[Nelson_2008]

Well I was finally able to find a front (or rear) mounting, 5" 3-jaw chuck at an apparently reasonable price of $110 on ebay.

Despite the best efforts of Vertex to prevent me from getting it, despite their scarce, careless and incomplete marketing literature, I persisted, and eventually "outsmarted" them.

Although I haven't tested it yet (and that may prove disappointing), at first glance, it "seems" like a nice piece of hardware.

Vertex makes it difficult because they don't provide good marketing literature to their distributors. Most anyone selling their products shows a generic "picture" of a chuck that doesn't show the through-holes for front mounting.

Nor do they give many specs. for the chuck. And when you do happen to see specs., they all have an error. They say TIR is "0.03 mm (0.012")", but they dropped a zero from the inch spec.; apparently it should be 0.0012".

Anyway, of the other 5" 3-jaw chucks I was able to find in the low-end price range, only the "HBM" chuck was front mounting (and I heard scary stories about that brand), and the runout spec. was always 0.003" max. So I was somewhat pleasantly surprised by the Vertex spec., if it's actually correct.

Unfortunately I'm not set up yet to test the chuck for runout, but in the meantime I'm wondering, has anyone else tested any Vertex chuck, and if so what did you find?

[handlewanker]

Hmmmmm, to what machine or piece of equipment are you going to mount the chuck on?

A dividing head?........a rotary table?.....a lathe?

The fitting is different for each purpose.

Assuming it is a lathe, the run out for a three jaw chuck is normal.......they all run out, even Pratt Burnard chucks run out........the secret is in the mounting.

My 150mm (6") 3 jaw Chinese make chuck, now 30 years old, runs to within .001" on all diams because I mounted it to do so.

For a lathe, when you mount the 3 jaw chuck, any 3 jaw chuck, make the register at the back of the chuck, ( where it fits onto the backplate), a slack fit, that is at least .003" slack on the register.

Then when you bolt the chuck to the back plate, not too tight at first, and put a test bar in the chuck you can tap the chuck body with a soft mallet until the test bar runs dead true, to within .0005" if necessary, then tighten up the bolts.

It may vary for different diams, depending on the quality of the chuck, but when you are doing a second op on a job with finished diams and want the job to be dead concentric you can "adjust" the chuck to make it run dead true by slacking off the holding bolts and tapping the high side as indicated with a dial indicator.

This method emulates the properties of the griptru type chuck (without the cost) where the scroll is moved in the chuck body by a screw mechanism on the outside to enable the chuck jaws to run true.....it works for older chucks where the jaws are bellmouthed and have been reground, but run out on different diams due to scroll wear.

If you mount a chuck a tight fit on the register and it subsequently runs out a couple of thou it will always plague you when holding finished second op work.

This method is especially true for dividing head and rotary table useage too, as any run out that cannot be corrected makes any gear cutting operation etc a failure due to eccentricity of the gear teeth to the spindle bore.....the blank must run dead true before cutting commences.
Ian.

[Nelson_2008]

Thanks for the ideas on mounting and tweaking.

I got this chuck to use primarily on the rotary table, but in the future I plan to make an adapter plate so I can also use it on my 7x14 mini-lathe.

My ideas on the manufacturer's runout spec. on chucks might be wrong, but I always thought it was like this: If the chuck is mounted and adjusted so that it is "dead on" while gripping something of a certain diameter, then for any other diameter within the range of the chuck, the maximum runout will be 0.003" (or whatever the spec. is).

BTW as far as mounting it on the rotary table, I was planning on using some kind of a blank MT2 arbor or collet chuck with a reamer blank or something. I thought I would bolt the chuck down loosely, put the MT2 arbor in the table bore, then grip it with the chuck, then tighten the 3 bolts holding the chuck. Does that sound reasonable, at least for a rough alignment?

[handlewanker]

Hmmmmm, 3 front holding down bolts.......rotary tables have four tee slots running at 90 deg to each other......you will probably need a back plate that gets located (on the centre hole) and bolted down to the table first, then you bolt the chuck to the backplate which has been drilled and tapped for the 3 mounting holes in the chuck front face.

The backplate needs a register to pick up the centre hole in the table and also a register to allign the chuck to the backplate for initial mounting......and as I have said before, make the register for the chuck a slack fit, IE at least .003" slack, then you can "adjust" any job on the table for precise concentricity.

Having a register for the chuck and backplate means you are almost there when you fasten down, and all it takes is a couple of turns against a dial indicator to get spot on.

The fact that a cheap, but still very useasble, 3 jaw chuck has looser tolerances means you can go to the bottom of the market for economy and still be able to get precise concentricity for whatever diam you are working on......a good chuck will eventually have a looser tolerance anyway after a few years of useage.

Personally I prefer to mount a 4 jaw chuck on a dividing head or rotary table due to the ability to grip anything, and also to get precise concentricity......takes a bit more time to set the job true, but accuracy is worth more than time any time.

A 4 jaw chuck will hold square material as well as round, but a 3 jaw will only hold round.

I've just bought a Vertex BS-1 dividing head, and part of the package was a 4 jaw chuck.

This is just my preference for the mentioned reasons......most people fit 3 jaw chucks without thinking because everyone else fits 3 jaw chucks.
Ian.

[Nelson_2008]

Actually, the Vertex 6" table has three slots (and IIRC I think it is *only* 6" table with three slots that I've seen), so the chuck will bolt directly to it, as shown here.

I thought about getting the similar Grizzly 6" table with four slots, but for most of the stuff I'll probably be doing, I think I can trade convenience for a slight loss of accuracy.

Of course it would be nice to have a 4-jaw chuck also, so I may get one some day in the future.

[handlewanker]

Hi, that's a pretty neat table.....I haven't see them with 3 T slots.

At our local tool showroom they have two makes of dividing heads, one by Toolmaster which in spite of it's prestigious sounding name is very far from the truth, and the other is by Vertex.....a much better build and also a bit dearer, a $100 dearer.

They look almost identical on the outside but differ fundamentally on the inside.

I compared the two models designated the BS-1 model (plain dividing without gears for compounding or spiral work), retailing at about $750 +- on a good day for the Vertex one and $650 for the Toolmaster, not to be recomended at all.

First problem was in the chuck mounting, the 'head had the screw on backplate, which is the normal way for mounting the chuck once you've machined it to fit the back of your chuck, but in this cheaper "design" which is an accolade far from the truth, there was no register for the backplate to locate on.....it had a screw thread, and a pretty poor thread it was at that, but no plain diam behind the screw thread for the backplate to register on.....the screw thread by itself is no good.

So I took it back and complained bitterly and they placated me by agreeing to swap it for the more expensive Vertex model but at the same price.

I see in the Sears catalogue in the USA they also do the BS-1 dividing head......can't say what make but as it's an import they have their own badge on it, so heritage and design unknown.
Ian.