Take a bog standard knurling tool and set the height either much lower or higher than usual, flip the end up/down so only one wheel is engaged and feed into the slowly rotating face.

Alternative is to set up in the mill and cut two sets of Vee Grooves at 90deg to each other into the face.

If you have a rotary table on a mill, you can produce the knurling, it just takes time. Washers with the knurling in association with nuts would be better, then the knurling will grip, but not be rotating when the nut is tightened.

Edited By old mart on 11/04/2021 15:47:35

Jason I'm curious how you machined the hole in that part with the flat

Dave

Just musing out loud, but might there be a way of 'cut-knurling' these.. ..driving the shallow-angled corner of a wheel across the face.. ..can't remember whether I've seen it done or not..

..only posting in the hope it might jog someone else's memory..

Jon,

Why are you using stainless steel for a critical item such as an axle nut? I certainly hope you're not using it for the axles themselves!

Racing motorcycles are prohibited from using stainless for wheel spindles after the death of Fritz Scheidegger at Mallory Park 50 odd years ago. Stainless has a high 'notch sensitivity' and his front wheel spindle failed under braking for the hairpin corner. Race Scruitineers check wheel spindles with magnets to enforce the ruling, this can, unfortunately, rule out other non magnetic materials such as titanium, although titanium is a far safer material due to its far higher ductility and toughness, apart from its excellent resistance to corrosion.

I would never ride a bike with stainless steel used in such a critical item, its OK for non critical fasteners but that is all.

Martin

Jason,

Accepted that it may be for a push bike – but to quote Jon "….toying with the idea of making some deep fit acorn style cycle/motorcycle wheel nuts". I've seen far too many wheel spindles on custom motorcycles made from stainless due to what I think is referred to as 'a little knowledge can be a dangerous thing'.

Scheidegger's death was a warning that even apparently highly skilled engineers need to be aware of the metallurgical dangers of a 'little knowledge'. The spindle broke at a size transition area due to tool marks even though a radius had been provided, the sudden break then caused a catastrophic failure at the other end of the spindle at another transition point. A front wheel detaching under heavy braking is not a nice experience to witness as I happened to at the time.

The other warning I would emphasise is the practice of chrome plating frame tubing, known to cause hydrogen embrittlement of the tubes; fine to use nickel plating but chrome plating is again frowned upon. In fact a lot of motorcycle racing sidecar frames were left bare metal and just varnished – this allowed for a visual inspection of the tubing for cracking to alert the owner of potential failure.

Martin

Oily Rag, Titanium has been banned by the ACU for some time. From Standing Regs

14.20CONSTRUCTION
The use of titanium in the construction of the frame, the front forks, the handlebars, the swinging arm spindles and the wheel spindles is forbidden. For wheel spindles, the use of light alloy is also forbidden. The use of titanium alloy nuts and bolts is allowed.

Stainless steel spokes seem to work just fine and are readily available from reputable suppliers such as Buchanans in the USA. Plenty of big horsepower Harleys using them. I have used them on Harleys and on a Rocket 3 (over-) restoration without problems. You can polish them to look like chrome or leave them natural or if you bead blast them they look closer to the old cadmium plated spokes than modern zinc plating does.

Make sure to use anti-seize on the threads if using stainless nipples too, or they can gall and lock up if you ever want to tighten them up down the road sometime.

lots of stainless fittings used on aircraft just need to use the right grade.

Oily Rag was talking about the dangers of stainless axles, not nuts.

And the data can be deceptive. Stainless bolts can have same or even higher tensile strength than carbon and alloy steel fasteners. But it is stainless's tendency to work harden and fracture under repeated severe load cycles that causes the problems. So things that get a repeated hammering like axles or caliper mounting bolts can fail. Nuts, not so much. And stainless fasteners used for things like holding an oil tank or seat in place are fine.

Edited By Hopper on 12/04/2021 12:07:07

I too dislike sweeping generalisations! Hard to avoid because few Model Engineers have a professional background in materials science, or the time and interest needed to tackle the subject in any depth. Thus we bundle vague ideas about entire families of alloys together, and often as not it's good enough to understand the broad differences between 'steel', 'aluminium', and 'brass', even though these all have wildly varying properties, good and bad! We're happy as long as metal machines reasonably well and doesn't break. Ignorance is bliss!

Fortunately, engineering for strength and reliability isn't often required in Model Engineering. As not much of my work is safety critical it doesn't matter my approach to metals is naive. I like Aluminium alloys because they are cheap, Brass because it it machines well, and mild-steel because it's strong and hard enough for what I need. I use what I have rather than buy in the most appropriate material for the job. My workshop choices are pretty brainless!

Slapdash methods aren't smart when the engineering has to be safe. Brakes, lifting gear, motorbike axles, wheel fixings, engine mounts, and anything where people get hurt if it fails need proper attention. To keep life simple there is a lot of general guidance around, such as building codes and type approvals, that tell constructors what to avoid, without going into detail. Behind the scenes, appropriately qualified engineers do the design, including selecting the suitable materials. Constructors can then apply their skills without needing to understand a mass of complicated design detail. It's iffy for constructors to modify or re-apply a design on the assumption they understand it! Might be OK, might not. Design decisions based purely on experience could be guesswork rather than understanding.

So as soon as someone might get hurt if a home-made part fails, it's necessary to look things up. Assume nothing. Read specifications, do the sums, and apply risk analysis. It's a thinking job. Bear in mind that the part might have to pass an amateur test such as magnetism; testing for stainless steel with a magnet is crude, and it might allow a mechanically unsuitable stainless through, whilst denying a well-chosen stainless because it happens to break the rules. Not daft, because the chap with the magnet is following a general guidance with a good chance of detecting a dud material with a simple test. Point is designs have to satisfy all the requirements, not just survive a short test drive.

If I wanted to make a wheel nut out of stainless, I'd start with the specification of the original and ensure the substitute was at least as strong. Where it gets complicated is the need to account for subtleties like work-hardening, fatigue cracking, and temperature sensitivity. This is why thousands of different steels are available, and several hundred different varieties of stainless, each designed to excel at a particular job. I'd also worry about why the original was drop forged with rolled threads – both methods are stronger than machining from stock.

WW2 Liberty Ships are an example of getting it wrong. A number, all virtually brand-new, fell apart at sea and in harbour.

Two reasons were identified. One was cutting cargo hatches with stress-raising sharp corners, the other was building the ships with a mild-steed steel alloy that becomes brittle below freezing point. The steel was fine for most stormy Atlantic crossings, but not for ships routed far North in some of the coldest winters ever recorded…

Using the correct materials and processes is about reducing risk. Replacing a motorbike wheel nut with a third-rate substitute doesn't guarantee failure: in practice, there's a good chance will last a long time – forever on a display bike. Doesn't mean the repair is acceptable. Foolish to put the same nut on a performance bike ridden aggressively over rough roads for hours on end.

Dave

Edited By SillyOldDuffer on 12/04/2021 14:39:30