i'm confused about new to me FORKHARDT lathe chuck with fast jaws

i'm confused about new to me FORKARDT lathe chuck with fast jaws that are controlled
by a single , square headed screw . is there a common method for centering the work
in this chuck? it is the only DIN mount chuck i currently own for my VDF lathe. i would
like to check the spindle bearings, but i can't understand this weird-o chuck
it's like having a 4-jaw with no adjustment screws.

anyone use one of these zip-jaw chucks? they seem to be european.

https://www.sepmo.fr/5630-large_default/forkardt-200-mm-diameter-chuck.jpg

thermite said:

Might not even be a current model?

https://www.forkardt.com/wp-content/uploads/Fplus_E.pdf

"Usually.." they are power-actuated. Though I guess you could use a powered socket wrench..

Either way, they are "ordinarily" run with custom top jaws cast, milled, EDM'ed, or turned where there is a need to suit a long production run of a single specific part - often as not an irregular shape, such as a casting.

In those taskings, predictable repeatability is important. No independent adjustment AKA "surprise!" .. is WANTED.

If it is all you have for now, Job ONE is to:

A) Use it like a self-centering 3-Jaw scroll. Like partaking of thick Dutch pea-soup through a soiled Red Army surplus boot-sock, but that's about all you can do until you can find and mount a conventional chuck.

B) Fab top jaws with adjuster screws in the jaws.

Plan B is a waste of time, though.

4-Jaw independent chucks . .even from China's San Ou .. are cheap and can work better.

4-J indies don't need the built-in precision of a 3-J scroll.

Go figure their precision is built into the operator instead of the chuck!

Click to expand...

Are you feeling alright? 99.5% of that post was sane and understandable.

thermite said:

By YOU?

Damn.

Click to expand...

Yeppers, by even liitle ole me.

Fast Times at Ridgemont High (4/10) Movie CLIP - I Don't Know (1982) HD - YouTube

after more digging - bison makes them .

http://www.bison-bial.com/public/data/resource/upload/00247/246690/3474-de.pdf

no operational instruction though. but no cast, milled or turned widgets in sight .
just a fast-acting 2 piece- 3-jaw, wedge-acting chuck . if you don't know....

it's ok, spiccoli. just don't make up bullshit when you don't.

obfuscate the answer?

no, i mean FORKARDT, but that could be BUCK,ROHM,BISON.... you either understand what i'm asking , or you obviously don't . if you think current BISON is junk, please tell us
what the GOOD stuff is?
the question was about this mid-1970s (they still make) fast
acting wedge-jaw chuck. the range without moving the jaws is about 1/2" of the diameter.
maybe common to european spindles, but this is my first one.

just want some idea of how the thing operates without reinventing the wheel to understand the basics.

i think you'll find out next year...jeff.

this man is on glue.

the forkardt chuck in question is irrelevant (other than it seems not worn, damaged
or rusted in any way) f-200mm

maybe you can "READ IT" to me , since my kindergarten butt can't.......

https://otec-industry.com.ua/en/show_catalogue_pdf/169561/1 i don't read much
non-english , but the pretty pictures also don't show any operator instructions. the "enlish" translation doesn't work.

perhaps my poor-self could be enlightened by an expert, such as yourself, to empower
your own ego...and shame a worthless slug as myself with the said documents and
knowledge you pledge to know with such profundity?

or- you still don't know, or you'd have said it by now.

or- you still don't know. i asked a real question here, not an invitation to scrutiny.

It would be a kindness if you deleted yourself from my thread.



and not humor us with your pretend knowledge..........

Oke
Let me take a shot
Ther forkhard only can span about 1cm or so in one position So you have to adjust the jaws for every diameter of your workpiece
To do so you open the jaws until you see a pin in the face of the jchuck comming out
In this position the jaws can slide in or out over their rack of teeth while pushing the knob at the circumference of the chuck (older ones do not have that knob) A spring loaded pin will prevent them from falling out
To make it vissable that all jaws are on the same diameter there are grooves in the face of the chuck
Once in position you close the jaws again Once the pin is completly flush with the face you can clamp your workpiece

Peter

thank you, Peter, for the insightful answer i was asking for...
yes, there's a springy pin on the face . i
had no clue as to its function . i will try that and see . the chuck is in fine
condition, it should be useful , once i get the hang of it .
cheers, peter.

now- if i could only find an english manual for an H & H hamburg VDF lathe...
actually , an early 1970's Boehringer or Gildemeister vdf would be very similar...

I have a similar chuck on my Romi M17 CNC lathe.
The one i have is made by Schunk. Very high quality and i love it!

The one i have is like yours in that it is manual. Has advantages over standard scroll chuck.
Jaws are quick change and are reversible, so going from outside clamping to ID clamping is almost instantaneous...

There are single piece jaws available or two piece jaws that allow the use of top soft jaws if needed.....
More accurate and repeatable than a scroll chuck as the moving element always has the same engagement rather than a changing radius scroll as the jaws change position.

The grip range is limited, ans as Peter describes above when the button on the face of the chuck is retracted you are in the safe grip range for that jaw position...Need larger, open the chuck fully till the button po;ps out
and move the jaws out....then close till the button is flush and you are good to go.

Aside from quick change and better repeatability this style chuck has much higher gripping power than a scroll chuck....

Here is a short video that shows the operation, and may clear up some questions....

ROTA_S_plus animation - YouTube

Cheers Ross

Rohm has a good 'factory" example for their version "Duro-T:

ROHM Keilstangenfutter DURO-T - YouTube

Forkardt, here's an amateur one of a tear-down:

Inside a Forkardt chuck - YouTube

Compare the ribs on the sliding wedge blocks.

The Rohm "might be" stronger, and the Schunk very much appears to have more metal engaged than the Forkardt.

Greater operating wrench LEVERAGE than a "face thread" scroll operated chuck?
Seems so.

Stronger ultimate grip?
Only "maybe" for THIS one.

But see also the Forkardt "QLC" family... and not-only..

Hardinge Workholding Presents: Forkardt Chucks - YouTube

"Competition improves the breed"

6-Jaw Compensation Chuck ROTA NCR - YouTube

Oh... and about messing with capscrews? More than one way to avoid that..

MMK Matsumoto QJC Quick Jaw Change, Power Chuck - YouTube

(Kanazawa Japan)

"Bison who?"