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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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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 |
#2
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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 |
#3
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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. |
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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 |
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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 |
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Bison lathe chuck: how much scroll friction is normal?
How clean is the scroll, etc. Is it full of grease and goo?
G |
#7
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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 |
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