results

rick-b · Dec 12, 2018

Thanks, I will give it a try.

Rstewart · Dec 12, 2018

MattiJ said:
Not what op asked but has anyone attempted to create the knurl with non-rotating tool?
CNC shaper if you will.
No feed rate limitations like with spot drill. Need to be able to index the spindle and obviously you cant do crazy deep knurls in single pass.

Yes I used to manufacture an aluminum part that needed a flat straight knurl pattern.
Left a .01" tall island and used a 90 degree HSS single flute engraving tool.
That HAAS did have Spindle indexing capability, so loading the tool initially wasn't too complicated.
Index spindle, feed down, rapid across, rough cut, then finish depth, step-over, rinse and repeat

Danny VanVoorn · Dec 12, 2018

Don't have anything to offer in the programming department but I have a serration cutter for the horizontal spindle. Being a flat surface it seems it could be used to cut serrations in one direction and the part could be rotated some degree (90?) and re-cut to produce what would appear as a knurl.
Dan

cyanidekid · Dec 12, 2018

think outside the "X-Y, spindle perpendicular" box. is that the only way anyone under 40 can conceive of milling being done?

how about ganged cutters on a horizontal, one pass, rotate stock, second pass... DONE!

also, look up "backstrap checkering" and have your mind blown by what a master 'smith can do with a hand file..

Milling a surface Knurl on a flat part

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