A 4 Jaw chuck suited to a less common use.

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dgoddard
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A 4 Jaw chuck suited to a less common use.

Post by dgoddard » Fri Feb 18, 2011 12:20 am

Grizzly offers a series of plain back, 4 jaw chucks with independent jaws which appear to be their lowest cost 4 jaw chucks. These differ from their other chucks in that they are to be attached to a backing plate by 4 bolts (included) which insert from the front of the chuck http://www.grizzly.com/catalog/2011/Main/628. This leaves the chuck well suited to mounting on a rotary table with 4 T-slots.
Chuck_Only.JPG
I chose the 8 inch model (G9866) of this chuck because
-- I could mount it on my Phase II, 8" table without any loss of size as commonly happens when using an 8" backing plate to mount a 6 inch chuck,
-- With the 4 independent jaws I could mount shapes other than round,
-- I could minimize any error in position and centering.

The following image shows a comparison between my lathe chuck and the Grizzly G9866.
Back_Sides.JPG
The G9866 has thicker webs and a thicker interior ring that allows the bolts to not pass through the thin portion of the chuck face. Nevertheless, at 31 pounds it weighs only about 1 pound more. The 4 bolts can be seen protruding from the back of the chuck.

I have only found 2 minor quality issues to criticize on the unit I got.
-- The counter bores varied by about 0.2 inches between the deepest and shallowest (quickly remedied by boring them) I saw no other balancing holes drilled in the chuck and I wonder if this is why made the counterbores different. In any case I wanted the counter bores to be equal in depth so I would not have to keep track of which bolt goes in which hole.
-- The other minor quality issue was it would have been nice if the screws which drive the jaws, had been "blunt started". It would be easier to reinsert the jaws when turning them around or removing them for cleaning.

The bolts supplied were M10 socket head cap screws and were far longer than needed and had to be trimmed to length so that they would not bottom in the T-slots of the rotary table. and I made them precisely the same length after the boring operation.
Chuck_Mounted_on_Table.JPG
I have no complaints as to the concentricity flatness or parallelism of the chuck surfaces. Even the clearance bore through the center is precisely concentric to the "precision alignment bore" in the back of the chuck. which makes it easy to center the rotary table under the spindle. I made an alignment plate that fits the precision bores in both the chuck and the rotary table to align them. In the above image there is also a lifting eye that engages below the jaws when the jaws hold the shank. This offers a non slip grip when taking the chuck off the table or allows lifting the chuck and rotary table together by someone with a good back or a small crane, (I use the latter if I move both together).

Curiously the 6, 8 10, 12, and 16 inch chucks in this series all use a 4 bolt pattern from the front and depending on details of the rotary table a chuck larger that the table can be mounted with little or no trouble if someone had a reason to do that (might be hard to read the dial on some models). I could have easily fit the 10 inch chuck on my 8 inch table had i been so inclined.
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BadDog
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Re: A 4 Jaw chuck suited to a less common use.

Post by BadDog » Fri Feb 18, 2011 1:34 pm

Yep, that's a great application that I've been using for years now. I have 4 jaw plain back chucks for (usually on) everything from my 6" Hartford spacer up to my 12" Troyke. Particularly for the Troyke, it's great because it is easy separated for movement (heavy SOB anyway) and reinstalled without any fuss or worry about concentricity. I don't have a single 3 jaw for use in this application.
Russ
Master Floor Sweeper

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dgoddard
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Re: A 4 Jaw chuck suited to a less common use.

Post by dgoddard » Fri Feb 18, 2011 5:10 pm

BadDog wrote:Yep, that's a great application that I've been using for years now. I have 4 jaw plain back chucks for (usually on) everything ...
Out of curiosity do your chucks use the "bolt from the front" scheme that makes mounting the Grizzly chuck so straightforward, or do you have to bolt on a back plate that gives you a flange extending beyond the chuck in order to attach them to the table. This bolt from the front scheme is so simple and practical that I would be surprised if several manufacturers did not offer such chucks, but Grizzly was the only supplier I found that had chucks made this way. (of course the low price, plus being on sale, plus a $10 discount coupon that could be piled on top of the sale price did not hurt my interest any.)

And just out of curiosity what do you think of my surmise :?: that the different depth C'bores might have been a way to adjust the balance of the chuck. It would work if the balance was not too far off and if someone was attaching a back plate and not frequently removing the bolts. Then unequal length bolts would not be a problem. It would be a cost efficient way to do it. Of course, dynamic balance is not of any concern on the rotary table seeing as how if I crank the hand wheel as fast as I can I can only get about 1 RPM :wink:
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EdK
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Re: A 4 Jaw chuck suited to a less common use.

Post by EdK » Fri Feb 18, 2011 6:51 pm

dgoddard wrote:This bolt from the front scheme is so simple and practical that I would be surprised if several manufacturers did not offer such chucks, but Grizzly was the only supplier I found that had chucks made this way
Bison makes 3 & 4 jaw chucks that mount from the front.

http://brassandtool.com/Chucks-Lathe.html

Of course, they are a whole lot more expensive than the Grizzly versions. :shock:

Ed
Vectrax 14x40 lathe, Enco RF-45 clone mill, MillerMatic 180 MIG.

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dgoddard
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Re: A 4 Jaw chuck suited to a less common use.

Post by dgoddard » Fri Feb 18, 2011 11:13 pm

EdK wrote:Bison makes 3 & 4 jaw chucks that mount from the front. Of course, they are a whole lot more expensive than the Grizzly versions. :shock: Ed
Yep, I checked out that link and you are right, they do make them but at more than 7 times the cost of the one I got from Grizzly, I don't think I could afford one for an add on to an auxiliary tool. Of course I would suppose that Bison probably would have properly blunt started the screw threads :wink:
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Lew Hartswick
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Re: A 4 Jaw chuck suited to a less common use.

Post by Lew Hartswick » Fri Feb 18, 2011 11:23 pm

The three jaw that I just had to make a new back-plate for is probably 50 years old and it
mounts to the backplate with (only3) screws from the front so I would imagine a 4 jaw from
the same "vintage" would also have the screws in from the front. Would be nice to have one.
Had to make a M30 x 3 threaded backplate to replace the 1 1/2 - 8 one to use it on the
Yuasa index head. A real "learning experience". First internal metric threads. :-)
...Lew...

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BadDog
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Re: A 4 Jaw chuck suited to a less common use.

Post by BadDog » Sat Feb 19, 2011 1:55 am

Sorry, been out all day.
dgoddard wrote:Out of curiosity do your chucks use the "bolt from the front" scheme that makes mounting the Grizzly chuck so straightforward
Yes, all of mine used like this bolt form the front. My little 6" on the Hartford is a Pratt Burnerd "plain back". My 10" Buck is an A4 (like D1-4, but bolts from the front instead of camlock) and so on. My 12" Buck is also a plain back. And I've got an ancient super heavy 8" Skinner that I have used on the mill table much like a 4 jaw vice bolted right to the t-slots (milling plastic blocks, needed solid location and reasonable grip against pull out without distortion). And I don't think I paid more than $50 for any of them (and as I recall, the PB and 10" buck were both less than $30. So don't forget to drop in on whatever surplus/scrap/whatever dealers you have near by. I nabbed that little PB out of a crate they hadn't even processed yet. And the 10 Buck was in a filthy grimy OD grinder cabinet behind/under a bunch of fixtures. It's a "light duty" 5 jaw, but looked like it had never been mounted, so the grinder grit had done no harm, cleaned up like brand new.
dgoddard wrote:And just out of curiosity what do you think of my surmise :?: that the different depth C'bores might have been a way to adjust the balance of the chuck.
On that I have no idea. My 12" buck is balanced by drilling out the back side of the rim. On my smaller chucks, I don't recall seeing any sort of lightening, and to my knowledge, none have different depth holes.

Just an aside, but to my knowledge, any "A" (short taper) mount chuck will bolt from the face.
Russ
Master Floor Sweeper

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Davo J
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Re: A 4 Jaw chuck suited to a less common use.

Post by Davo J » Sat Feb 19, 2011 4:44 am

Hi,
The 8 inch back plate mount chuck that came on my lathe has the 4 bolts from the front. I bought a 10 inch 4 jaw for my 10 inch rotary table like you, and the chuck has the 4 bolts from the front as well. The 4 bolts where not much good to me because the table has 6 slots which wont line up with the chuck, so a sub plate needed to be made. My 3 jaw back plate mount that came with the lathe has 3 bolts from the rear not the front, though they can be bought over here at around $50 more.
Instead of just making the sub plate to suit the 10 inch 4 jaw, I made it to suit the 6 inch 3 jaw, 8 inch 4 jaw and the 10 inch 4 jaw so I can mount either one. The DRO bolt hole circle came in handy making all the holes.lol
The reason I bought the 10 inch chuck was so it could also be mounted on my 12 x 36 lathe for odd jobs that I have had trouble with. I used a 10 inch face plate as a back plate for it as I would have had to import a 10 inch back plate from the US if I wanted one, because they don't sell them here.
The cheap chucks over here in Aus are FUERDA brand and by the looks of it anything over 160mm has 4 bolts from the front.
https://www.machineryhouse.com.au/4-Jaw ... the-Chucks

Dave

Old Grandad
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Re: A 4 Jaw chuck suited to a less common use.

Post by Old Grandad » Sat Feb 19, 2011 6:05 pm

I am currently using my South Bend 6" 4 jaw on my 6" Phase II RT. I was not able to use the four through holes on the chuck for mounting even though I have 4 slots. The bolt circle on the chuck is just slightly too small to fit the slots of the RT. I made a back plate adapter, but it is rather unhandy lining everything up when removing and re-installing the chuck. I may have to look into it again and see if I can grind down one end of the T nuts and gain enough to mount the chuck directly. It is only off about one half a hole if I remember correctly.

dgoddard, are you happy with the quality of the Grizzly chuck at this time? I have been considering another one, so I don't have to remove the back plate from my SB chuck.
Tom

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dgoddard
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Re: A 4 Jaw chuck suited to a less common use.

Post by dgoddard » Sat Feb 19, 2011 9:55 pm

Old Grandad wrote:... The bolt circle on the chuck is just slightly too small to fit the slots of the RT. ... I may have to look into it again and see if I can grind down one end of the T nuts ...
I had made some t-nuts for my rotary table and found the same problem about not being able to slide the t-nuts all the way to the end of the t-slots because the square corners on the t-nut ran into the rounded end of the slot. My solution was to rig up a way to hold the t-nuts at the center of the rotary table and then used the rotary table to mill a round the end on the t-nut at both levels.
T-Nut.jpg
The one precaution worth noting is that the wall around the threaded hole is pretty thin on the one side, so one would want to make sure that the bolt ran all the way through the t-nut but still did not bottom in the t-slot. The t-nut in the picture was the prototype. I fudged the dimension on the ones I made for general use to thicken the thin wall around the thread a bit.

I suppose that if someone made a rotary table where the t-slot ran all the way across this would never be a problem
Old Grandad wrote:dgoddard, are you happy with the quality of the Grizzly chuck at this time? I have been considering another one, so I don't have to remove the back plate from my SB chuck.
Yes, I am quite pleased with the Grizzly G9866. Other than the different depth C'bores (which may have been a balancing scheme) and the lack of a thorough blunt start on the jaw screws, I have not found anything to complain about. The flatness & concentricities exceeded my expectations and the fit and finish are very good as well. In the best of all possible worlds I suppose that I would have liked it if the chuck was not so thick, but the weight savings would be minimal and my Lagun FTV-2 10x50 mill has so much knee travel (about 20") that I have never even come close to using it all.
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BadDog
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Re: A 4 Jaw chuck suited to a less common use.

Post by BadDog » Sun Feb 20, 2011 2:28 am

I just remembered, I have a pic uploaded that shows one of my favorite setups, the 6" PB 4 jaw on 6" Hartford Indexer. Click for larger image.
Image
Russ
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Harold_V
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Re: A 4 Jaw chuck suited to a less common use.

Post by Harold_V » Sun Feb 20, 2011 4:25 am

BadDog wrote:I just remembered, I have a pic uploaded that shows one of my favorite setups, the 6" PB 4 jaw on 6" Hartford Indexer. Click for larger image.
Image
Those Hartford indexing tables are really nice. Haven't set eyes on one in many, many years. If memory serves, they come equipped with a series of plates that permit indexing @ pre-determined intervals.

You've likely made mention, but my memory isn't what it used to be. Did you get it from ebay?

Harold
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