Bison lathe chuck: how much scroll friction is normal?
 

I have a new Bison 8" 3 jaw chuck that seems to have a lot of friction
when turning the scroll. The torque to turn the chuck wrench measures
~36 inch-pounds. The scroll can be turned w/ one hand on the chuck
wrench but it is really a two hand process. I thought lathe chucks
adjust pretty freely, but then I don't think I've ever used a brand
new chuck. My question is, is this considered normal for new?

Some history: I called Bison (Toolmex); they said "it should turn
freely--send it back", so that is what I did (Enco). The 2nd chuck
has a similar amount of friction. So this time I measured it (36
in-lb), thinking, "there must be a spec for this", but when I called
Toolmex again they didn't know what to do w/ that number and couldn't
get an answer from the factory. They said send this one back, too,
but I'm wondering if that is pointless. Either the friction is
normal, or there was a bad batch of chucks. Guidance appreciated.

Other info: The chuck was packed in oil, w/ plenty of grease in the
scroll – no cosmoline. Chuck is unmounted. Removing the jaws makes
little if any difference-—the friction seems to be between the scroll
ID and the chuck body. In addition to the friction, there is some
noticeable roughness due to the engagement of the individual teeth
between the pinions and scroll ring gear.

Can anyone who can shed some light on this, esp. how much torque is
considered normal for a good, new 8" chuck?
Thanks, David

Bison lathe chuck: how much scroll friction is normal?
 

In article 76a4c976.0407041616.2a23af46
@posting.google.com, says...


Can anyone who can shed some light on this, esp. how much torque is
considered normal for a good, new 8" chuck?

You should be able to spin the chuck wrench easily with
your index finger. I have a 6" Bison 6-jaw (purchased from
Enco) and a 6" Buck 3-jaw; I'd be hard pressed to find
fault with either.

I'd ask Enco to unpack and check the next chuck before
shipping it to you.

Ned Simmons

Bison lathe chuck: how much scroll friction is normal?
 

Quick experiment: I balanced a bit of 1" dia brass bar about 3
inches long on the (horizontal) handle of the key on my chuck and
rolled it along the key handle while supporting the bar as little as
possible (less than an ounce for sure) to keep it balanced. The
key turned when the bar had rolled about 1.5 inches.

The bar weighs 287 grams (0.632 lb) so torque was 0.95 lb-in or 15
oz-in. My other 3-jaw chucks "feel" about the same as this one.

Bison lathe chuck: how much scroll friction is normal?
 

Ditto

I have the Bison 6" 6-jaw, used for 6 years in a job shop on a cnc machine
for single parts thru 100 piece production, it only feels stiff when the
scroll needs cleaning.

had a wee bit of a mishap with it the other day, on my 3rd set of hard top
jaws now...




"Ned Simmons" wrote in message
...
In article 76a4c976.0407041616.2a23af46
@posting.google.com, says...


Can anyone who can shed some light on this, esp. how much torque is
considered normal for a good, new 8" chuck?

You should be able to spin the chuck wrench easily with
your index finger. I have a 6" Bison 6-jaw (purchased from
Enco) and a 6" Buck 3-jaw; I'd be hard pressed to find
fault with either.

I'd ask Enco to unpack and check the next chuck before
shipping it to you.

Ned Simmons

Bison lathe chuck: how much scroll friction is normal?
 

Thanks, everyone, for your posts, esp. Don for the measurement. Per
Ned's suggestion, I've asked Enco to check it first; they agreed to
that.
Thanks again, David

Bison lathe chuck: how much scroll friction is normal?
 

How clean is the scroll, etc. Is it full of grease and goo?
G

Bison lathe chuck: how much scroll friction is normal?
 

FYI and for the archives, an update on the chuck: the new (3rd) one
is just fine, turns reasonably easily w/ 1 finger. Measures 6 in-lb
torque to turn it, down from 36. Many thanks again for your advice!
David