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KEJR
09-25-2010, 11:33 AM
Hello,

Are there any good quality new import 4 jaw chucks out there for a home hobby person looking for decent precision? I'm looking for a 6" 4 jaw and I'm not sure I want to roll the dice just yet with the import stuff. I have my eye on ebay for some good old american/english chucks but you never know what you get sight unseen. Some look pretty beat and I can't tell what environment they came from.

In particular I am interested if the import chucks have good parallel chuck slots and jaws and if the material is too soft. Alot of the cheaper ones seem to be semi-steel which I'm assuming is a cast steel alloy. I'm interested in getting a chuck that has the front and backs parallel to the chuck slots too, although I could true this up if it were out too much (I'd rather not have to though!).

~KEJR

lakeside53
09-25-2010, 11:56 AM
Bison is top quality; you'll pay for it, but only once.

dalee100
09-25-2010, 12:03 PM
Hi,

Yep, Bison is well worth the money for a new chuck. Problem with old used chucks is you don't know how well they've been cared for and how many crashes they've endured. A used one may very well be worse than the cheapest import for accuracy.

dalee

wierdscience
09-25-2010, 12:11 PM
+1 for Bison

Frank Ford
09-25-2010, 12:11 PM
I'll second (or fourth) the Bison.

Here's my new 3-jaw, reading Up close to the chuck jaws at .001" TIR:

http://www.frets.com/HomeShopTech/Projects/Bison/BisonAnime/bisoncloses.gif

.003" TIR eight inches outboard on a ground shaft - good enuf for me

Dr Stan
09-25-2010, 12:17 PM
2X on the above posts. Go with a quality chuck.

Walter
09-25-2010, 01:10 PM
Well, I have two schools of thought on this...

First is previous experience with an import 4 jaw. It was a good solid chuck. Rough in some respects, but was completely serviceable. It did fine work for me and I was very very happy with it, especially for the price. It was an Enco offering several years back.

I run Bison 3 jaws and a nice name brand (it escapes me at the moment) 4 jaw.

The nice name brand 4 jaw is much lighter and easier to handle at 8 inches than my massive 6 " 4 jaw import, but it quite literally does exactly the same job with the only other noticeable difference being that the screws are more responsive when tightening the jaws.

I had asked the same question you did and the response I got was... "It's a 4 jaw, not a 3 jaw"

It doesn't need to be top quality or name brand to do it's job. proper prep of the backing plate and careful installation will ensure a high probability of great results. Either way you go, best of luck and enjoy what you get.

MotorradMike
09-25-2010, 01:43 PM
Hi K:

If you're willing to consider used, email this guy (http://www.plazamachinery.com/).
He's a straight shooter and will ship anywhere.

Don't bother looking at his list, just email him with what you're looking for, he doesn't deal Chicom.


Mike

quadrod
09-25-2010, 02:09 PM
Also look here, i have a six jaw that has been pretty darn good.
http://www.tools4cheap.net/products.php?cat=15

KiddZimaHater
09-25-2010, 02:51 PM
4 Jaw chucks don't need to be super-high-quality in order to work well.
The Import 4 jaws chucks are just fine. I have an 8" Chinese that works great.
You will need to indicate your work in anyway while using a 4-jaw, so precission really isn't an issue..
Better to have a high-quality indicator. :D

Forrest Addy
09-25-2010, 04:43 PM
Two thing,
#1 is a worn out 4 jaw chuck can be made to run as accurately as a brand new Cushman heavy duty production 4 jaw chuck. Naturally the precision is a product of the care and dial indicator used to center the work.

#2 is the chief benefit of a new chuck is its predictability and the new sharp serrations for gripping.

A cheap import works a well as Bison's best for the first few years because of the Bison's superior metallurgy and it might be a trifle huskier in its proportions.

When you stop to think of how a 4 jaw independent chuck is typically used you sooner of later conclude that it really doesn't matter if the jaws are even indexed accurately so long as opposed pairs - um - oppose each other. The jaws are independently adjusted so the accuracy can be almost infinitely refined. Once on a bet, I broke out my Federal gage head and amp and dialed in a precision groud part to 5 millionths; a pointless exercise that won me a pizza.

The spindle mount has to fit the lathe spindle accurately and the parts have to fit well, the jaws have to be hard, the serrations consistant. etc.

Where many people err is when they "swallow" the work, place it far back in the chuck so the jaw grip full length. The doer might expect extra rigidity and accurate alignment in nutation but it aint that simple. This requires the jaws to be "inverse taper" ground so when the jaws deflect under clamping load they grip the work full length. With no inverse taper, the jaws deflect to splay slightly and grip at the heel. No off-the-shelf chuck I've ever seen has this level of refnement though I've re-ground a few that way.

So: go for a Bison chuck if the budget will stretch. They really are good. However you probably won't be dissatisfied with a better import of about 1/2 the cost of the Bison.

KEJR
09-25-2010, 05:03 PM
Thanks guys,

I'm torn now. I've had pretty good luck with Tools4Cheap, but I have heard great things about Bison and they are still cheaper than a buck chuck. Its just a heavy price tag for a 4 jaw chuck when buying from Bison.

I guess for 5-10 times a year usage the import might not be a bad deal. I can do most of my work on a standard 3 jaw chuck, its just sometimes I need to flip something around and re-indicate it. I can't justify the Bison 6 jaw set true just yet!

For the folks that commented on the import chucks being OK, have you indicated them with a test bar? I know you can dial out any crappy 4 jaw, but you still want the jaws to actuate parallel to the back of the chuck or else your part will be tilted (and thus runout) at several inches out from the chuck.

Thanks,
~KEJR

Arthur.Marks
09-25-2010, 05:54 PM
I know you can dial out any crappy 4 jaw, but you still want the jaws to actuate parallel to the back of the chuck or else your part will be tilted (and thus runout) at several inches out from the chuck.

Smart man :) That said, if the work is of any sufficient length, I use a center drill and indicate it in on the 4-jaw while the far end is supported by a dead center in the tailstock.

Mcgyver
09-25-2010, 07:23 PM
High quality import? Rohm, Pratt Burnerd.....are there any that aren't imported?

Forrest Addy
09-25-2010, 08:39 PM
Let's make something clear: If you expect the gripping urface of a chuck's jaws to hold a machined diameter concentric to the spindle axis some distance out simply by snugging up the jaws, you're dreaming.

Chuck jaws ALWAYS splay a small amount often irregularly. It's not a reasonable expectation for a chuck of some time in service to hold extended work concenteric along its axis without some adjustment such as bumping the work with a soft hammer.

Let's give this a word: Say a work axis is concentric to the spindle at one point but at some distance away the work axis describes a cone. Thus at the spindle rotates the work axis is said to "nutate." Accurate work diameters gripped in plain hard chuck jaws will always nutate to some degree. The work almost always has to be tweaked.

Dr Stan
09-25-2010, 09:05 PM
Both of Forest's posts are dead on. I have no idea how many large centrifugal pumps I have indicated in and it always required dialing in near the chuck and 2 ft or more away from the chuck. It required working back & forth between the two points to finally get the shaft aligned with the axis of the lathe. These were shafts that had a .001" TIR between the bearing journals, so they had to be correct. Too much out of concentric between the two diameters resulted in very early bearing failure and believe me if that happened we heard about it. :(

oldtiffie
09-25-2010, 09:31 PM
Let's make something clear: If you expect the gripping urface of a chuck's jaws to hold a machined diameter concentric to the spindle axis some distance out simply by snugging up the jaws, you're dreaming.

Chuck jaws ALWAYS splay a small amount often irregularly. It's not a reasonable expectation for a chuck of some time in service to hold extended work concenteric along its axis without some adjustment such as bumping the work with a soft hammer.

Let's give this a word: Say a work axis is concentric to the spindle at one point but at some distance away the work axis describes a cone. Thus at the spindle rotates the work axis is said to "nutate." Accurate work diameters gripped in plain hard chuck jaws will always nutate to some degree. The work almost always has to be tweaked.

I agree with Forrest.

If you want or need a job so that it is accurate within "tenths" over an extended length it should be between centres - with the head-stock centre re-turned/re-ground in-situ and a dead centre in the tail-stock.

That is starting to sound an awful lot like a cylindrical grinder set-up.

Even if all is perfect statically, there is no guarantee that it will remain that way dynamically - especially if it is held in a chuck.

These sorts of set-ups and accuracy usually demand a pretty high quality finish as well.

The further we go the more it sounds like a grinding and metrology issue.

I try not to have to get closer than 0.02mm (~0.0008") - say 0.025mm ~ 0.001" most times - and if it needs to be closer, I set about seeing if that level of accuracy is really needed - or not. Most times it isn't needed. I can quite easily turn to 0.01mm (0.0004") - boring included - and get a good class of finish - if needed.

I have a "tap-true" (as opposed to a "set-true") on my adaptors for my 3-jawed chuck and ER-32 collet adaptor on the spindle flange on my lathe. It is simply that there is about 0.005" clearance between the adaptor back-plate bore and my lathe spindle flange spigot. I set the chuck up with the securing bolts just lightly "nipped", put a test piece in the chuck, put a good (0.01mm ~ 0.0004") Test Dial Indicator onto test piece, rotate the spindle by hand and "tap" the chuck back-plate OD with my "use every-where" bronze "dolly" until there is minimal/zero (??) Total Indicated Run-out (TIR), tighten the securing screws, re-test the TIR, if OK -job done, if not repeat until OK.

All of my chucks are "Chinese" and are excellent. I do not abuse my tools - chucks included.

If the chuck is suspect, or faulty it goes straight to scrap - after a visit to the oxy-acet cutting torch or plasma cutter and the MIG welder. It gets replaced with a new chuck.

For those that need convincing about the differences between the static concentricity and the dynamic when work is held in a 3 or 4 jawed chuck at reasonable speeds, try this.

Set up "dead true". Put the final drive to your head-stock spindle to "neutral" (disengaged). Now put a glass of water on top of your head-stock. "Start" the head-stock drive motor. Note the "ripples". Now re-engage that final drive and start your head-stock. Note any change in the ripples on the surface of the glass of water. Try it at varying speeds and note the ripples. It will probably get worse as the speed increases. Other than super-imposed "gear-noise" it will probably be due to eccentricity which is due to "throw" as the spindle rotates.

It will be worse for heavier chucks.

And that is one of the main reasons why relatively compact collets and collet chucks are often better than 3 and 4 jaw chucks.

It is one of the main reasons why I always try to take fine accurate cuts at low speeds.

A good quality chuck used correctly is only as good as the machine it is on and the user-operator.

Most good quality (Chinese included) chucks should last a HSM-er for many years.

Mcgyver
09-25-2010, 10:18 PM
ok, to make it interesting all do the opposite and disagree with Forrest


#1 is a worn out 4 jaw chuck can be made to run as accurately as a brand new Cushman heavy duty production 4 jaw chuck. Naturally the precision is a product of the care and dial indicator used to center the work.

all dialling it in does is ensure a point is concentric. I agree its an important and basic skill and like you advocate use it all the time. I use tenths indicator and find its no trouble to dial into a couple of tenths quickly and without issue....however....the quality and accuracy of the chuck absolutely matters as having the the jaw surfaces true to the lathe's axis is the only way you will get the work's axis aligned with the lathes. Dialing something in concentric to a tenth serves little purpose if its 5 though over a few inches.

Accuracy is more important with the four jaw - with the three jaw you know you're not concentric if you remount whereas you need to be able to trust that when you indicate true a point along the work's axis using the four jaw, the axis of work and lathe are one.

Forrest Addy
09-25-2010, 11:07 PM
OK. while we're being so productive I cooked up a couple of new terms "radial grip" and "annular drive."

Imagine a long skinny shaft you need to chuck so you can turn the full length. You install a chucking center - a longer than standard dead center that extends just to the end of the chuck jaw faces. This allows you to nip the end of the shaft in the jaws using copper padding to protect the existing surface. But it's important to be sure the copper pads are in a radial plane.

When you set up you place the shaft between centers, place and adjust the pads so they lie in a true radial plane (the chuck serrations are a prime guide for this). Then you bring the jaws up snug enough to drive the work and tweak the jaws a trifle to dial in the reference diameter the jaws are gripping. When the padding is in a true radial plane to the work axis there is no "moment" trying to bend the shaft. Thus you have a true annular drive - the grip forces are 90 degrees from the shaft axis producing no bending action or "moment" to deflect the work. These are importaant considerations for sensitive long skinny work.

The chuck/chuck center is thus a true annular drive.

Moving on to a dead center and dog drive. Most everyone has used or seen in pictures a bent tail dog and a driver plate that transmits rotation from the lathe spindle to the work when turning between centers. A bent tail dog does not provide an annular drive. The bent tail is driven by the plate an inch or more back from the radial plane of the center's contact with the work. In long skinny work the cutting force of the tool require a proportionat force on the bent tail of te dog. Since the force on the tal tries to force a slight spiral shape into the turned diameter. The everit of the piral depends on the lendernes of the work, whether it has intermediate upport as from a steady ret, the depth of cut and feed, material characteristic etc.

Work that has to be on the money probably should be rotated by a straight tail dog and stud. There the moment is applied more or less in plane with the headstock center minimizing the "S" shape reulting from the bent tail dog. In other words an annular drive where little or no distortion results from driving torque,

Most importantly, when do you sweat this kind of detail? Answer: when you're working very slender work and holding unrealistic tolerances for lathe work. n other words rarely but the lesson here is think deeper into the problem than strictly necessary to accomplih the work at hand. I used to machine 9 ft long main feed pump shafts from raw forgings of CRES 410. These had about 10,000 machined detials (seemed like it anyway) and were supposed to finish with 0.003" max TIR. Very difficult ulcer job. We could expect three or four rejects from a lot of 24 forgings with the shop' bet hands on them. The materal machined beautfully but the slenderness and close tolerances made it a minefield.

oldtiffie
09-25-2010, 11:31 PM
First of all, I've just seen Forrest's latest post - with which I agree - just after I'd finished typing and when I checked just before I posted/"sent" - here it is:


OK. while we're being so productive I cooked up a couple of new terms "radial grip" and "annular drive."

Imagine a long skinny shaft you need to chuck so you can turn the full length. You install a chucking center - a longer than standard dead center that extends just to the end of the chuck jaw faces. This allows you to nip the end of the shaft in the jaws using copper padding to protect the existing surface. But it's important to be sure the copper pads are in a radial plane.

When you set up you place the shaft between centers, place and adjust the pads so they lie in a true radial plane (the chuck serrations are a prime guide for this). Then you bring the jaws up snug enough to drive the work and tweak the jaws a trifle to dial in the reference diameter the jaws are gripping. When the padding is in a true radial place to the work axis there is no "moment" trying to bend the shaft. Thus you have a true annualt drive - the grip forces are 90 degrees from the shaft axis producing no bending action or "moment" to deflect the work. These are importaant considerations for sensitive long skinny work.

The chuck/chuck center is thus a true annular drive.

Moving on to dead a center and dog drive. Most everyone has used or seen in pictures a bent tail dog and a driver plate that transmits rotation from the lathe spndle to the work when turning between centers. A bent tail dog does not provide an annular drive. The bent tail is driven by the plate an inch or more back from the radial plane of the center's contact with the work. In long skinny work the - oops! Gotta go. Finish this later. Someone want to complete my remarks, go ahead. Most importantly, when do you sweat this kind of detail?

This is possibly the most important and relevent sentence in that post.


Most importantly, when do you sweat this kind of detail?

So, back to where I was - responding to Mcgyver's post.


ok, to make it interesting all do the opposite and disagree with Forrest


#1 is a worn out 4 jaw chuck can be made to run as accurately as a brand new Cushman heavy duty production 4 jaw chuck. Naturally the precision is a product of the care and dial indicator used to center the work.

all dialling it in does is ensure a point is concentric. I agree its an important and basic skill and like you advocate use it all the time. I use tenths indicator and find its no trouble to dial into a couple of tenths quickly and without issue....however....the quality and accuracy of the chuck absolutely matters as having the the jaw surfaces true to the lathe's axis is the only way you will get the work's axis aligned with the lathes. Dialing something in concentric to a tenth serves little purpose if its 5 though over a few inches.

Accuracy is more important with the four jaw - with the three jaw you know you're not concentric if you remount whereas you need to be able to trust that when you indicate true a point along the work's axis using the four jaw, the axis of work and lathe are one.

While I agree with you in principle Mcgyver, I thought that as the "straight test bar" has been mentioned again, I thought that I'd throw in a few cautions.

Given that ideally the stuff you use as a reference has to be at least as good as the degree of accuracy you require, it follows that the test bar has to be both round/circular and straight to quite high orders of accuracy.

If the test bar is say O1/"Silver steel" or similar that is centre-less ground it may not necessarily be the same diameter throughout its length, and if centre-less ground it may be "lobed" (which means that while not round it may well show up as very accurate with a micrometer), and it may not necessarily be accurately straight either.

If it were me in those circumstances - and if it were accurately centre-drilled and bored (to be concentric) - I'd check it on a surface plate - first to see how it "rolled" (to see if it was straight and round) and then between centres and then on a matched pair of good vee-blocks and using the best Test Indicator that I have (0.002mm = 2 microns ~ 0.00008").

I would tabulate any errors and make due allowance for them in my checking of the lathe chuck.

But do I do it? Not if I can help it - but that's because I rarely need to.

Even many commercially available test bars for the lathe spindle taper and alignment have a tolerance of about 0.005mm (0.0002") to 0.01mm (0.0004").

As a point of interest, here are the specification sheets that came with some of my 3-jaw chucks - "Chinese" - of course - and all of the chucks are within specifications.

For information:

0.01mm ~ 0.0004"

0.02mm ~ 0.0008".

0.05mm ~ 0.002"

0.10mm ~ 0.004"

0.125mm ~ 0.005"

0.15mm ~ 0.006"

0.20mm ~ 0.008"

etc.

http://i200.photobucket.com/albums/aa294/oldtiffie/Lathe_misc/3-jaw_chuck_specs1.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Lathe_misc/3-jaw_chuck_specs2.jpg

Mcgyver
09-26-2010, 12:08 AM
While I agree with you in principle Mcgyver, I thought that as the "straight test bar" has been mentioned again, I thought that I'd throw in a few cautions.



Balls. I don't know why you going on about test bars, All I've pointed out is that wear/quality on the four jaw absolutely matters. You're talking like I'm spitting tenths. Forrest made a post essentially saying wear/quality doesn't matter with the four jaw, skill and indicator quality does. Sure you get your point to a tenth but balls because the crap worn out four jaw can easily hold stuff out a thou per inch. Hold a 4" long piece of stock and have your bore turn out 5 thou in the wrong place at the other isn't splitting hairs or tenths....which is why I disagree with Forrest's point 1 - quality and condition of the 4 jaw DOES matter.

To repeat, the point was that success in using 4 jaw isn't just getting a point concentric, its having the desired axis of the work (which obviously is supposed to parallel to the surfaces being chucked) parallel to the lathe's axis....I don't how wear and quality of the chuck isn't a factor there?

Using a good Pratt chuck I'll do iterations of indicating along the axis and to the point and tap it parallel with a piece of copper when it matters is it can be out a few thou....not a new chuck but I wouldn't call it dodgy either. How many go through that fidgety BS, indicating concentric and parallel? Hardly anyone and no one wants to ....but of course the more worn or worse it was to begin with, the bigger the more the work will be out, and we're talking thou's not tenths.

oldtiffie
09-26-2010, 01:06 AM
Originally Posted by oldtiffie
While I agree with you in principle Mcgyver, I thought that as the "straight test bar" has been mentioned again, I thought that I'd throw in a few cautions.

Balls. I don't know why you going on about test bars, All I've pointed out is that wear/quality on the four jaw absolutely matters. You're talking like I'm spitting tenths. Forrest made a post essentially saying wear/quality doesn't matter with the four jaw, skill and indicator quality does. Sure you get your point to a tenth but balls because the crap worn out four jaw can easily hold stuff out a thou per inch. Hold a 4" long piece of stock and have your bore turn out 5 thou in the wrong place at the other isn't splitting hairs or tenths....which is why I disagree with Forrest's point 1 - quality and condition of the 4 jaw DOES matter.

To repeat, the point was that success in using 4 jaw isn't just getting a point concentric, its having the desired axis of the work (which obviously is supposed to parallel to the surfaces being chucked) parallel to the lathe's axis....I don't how wear and quality of the chuck isn't a factor there?

Using a good Pratt chuck I'll do iterations of indicating along the axis and to the point and tap it parallel with a piece of copper when it matters is it can be out a few thou....not a new chuck but I wouldn't call it dodgy either. How many go through that fidgety BS, indicating concentric and parallel? Hardly anyone and no one wants to ....but of course the more worn or worse it was to begin with, the bigger the more the work will be out, and we're talking thou's not tenths.

OK.

The "test bar" was the work in question.

First of all, assuming the work does not move under load in the chuck, as soon as a cut is made the set-up to a large extent can become irrelevant as the cut will be parallel to the lathe bed axis and if there is a taper it is due to the head-stock axis not being aligned to the lathe bed axis.

It is quite possible that the axis of the work and the spindle will "gyrate" (not be concentric when rotating) due to dynamic imbalance - as said previously.

I have deliberately ignored any potential "water barreling" that may be due to a horizontal bend/wear in the lathe bed. I have also ignored any "spring" in the tool, the job, the job in the chuck and in the head-stock bearings.

With a theoretically perfect chuck you would not be able to "tap true" with a bit of copper bar. If the amount of accessible/usable "tap true" is significant, I'd be looking for "bell-mouthing" in the chuck jaws and wear or "spring" in the radial jaw ways/slots.

The jaws will spring under load - the more so with a shorter work-piece or a work-piece that is only gripped for a short length at the front of the chuck.

The amount of pressure that can be put on the chuck jaws for a given torque of the handle is huge near the closed position due to the larger mechanical advantage - even allowing for the "steeper slope" on the scroll spiral near the centre.

At the outer limits of the jaws the mechanical advantage as regards torque is reduced but the increased leverage due to the less steep scroll spiral is not inconsiderable either.

As soon as I see anyone "pull and grunt" (with or without a "cheater bar") on a lathe chuck (or a mill vice) I wince. If anyone did that to one of mine it would be their first and last time - period.

Chucks (and vises) should only need a "firm" hand-tightening - and perhaps a "bump" with the ball/palm of the hand.

They are after all simply 3 or 4 moving jaw vises that rotate. The moving jaws of a lathe chuck "lift" for exactly the same reasons as the moving jaw on a mill vise does. So all lathe chuck jaws will "lift" if the load is not spread evenly over the length of the bore of the chuck jaws.

I've seen people put more torque on a lathe chuck or a mill vises that is used on some automotive wheel-nuts.

A lot of work that "needs" some of that amount of torque on a lathe chuck would be better done on a face-plate or a rotary table.

oldtiffie
09-26-2010, 07:38 AM
Further to my previous post, I thought I'd re-post an old sketch which shows a lot of the strains on a vise, say on a machine table. It applies in large part to lathe chuck jaws which operate on similar principles - see bottom sketch:
http://i200.photobucket.com/albums/aa294/oldtiffie/Sketches/Vicestrainandangles1.jpg

Mcgyver
09-26-2010, 08:56 AM
OT, that's all nice, but what has it to do with my post which I assume is what you're trying to address since I'm quoted?

Do you think quality/wear of a 4 jaw has a meaningful affect or not and your reasons?

oldtiffie
09-26-2010, 09:40 AM
OT, that's all nice, but what has it to do with my post which I assume is what you're trying to address since I'm quoted?

Do you think quality/wear of a 4 jaw has a meaningful affect or not and your reasons?

Of course quality and wear are advantages when quality is high and wear is low - and the converse equally applies.

It is a self-evident truth - here anyway.

I only need enough quality to satisy my shop needs and for wear to be above the level where the chuck or tool gets tossed out and made unuseable and irrepairable.

Chucks are a consumable item.

I know what my requirements are as regards usability. If it within those limits I keep or buy it. If it is not within those acceptable limits I either don't buy it or I trash it.

Its as easy and simple as that.

Arthur.Marks
09-26-2010, 11:57 AM
So...

what is your test for "above the level where the chuck or tool gets tossed..." with a 4-jaw; furthermore, what are your personal "acceptable limits" for the test data?

MarkBall2
09-26-2010, 01:01 PM
Basically for the hobby machinist any 4 jaw can be made to run well enough for the dimensions we normally work with.

The original question was "where to find a reasonably priced 4 jaw chuck".

Look here for a low cost Chinese 4 jaw:

http://www.cdcotools.com/

Mcgyver
09-26-2010, 01:44 PM
Basically for the hobby machinist any 4 jaw can be made to run well enough for the dimensions we normally work with.

how does being a hobbyist determine acceptable tolerances? And 'we', there's a universal tolerance applicable to the hobbyist? :rolleyes:

Whether the hobbyist works to a great or lesser set of tolerances to a guy down the street in a job shop is a function of the part/job at hand.....good enough is good enough etc

I know what you're getting at, many hobbyists might not work very carefully and if they don't who cares, there's no QC, they're having fun and the work might had a low duty cycle in non critcal applications....but many do work carefully. The OP asked for a good quality 4 jaw, accuracy is accuracy, tolerance is job determined not whether it's a hobbyist or commerical guy making it.

Probably what the OP meant was what's the best of the cheap asian chucks.....as Rohm and Pratt Burnerd are imports and perhaps the best quality on the planet...but far from inexpensive...for someone seeking quality above all else, they're the choice

MarkBall2
09-26-2010, 02:09 PM
A 4 jaw is only as accurate as the operator. Hobbyist or professional tool & die maker........... a 4 jaw still needs indicated in. If you are careful you can get a cheap/inexpensive 4 jaw to work accurately.

My point is if someone is looking for an inexpensive 4 jaw, why spend $300-$500 for a "name brand" when the less expensive one will do. I just bought an 8" $85, 4 jaw from CDCO & I expect it will work for what I plan on making.

Although, I'm not making critical parts for NASA, so my accuracy isn't as critical, nor is my budget as large, as their needs.

Mcgyver
09-26-2010, 03:19 PM
A 4 jaw is only as accurate as the operator. Hobbyist or professional tool & die maker........... a 4 jaw still needs indicated in. If you are careful you can get a cheap/inexpensive 4 jaw to work accurately.

that's not so......getting your mark centred to a tenth is only half the story....it doesn't address whether the desired axis of the work parallel to the lathe's. What if the jaw face isn't square to the slot, if there's excess play between jaw and slot in the body, if the slot is perpendicular to the mount ..... Just because you dial in a point very accurately that's largely irrelevant to whether said desired work axis is on the lathe's....hence quality/wear does matter.

Whether an $85 chuck is good enough or you need a 1300 Rohm will depend. I'm not judging; that will depend on each shop/person and the type of work they're doing/want to do. I'm simply saying its incorrect to assert condition doesn't matter because you can dial it in. Dialing it in doesn't align the axis; what makes sure the axis are aligned is the quality/condition of chuck

ldbent
09-26-2010, 04:17 PM
I have bought two new 4 jaw chucks from Grizzly;
1.Made in Taiwan eight inch bought over 20 years ago. Excellent chuck with quality equal to Bison.
2.Made in China twelve inch bought two or three years ago. If the chuck had been free it still wouldn't be worth anywhere near the cost of shipping. No deburring had been done on any machined surface of the body, jaws or studs.
It took many hours of filing to knock of all the sharp edges that could be reached. It took more hours to make the gouges on the studs resemble threads so that the chuck could be mounted. What a total waste of time and money.
I haven't felt the need to buy anything further from Grizzly and doubt that I will.
I bought an eight inch D-1-6 adaptor from CDCO that was serviceable and inexpensive.

oldtiffie
09-27-2010, 12:08 AM
OK.

Back to the OP:


Hello,

Are there any good quality new import 4 jaw chucks out there for a home hobby person looking for decent precision? I'm looking for a 6" 4 jaw and I'm not sure I want to roll the dice just yet with the import stuff. I have my eye on ebay for some good old american/english chucks but you never know what you get sight unseen. Some look pretty beat and I can't tell what environment they came from.

In particular I am interested if the import chucks have good parallel chuck slots and jaws and if the material is too soft. Alot of the cheaper ones seem to be semi-steel which I'm assuming is a cast steel alloy. I'm interested in getting a chuck that has the front and backs parallel to the chuck slots too, although I could true this up if it were out too much (I'd rather not have to though!).

~KEJR

I have trawled through all the major chuck "names" - Bison, Pratt-Bernard, Fuedra etc. - and all the I can find are tabulated sheets of nominal sizes (no tolerances or limits) and with no "run-out" etc. data.

Bison:
http://www.lathe-chucks.com/BISON/BISON-4-JAW-INDEPENDENT-LATHE-CHUCKS.htm

Pratt-Bernard:
http://www.workholding.com/products/p19.pdf

Fuerda:
http://www.cnfed.com/Uploadfile/2009061815312261862.pdf

All that I could find was these sheets that came with one of my excellent Chinese 4-jaw chucks. These chucks have done all that I require of them:

http://i200.photobucket.com/albums/aa294/oldtiffie/Lathe_misc/4-jaw_chuck_specs1.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Lathe_misc/4-jaw_chuck_specs2.jpg

As a reminder:
0.01mm ~ 0.0004"

0.02mm ~ 0.0008"

0.03mm ~ 0.0012:

0.04mm ~ 0.0016"

0.05mm ~ 0.0020"

0.06mm ~ 0.0024"

0.75mm ~ 0.0300"

1.00mm ~ 0.0400"

I have posted a similar sheet previously in this thread for my excellent Chinese 3-jaw chucks.

http://i200.photobucket.com/albums/aa294/oldtiffie/Lathe_misc/3-jaw_chuck_specs1.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Lathe_misc/3-jaw_chuck_specs2.jpg

So, in my recent experience I only get the detailed limits/tolerance sheets packaged with a new chuck.

For the "China knockers" - I have taken random checks of these chucks and all have been within the specified limits and all are very smooth, "tight" and very well finished.

In the event of not having anything similar for a chuck that may not be new, I'd suggest that the data sheets above should suffice as a guide to performance and adequacy.

.RC.
09-27-2010, 12:36 AM
While it is true that a cheap and nasty 4 jaw can hold material in the jaws to the same accuracy as a very expensive pratt or rohm...

However that is not the be all and end all....

What speed is the cheap and nasty chuck rated at (if they even give you a rating)

Are the jaws hardened and the jaw slots concentric and perpendicular..

The simple fact is cheap 4 jaws are still cheap and might be OK for your use depending on what you want to do, but an expensive one is better no matter what..

And if I am wrong I will let Jennifer Hawkins sleep with me... http://en.wikipedia.org/wiki/Jennifer_Hawkins

MarkBall2
09-27-2010, 01:25 AM
I'm gonna steal that data sheet & check some measurements on mine once I get it mounted to the backing plate.

As far as Jennifer.................... I've got a daughter older than her & I'm afraid that's jail time for someone as old as me...........:eek:

oldtiffie
09-27-2010, 02:03 AM
While it is true that a cheap and nasty 4 jaw can hold material in the jaws to the same accuracy as a very expensive pratt or rohm...

However that is not the be all and end all....

What speed is the cheap and nasty chuck rated at (if they even give you a rating)

Are the jaws hardened and the jaw slots concentric and perpendicular..

The simple fact is cheap 4 jaws are still cheap and might be OK for your use depending on what you want to do, but an expensive one is better no matter what..

And if I am wrong I will let Jennifer Hawkins sleep with me... http://en.wikipedia.org/wiki/Jennifer_Hawkins

Ringer, if all you are going to do is sleep then you are beyond redemption.

I suspect that all the blood rushed out of your head (to you know where) and you had a dizzy fit, fell off the end of it, fell on your head and got quite concussed and quite delusional.

I don't think that you are going to do either of you any harm - or any good either.

I can hear Lara B calling "Ringer - where the bloody hell are you".

http://en.wikipedia.org/wiki/Lara_Bingle

http://www.google.com.au/#hl=en&source=hp&biw=1277&bih=519&q=lara+bingle+%2B+pics&aq=f&aqi=g2&aql=&oq=&gs_rfai=&fp=19de4d67b5fdf093

Anyway.

If you back-track through some of the chuck links I provided you will see that most rate their chucks in terms of maximum RPM.

MuellerNick
09-27-2010, 02:03 AM
You might think that even the cheapest 4-jaw is good enough. That will quickly change if you have used a better one.

First, are the jaws' gripping surfaces straight (or as Forrest Addy rightly noted conical)?
Second, do they have play sideways?
Third, and most of all, do they have axial play? It is no fun when the screw wobbles and tumbles around and there is no means to adjust for centricity in a controlled manner.

I have a 4 jaw combi chuck. 4 independent jaws, plus one central lock that moves all 4 jaws synchronous (at least it should). Having dialed in the part, opening the central lock and closing it again, the part is completely off. That's real fun if you have to make 10 pieces. :(

Buy a Bison, that is reasonable quality.


Nick

oldtiffie
09-27-2010, 02:49 AM
I'm gonna steal that data sheet & check some measurements on mine once I get it mounted to the backing plate.

Please do use them Mark.

I hope it helps.

I suspect that there are a lot of others who don't have those data-sheets either.

If nothing else it gives them something of substance to talk about and refer to instead of "just talking".

oldtiffie
09-27-2010, 03:01 AM
You might think that even the cheapest 4-jaw is good enough. That will quickly change if you have used a better one.

First, are the jaws' gripping surfaces straight (or as Forrest Addy rightly noted conical)?
Second, do they have play sideways?
Third, and most of all, do they have axial play? It is no fun when the screw wobbles and tumbles around and there is no means to adjust for centricity in a controlled manner.

I have a 4 jaw combi chuck. 4 independent jaws, plus one central lock that moves all 4 jaws synchronous (at least it should). Having dialed in the part, opening the central lock and closing it again, the part is completely off. That's real fun if you have to make 10 pieces. :(

Buy a Bison, that is reasonable quality.


Nick

Nick, I generally agree with what you say, but I'd not agree with this:


You might think that even the cheapest 4-jaw is good enough. That will quickly change if you have used a better one.

Cheapest is not always the worst and the most expensive is not always the best - although as a generalisation is probably pretty close - as the seller/"market" will sell or buy for what-ever it can get and is willing to accept on the day.

The reason I posted the data-sheets was that it seemed that many did not have them and had no idea of what the data was that they should evaluate a chuck on. I asked for and was shown those sheets by the Supplier I buy most of my stuff from. So I knew what the chuck's specifications were and could compare them to my requirements and limit of cost. I also had a warranty which is fully supported if needed - which it was not and is not.

MuellerNick
09-27-2010, 03:33 AM
and had no idea of what the data was that they should evaluate a chuck on.

So here they are for a 160 mm Bison 3 jaw chuck:
* radial runout of chuck: 0.03
* radial runout of testbar (L = 60) 0.035
* radial runout of testring (inside & outside clamping) 0.035
* axial runout of testring (inside & outside clamping) 0.02

I didn't check this chuck, but I bet the actual values are about half of the limits.



Nick

oldtiffie
09-27-2010, 03:49 AM
So here they are for a 160 mm ~ 6.3" Bison 3 jaw chuck:
* radial runout of chuck: 0.03mm ~ 0.0012"
* radial runout of testbar (L = 60mm ~ 2.4") 0.035 ~ 0.0014"
* radial runout of testring (inside & outside clamping) 0.035 ~ 0.0014"
* axial runout of testring (inside & outside clamping) 0.02mm ~ 0.0008"

I didn't check this chuck, but I bet the actual values are about half of the limits.

Nick

Nick.

I've taken the liberty of inserting the "inch" equivalents into the mm figures.

Note that there is only one figure (0.02mm ~ 0.0008") that is lower then or "better" than 0.001"

It seems that those "super good" Bison figures are far less good than some here either believe or have convinced themselves - and others - about.

Other than the radial run-out there is not one figure that I cannot "correct (for)" on a job-specific basis using my "tap-true" method - on my Chinese chuck/s on my Chinese lathe.

MuellerNick
09-27-2010, 05:55 AM
It seems that those "super good" Bison figures are far less good than some here either believe or have convinced themselves - and others - about.


Bison is not super good. They are good. And as I said, the actual values should be well below. And that even after some usage.

A friend simply threw away his Chinese chuck after 3 years of low HSM usage. He even didn't keep it for the rotary table.
My Chinese 4 jaw was replaced two times, because it even didn't conform to their lousy "quality" promises. The third one was kept, simply because I gave up complaining about.

One should compare a Chinese and a Bison side by side. That will open your eyes.
Yet alone if you compare how rough the beveled gears mesh, it will make you look for gravel inside of the Chinese chuck.


there is not one figure that I cannot "correct (for)"

Well, ...


Nick

oldtiffie
09-27-2010, 08:06 AM
Nick.

I am not arguing that really good tools are neither needed not nice to have - at all.

In my opinion, its a matter of knowing what you need for the job which may be less than you want - but its your choice.

A buyer cannot make a completely rational decision until he knows just what he needs, what he can afford to pay and what is on offer in terms of quality, performance and cost in meeting his objectives.

If he buys a second-hand chuck he is largely in the hands of the seller if he has no specification data and if he is unable to verify that the chuck meets those criteria.

Other than you and I so far, no one had "fronted up" with a data sheet to use to check a chuck they already have or are considering buying.

It is not enough to buy one on eBay or Craig's list or what-ever and then complain that you "don't like it (anymore?)" because it "isn't right" unless the seller sold it as being in accordance with a set of manufacturer's specs or unless the buyer has a set specs.

It is no more than one person's word against another and the odds are in favour of the seller.

Same goes with paying a premium for a "Name" when an equally good cheaper "no-name" alternative may do just as well.

But the buyer needs to have this information - and he won't get it from the manufacturers sites.

Just about all of my chucks are Pratt-Bernard and Fuerda and the few that aren't seem to be just as good - so I am pretty well provided for.

I don't need to be convinced that a lot of garbage comes out of China in the form of machines, tools, accessories etc., but there is some pretty good stuff too at considerably less cost than stuff made outside of China. Its just matter of finding it.

If someone makes an uninformed choice or purchase based solely on cost then there is a pretty good chance that they will be sold garbage.

There are not a lot of people who will take any or all of the blame if they get "done" for or by "buying for cheap" as its all too often the "other guy's" fault - which may be true - and it might not.

I've taken my share of "hits", but I've learned from it and generally do pretty well.

Lathe and mil chucks included.

Mcgyver
09-27-2010, 09:04 AM
While it is true that a cheap and nasty 4 jaw can hold material in the jaws to the same accuracy as a very expensive pratt or rohm...


I agree with your other points but don't think the above is true; see post 30

you lucky Dawg, when's she coming over? :D :D

MotorradMike
09-27-2010, 01:44 PM
Hi K:

Just got my KBC Tools flyer.
They have a 6" Bison 4 jaw on for $235.66 Canadian.
Part number 7-850-0600

They claim regular price is $673.

Worth looking into.

KEJR
09-29-2010, 11:18 PM
Hi guys,

Thanks for all the good advice. I think I'm going to spend some time and look for a quality name brand chuck on the used market that looks lightly used (Maybe from another HSM user or prototype shop that took care of things). If I don't see anything that floats my boat then a trip to CDCO or tools4cheap might be in order. For the cheap money I might roll the dice.

I had not considered tapping the work to get a piece that overhangs 3-5 inches to run true, but it makes sense since the jaws aren't gripping purely parallel anyway. Sometimes you can't always work between centers, but I suppose using the hammer method and/or a steady rest can be a tactic for those times when you can't use a center in the tailstock and need decent concentricity over those lenghts.

Most HSM work can probably be said to be low tolerance, but there will be that project for me where I'm making a tool or fixture and a I want to get under 0.001" TIR. I don't think that is too much to expect even on an old lathe with a 4 jaw.

Thanks alot guys, I appreciate the feedback.

~KEJR