John Deere Tappet Lever Adjusting Screw

[Onoff]

An old farmer up the pub has asked whether I could make him what I think is one of these:

I'll have to pop up tomorrow with a Vernier & Zeus book as he's bringing me a sample one. Reckons he can't find one other than from the States.

Is it anything special steel wise? With thinking to just get an imperial bolt and knock one up. Grade 10.9, 12.9, softer?

(Not the strangest thing I've been asked to make by a long shot).

 

[addjunkie]

Hard for the rounded ball-end Id say.

 

[roofman]

Hard for the rounded ball-end Id say.

yep hardened deffo on the business end.

 

[Onoff]

If I used a say 10.9 or 12.9 bolt then is that something I can harden at home with say Kasenit or similar case hardening powder?

Or just heat to cherry red, quench in oil then temper for a couple of hours?

 

[addjunkie]

By heating a bolt cherry red you will change its already set metallurgy. Just make him a few so when one wears he can replace it!

 

[finyuk2005]

what about a good blob of hardfacing rod with an arc welder?

 

[Onoff]

By heating a bolt cherry red you will change its already set metallurgy. Just make him a few so when one wears he can replace it!

So heating a 10.9 or 12.9 to cherry red does exactly what to it? Last time I did any hardening was at college over 40 years ago. Immersed the workpiece in powder and baked in a bfo oven. I just remember there being a cyanide antidote on the wall.

 

[addjunkie]

So heating a 10.9 or 12.9 to cherry red does exactly what to it? Last time I did any hardening was at college over 40 years ago. Immersed the workpiece in powder and baked in a bfo oven. I just remember there being a cyanide antidote on the wall.

Without resorting to my over 40 year old text books I cant remember exactly…..but doubt it would be better than what it starts out with.

Google says

Quenching and Tempering Process of Grade 12.9 Fastener Steel​

The automotive industry is moving toward high performance and light weight. Advances in the automotive industry have placed higher demands on bolts for coupling, namely high design stress and light weight. High-strength bolt has become one of the iconic parts of automotive quality and cost. For example, engine bolts, the original materials have been difficult to meet the requirements of the new engine high stress. The main raw material for the production of fasteners is cold heading steel wire rods. High-strength and high value-added cold heading steel is an important research and development direction of material production enterprises. The rational quenching and tempering treatment process of high-strength fasteners is also one of the important contents of metallurgical industry research. Quenching and tempering is a key process in the production of high strength fasteners. After quenching and tempering, the fasteners have good strength and toughness, and have excellent comprehensive mechanical properties. In the quenching and tempering process, the quenching and tempering process parameters will affect the overall mechanical properties of the final product. SCM440 steel is high-strength fasteners steel, which requires strict heat treatment parameters.
The production process of high-strength fasteners includes wire rod, spheroidizing annealing, pickling, phosphating, saponification, drawing, cold heading, rolling, surface inspection, quenching and tempering, inspection and storage. It can be seen from the production process that the fastener is deformed before the spheroidized structure. SCM440 steel has good plasticity and can achieve high reduction of area. In the case of the same quenching process, the higher the tempering temperature, the lower the tensile strength and the yield strength, and the yield ratio of quenching at 850°C reaches 0.9, which is higher than 870°C. The purpose of tempering is to eliminate the internal stress generated during quenching and improve the comprehensive performance index of steel. As the tempering temperature increases, the tensile strength and yield strength of SCM440 steel decrease, and the area shrinkage rate shows an increasing trend. Microstructure determines the mechanical properties, and the size, morphology, and distribution of carbides also affect the mechanical properties of steel.
The suitable quenching and tempering process is 850 °C for 12.9 grade fasteners made of SCM440 steel. The holding time is 80 minutes, then quenching, and 480°C for 3 hours tempering. The tensile strength, yield strength and end face shrinkage after quenching and tempering treatment were 1242 MPa, 1163 MPa, and 55%, respectively, which met the technical requirements of 12.9 high-strength fasteners. The quenching temperature has an effect on the grain size of the prior austenite. If the quenching temperature is too high, the grain is coarsened, resulting in a decrease in the yield ratio. Tempering treatment is an important factor affecting the mechanical properties after quenching and tempering. The higher the tempering temperature, the easier the carbide grows and the lower the tensile strength.

 

[m_c]

Looking at that photo, that could be made in two parts, as it looks like a split/joint at the bottom of the ball.

It would certainly make sense, so that the ball is harder than the threaded section, and things like induction hardening for localised heat treatment wouldn't have been in use when that part was originally made.

 

[Seadog]

A bolt is tempered for tensile strength. A tappet needs to be wear resistant. It's all down to tge material grade and hardening method.

 

[Onoff]

Struggling to find one of these online. Anyone?

 

[sako243]

What model tractor / engine? If we can track down a part number then might be able to find one in the UK. I'd be surprised if they're only available from the US.

 

[Onoff]

Sorry for the bum steer. It's not a JD but a deffo a David Brown tractor. Model 800 maybe?

 

[sako243]

You mean like this?

Valve Adjusting Screw & Nut (Tappet), 5/16"BSF | David Brown Parts

www.davidbrownparts.com

 

[addjunkie]

Sorry for the bum steer. It's not a JD but a deffo a David Brown tractor. Model 800 maybe?

Even more likely to find one in the uk then….model number doesnt look right!

 

[sako243]

800 series? There's 880 from some Googling.

 

[Onoff]

You mean like this?

Valve Adjusting Screw & Nut (Tappet), 5/16"BSF | David Brown Parts

www.davidbrownparts.com

Looks like that but the one I have here is 3/8" diameter.

 

[Kram]

The pic in your first post appears to have an extremely worn nut, or its been tapped piissed!

If I used a say 10.9 or 12.9 bolt then is that something I can harden at home with say Kasenit or similar case hardening powder?

Or just heat to cherry red, quench in oil then temper for a couple of hours?

Casenit and hardening compounds are only for low carbon mild or case hardening steels, those that lack adequate carbon to harden with a simple quench.

The 4.8, 8.8, 10.9, 12.9, 14.9 tensile strength is a metric measure. Imperials will have a different grading names. The Americans I believe call it class or grade 2, grade 5, grade 7 etc.. but cant tell you what each means. Likely the grade number is the inverse of the number that will round of on any general purpose application.

If making one from scratch, steel supplied in the T tempered condition should give roughtly between 8.8 and 10.9 grade in the supplied temper. 605m36T, 708M40T, 817M40T etc.. I'd say that most 12m9 bolts will be a chrome steel like 817m40, from the few I have turned.

I would suggest using silver steel and two ways to go about hardening. One, is to heat, quench as normal then to fully temper the threaded section whilst keeping the head at around 220c.
The easier way is to only quench the head which will leave the rest of the bolt soft. On something this small the thermal shock shouldnt be a problem. Temper the head as normal 220c or so.

 

[Onoff]

The pic in your first post appears to have an extremely worn nut, or its been tapped piissed!


Casenit and hardening compounds are only for low carbon mild or case hardening steels, those that lack adequate carbon to harden with a simple quench.

The 4.8, 8.8, 10.9, 12.9, 14.9 tensile strength is a metric measure. Imperials will have a different grading names. The Americans I believe call it class or grade 2, grade 5, grade 7 etc.. but cant tell you what each means. Likely the grade number is the inverse of the number that will round of on any general purpose application.

If making one from scratch, steel supplied in the T tempered condition should give roughtly between 8.8 and 10.9 grade in the supplied temper. 605m36T, 708M40T, 817M40T etc.. I'd say that most 12m9 bolts will be a chrome steel like 817m40, from the few I have turned.

I would suggest using silver steel and two ways to go about hardening. One, is to heat, quench as normal then to fully temper the threaded section whilst keeping the head at around 220c.
The easier way is to only quench the head which will leave the rest of the bolt soft. On something this small the thermal shock shouldnt be a problem. Temper the head as normal 220c or so.

Erm...yeah, that's why I'm hoping I can buy one.

Optical delusion. Nut is fine and square on the bolt.

 

[OJCar]

David Brown 880 valve train for sale at https://antiquetractorparts.co.uk/david-brown