Large-ish bore dividing head

wildo

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Can anyone recommend a dividing head that I can use a collet to pass through up to 1.250" rod through? I have no experience with dividing heads, and I don't quite understand how things mount to them. Saying that- I'd be ok with holding the work in a 3 jaw as well, but I still want to be able to pass through stock up to a 1.25"

One part of machining that I'm still finding shocking is just how much material is wasted in work holding. I'd like to try to reduce this by NOT needing to cut off my material twice (or three times- or more) longer than what I'll need for the part. If I ever get good enough to spring for the super fancy materials like timascus, mokume, or dimascus where a 12" bar can cost more than $1000, then this will be absolutely imperative. With that material, the part off along is literally $50 down the drain.

But even for now- my 12" long bar of 1" diameter tellurium copper set me back $50. I'd like to get ten $5 parts out of it rather than three $17 parts!
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For what it's worth- I'm aware of tailstocks for dividing heads. Perhaps I'm thinking about things wrong and using a chuck/tailstock is the correct answer to my question. The problem though is that for what I want to do, I think I will need to mount the dividing head at a 45 degree angle to either x or y axis because I want to mill some 45* slits equally spaced around the rod. For that reason, I figured that working near the dividing head chuck would be the only option rather than at the tailstock end.

[EDIT]- Oh, and it has to fit on my Millrite table which is 8" wide.
 
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I'm afraid you're in for some disappointment, Wil. Most dividing heads I've seen have a smallish Morse taper. If I recall correctly, a 12" Yuasa dividing head has a MT3 taper - no way are you going to pass through something large. Moreover, the rear of the head is typically rounded and closed off because it has to swivel so I don't think a dividing head (or rotary table) will work with long pieces.

Not sure what you're making but maybe a collet block, angled in the vise, would work if its simple enough?

You're right; there is a lot of waste in the shop. It is a fact of life. Be wary of trying to work with really small falloff pieces that should probably go in the trash - you'll get away with it most of the time, until you don't.
 
Question- do 5C spin indexes have built in draw bars? I was checking some out on eBay and none seem to mention shipping with a drawbar.

[EDIT]- nevermind. I found a youtube video on using the spindex and yes, the drawbar is built in.
 
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Phase-II has a 5C version with up to 1.125" capacity.

That's not through capacity. Most 5c 1" collets will not pass 1" stock through. I have one that will and one that won't. Anything above 1" will not pass through it's collet in 5c.
 
That's not through capacity. Most 5c 1" collets will not pass 1" stock through. I have one that will and one that won't. Anything above 1" will not pass through it's collet in 5c.

Ugh. So much for me to learn... especially when stuff doesn't work as advertised! Collets are for through stock. And yet a 1" 5C can't pass through 1" stock!?? :( How do you know if a specific 1" collet can indeed handle 1" stock- is there some other spec that provides this info?

Is this because of the 1-24 internal thread? Looks like this collet from MSC has a 1.041-24 thread which I assume is not the same as a 1.0-24 thread?
 
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Max pass through on a 5C collet is normally 1.0 inch. There are 5C collets that will accept 1.25 in the nose, but the pocket is only about 3/4 deep. The OD of a 5C collet body is 1.250.

Your best option might be a Super Spacer with a 3 or 4 jaw chuck. For your 45° slots, a CNC would make quick work of that.;)

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Ok- so:
  1. 1.041-24 is the standard size for a 1" - 24 thread. Good to know.
  2. I contacted Hardinge and got some info about passing stock through 5C collets at the 1" and above size:
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