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Smokedaddy
05-16-2008, 05:00 PM
Does anyone know specifically HOW to mount (like what PARTS do I need) a 3 or 4 jaw Bison chuck to this rotary table? KBC email support wasn't very helpful so I thought someone here might know. I know it has a 3MT but I'm not sure what it would be used for as I have no MT's.

http://www.pbase.com/smokedaddy/image/40371536/large

Also, is an adjustable tailstock a necessary item when holding something in the chuck on the RT, or only for longer length items?

Regards,
-SD:

sidneyt
05-16-2008, 05:24 PM
I make a back plate for my chuck that was larger in diameter than the chuck, bored a hole through the center of the backplate, and then turned a stub that was mt3 one end and other end I turned it to fit in the hole I had bored in the backplate. This will get you pretty close.

Smokedaddy
05-16-2008, 07:37 PM
Is the "concept" to buy a MT Bison chuck (if they make them) for the tailstock accessory, then a 3MT live center for the RT?

-SD:

pcarpenter
05-17-2008, 12:27 AM
I say this not from experience, but from observation....

Usually....you put a dead center in both the tailstock and in the RT center hole and put a long narrow part between the two centers. You still need some sort of dog to insure that the part stays in fixed orientation relative to the RT. In any case, you don't need a chuck, and given that you are not spinning the thing, you don't need a live center either.

A chuck mounted on the RT gets used mostly for holding centered shorter parts without the use of the tailstock.

I think that sydney was just suggesting a home-made morse tapered plug as a quick way to center the chuck and its backplate on the rotary table before you bolt it down.

I would not be surprised if the vendor did not offer much information on mounting a chuck. This tends to be a shop-made affair. Its been discussed here before, so you may want to do a search for some older topics. John Stevenson even showed a neat way to mount a chuck and backplate where the chuck was the same diameter as the rotary table. This is much more complex because there is no "flange" to the backplate for easy front access for mounting bolts into the table t-slots.

Paul

Smokedaddy
05-17-2008, 12:32 AM
I was "thinking" that "next time" it would be better and faster if I used my Bridgeport to put the groove in this part (shown in the link). I figured I could place it in a chuck and use a ballnose endmill to make the groove by turning the RT. I just don't know how to setup the RT to accomplish it.

http://www.pbase.com/smokedaddy/image/97148874

-SD:

pcarpenter
05-17-2008, 12:40 AM
I dunno...I would do it the way you did....much faster than even getting the RT up on the mill table and mounted square to the axis of travel.

The short part you are talking about, is, however, a good candidate for a chuck mounted to the RT table if you really wanted to go that route. It does require that you be able to get the quill down close enough (without the spindle colliding with the chuck jaws on the RT (with the RT turned vertically as you mentioned). This might be difficult depending on just how small the part is and how close the groove is to were its gripped in the chuck.

Paul

Smokedaddy
05-17-2008, 01:19 AM
It does require that you be able to get the quill down close enough ......


Paul,

Never thought about that, good call!

-SD:

Paul Alciatore
05-17-2008, 01:22 AM
As said above, you don't always need a chuck. Most of the work I have done on my RT has just been clamped down to it, with some spacers between the table and the work to allow the drill to penetrate.

For one setup I have used for multiple parts I made a MT with a cylindrical end that fit the center hole in the part for quick centering. Just slap it on and clamp it down.

As for a chuck, I did buy a 6" four jaw for it. I found that the outside edge of the four jaw had at least 5/8" to 3/4" of solid metal so I drilled three 3/8" holes completely through the chuck. My table's slots are sized for 3/8" clamping hardware and I have a kit in that size. I put three tee nuts from my kit in the RT's slots and three 3/8-16 bolts (grade 5) through the chuck. This fastens it down quite nicely with no backplate at all and leaves three more tee nuts in the set for clamping. As for centering, I will be doing a precise job of centering the work in the chuck, but the four jaw chuck does not need to be all that accurately centered on the table. So I just use a combo square and set the blade for the appropriate distance and quickly center it on the table with a push from several sides. This gets me within 0.01" or so of centered. As I said, the work is centered more accurately when I use the chuck and that has to be done regardless of how accurately the chuck is or isn't centered so why waste time on centering the chuck.

Another advantage of this scheme is that it does not add any height to the assembly so I keep a maximum amount of space under the quill to work in. This could be important with large parts.

I don't think this method would work as well with a three jaw or any other self centering chuck. Although, if you took a little time to initially center a three jaw with a rod of the same diameter as the work will be, then you could chuck up multiple parts quickly with fairly good accuracy. You would have to be careful drilling completely through a three jaw as there may not be as much meat in the casting as my four jaw has.

oldtiffie
05-17-2008, 01:48 AM
That "Bison" 12 rotary table is one very nice unit SD - but will be hard to lift though!!

This might upset the purists and "traditionalists" etc. but the dead-set easiest quickest and cheapest way is to just put any old 3 or 4 jaw chuck that you have that will do the job - perhaps not larger than 5" or 6" - straight onto that table and clamp it!!.

No need for a backing plate to/for the chuck or chuck-to-table adaptor either.

(My chucks have 3 counter-bored through-holes in them for hex-headed socket screws - but they are not essential at at all unless you want/need the chuck to be almost as big as the rotary table top - as I do. Your table is 12" and a 5" or 6" chuck can be easily fixed with clamps. My rotary tables are 6" and 8").

Put chuck on the table, "eye" it in - anywhere with 1/4" is near enough but as good as you can get it. Fit 2 or 4 machine clamp sets (bridge, bolt/screw/nut/tee-nut/packing etc) to the table and lightly clamp the chuck to the table.

Put part required in chuck and fasten/tighten chuck.

Release/dis-engage worm from wheel on rotary table, release table rotary clamps so that table can be spun/turned by hand.

Fit dial indicator base to mill table with indicator on job.

Rotate table - reduce indicated run-out on dial by tapping chuck sideways/laterally until indicated run-out is as you require (same principle as setting up in a 4-jaw chuck actually).

When run-out is OK tighten clamps and recheck run-out. If OK - job finished - if not - keep repeating until it is OK.

The job/work is now centred to and concentric with the table axis - no "flash" adaptors needed.

The wormand whell can be re-engaged if required, otherwise leave them disengaged.

To centre the job/work and the rotary table to the mill quill spindle, just put a dial indicator in a collet or Chuck in the quill spindle and rotate the indicator around the work/job. Move the mill table in the "X" and "Y" directions until the indicated run-out on the dial indicator are as near as you require. Lock/clamp the mill "X" and "Y" motions.

The axis of the mill quill, rotary table and the chuck are all now aligned and co-incident.

If you don't need to have the job rotated - don't use the rotary table - just clamp the chuck to the mill table, put the job in the chuck as re-centre the work and quill as before.

That's all I need to do on my mill.

Dissenters and traditionalists can now take an aspirin, have a cup of tea/coffee (or something stronger) and have a good lie down.

http://i200.photobucket.com/albums/aa294/oldtiffie/HF45-5.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/HF45-4.jpg