Knurl pitch standard?

[Russel]

I have looked and looked and can't seem to find any guidelines as to what pitch knurls to use for any given diameter. Specifically, I am wondering what straight knurl pitch (or set of pitches if you recommend more than one) would be best for thumbscrews of a half inch and smaller.
Any recommendations?

[bogstandard]

Russel,

In the UK, knurls are usually classed as fine, medium and coarse.

Normally, you will use a single wheel for straight knurling and double wheels for diamond pattern. But if you have a smallish lathe, that can't take the side loads, or small parts to be knurled, I would recommend a scissor type tool for both, and use double wheels for straight. The pic at the bottom shows what I mean. Middle wheels are fine and two outers are medium.

The rule of thumb for knurling is that you use a straight knurl for tightening and slackening (adjusting knob), and a diamond knurl for grip (centre punch)

I have found that a medium one is good for most things.


Bogs

[Bernd]

Russel,

PM sent. Let me know if that's what your looking for.

Bernd

[Russel]

Thank you both for the information!

I have the knurler made by Sherline for the Sherline lathe. It comes with a single pair of medium knurls (30 degree spiral knurls with a 90 degree tooth angle at 25 TPI) for making diamond knurls, but I wanted to order straight fine knurls for making thumbscrews.




The difficulty that I'm having is choosing the best pitch and tooth angle. Sherline offers straight tooth knurls in 16, 20, 25, 30, 32, 35, 40, 41, and 47 TPI with a 90 degree tooth angle, and 35, 50, 53, 60, and 80 TPI with a 70 degree tooth angle. I'm guessing that for smaller parts a fine straight knurl would be around 40 TPI. I was wondering if there is any kind of guideline for determining the best pitch for a given diameter. I can count the teeth from a 10-32 socket head to get extra fine.

I'm thinking that I might want something more course for 3/8" to 1/2" diameter.

[bogstandard]

Ahah!!

I now see your problem. You want to do it technically rather than by the seat of your pants. What you are looking for is perfection in what you want to do.

As I said, we tend to go for the easy to understand stuff.

http://www.arceurotrade.co.uk/Catalogue/Cutting-Tools/Knurling-Tools

http://www.chronos.ltd.uk/cgi-local/sh000001.pl?REFPAGE=http%3a%2f%2fwww%2echronos%2eltd%2euk%2fcgi%2dlocal%2fss000001%2epl%3fRANDOM%3dNETQUOTEVAR%253ARANDOM%26PAGE%3dSEARCH%26SS%3dknurl%26TB%3dA%26GB%3dA%26ACTION%3dSearch&WD=knurl&PN=Chronos_Catalogue_Knurling_Tools_81%2ehtml%23aKN_2e_2e_2e#aKN_2e_2e_2e

There is nothing wrong with what you are attempting to do, in fact you will have learned a lot more about knurling than all of us put together by the time you have finally sorted it.

Unfortunately, what I have said is about the limit of my knowledge (which isn't much) about knurling.

Keep up the good work, and I will look forwards with great interest to your final conclusions. I will be able to add to my database.


Bogs

[Russel]

Thank you Bogs! That gives me a better idea. "Fine" on the first link is .5mm pitch. If I used my calculator correctly, that comes out to about 50 TPI. I was thinking 40, but 50 might be a better choice.

Since reading many of the posts here I have come to realize that the most important tool that anyone has is their brain. We must care for it and sharpen it just as we would our most prized tools. I came to realize that I was just being lazy not taking the time to learn more about machining and to take the time, within reason, to do the job right. This really became apparent after reading your post "Fixing Darrens Lathe." I am not really trying for perfection. I'm just trying to make sense of the vast number of knurl choices avalible to me. I think simple is good and course, medium and fine make a lot of sense to me. I am just trying to figure out what pitch I should consider "fine." I appreciate your help!

At the other end of the the knob spectrum, I figure that I can use the rotory table to overcome the maximum capacity of my little knurling tool, which is one inch.

[bogstandard]

Russel,

I use that method of RT work when needing a little more tightening power on my small steam engine oilers, and it has the advantage it is dead easy to make a small peg spanner for it as well. See pic.

I don't blame you at all for going the F-M-C route. Leave the complicated bits to the specialists, and just use your gut feeling to put what is right on each knob. No-one here is going to get out feeler gauges and mics to check your work out. You will be your own judge and jury.

If it looks right to you, then who are we to judge.


Bogs