Knurling advice

[woodchucker]

It's math for the diameter. So you get nice crisp knurls

 

[JohnnyTK]

Um, I wasn't trying to.



I hear some people call it spiral knurling (easier I guess) but I think the proper term is single diagonal knurling, at least that what I call it. For diamond knurling you use LH & RH knurling wheels. For the single diagonal knurling both knurling wheels will be the same direction, 2 LH or 2 RH, doesn't matter. Or if you're using a bump knurler you can just one wheel but again I don't like bump knurlers, well my lathe doesn't like them much either.


Here's a pic of when I was knurling that Ti spear. I had to use a follow rest when knurling it.

One of these blanks turned into this (I didn't make the light, just did the knurling for Fred)

Here's a Ti ice pick that I made for Matt at QMT (Precision Matthews)

Sorry for the thread hijack, back to knurling, lets help the OP get some good knurls!

How did you do the bluing on the knurls?

Tks.

 

[mikey]

Took a look at the Grizzy Micro-lathe and it has a 1/5hp motor so now its clear why you can't use power to knurl with. You might have some success with a partial form straight knurl in aluminum; they require less pressure to form a pattern vs a diamond.

I don't know what your plans are but you might want to keep an eye out for a used Sherline lathe. The standard length bed is bigger than yours and it has the equivalent of a 1/2hp motor on it. It will knurl without any problems at all.

 

[darkzero]

How did you do the bluing on the knurls?

Tks.

I anodized the titanium.

 

[mikey]

I looked at the Boston area CL and saw this for sale in Needham, MA: https://worcester.craigslist.org/tls/6046805625.html

I would be on this in a heartbeat, even if I didn't need it. Complete machine shop for 3K!

 

[Maplehead]

Mike, does it need to be under power?
When I do it I just turn the chuck by hand.
Speed isn't an issue is it?

I ran the calculator for a .375" brass rod using a 33 LPI knurl and I get .367. So as I am to understand this, I should turn the rod down to .367" and then the knurl pattern should fall into place upon a full rod rotation. This is assuming the clamp doesn't start wandering diagonally off as it does.

 

[Maplehead]

I looked at the Boston area CL and saw this for sale in Needham, MA: https://worcester.craigslist.org/tls/6046805625.html

I would be on this in a heartbeat, even if I didn't need it. Complete machine shop for 3K!

If I only had the money. And that's not even the saddest part. I make guitars on the side and I just started getting into making the hardware for my guitars, hence the machining. Just a few years ago I could have had ten times or more that amount of high end machinery since my father-in-law, a very generous guy and somebody I was close with, bought and sold machinery. He sold into the hundreds of thousands every year and bought up little shops like this ad shows with his pocket change. He used to tell me, "anything you want". Sadly he's incapacitated in a nursing home now.
My guitars are unique in that the wood is joined on curves. Pictured is not inlays but maple and walnut joined on curves.

 

[darkzero]

Mike, does it need to be under power?
When I do it I just turn the chuck by hand.
Speed isn't an issue is it?

I ran the calculator for a .375" brass rod using a 33 LPI knurl and I get .367. So as I am to understand this, I should turn the rod down to .367" and then the knurl pattern should fall into place upon a full rod rotation. This is assuming the clamp doesn't start wandering diagonally off as it does.

I pretty much always knurl under power. But if you just want a single band of partial profile knurl then turning the spindle by hand is ok.

For your dia & wheel pitch it is .3665". Don't have to hit that mark but if you still get double tracking shoot for a thou or 2 over for hard or dense materials. You'll run into inconsistencies depending on the quality of the knurling wheels & how much slop your mounting pins might have. You'll have to figure out how your tool & wheels perform if you do. Quality wheels matter. I personally won't even bother with the cheap stuff. I only use Accu-Trak wheels.

 

[Maplehead]

I doubt mine is quality. What I don't like about it is that it has lateral play and that play seems to get it to start diagonally drifting off the rod.

 

[mikey]

No, it doesn't have to be under power, and speed is not an issue in your case.

Ideally, a calculator should give you the OD you need so that a full pattern knurl will produce a knurled OD of a predictable size. It is the finished knurl size that matters, not whether the knurls will track and this is a point of confusion for a lot of folks. Typically, parts with knurls must fit into a hole of a specific size so that the knurl will resist the pulling forces the part is expected to experience. There are tolerances for these kinds of fit and the calculators are intended to help you figure out how to produce parts that fall within those tolerances.

I've seen discussions about the math behind the calculators and spreadsheets and this is all theory, in my opinion. I tried many times to get it to work for me (so that my wheels track) and sometimes it works, sometimes it doesn't. Most often, it doesn't so I've learned to just increase pressure until the wheels track and they do. The only time I use a calculator is in the above situation, where I need a knurl of a specific size to fit in a specific hole to provide a specific fit; this is a rare thing in my little shop.

So, to answer your question. If you turn the starting OD to 0.367" then theoretically, it might allow the wheels to track.

Then again, it might not.