What type of steel to use for a vice tommy bar?

[mangocrazy]

I'm presently half way through restoring an old Record 111P vice. but the problem I have is that the tommy bar it came with was bent and damaged beyond further use and I need to make a new one for it. As far as I can tell I will need 11/16" steel rod, of a length approximately 13" / 300mm. My concern is, what grade of steel should I use for this? Mild steel would be cheapest and easiest to source, but would it stand up to hard use? Should I be looking at silver steel or some higher quality steel for this? The other complication is that I will need to get some end caps made and these will need fixing to the bar, either by bonding, welding or screwing on. If I go with welding, I presume that will restrict my choice of steel. Do I go with something 'hard' and possibly brittle or softer and more ductile?

 

[dan.taylor.1]

I used stainless on the 2 record no. 25 I rehandled a few years back. No issue with them rusting. I tugged a stainless ball to one end and threaded a ball for the other end. I think I used 16mm bar and 25mm balls.

 

[Agroshield]

Every type and grade of steel will have identical behaviour under bending stress.

Thus, do not walk down the dangerous path of thinking 'better' steel is 'stronger' or 'stiffer'. A better steel will just be tougher, more hard wearing and less likely to suffer dings.

If the hole in the vice is worn and sloppy, consider upgrading to 18mm dia. and make the hole a touch bigger for a nice sliding fit.

Drill and tap the ends of the tommy bar. Drill and tap the end caps. Use a piece of threaded rod and loctite to secure. Add a rubber buffer at each end before final assembly.

As above, 303 stainless would do well. It is not too shiny to be bling but also will not corrode and is easy enough to drill and tap.

303 ST ST Round Bar - 18mm x 300mm

Available here is 18mm Diameter 303 Stainless Steel Round Bar. 303 Stainless Steel is a free machining grade of stainless, it has excellent strength

www.gwr-fasteners.co.uk

GWR also sell larger diameters in 100mm lengths, which would do for the caps.

 

[Shedendman]

I had a vice with a missing bar,i found an old shock absorber stripped it down took the ram out welded some wheel nuts on each end,rounded them off job done,battered the hell out of it many a time,never faulted

 

[mangocrazy]

Thanks for the replies. The hole in the screw end seems remarkably unmolested, and I've already had it electroless nickel plated, so I'm not keen on opening the hole out. I'll probably stick with 11/16", as that would seem to be the original size bar. Stainless certainly would do the job nicely and screw fixing obviates the need for any welding, which is good.

 

[MattF]

I'd just go with mild, unless you want something slightly more aesthetically pleasing to the eye.

I used brass rod on one of mine, threaded the ends, & made the knobs from mild.

 

[mangocrazy]

I've found a supplier of 11/16" stainless 303 round bar not much more than a mile away from my house, but then I do live in Sheffield...

 

[MetalMonkey]

You want the handle to bend first, before anything else does.

 

[Ed.]

I have always used Stainless rod for my vices, never had any problems with it and it doesn't rust.

 

[hunter27]

My vice handle never gets the chance to rust it is used several times most days???

 

[chunkolini]

Good tip from Argoshield about rubber bumpers.
As a kid playing with granddads vice the handle fell and nipped my fingers.
Blood blisters and tears.
I always have a ring of old inner tube on my big vice

 

[Gareth J]

Every type and grade of steel will have identical behaviour under bending stress.

Can this be right?! Surely different steels with different properties will have different yield stresses when subjected to bending? I intuitivly know it to be true...

 

[Screwdriver]

I would go for a nice length of cold rolled mild steel, machine two shoulders each end and peen a ball on each end.

You're not going to bend a foot long half inch steel bar by hand and if you use a cheater bar, you risk damaging the vice by the time it gives way.

If I was decorating the kitchen, I might go for stainless.

 

[PhillipM]

As others have said, you want the bar to bend before something breaks if you're wailing on something - so you don't need anything high strength. Mild is fine, or 304

 

[Screwdriver]

Can this be right?! Surely different steels with different properties will have different yield stresses when subjected to bending? I intuitivly know it to be true...

Yes @Agroshield is entirely correct and I will defer to his knowledge of the subject to explain why. Your intuition is probably telling you how steels "yield", i.e. when they begin to permanently deform. That is very different from how they will behave under stress which is different again to how they behave under strain. The upshot is, you need to upgrade your intuition to understand the difference between stress and strain.

I have to fact check myself because I always get stress and strain the wrong way round (not my job mate...) and this is as good a resource as any to start to explain this vastly complex subject: https://openstax.org/books/university-physics-volume-1/pages/12-3-stress-strain-and-elastic-modulus

 

[bricol]

Youngs Modulus is your indication of resistance to bending - and all steels, including stainless are pretty similar.

Young's Modulus of Steel

If the bar is excessively bug gered from previous owners abuse, I'd have a slight concern of the state of the rest of it - at the very least, a worry over the parallelism of the jaws. I'd be peering at the neck for signs of cracks . . .

 

[brightspark]

if it gets to the stage when your bending the bar your overloading the vice

 

[carbonarc]

The use of 303 stainless 11/16" dia. round bar should not be a problem. If hand pressure is used to close the vice with the tommy bar at around 8" lever arm then to exceed the material's elastic limit and cause a permanent bend you will need a force somewhere around 240lb. A thing to watch is that 303 stainless does not weld well.

 

[Misterg]

Yes @Agroshield is entirely correct

I don’t think he/she is in this case.

Every type and grade of steel will have identical behaviour under bending stress.

Until the yield point which *does* vary by grade and prior treatment.

Thus, do not walk down the dangerous path of thinking 'better' steel is 'stronger' or 'stiffer'.

Stiffer: no. Stronger: yes. (In that it will support higher loading without permanent deflection.)

Hot formed bar will bend more easily than cold drawn, for example.

Not hugely critical here though.

 

[Screwdriver]

Again it comes down to the difference between stress and strain. Incredibly, all steels have a very similar resistance to stress, that is, in your hands any steel will exihibit the same resistance to bending stress regardless of alloy (all things being equal) or temper. That is counterintuitive because it is easy to assume a hardened high carbon steel or tool steel would behave very differently.

They don't. At least in the elastic limit right up until they begin to deform permanently. Only then do they behave differently. A hardened steel might snap or shatter, mild steel just goes like plastic, spring steel will (eventually) take a permanent set.

I am not qualified to comment but I understand materials properties sufficiently to perhaps describe it in laymans terms.

Short answer is, it's all down to the size of the steel handle (strictly the x-sectional area), not the alloy or temper. It is a moot point what happens by the time it starts to bend because by then, you have typically exceeded the design parameter of your vice.