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View Full Version : Why I like two-piece chuck jaws (pics)



wierdscience
02-06-2009, 11:19 PM
With the advent of low-profile tires and their inevitable adaptation to trucks and even offroad applications the need to modify large diameter wheel rims has came to be.

Used to a weekend hot rodder needing to save a buck would buy a second hand set of alloy rims and modify the bolt pattern or tunout the pilot bore.That was easy enough to do since most rims were less than 16" on the OD and would easily fit in our 16" 3jaw.

This week I get a set of used 22" rims with a bolt pattern that's right,but a pilot bore that's to small.

To turn these in our 24" swing lathe would normally mean removing the gap and fitting the larger 4 jaw chuck and dealing with the ridiculous overhang produced by the silly wide gap bed.

I said screw it and made a set of aluminum top jaws.I profiled them to fit the contour of the rim and extend the limit of the 3 jaw chucks reach.

What would have normally taken 4hrs of setup and 30 minutes of actual machining was reduced to 45 minutes of setup and machining.More profit,less time and better result.The customer is happy,I am less grumpy:D and I have a new tool in the arsenal.

They managed .250" DOC @ .018" per rev and 80 rpm,no slip,no chatter and no scratches in the pretty chrome.

http://img.photobucket.com/albums/0903/wierdscience/DSCF0050.jpg

http://img.photobucket.com/albums/0903/wierdscience/DSCF0048.jpg

http://img.photobucket.com/albums/0903/wierdscience/DSCF0051.jpg

oldtiffie
02-06-2009, 11:48 PM
Very nice job WS.

I hope this gives some comfort and reassurance to those who may want to "dip their toe" into soft-jaws as well as quieten down the "Never work" and "Doubting Thomas" brigades.

Solves most of the 3-jaw "problems" too.

Ken_Shea
02-06-2009, 11:52 PM
Outstanding !

Willy
02-06-2009, 11:53 PM
I've had a couple of chunks of aluminum looking for a project,guess where they are going tomorrow?
Heck of a fine idea Wierd, Thanks for the tip. Nice range extenders.

Can't for the life of me figure out why people want 22 or 24" rims on their vehicles, but hey if they're gonna run them you might as well make it profitable.;)

lenord
02-07-2009, 01:26 AM
Weird,

THANK YOU for posting that little tidbit !!!

Lenord

Teenage_Machinist
02-07-2009, 01:29 AM
I dont do rims or the like but I sure wish 4 inch lathe chucks could have 2 piece soft jaws!

oldtiffie
02-07-2009, 03:47 AM
Well TM,

As your lathe will take a 4" chuck, I doubt that a 5" chuck would kill your lathe so try these:
A selection:
https://www.machineryhouse.com.au/Lathe-Chuck-Soft-Jaws

An individual set:
https://www.machineryhouse.com.au/Products?stockCode=C2851

For a chuck:
https://www.machineryhouse.com.au/3-Jaw-Backplate-Mount-Lathe-Chucks

An individual chuck:
https://www.machineryhouse.com.au/Products?stockCode=C202

Ian B
02-07-2009, 03:51 AM
Nice setup!

The 2 piece jaws are very handy - I used then yesterday to turn a thin section ring.

Has anyone seen 4 jaw chucks that have 2 piece jaws? It always seems to be 3 (or 6) jaw chucks that have them.

Ian

ACF
02-07-2009, 07:47 AM
Ian,
I have an 8" Bison 4 jaw that came with one piece jaws, however I purchased a set of two piece jaws for this chuck. I think they were listed in the Bison catalog.

Chris

japcas
02-07-2009, 08:25 AM
Has anyone seen 4 jaw chucks that have 2 piece jaws? It always seems to be 3 (or 6) jaw chucks that have them.
Ian

We have several American Pacemakers at work that have 2 piece 4 jaw chucks on them. We also have a bunch of one piece four jaws. Not sure what make the chucks are but they do come in real handy.

I set up and made 4 sets here at home for my 6 in. 3 jaw chuck. I've only used them a couple of times but there are worth a ton when you need them.

mochinist
02-07-2009, 08:49 AM
as well as quieten down the "Never work" and "Doubting Thomas" brigades.Did I miss a thread where soft jaws were blasted and put down, or are you just full of it?


Looks good weird, I've done some similar jaws before, they work great. It also helps on thin or odd shaped items to drill and tap a hole on the outer edge for a small toe clamp.

I hate removing the damn gap bed also:)

wierdscience
02-07-2009, 01:27 PM
I've had a couple of chunks of aluminum looking for a project,guess where they are going tomorrow?
Heck of a fine idea Wierd, Thanks for the tip. Nice range extenders.

Can't for the life of me figure out why people want 22 or 24" rims on their vehicles, but hey if they're gonna run them you might as well make it profitable.;)

Well it's not my cup of tea either,but it pays the bills.

I seem to recall some piece of legislation a few years back that was supposed to reduce the rubber on the road literaly.Something about cutting down the amount of rubber in a tire/lanfill space yada,yada,yada.

TM,I have a 4" 3 jaw I bought from CDCO.I'm thinking the jaws on those are just case hardened.I may try making them into step jaws if I get time.

Scishopguy
02-07-2009, 01:43 PM
I have always loved what could be done with soft jaws. If you are turning a fragile part or something that needs extra support, you can turn the exact radius to grip the stuff you are working with. Not only that, but if you have the same size chuck, with 2 piece jaws, on your indexer or rotab, you can do operations where you have to drill into the jaw to drill through the part. Working with all the odd stuff we had to make at the university, soft jaws were a way of life. We made our own when we had a little time without any deadlines pushing us.

I always wanted to make a set of "pie jaws" for turning rings and thin sheets. They sold those for a pretty price but they were just aluminum soft jaws that were triangular, like a slice of pie. I could have put a set of them to use for the plex tube turning jobs I had. :D

wierdscience
02-07-2009, 09:13 PM
I always wanted to make a set of "pie jaws" for turning rings and thin sheets. They sold those for a pretty price but they were just aluminum soft jaws that were triangular, like a slice of pie. I could have put a set of them to use for the plex tube turning jobs I had. :D

Ya,I have seen those,pie quarters.I have a section of 3/4" tooling plate sitting doing nothing,sounds like a good use for them.

oldtiffie
02-07-2009, 10:23 PM
Originally Posted by oldtiffie
as well as quieten down the "Never work" and "Doubting Thomas" brigades.


Did I miss a thread where soft jaws were blasted and put down, or are you just full of it?


Looks good weird, I've done some similar jaws before, they work great. It also helps on thin or odd shaped items to drill and tap a hole on the outer edge for a small toe clamp.

I hate removing the damn gap bed also:)

I will answer the second question first.
are you just full of it?

Yes - absolutely, I thought I'd made it pretty clear.



Now, to the first question.

Did I miss a thread where soft jaws were blasted and put down

No.

So far as I know there was no such thread specifically - so you didn't miss it - so far as I know.

My reference was to those who, in threads relating to chucks that were "out" to varying degrees, as well as collets and collet-holders etc. as well as costs, who when I referred to the many advantages of soft jaws just chose to not comment.

The OP made a point - very well too - that I have often referred to - the range of sizes that soft jaws can address as opposed to collets etc.

Soft-jaws can grip "thin disks" as well any and much better than most other alternatives.

If cost is an issue and there is a 3-jaw chuck with "two-part" jaws, soft-jaws as a viable option is a "no-brainer" - particularly as it doesn't matter if the chuck and jaws themselves are "bell-mouthed" or have any other defects as the machining of the soft jaws will be as true as the lathe itself.

S_J_H
02-07-2009, 10:43 PM
Wierd-
That's a great example of what can be done! I have never used soft jaws before. I can certainly see how useful they can be.

Tiffie,
I'm going to have to try soft jaws soon. I have an old 3 jaw I think I'll modify the jaws on to accept them.


Steve

oldtiffie
02-07-2009, 11:08 PM
Thanks Steve.

You won't regret it.

If you can bore the hole you are there!! Further, as the OP had pretty well done, you can incorporate an internal "stop" as well (counter-bore etc.). Just about every soft-jaw you see only shows them gripping on external surfaces - they work just as well as "internal" jaws gripping tubes, bores etc. The "trick", generally, is to clamp the jaws onto something while they are being machined for the part. The more accurate it is, the closer you will be to having the same points of the scroll and jaws in contact when the part is being clamped.

Using soft-jaws all but wipes out the case for 6-jaw chucks (expensive) for "thin round" material as well. I have two 6-jawed chucks on specialist grinding tools and I've never even had to consider let alone use them on my lathe.

There is no reason why soft-jaws cannot be prepared on the lathe and then transferred to the mill table or rotary table.

They can be very versatile.

They can beat the snot out of collets and 4-jawed chucks for accuracy and repetition.

lazlo
02-08-2009, 01:14 AM
Well TM,

As your lathe will take a 4" chuck, I doubt that a 5" chuck would kill your lathe so try these:
A selection:
https://www.machineryhouse.com.au/Lathe-Chuck-Soft-Jaws

Tiff, most chuck jaws from different manufacturers aren't interchangeable.
Heck, many machinists will tell you that replacement jaws from the same manufacturer never fit as well as the original jaws.

If you want soft jaws, you really need to buy a chuck with 2-piece jaws.

Nice job Darrin!

oldtiffie
02-08-2009, 01:59 AM
Sorry lazlo.

I went to a lot of trouble to make sure that the specific soft-jaws or "2-piece" jaws fitted the specific chucks.

The chuck I bought had the normal inside/outside 3-jaws. The 2-piece jaws are an accessory/extra.

I've seen chucks modified by then arc/stick now MIG welding a "U" to each jaw ("open" end inward) with a tightening radial bolt on the "outer" part of the "U" with the sides of the "U" drilled for bolts that pass through the "U" and the "soft-jaw". The soft jaws were made to suit.

Sure, it was a "jury rigged" job, but it worked.

I've seen HR mild steel "soft jaws" "stitch"-welded (not too much!!) to the chuck jaws and just ground off and replaced when necessary. Didn't do the chuck a lot of good, but it was pretty well buggered before the welding anyway. The machining of the soft jaws "corrected" (m)any of the "faults" in the chuck.

There are a lot of misconceptions about the accuracy of 4-jaw chuck and collets. Both may be reading "spot on" near the chuck jaw face but can also "throw" and be "off-centre" say 2", 3", or what-ever out from the jaw faces so that the job describes a cone instead of a cylinder. And they will be with the manufacturers specs or industry bench-marks.

If you have a short length of a job protruding from a 4-jaw chuck or collets and it is "spot on" as regards TIR and most of the job is inside the lathe spindle bore, you will have no real idea - just a lot of trust and hope - that the job TIR is just as accurate "in there". Maybe so - but bore the soft jaws and you can have a LOT more, perhaps pretty well total confidence in the concentricity and TIR of the part of the job inside the lathe spindle bore.

Next, any "throw" in any holder (chuck or collet) is not a real problem at all if the finished job is within the work-piece envelope inside the "throw". In short if the TIR is 0.100" and there is 0.105" to be removed, the throw will not affect the accuracy of the finished job.

A passable set of soft-jaws on a three jaw chuck can not only "correct" these "errors" but can operate to the full extent - and beyond - the limits of the 3-jaw basic jaws - just as the OP showed in fine fashion.

There is far too much made of collets and 4-jaw chucks to the detriment of 3-jaw chucks with soft jaws.

I suggest that anyone who is pushed for money and has a need should seriously consider getting a 3-jaw chuck with "2-piece" jaws for use with soft jaws.

JCHannum
02-08-2009, 09:02 AM
I don't think anybody has denied the advantages of a three jaw chuck fitted with soft jaws that are machined to fit the workpiece. It is a very accurate way to go.

The soft jaws are also expensive to purchase and time consuming to make. They are usually only used when no other means is available or when repeat parts are to be made. The soft jaw is just another tool in the box to be used when it's advantages outweigh it's shortcomings.

A well equipped lathe should have a face plate, four jaw chuck and three jaw chuck, pretty much in that order.

mochinist
02-08-2009, 09:28 AM
I don't think anybody has denied the advantages of a three jaw chuck fitted with soft jaws that are machined to fit the workpiece. It is a very accurate way to go.

The soft jaws are also expensive to purchase and time consuming to make. They are usually only used when no other means is available or when repeat parts are to be made. The soft jaw is just another tool in the box to be used when it's advantages outweigh it's shortcomings.

A well equipped lathe should have a face plate, four jaw chuck and three jaw chuck, pretty much in that order.For a homeshop you guys always say time isn't an issue. For a pro shop, face it we all have slow times occasionally, thats when you make up stuff like soft jaws for the lathe and your mill vice, if you have a cnc mill even better as you can pump them out pretty quick. Say you never have any slow times, then you can afford the expensive ones out of the tool porn catalog, good for you.


Once again, I go in a lot of shops, the four jaws are usually covered in dust because of lack of use.

wierdscience
02-08-2009, 09:51 AM
For a homeshop you guys always say time isn't an issue. For a pro shop, face it we all have slow times occasionally, thats when you make up stuff like soft jaws for the lathe and your mill vice, if you have a cnc mill even better as you can pump them out pretty quick. Say you never have any slow times, then you can afford the expensive ones out of the tool porn catalog, good for you.


Once again, I go in a lot of shops, the four jaws are usually covered in dust because of lack of use.

Yup the four jaw is sitting on the floor infront of the lathe,last time it moved was last week when somebody swept under it,before then????

As for making the jaws it took longer to bandsaw out the stock than it did to mill,drill and counterbore.If I had some 2x2 stock it would have took 45 minutes tops.

Spin Doctor
02-08-2009, 10:23 AM
Yes Soft Jaws work quite well. The problem I hve with them is measuring the diameter :rolleyes:. In a perfecrt world we'd use the pie shaped sections

JCHannum
02-08-2009, 10:34 AM
There is no best way of doing something other than the one that is at hand and works.

Every job has a cost and time is only one part of that. In the home shop, most jobs are one off, and a four jaw chuck is usually much faster to set up and run the part that to fit and machine a set of soft jaws. In a production or job shop where multiple parts are usually the case, the soft jaws will quickly pay off.

The other difference with the commercial shop is that the soft jaws are usually figured into the cost the customer pays as either tooling or amortized as overhead. You might not find an over used four jaw in a commercial shop, but you may well find a large pile of equally dusty soft jaws under a bench. I have seen both in many instances.

lazlo
02-08-2009, 11:14 AM
In the home shop, most jobs are one off, and a four jaw chuck is usually much faster to set up and run the part that to fit and machine a set of soft jaws. In a production or job shop where multiple parts are usually the case, the soft jaws will quickly pay off.

A well equipped lathe should have a face plate, four jaw chuck and three jaw chuck, pretty much in that order.

Agree Jim. The 3-jaw chucks for my big lathe have 2-piece jaws, but my "go-to" chuck is a superb Burnerd heavy-duty 4-jaw.

I've made soft-jaws for the 3-jaw a couple of times, including Forrest's recommendation of turning an acme thread into them to hold a leadscrew while I was turning down the ends, but in general they're not worth the time/effort for 1-off jobs, especially if you have a collet setup.

lazlo
02-08-2009, 11:16 AM
The chuck I bought had the normal inside/outside 3-jaws. The 2-piece jaws are an accessory/extra.

But have you purchased the optional 2-piece soft jaws for them? Those optional jaws will only work on the same brand/model chuck.

Teenage_Machinist
02-08-2009, 04:59 PM
I would have a few for the 3 jaw just for those odd thin parts that are nigh impossible to hold.

lazlo
02-08-2009, 05:15 PM
Ian, to hold really thin parts, like for making washers, in a normal 3-jaw chuck, see the neat jig that Peter Neill made recently.

oldtiffie
02-08-2009, 05:27 PM
Deleted - duplicated post

oldtiffie
02-08-2009, 05:30 PM
Originally Posted by oldtiffie
The chuck I bought had the normal inside/outside 3-jaws. The 2-piece jaws are an accessory/extra.


But have you purchased the optional 2-piece soft jaws for them? Those optional jaws will only work on the same brand/model chuck.

In a word, and to "dot the "i"'s and "cross the "t"'s, yes.

That was a the reason I bought the chuck - and the "2-piece" jaw accessories/"extras" for the convenience of the "2-piece" jaws and the soft jaws. It was not cheap but I was more than satisfied.

I often see here where people have C5 or R8 collets (which have a limited range over which they will grip) and/or a "missing" ER collet (which has a gripping range of 1.00mm (~0.040") for your lathe, then "soft jaws" may rescue you. If you have limited normal use for say ER or metric collets and you have a "2-piece" (soft) jaw sat, it may just do the job for you.

I am surprised that "time" is such an issue for so many HSM-ers as it suggests that, at least in part, that "time = money" which suggests a commercial component. If that is the case, then perhaps the question is not so much as to whether you can afford to buy them, but whether you can afford not to.

I am not suggesting that "soft jaws" are the panacea for all the ills, ailments and problems with "chucking" on the lathe (or mill) but they are a very handy tool or accessory to have.