SBF Ford raw forging, crank

[agertz1]

Should be 4340 chrome moly ? Annealed state ? I plan to rough machine, prior to final heat treat and grind. How much SFM. for live-tooling-
machining, with spray-mist, without work hardening ?
Thanks, Art.

[agertz1]

Would a skilled crank guru please reply ?

[SchmidtMotorWorks]

Should be 4340 chrome moly ? Annealed state ? I plan to rough machine, prior to final heat treat and grind. How much SFM. for live-tooling-
machining, with spray-mist, without work hardening ?
Thanks, Art.

I was part of the startup at Bryant Crankshafts.
Machining parameters are a trivial issue in the big picture of making crankshafts.

Why do you want to make one when they are so inexpensive to buy?
Do you have a forging that you plan to use?

[Momus]

Should be 4340 chrome moly ? Annealed state ? I plan to rough machine, prior to final heat treat and grind. How much SFM. for live-tooling-
machining, with spray-mist, without work hardening ?
Thanks, Art.

Get a small sample of the material analysed would be my first step.


Whatever it is won't change due to anything reasonable you do machining it,

.

[agertz1]

I bought a Ford made raw forging, through Joe Castillo. It will be machined to fit serious Rover V8. I can rough machine on a conventional lathe, with
live tooling. No pipe dream of competing with specialized machines. Just a one-off.
Thanks, Art.

[BCjohnny]

The OE Ford forgings came in different material specs ...... I've an unmachined 'economy' one knocking about which I think is 5140 or close, it's definitely not 4340 ...... so you'll need to mass spec it to be sure

Depending on how accurate you can rough machine it, particularly the index, I'd still leave 30-40 thou or so on for the grinder, possibly a shade more, unless it's nitrided and you're absolutely sure it's on spec when you can leave less

No experience with 'live tooling', I've only ever manually done them on a lathe and/or mill hence the large SFM, but either way I don't think work hardening will be much of an issue unless you go at it ..... however I'm certainly no expert

Long ago a wise old machinist I knew said machines for taking metal off were ten a penny ...... for putting it back on properly, not so

[agertz1]

Still waiting to hear from Joe Castillo, through "Teddy". Joe has covid. Sell your 5140 raw forging ?
Thank You, Art.

[BCjohnny]

Sell your 5140 raw forging ?

I think the postage costs might just kill it ...... besides it's slated for a questionable folly when the new workshop is better sorted, but thanks for asking

[BCjohnny]

I've dug the notes out with mine, which is semi-finished and has the Ford logo forged into the web

It says AMS6415, 'aircraft quality' no less, which cross references to 4340 .... which is a bonus, lol

[canuc]

Art I'm not a crankshaft guru but I have been machining for over 40 yrs , stayed at a holiday inn couple times too . I was wondering what live tooling you have set-up on your conventional lathe ? Does your forging come with centres in each end ? To me that would be the biggest challenge to get right , as far as cutting speed start off conservative for what the tool is and try to get a deep enough cut to get under the outer crust using a moderate feed . Flood coolant would be best imo .
cheers Rick

[agertz1]

I have center-drilled both ends, ( steady-rest) on lathe. Since live tooling is 25k rpm, maybe down to 10k,( speed controller). Chip load very low
and coolmist so as not to cavitate around all that rpm. Spindle in neutral, variable accessory driven by flywheel/worm gear, mounted on spindle,
( D6). Will offset for rod journals with independent, 4 jaw chuck and dedicated locked-on, offset adapter for live center. Since crank will turn 1+/-
rpm, I don't anticipate inertia problems.
Art.

[canuc]

Art interesting - challenging project , sounds like you put some thought into the set-up .
cheers Rick