MG 1275 crankshaft.

[smithskids]

Just been looking at the discussion on the MG1275 crank and wondered what the brinell hardness was of the standard crank, the nitrided one and the tuftrided one. The spare crank I have is 275 Brinell according to my tester( an old fashoned gravity type like a big tyre test pressure gauge with a small ball bearing in the bottom )

[bmcecosse]

Can't help with that - are there any markings on the crank.... EN number ? Only an EN 40B could be nitrided.

[smithskids]

EN19T on crank, There are some other numbers, I'll have a look tomorrow ta.

[smithskids]

Had a good look at the crank in daylight. Nuber is not en19T but en16 t, and the same numbers as the one shown in the previous thread. Still interested if any one has the hardness readings from any other cranks.

[philthehill]

The majority of the 1275cc Midget crankshafts were EN16T Tuftrided and latterly towards the end of production some were EN16 and not even Tuftrided.
A few of the very early 1275cc Midget cranks were made from Nitrided EN40B but the use of EN40B was quickly dropped in favour of EN16T.
So to sum up there are three types of production 1275cc Midget crankshaft:-
1. EN40/EN40B (the same product/item) - Nitrided.
2. EN16T - Tuftrided
3. EN16
As bmc says only the EN40/EN40B crankshafts could be Nitrided but the processing of Tuftriding can be applied to most cast iron products.

[smithskids]

Cast iron?

[philthehill]

Cast iron - generic term.
The Midget crankshaft, con rods, flywheel and other cast parts are a variation of cast iron. They are not steel in the true sense but are at the better end of the cast iron spectron.

[MarkyB]

What did you think?
The unmachined surfaces show where it was cast in sand.

[smithskids]

I thought it was forged

[bmcecosse]

I think it is !

[IslipMinor]

The reduction in material specification of the 1275 crank is an interesting exercise in cost reduction over quite a short period of time. Continued with the Marina/Ital where BL had to increase the big-end journal size to compensate for the further reduction in steel spec., as they were still EN16, but with no heat treatment.

EN = Emergency Number, and dates back to WWII and are all grades of steel, but as far as I know none are grades of cast iron. Some are available as cast steel bars, but the crank and rods are both forgings. The flywheel is a casting.

[MarkyB]

Plentyu of metal bashing involved, crankshaft being made at about 26 minutes in;

http://www.youtube.com/watch?v=v2_0V58ocq4

[IslipMinor]

Have watched bits of it and very interesting it is to. I started work at Dennis in Guildford and at that time they had hot forging/stamping as one of the manufacturing processes. Great place to be in winter, but to be avoided in the summer! Except that there was a water tap in the middle of the forging shop that drew beautiful cool water from a spring way below the factory floor - very refreshing.

[MarkyB]

I'm not sure if this crankshaft to be used or just to show off the CNC lathe, pretty impressive either way
https://www.youtube.com/watch?v=81UjjSH2iFw

[Trickydicky]

I'm not sure if this crankshaft to be used or just to show off the CNC lathe, pretty impressive either way
https://www.youtube.com/watch?v=81UjjSH2iFw

I would like to shake the mans hand who created the program! No mean feat.

[bmcecosse]

Amazing!