# Spin indexer vs. dividing head



## DavidR8 (Nov 1, 2020)

I think both of these basically allow a person to incrementally rotate a workpiece on horizontal axis. 
Is a spin indexer for smaller work?


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## mmcmdl (Nov 1, 2020)

A spin indexer is used more on a surface grinder being it can spin and grind ODs . In the trade it is known as a whirly jig . 

A simple indexing head such as a Hardinge allows you to index down to 15 degree increments .

A full out dividing head gives you infinate increments and requires plates . 

A Hartford head is similar to the indexing head but on a much larger scale .


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## DavidR8 (Nov 1, 2020)

Thanks Dave, that's helpful.
Some Google-fu found this too:








						What is a "spin indexer" and how does it differ from a "dividing head"?
					

What is the difference between a full dividing head and a "spin indexer"?  Spin indexers:  Stevensons: http://www.arceurotrade.co.uk/Catalogue/Collets/ER-Collet-Fixtures   On Ebay:  http://www.ebay.de/itm/ws/eBayISAPI.dll?ViewItem&item=140496496795&ssPageName=ADME:X:eRTM:DE:1123    :tiphat:Nelson




					www.hobby-machinist.com


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## projectnut (Nov 1, 2020)

mmcmdl said:


> A spin indexer is used more on a surface grinder being it can spin and grind ODs . In the trade it is known as a whirly jig .
> 
> A simple indexing head such as a Hardinge allows you to index down to 15 degree increments .
> 
> ...



I just used my Phase II spin indexer for that very purpose.  I needed to cut down the shaft diameter on a woodruff key cutter to make a T slot cutter.  I have also used it on occasions to put graduation marks on a degree wheel and other similar work that only needs 1* resolution.  My spin indexer only works in the horizontal position unless it's clamped to an angle plate.  I have seen some that can be used in both the horizontal and vertical position.

I think I paid about $50.00 for mine (used) about 15 years ago.  It came in a padded fancy wooden carrying case with instructions and spaces for a few collets.  There are several new units (not Phase II) available from eBay listed for around the same price.  I have no idea of their quality.


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## mmcmdl (Nov 1, 2020)

They are a useful tool to have in the shed pn !


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## Aaron_W (Nov 6, 2020)

Something not mentioned is while limited compared to a dividing head a spin indexer is cheaper and simpler to use, when you don't need to divide by fractions of degrees. Most of the cheap spin indexers can divide by 1 degree (36 positions + a 1-10 "fine tune" adjustment) increments. No need for plates like on a dividing head. You need a dividing head for making most gears, but a spin indexer can be used (and is faster) for making shapes, regularly spaced grooves etc. Set at 90 degree increments you could mill a square end on a bar, say to make a chuck key, or mill four evenly spaced slots, 72, 60 or 45 degree increments would mill a pentagonal, hexagonal or octagonal pattern.

Of course even simpler than the spin indexer for square or hex shapes would be square or hexagonal collet blocks.

Spin indexers usually use collets, 5C is most common, but I have one that uses ER32 collets. Dividing heads can usually use a lathe chuck, face plate / tail stock to turn between centers or collets (MT or B&S seem to be common).

So the more complex dividing head is not always "better", but it is more capable.


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## DavidR8 (Nov 6, 2020)

Aaron_W said:


> Something not mentioned is while limited compared to a dividing head a spin indexer is cheaper and simpler to use, when you don't need to divide by fractions of degrees. Most of the cheap spin indexers can divide by 1 degree (36 positions + a 1-10 "fine tune" adjustment) increments. No need for plates like on a dividing head. You need a dividing head for making most gears, but a spin indexer can be used (and is faster) for making shapes, regularly spaced grooves etc. Set at 90 degree increments you could mill a square end on a bar, say to make a chuck key, or mill four evenly spaced slots, 60 or at 45 degree increments would mill a hex or octagonal pattern.
> 
> Of course even simpler than the spin indexer for these shapes would be square or hexagonal collet blocks.
> 
> ...


What indexer do you have that uses ER32 collets?
I have not seen one that doesn't use 5C...


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## Aaron_W (Nov 6, 2020)

DavidR8 said:


> What indexer do you have that uses ER32 collets?
> I have not seen one that doesn't use 5C...



Much less common but they are starting to show up. 

I have this one

HHIP ER-32 Indexer


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## DavidR8 (Nov 6, 2020)

Aaron_W said:


> Much less common but they are starting to show up.
> 
> I have this one
> 
> HHIP ER-32 Indexer


Just found that one also


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## francist (Nov 6, 2020)

Don’t know if this extends across the whole of their offerings but I have an AGD-1 indicator by HHiP that I quite like. I think their tools might be a slight notch higher than other regular import stuff. But, the indicator is the only thing of theirs that I own (I think) so take that for what you will.

-frank


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## Aaron_W (Nov 6, 2020)

francist said:


> Don’t know if this extends across the whole of their offerings but I have an AGD-1 indicator by HHiP that I quite like. I think their tools might be a slight notch higher than other regular import stuff. But, the indicator is the only thing of theirs that I own (I think) so take that for what you will.
> 
> -frank



I have a couple of things from HHiP, although what beyond the indexer escapes me at the moment. Based on a small sample I agree, they seem to be at the higher end of still fairly inexpensive import tools. 
The indexer seems to be well made, everything turns smoothly and they left out the usual mystery oil and grit. At $95 + shipping it does put it about 50% more expensive than the cheapest 5C indexers.


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## mickri (Nov 6, 2020)

Couldn't you achieve the same result with a vertical/horizontal rotary table?  I played around with the huge rotary table that came with my mill/drill before I sold it.  It had some dividing plates.  I found trying to keep tract of where I was with the dividing plates was a nightmare.  Seemed easier to divide the circle into however many parts you needed and move the table accordingly.


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## mmcmdl (Nov 6, 2020)

mickri said:


> Couldn't you achieve the same result with a vertical/horizontal rotary table? I played around with the huge rotary table that came with my mill/drill before I sold it. It had some dividing plates. I found trying to keep tract of where I was with the dividing plates was a nightmare. Seemed easier to divide the circle into however many parts you needed and move the table accordingly.



Yes . The rotary table also has great benefits over these other devices . Much larger work envelope as well as better precision . 

The indexers are quicker though if you're not splitting hairs .


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## Larry$ (Nov 6, 2020)

I've had my Spin Indexer for about 4 years, I like it. Seems quite accurate even though it was only about $50. Mine is a 5C model which I like because I have a set of collets for my chuck. There is a good video of reversing the way it holds the work so you can get closer to the collet. I've considered making a tail stock for it, to do list. I also have collet blocks that take 5C and are faster yet to setup. A rotary table with dividing plates is another step up in what it can do. Next step, semi-universal dividing head, then the full blown universal dividing head. Like all things in this hobby it is a never ending progression.


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## Winegrower (Nov 7, 2020)

The sad truth is you need all three of spin indexer, dividing head, and rotary table.   Most recently, i used the spin indexer to mill reference flats on a custom tilt table, the dividing head to make a 100 hole 4” bolt circle of 0.104” holes to hold diodes for a 100,000 volt bridge rectifier, and the rotary table to mill some large diameter holes and arcs.   In addition, you need square and hexagonal collet blocks.   Really.


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## projectnut (Nov 7, 2020)

mmcmdl said:


> Yes . The rotary table also has great benefits over these other devices . Much larger work envelope as well as better precision .
> 
> The indexers are quicker though if you're not splitting hairs .


Not only are the indexers quicker for basic work, they also have a small footprint, and are considerably lighter.  I would guess my spin indexer weighs in the neighborhood of 10 lbs.  My smallest rotary table (8") is in the 75 lb. range, and the larger one (12") is around 125 lbs. 

The downsides of an indexer (at least to mine) are that the base wasn't originally machined square to the collet axis, and there are no slots for T nuts.  When using it I originally had to indicate off the part (until I squared the base), and I still have to use standard table clamps to hold it in place.  Also mine is only designed for horizontal work.  To do anything vertical it has to be clamped to an angle plate.  Even with these minor drawbacks it's the go to tool for work within it's envelope that doesn't require location within less than 1*.

Anything needing greater accuracy goes on a rotary table.  Both have scales that read down to 1 minute of a degree, but that's the limit of their accuracy.  Anything needing resolution down to a second, or fraction of a degree would need a dividing head with the appropriate plates.


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## Weldingrod1 (Nov 7, 2020)

Key difference: motion under cutting load. Spin indexers: set position and cut. Dividing head and rotary table can cut while rotating in addition to set and cut. A lot of rotaries can tilt too.
Spin indexes are easier on your back and take up MUCH less space in your setup.

So: rotaries do it all, but indexers are faster and lighter. I'm in the "well of course I want ALL of them!" school ;-) Who doesnt want more tools???

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## DavidR8 (Nov 7, 2020)

I think I'm leaning toward a rotary table with dividing plates though a spin indexer looks pretty handy.


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## Aaron_W (Nov 7, 2020)

Spin indexers are also relatively cheap $60-70 including shipping for a 5C import on ebay, the ER32 I have was $115 with shipping. 

A 6" import rotary table is $200-300, 8" $300-500 with vertical / horizontal types at the higher end. Dividing plates extra.

Import dividing heads are pretty inexpensive now, although it looks like the prices have gone up in the past year since I bought mine. There were some BS-0 in the $250-300 range with shipping, now the cheapest BS-0 seems to be $350-400, and BS-1 $400-500.

As Winegrower says each has their place. Rotary table is probably the most versatile, the dividing head the most accurate, and spin indexer cheap and easy to use.

I'm really not sure how a rotary table with dividing plates compares to a dividing head of similar quality for accuracy.


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## Winegrower (Nov 7, 2020)

projectnut said:


> The downsides of an indexer (at least to mine) are that the base wasn't originally machined square to the collet axis, and there are no slots for T nuts.



I am starting to think of these lower cost items, like spin indexers, swivel vises, tailstock live chucks, anything from India, etc., not with disgust at the quality lack, but with appreciation for providing 80% of the solution and an interesting challenge to take it the next 20%.

it would be difficult for me to afford all of these gizmos if they were all US or German made precision stuff, so I now think of these as “kit” items but with not so much boring machining required.  Self delusional maybe, but it prevents some disappointment, and spurs some creative thinking opportunities.

And when you get done, you have a tool that you really understand and have characterized pretty thoroughly.

Wadda ya think, are you with me?


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## DavidR8 (Nov 7, 2020)

Winegrower said:


> I am starting to think of these lower cost items, like spin indexers, swivel vises, tailstock live chucks, anything from India, etc., not with disgust at the quality lack, but with appreciation for providing 80% of the solution and an interesting challenge to take it the next 20%.
> 
> it would be difficult for me to afford all of these gizmos if they were all US or German made precision stuff, so I now think of these as “kit” items but with not so much boring machining required.  Self delusional maybe, but it prevents some disappointment, and spurs some creative thinking opportunities.
> 
> ...


Indeed, I could not afford to do this hobby otherwise. I try to buy as much quality used gear as I can but some stuff is unobtainable for me.


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## projectnut (Nov 7, 2020)

I guess I have different thoughts about low end imported tools.  I've bought a few over the years, but avoid it whenever possible.  In our area there's an abundance of lightly used older machine tools and tooling made in the USA.  In almost every case the older used stuff has been superior to the new imports in both quality and functionality.

When I buy a tool I research what quality level is needed to do the job, what's available, and the cost.  If it's for a one time use, and the price is right I'll probably buy cheap Chineseium.  If I intend to use it on a regular basis I'll go for something I think will last even if it's a bit more expensive.

A couple examples outside the realm of machine tools are:  A few years ago we were putting a new deck on the family cottage.  We needed railings/guard rails to keep the young nieces and nephews from taking a 15' dive.  We researched the cost of having them made, and the cheapest was over $2,600.00.  I knew I could make them for far less so I set out to get the needed materials and a few tools.  

The wife wanted radiused corners where the balusters met the horizontal rails. I did the bulk of the work on the mill, but needed a die grinder for finishing.  I ended up with a HF die grinder because I knew it would be a one time use.  It did the job, but would get extremely hot when using it more than a few minutes at a time.  The grinder hasn't been used since that job was finished.  It was however cost effective.  I was able to fabricate the railings for a total cost of less than $800.00.

Another project was replacing the deteriorated tile on our screen porch.  The contractor wanted $1,000.00 to remove the old tile.  Again I knew I could do it for far less so I purchased a Bosch hammer drill.  I knew this tool would be used on a regular basis, and with the previous HF experience I didn't feel comfortable that one of their tools would do the job.  I got lucky in that the drill was on sale and the company was offering a rebate.  The total cost was less than $300.00.  I have used it dozens of times since then, and it has always worked as expected.

The last thing want to do is repair or modify a tool before I use it, or have to do it during the course of trying to use it.  A tool is supposed to make a job easier, not add frustration to the process because of poor design or construction.


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## Aaron_W (Nov 7, 2020)

Kind of drifting here, but there is cheap, and there is cheap. Harbor Freight has a lot of cheap tools, really only good for those things where you might use it once or twice, or where my use is very light duty. They also have some stuff that is actually quite nice and still affordable. Their 4x6 bandsaw and US General Tool Chests fall into this second category. 

It seems like a lot of the more recent import machine tools have really good bones to work with. It may take some clean up and fine tuning, maybe even a little modification but then you have a very good hobby grade tool for just a fraction of the price of a used vintage piece. I really wanted a vintage dividing head, but most that I could find were missing parts, often looked well used and were still twice the price of brand new Chinese dividing head. For something I won't use much it just made more sense to get the import which is actually quite well made. I did spend a little extra to buy it from PM where I knew I could get some service if I got a reject.


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## Larry$ (Nov 8, 2020)

Buying a 30+ year old industrial machine has it's risks and parts are likely to be really expensive, if available. I'd have no problem buying a Taiwan made from a reputable reseller (PM) but some of the stuff sold on eBay would be a shot in the dark. My spin indexer was a bit crude but not bad as a kit. Now works fine. My Vertex rotary table and index plates seem well made. I could do a Stefan or Robin job on it but it is not necessary. My collet blocks are disappointing, could be fixed, if I had a surface grinder. My collet chuck is excellent (from PM.) The cheap Chinese stuff has made it possible for many of us to enjoy this hobby. It does appear that many of us spend more time modifying our tools than making things. For me it's a game of pushing my limits.


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## Larry$ (Nov 13, 2020)

Aaron_W said:


> I'm really not sure how a rotary table with dividing plates compares to a dividing head of similar quality for accuracy.


I only have the rotary table so no dividing head to compare to. That said, my Vertex RT seems well made and has no discernable slop. Moving the worm into proper mesh is easy and there is no noticeable variation in fit as the table is rotated. Quite accurate positioning can be done w/o the use of the indexing plates when working in #s that evenly fit into 360. The plates and sector arms make it easier to keep track of where you are. The semi-universal dividing head allows the axis to be tilted. Might be able to do that with some Rube G. work on a RT.  The full blown universal is quite another animal. I doubt there is any difference in accuracy between RT & dividing HD. 
I've seen the videos of modifying a Spin Indexer to make finer than one degree incrementing possible. Certainly a cheap option for some uses. 

Just found out I've been exposed to the virus via a grand kid. Now in quarantine.


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## NC Rick (Nov 13, 2020)

Oh man!  I hope your all fine with the virus thing.  Really!  We have grand kids crawling all over this place and I love it.  

I want a dividing head!  I'll say, the spin indexer is one of the best 70 bucks I have spent on machining.  I squared the edges in the mill and can drop it in the vise in a few second.  I use it primarily for flats on hexes, squares etc.  I haven't needed an uneven number of degrees.  Never made a gear either.  That would be cool. When I grow up I might get to do that!


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## RJSakowski (Nov 13, 2020)

projectnut said:


> Anything needing greater accuracy goes on a rotary table.  Both have scales that read down to 1 minute of a degree, but that's the limit of their accuracy.  Anything needing resolution down to a second, or fraction of a degree would need a dividing head with the appropriate plates.


My 12"Enco RT resolves to 5 seconds of arc with its vernier.


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## RJSakowski (Nov 13, 2020)

And my 6" Tormach 4th axis (a stepper motor driven 6" Phase II RT) increments in .0001º steps.  That's .36 seconds of arc.


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## francist (Nov 13, 2020)

Larry$ said:


> Just found out I've been exposed to the virus via a grand kid. Now in quarantine.


Wow, hope that turns out okay for you Larry. Fingers crossed.

-frank


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## DavidR8 (Nov 13, 2020)

Larry$ said:


> Just found out I've been exposed to the virus via a grand kid. Now in quarantine.



Oh brother. Be well Larry! 


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## Logan Novice (Nov 18, 2020)

DavidR8 said:


> I think both of these basically allow a person to incrementally rotate a workpiece on horizontal axis.
> Is a spin indexer for smaller work?



Yeah ...  I bought a dividing head with a tail stock and series of plates a few months back.  I use it primarily on the mill for drilling ports in muzzle breaks.  I think now that a spin index unit might have been a more cost effective choice.


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## DavidR8 (Nov 18, 2020)

Logan Novice said:


> Yeah ...  I bought a dividing head with a tail stock and series of plates a few months back.  I use it primarily on the mill for drilling ports in muzzle breaks.  I think now that a spin index unit might have been a more cost effective choice.


I just sprang for a Phase 2 rotary table from Travers. I have some moto parts that are going to demand the ability to cut radii.


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