The Nerdy video thread.

[Stu Faulkner]

How many hours do you sit watching videos on youtube and the like of random things being made and can't stop watching.

Crank shaft from a billet......

 

[Man On The Clapham Omnibus]

Hypnotic is the best way to describe it. I am in awe of the machine tool manufacturers skill. Historically, I had assumed, the crankshaft would have been forged into a rough form and machined from that rather than starting with a large diameter bar and cutting away all the unwanted metal. It's a long time since I visited a car manufacturing plant (Ford at Dagenham in the Escort Mk1 days, and Standard Triumph In Coventry during the Herald era) so my experience of seeing machining is archaic to say the least. I am now going to try to find clips of crankshaft manufacture in that time... Afternoon wasted! 

This Wikipedia article is very helpful. Casting, forging, and machining from solid are all discussed. Thanks for the link Stuart.

[Dave Eastwood (Gadgetman) - Club Chairman]

My old metallurgy etc days from university are a long time passed now, so theory may have moved on and changed. But from a point of view of high strength items like a crankshaft, I was always taught that forging was the way to go, as it caused the grain of the metal to realign and follow the shape.

What we now refer to as billet items were considered very much a second class approach where ultimate strength was concerned, as there was no re-flow of the material, instead it was simply cut across the grain as part of the shaping process. It’s big advantage though was cost.

[Man On The Clapham Omnibus]

I thought the same Dave. The Wiki article agrees but says that the steel for the billets is of sufficiently better quality than the steel for forged items such that the lack of grain orientation is more than exceeded in higher strength. This type of steel does not lend itself to forging though. The machining process, whilst wasteful, offers short runs as practicable, and for specials to be made. Neither would apply to forging and casting is an inferior process apparently. My speciality at college was polymer technology so my information is necessarily second hand.

[pistonbroke]

a friend owned a crank re grinding facility, watching the machine as the crankshaft was automatically rotated around the grinding wheels was an amazing sight , the operator was a skilled performer . nearest thing I saw previous to that was a rock making machine that stretched and turned the toffee , that was so good it was placed on show in the shop window , crowds used to stand and watch for hours . ( may have been in the days before telly )  

[Man On The Clapham Omnibus]

9 hours ago, pistonbroke said:

a friend owned a crank re grinding facility, watching the machine as the crankshaft was automatically rotated around the grinding wheels was an amazing sight , the operator was a skilled performer . nearest thing I saw previous to that was a rock making machine that stretched and turned the toffee , that was so good it was placed on show in the shop window , crowds used to stand and watch for hours . ( may have been in the days before telly )  

I recall a seaside rock making machine on show in a sweet shop back in the 1980s somewhere in Norfolk - Lowestoft, Great Yarmouth, or thereabouts IIRC. There was a crank grinding machine at the Earls Court Motor Show, upstairs, back in the days when I went with my Dad. Too long ago to remember, sadly... 

[BenD]

i think alot of the difference nowardays is the advancemnt in cutting tools. rather than material. you stil lget inperfectons in billet materials but material of the highest grade know as exotics where i work is amazing to work with with the correct tools to machine

[Man On The Clapham Omnibus]

I did a year of a toolmaking apprenticeship before moving into materials technology, and clearly recall tool bits on the lathes and shapers were simply something like 1/2" square section bars of tool steel that the operator had to take to the offhand grinder to form into whichever tool bit he required: roughing, finishing, etc. The tools in that clip were clearly mounts for specialised bits fixed on to the ends of the carriers. The rate of material removal was very impressive.

[Peter (Monty)]

@Dave Eastwood (Gadgetman) - Club Secretary I graduated a few years ago and we were still taught the same  Although the overall strength of the billet material might be higher I would be interested to know if the machined part also matches a forging in fatigue, especially with rotating stresses.

[BenD]

23 hours ago, Man On The Clapham Omnibus said:

I did a year of a toolmaking apprenticeship before moving into materials technology, and clearly recall tool bits on the lathes and shapers were simply something like 1/2" square section bars of tool steel that the operator had to take to the offhand grinder to form into whichever tool bit he required: roughing, finishing, etc. The tools in that clip were clearly mounts for specialised bits fixed on to the ends of the carriers. The rate of material removal was very impressive.

that type of tooling in any toolroom is the norm nowardays. indexable inserts are much more econmical and last longer and can be specced for material specifics. weve just had a new trial cutter that can remove 5mm of tool steel at 15meters a minute.

[Dave Eastwood (Gadgetman) - Club Chairman]

36 minutes ago, bunje said:

that type of tooling in any toolroom is the norm nowardays. indexable inserts are much more econmical and last longer and can be specced for material specifics. weve just had a new trial cutter that can remove 5mm of tool steel at 15meters a minute.

wow!

[BenD]

all ill say is it makes for some interesting crashes

[Stu Faulkner]

A more traditional way of making a crank.

One hell of a machine...