Asian/Chinese made Dividing heads

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pete
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Re: Asian/Chinese made Dividing heads

Post by pete » Tue Feb 12, 2019 2:43 pm

Maybe start a thread Britt and I can give you some dimensions from my RT and DH. I'd rather not take Wally's OT.

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Re: Asian/Chinese made Dividing heads

Post by BadDog » Tue Feb 12, 2019 3:27 pm

alco2350 wrote:
Tue Feb 12, 2019 12:17 pm
Can these dividing heads be used as rotary tables (provided you can hold what you need to in the chuck). I have neither, but would rather have the dividing head for obvious reasons.
I would say the answer is, "sort of".

Technically it would work for many things, but only if you could sacrifice the rigidity, and work with the divisions provided.

A rotary table is a much broader stable work platform that can be advanced by arbitrary degrees generally including a vernier for very precise angular location.

A dividing head as shown in the pictures is really designed for relatively light work which needs reliable quick indexing by division. For instance, 4, 6, or 8 even divisions for fluting a shop made cutter/reamer/etc, or gashing a gear with even divisions to rapidly produce consistent and equal size increments.

And direct in indexers (often call spacers) allowing only the indexing built in (with mask plates for easy subdivision).

And incrementals between with things like Super Spacers that often have accurate arbitrary degree support AND dividing attachments AND indexing, but generally lacking in the tilt function of the dividing head shown above. And the discussion goes on...
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Re: Asian/Chinese made Dividing heads

Post by Harold_V » Tue Feb 12, 2019 5:44 pm

Terminology is being trampled here. A dividing head is not an indexing head, nor is an indexing head a dividing head. Of the two, a dividing head provides unlimited indexing, while an indexing head generally has preselected stops. Both are useful, but not necessarily interchangeable.

A rotary table is more likely to be used than a dividing head, but that depends on the nature of work one intends to pursue. If gears are a part of one's agenda, a dividing head would most likely be mandatory. Using an indexing or dividing head in lieu of a rotab may or may not be a good idea. All depends on what one is trying to accomplish.

Indexing heads, especially those built to accommodate collets, are exceedingly handy to own.

H
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Re: Asian/Chinese made Dividing heads

Post by BadDog » Tue Feb 12, 2019 7:01 pm

I thought that was what I was saying.

The only thing I see different is your comment that dividing heads offer unlimited indexing, which I don't understand. Perhaps effectively unlimited, but I would say that you are limited by the practical maximum resolution of the indexing disks when applied to the differential.

In any case, I have all 3. I would say I most often using the indexing heads (mainly a 6" Hartford, collet blocks, and a Hardinge 5C) followed by rotary table. As of yet, I have never had requirement to use my dividing head (ellis) more than playing around with it when I got it.
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Re: Asian/Chinese made Dividing heads

Post by spro » Tue Feb 12, 2019 10:10 pm

Since I had mentioned some concerns about the Yi Yuan chuck, I did a further investigation of these Asian chucks. Whether included on a dividing head or sold separately, they follow a similar pattern. The scroll teeth and slide above are thinner but hard ground. Really good fit. I tried a file on one innocuous section of a jaw and it scratched it but obviously hardened. The jaws are all numbered. My example; Inside jaws L 4831 - (1, 2 ,3). Outside jaws L 3593 - (1, 2,3). Glad I checked because there isn't a #stamp on the body.

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Re: Asian/Chinese made Dividing heads

Post by Harold_V » Wed Feb 13, 2019 2:52 am

BadDog wrote:
Tue Feb 12, 2019 7:01 pm
I thought that was what I was saying.
You said:
A dividing head as shown in the pictures is really designed for relatively light work which needs reliable quick indexing by division. For instance, 4, 6, or 8 even divisions for fluting a shop made cutter/reamer/etc, or gashing a gear with even divisions to rapidly produce consistent and equal size increments.
That describes an indexing head, not a dividing head. That said, it certainly can be used for the purpose you mentioned. That particular dividing head may even offer indexing capabilities. Some do.
The only thing I see different is your comment that dividing heads offer unlimited indexing, which I don't understand. Perhaps effectively unlimited, but I would say that you are limited by the practical maximum resolution of the indexing disks when applied to the differential.
Do you have a misconception of the purpose of the plates?
Dividing heads tend to be slow to use, and offer pretty much any possible angle one can conjure, assuming the proper plate and hole combination is used for the purpose at hand. As you know, it's all to do with the number of holes in the circle selected. The various circles provide different hole spacing, so degrees can be finely split. The use of the plates as recommended is the reason 73 (or other fractional angle) toothed gears can be indexed.
In any case, I have all 3. I would say I most often using the indexing heads (mainly a 6" Hartford, collet blocks, and a Hardinge 5C) followed by rotary table. As of yet, I have never had requirement to use my dividing head (ellis) more than playing around with it when I got it.
First, I envy you your Hartford. I've used them and they're really nice. I'm limited to my Hardinge, equipped for 5C collets. It's still quite useful, even for larger parts. I''ve been known to build holding fixtures with either a 1" or a 1.125" shank for pretty much any need I've had for fast indexing. The time needed for making the fixture pays huge dividends by allowing rapid indexing that is reliable.

I certainly agree with your assessment of a dividing head. I operated my full time machine shop for 16 years and never once needed one. However, I was not involved in gears, where not having one is most likely not feasible. I have one now, but it has never been used. I'm not a gear man! :D

H
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Re: Asian/Chinese made Dividing heads

Post by BadDog » Wed Feb 13, 2019 11:34 am

By "indexing by division" I meant division by equal parts where (once calculated and setup) you don't have to be concerned with calculating and reading some incremental additional degree from a dial, but rather just count crank rotations and drop a pin in the next appropriate hole as indicated by the sector fingers. The specific low division's mentioned would be possible and easier done on an indexer, but are also doable on a dividing head as well. Gashing the teeth of a gear however would most often not be possible on an indexer due to exceeding the max number of positions. For indexers that number is usually 24, giving 15* increments. And the dividing head having MUCH higher resolution can fill in between the 15* increments.

As you say, the divider provides much more because the max number of holes on a plate is multiplied by the number of times you crank for a full rotation to determine the maximum number of divisions. In most cases, that is far more than you can practically use, but the high hole count on a plate ring combined with the sector is what makes most divisions possible, so it's not about max number of divisions. But that is not infinite in either resolution (though it is as a matter of practical limit), or even covering all possible divisions.

So I believe I do understand the difference, and I'm still not sure where I trampled on the terminology. I try to be precise, so I genuinely want to know what I said that was wrong.

Regarding the Hartford, I agree. I would be very disappointed to lose it, though I wish it had come with the masking plates.

I also have a HV4 5C indexer I like very well, but don't use it very often. Most of my 5C work is more conveniently done using collet blocks, and with the Hartford I'm not motivated to build 5C fixtures. It's also missing it's lever advance, but that's not the end of the world. I do wish it had a threaded spindle rather than the bayonet taper lock so I would have easier (cheaper) access to mount a small chuck. Still, no real motivation to make a bayonet backing plate with the hartford available.
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Re: Asian/Chinese made Dividing heads

Post by Harold_V » Wed Feb 13, 2019 4:47 pm

BadDog wrote:
Wed Feb 13, 2019 11:34 am
So I believe I do understand the difference, and I'm still not sure where I trampled on the terminology. I try to be precise, so I genuinely want to know what I said that was wrong.
I prefer that it be addressed as confusing, not wrong. In both instances, indexing is precisely what occurs. The difference is, with an indexing head, you have no options. There's a preselected position and you go there. With a dividing head, that's not true. With a dividing head, you must select the proper plate, then you must count turns and hole spaces. As you alluded, you can split degrees, whereas with an indexing head, you can not. For an indexing head, the common interval is 15°, with an optional plate that allows for 12° intervals. In the end, yeah, the same thing is accomplished, but if you discuss this with those in the know and you reference an indexing head as a dividing head, you offer some degree of confusion. It's all just a matter of semantics, but there's acceptable names for each device, so they are not confused. It is also true that there are heads that perform in both capacities.

My Hardinge head does not have provisions for mounting a chuck (I made that choice). It did come equipped with the advance lever, which I do not use. It gets in the way when working close. Not having the lever is not a deal breaker, and you'd likely not use it if you had it.

Masking plates for the Hartford would be nice. With them, you limit the chance of making mistakes. That's why I like the Hardinge so well. As you know, they provide blocking screws for all positions, and they're easy to turn in or out. Rarely will I use the head without setting them as required. The sole exception would be if I use the head simply for holding, not indexing. In that case, so long as one hole pins, I'm happy. doesn't matter which one.

H
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Re: Asian/Chinese made Dividing heads

Post by BadDog » Wed Feb 13, 2019 5:22 pm

Agreed and understood on all points. Including Hardinge screws and lever, though it would be handy to have a small 3 or 4 jaw bayonet chuck for it, but I just use the Hartford and count notches or degrees instead.

But I reread and don't see where I referred to an indexer as a dividing head or the reverse.

The closest I can find is my comment "indexing by division", which I would maintain is an accurate statement. You are dividing the part rotation by whatever value, selecting the proper plate, mathematically determining whole revolutions based on ratio, and setting the sector fingers for any partial revolution.

It's still indexing, but with the plate options and ratio in the mix, the resolution (number of divisions possible) is orders of magnitude finer. But still indexing by definition because you aren't calculating incrementals and measuring degrees for each increment, but certainly not ever referred to as an indexing head.

As I recall, the scope of difference is referred to as and defined by direct, dividing, and differential indexing.

Direct being by 1:1 rotation where the indexes represent degrees of work rotation such as pins in a lathe spindle, spindex, indexer, collet block, use of saw blades etc tied directly to the rotation of the part.

Dividing being the main topic here where there is a ratio applied to input, usually via plates on a shaft driving a worm gear for rotation.

And finally differential being a variable geared input otherwise similar to division but providing still more flexibility in chosen results. I believe the latter are what are generally used via gear drive trains for helical milling.

All this is from my all too fallible memory and goes well beyond the scope of application in my shop...
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Re: Asian/Chinese made Dividing heads

Post by Harold_V » Thu Feb 14, 2019 5:23 am

BadDog wrote:
Wed Feb 13, 2019 5:22 pm
But I reread and don't see where I referred to an indexer as a dividing head or the reverse.
I see your point. I was concentrating on your comment about rapid movements with a dividing head (that is generally not the case, but is true of an indexing head), overlooking the possibility that it may be one of the types that offer both features. Upon review, I see that it does. So, yes, the indexing head in question apparently can be used as you said. I was wrong. :oops:

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Re: Asian/Chinese made Dividing heads

Post by BadDog » Thu Feb 14, 2019 12:11 pm

Thanks, I appreciate the clarification.

By "rapid", I only mean by spinning to the crank until eventually you do a partial rotation and hit the hole resulting in accurate location. That is as compared to what you would do with a rotary table where to match you would need to mathematically compose a table of target settings, or do the math on the fly, and then carefully read and locate (ultimately using the vernier) while considering and accommodating backlash. Much time being spent to double check and avoid errors, perhaps using a previous face layout (more time) for sanity checking. So by "rapid", that was only in comparison to rotary table use to do the same.

That hit would be multiplied by number of dimensions, making a 120 tooth gear would be painful using a rotary table (ignoring the interference aspect, some do come with tailstocks), impossible on any indexer I know of, but "quick and easy" by comparison using a dividing head. Conversely, using an indexer of any sort for 8 positions (or rather any supported index) would be much faster than rotary or dividing. The rotary table being able to do either with care, but requires focus and much additional care, often requiring measures to avoid getting in the way; it's strength being in milling arcs and moving to arbitrary locations with a nod to ultimate flexibility.

Then there are the hybrids like Super Spacers plus tilting, feed driven, rotary/cherrying heads, and cross-slide rotary, etc; all bringing various features but beyond the scope of this topic...

Also, some of the commentary was provided as pertaining to the question about using one in place of others. For example, ignoring the potential rigidity issues, speed and ease of use, a properly equipped dividing head could provide the same features as an indexing head.
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Re: Asian/Chinese made Dividing heads

Post by 4gsr » Thu Feb 14, 2019 3:05 pm

alco2350 wrote:
Tue Feb 12, 2019 12:17 pm
Can these dividing heads be used as rotary tables (provided you can hold what you need to in the chuck). I have neither, but would rather have the dividing head for obvious reasons. I was looking at this one here: https://www.precisionmatthews.com/shop/ ... idinghead/

Thanks,

Britt
You can. They don't make very good rotary tables. But for light work, they be okay. Just remember, with the face plate rotated where the spindle is vertical on the dividing head, your distance from the mill table to the top of the face plate can be upward around 7-9" in height. Where as on a typical rotary table, that height may only be about 3-4". Something to think about in decision making.

Ken
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