Ditto. If they wear, make some more and harden those.

Blue is softer than straw? I would (if I could see the colours🙂 ) temper them as hard as possible, so to straw colour.

At the risk of annoying dc31k, or whoever it is that complains of not answering the precise question tabled, I would recommend making a scissor type of knurling tool, rather than a push type – so much easier on the machine (and workpiece, if of thin section).

I have a push type (if I could find it) that I would give away (less the knurls, of course) as I think they are cheap carp. The knurler came as part of a set of tool holders I bought, thinking a set was good value. I won’t make that mistake again.

Normal procedure is to use standard hard, parallel, location dowel pins as axles for the knurls to run on. Cheap enough that its not worth rolling your own and exactly the right size for the knurls.

Boneham & Turner do appropriate sizes for around 10 p to 15 p each and are quite happy to send small quantities although most of what you pay will be for post and packing. I got 10 of two lengths in 7/32 diameter for about £ 10 to suit the wheels for my Marlco and P&W knurlers.

Wheels from Zoro seemed good value and work well. Didn't trust the uber cheap ones. Not sure what was on my Marlco when I got it but a fairly innocuous bit of steel ripped the teeth off one leaving it sort of D shape!

If you want 1/4" by 3/4" long pins I have a mega overstock and could easily send a few if you pay the postage.

Clive

Good tip about dowel pins.

I replaced my own hardened silver steel pins with modified scrap Clarkson end mills. I don't know how hard the shanks of these are but they are standing up well in my knurling tool. I lubricate them with moly grease.

Agree with John that the pins should be considered consumables. Change when you change the wheel.

Surface finish appears to be important. There is a difference in how free running a new wheel is on a new pin when compared to an old one even though there is no easily visible difference in surface quality or wear.

If you plan to make your own push tool may I suggest that you follow the Pratt & Whiney design where the pivot is offset so one wheel is effectively underslung.

My experience is that this style is less likely to mis register producing double knurls. Subjectively it seems to need a bit less force than the common style of pivoting push knurling tool. But that may be due to the push tool in question being hobby bran whilst P&W were a high end maker of machines and tooling.

That said I still consider the "nutcracker" hand squeezed style excellent for casual use. Mostly because set up time is about 30 seconds!

Clive

I used HT bolts, 40 years ago and it still works fine. Noel.

ega

Leaning a bit to one side will cause the nutcracker to traverse so you can make longer knurls.

A bit of a knack to it, especially if your knurls are sharp edged rather than having a slight bevel, as the edge can dig in a touch producing random lines. Most likely if you get a bit heavy handed. Takes several passes to get a full depth knurl.

Main disadvantage is that the depth setting is a bit iffy. I just do it by eye.

Obviously not for harder materials, light alloy and the ordinary range of steels are fine but anything a bit obdurate needs too much squeezing.

Drawings for one like mine were published in Model Engineer, 29 January 1999.

The American Magazine Popular Mechanics published a more man sized version in May 1965. Google books link to the article here :-

**LINK** ,

https://books.google.co.uk/books?id=buQDAAAAMBAJ&q=knurl#v=onepage&q=knurl&f=true . Have to work off the screen as it can't (I think) be printed. Link found by MichaelG in a previous thread.

Can be found on Archive.Org too so download is possible but very slow.

Clive

Edited By Clive Foster on 18/04/2021 11:44:50

Clive Foster:

Many thanks for the comprehensive response.

Getting back to the OP question, I notice that the ME author, R V Howis Senior, tempered his Silver steel pins to blue.

Edited By ega on 18/04/2021 12:52:21

You don't need to harden the pins.

All journals benefit from having the cheap part softer, and they can even last longer as a result, so mild steel will be sufficient.

Its difficult to imagine an amateur wearing the bore of a knurling tool such that it does not work, so any accurate material will do for what you need.

I used an HSS drill shank as a 'temporary spindle' for a knurl, it wore badly!

Make bronze pins

Neil