Scissor knurler.

[toglhot]

Another tool I made quite a while ago. I bought the wheels on ebay for a few bucks and put the rest together myself. I've had a bit of use out of this fella. It tends to walk if if not set up perfectly square to the job. I assume that's a typical thing with these type knurlers.

A bit rusty now, but it still works well.

 

[PeterT]

Maybe you already know this but passing on FWIW. It took me a while to figure out there was a relationship to stock diameter & knurl pitch, which was a big contributor to hit & miss results. Kind of makes sense, they are somewhat like gears in that they have to mesh or else profile looks mashed or worse. An added complication is the stock itself is physically forming (growing). Anyways I made a spreadsheet of the Accu-Trak calculation, but recently I stumbled on this web calculation. It has some other handy dandy tools in there like a hardness scale converter (yet another spreadsheet I can retire -LOL)

Knurling: Calculator & Formulas (Diameters, Speed & Feed)

All you need about Knurling: Online Calculator, Cutting Conditions, Formulas for diameter growth and pitch.,Charts and methods.

www.machiningdoctor.com

Blank Diameter Selection

Blank Diameter Selection

accu-trak.com

 

[toglhot]

Funny you should say that, I did think of that when building the thing, but for some reason the knurling comes out clean regardless of stock size. The knurling in the first post was on 8mm stock, the stock in this picture is 19mm. I've also knurled some bigger stock, nothing too outrageous, probably 25mm or thereabouts, same story, the knurling comes out clean. I think the knurling wheels must adjust themselves as they are turning???

 

[PeterT]

Nice bling!
I'm no knurling expert but here's a few thoughts. It might be like describing surface finish; what is acceptable for one person, another may say that's not quite right. I suspect for many of us hobbyists as long as its not double tracking or a mangled pattern we are generally happy. I got exposed to knurling in a machining class (old tymey cross feed bump knurler -ugh). First we did 1" aluminum scrap to get the hang of it,. Easy peesey. Then a 0.75" plumb bob from 12L14 (leaded steel). A bit harder but pretty forgiving alloy. Then a center punch from O1 tool steel, about 3" finer DP knurl on a skinny ~0.4" diameter. The O1 was definitely more difficult, presumably because the material doesn't flow as well & start diameter becomes more critical. Knurling is a rolling deformation process where correct pressure is key. Cut knurling is different again.

Anyway, everyone got one stick of stock & got graded. I was initially happy with my result. Aside from a few exceptions most students looked similar at arms length. Then instructor put them under magnification & the differences really showed up. If the diamonds don't form to a perfect Egyptian pyramid point, deduction. If the pattern height / size/ profile deviates from one end to another, deduction. If the pattern orients on a bit of helix as opposed to axial along the length, deduction. Etc. etc. When you see & feel perfect, crisp knurls they are a thing of beauty. Ever since then I cant help myself but look at knurled tools & objects closely. I think scissor knurls give us the best chance of success on hobby machines when set up & operating properly.

 

[toglhot]

If it looks ok and performs ok it is, OK. Looking under magnification to see if the pyramids are perfecty formed is just ridiculous. You can bet your life that any commercialy available item with knurling would not pas the magnification test.