# Tell me of 5C collets, collet blocks and spin indexers



## Aaron_W (Apr 11, 2018)

I've had my eye on picking up a set of collet blocks since I found out what they are. I spent several hours today looking at 5C collets, collet blocks and spin indexers. 

On a whim I also checked eBay and found some ER32 collet blocks. Since I already have a set of ER32 collets, that seemed the most cost effective route, at least for the moment. The pair cost me less than even a modestly priced 5C set with 1/16" spacing, and far less than a comprehensive 1/32 or 1/64 spaced set.


I am left with some questions and since longer term I expect I will be revisiting the idea of 5C collets I might as well ask now while the questions are fresh. I have already spent quite a lot of time searching this site as well as finding threads elsewhere that google turned up. Surprisingly I didn't find any that really went over these in any depth. Mostly touched on through other questions.



It does appear that the 5C collets have the advantage of allowing larger diameter and longer stock to pass through them compared to the ER style. Also some odd shapes available beyond round which I suppose could be useful. On the downside they seem to have very little range for adjustment, so require a fairly large collection or buying very specific sizes based on need.



On the collet blocks, other than the mentioned potential to allow larger stock to pass through, the 5C seems to fit within the block a bit better. I don't expect any serious issues, but the ER blocks I ordered do have a large ring at the front due to the chuck which will somewhat limit how it fits into the vice. 

On the other hand since the back end of the ER blocks are clear of any locking mechanism it seems like I should be able to mount the block vertically or horizontally. The 5C blocks I looked at have locking levers at the back which could perhaps be an issue for vertical mounting.


Square blocks seem pretty straight forward, squares, rectangles and right angles. 

If I'm thinking correctly a Hex block can do a hex or by skipping sides also an equilateral triangle, possibly other triangles?


There don't seem to be any other shapes but square and hexagon. No Pentagon or Octagon? These seem like fairly common shapes. Not nearly as common as hex nuts but there are pentagonal nuts out there. The stem nut on a fire hydrant being a very common one. 

I'm not coming up with a lot for octagons except for stop signs, and old rifle barrels and some iron bars. Actually I guess you could use a square block in a V block holder? Seems like an actual Octagonal block would be easier though.



Last I come to the spin indexer. It doesn't appear that this does anything that couldn't also be done with a rotary table. A spin indexer does seem like it might be easier to use for some tasks and there are plenty of cheap ones around $50 and even presumably higher quality ones are only around $200. 

It does appear than they are only offered for 5C collets, but I did find someone offering a 5C - ER32 adapter, so maybe I don't have any need for 5C collets until I find a need to hold something other than round stock.


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## Dave Paine (Apr 11, 2018)

Every type of taper has pros and cons.

5C allows for larger stock diameter than ER40 which is larger than ER32.

5C pulls the collet in from the back.

ER collets are pushed into the taper by the nut on the front.

5C collect blocks need to be removed from the chuck to change the collet or work, but the nut at the rear is smaller than the large nut of an ER collet block.  ER collet blocks having the nut on the front allow changing stock or collet without removing the block.

I use my hex 5C collet block in the lathe often.   In this picture to hold a bolt so I can machine the end of a bolt.

My hex and square 5C collet blocks can stand vertical in a milling vise if needed.    I have done this but not finding a picture.

I have used my 5C hex and square collet block in the milling vise to machine a hex or square on the end of a piece.




A 5C spin indexer is less expensive than a rotary table.   Also if the work is round and within the range of a 5C collet, it is easier to hold in a 5C spin indexer than mounting on a rotary table.


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## brino (Apr 11, 2018)

Aaron_W said:


> The 5C blocks I looked at have locking levers at the back which could perhaps be an issue for vertical mounting



Most 5C collet block sets that I have seen look like this:
http://www.shars.com/5c-collet-block-set

They supply a couple of nuts that can be used in place of the lever. So it can be "low profile", but still not accessible at the bottom of the mill vise.
The nut is turned with a pin wrench.

-brino


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## Bob Korves (Apr 11, 2018)

Aaron, you understand the choices pretty well.  Dave Paine also gave you some useful comments.

5C collet block sets normally come with a lever closer as well as a ring nut closer that uses a spanner wrench or pin to tighten and loosen.  The ring nut does not get in the way of anything, the lever closer is quick but mine does not clamp nearly as tight.

The biggest advantage of collet blocks in their speed.  The cheap ones have some inaccuracy, but are totally acceptable for the vast majority of jobs.  High quality ones also bring high prices.  A rotary table is more versatile, especially if it is horizontal/vertical and you also have a tailstock for it.  Rotary table setups usually take much more time than sticking a rod in a collet, and they are much more expensive.  In my shop my 5C collet blocks are used many times for each use of the rotary table.

You can also mount the blocks at an angle and make tapered facets.

Spin indexers are also for 5C collets and therefore quick to mount the work.  The indexing scheme is also quick and easy if you only need whole degree increments.  A dividing head does a lot more, and is more accurate, but a lot slower and fussier to use.

The correct answer is that you need them all!    But it might be wise to wait until you actually have a project coming up where you will definitely need the more specialized and expensive option before buying it.  That also gives you time to look for a killer deal on a new or pre-owned one if you really think you need one in your shop.

Octagons can be made with a V block.  Another thing that comes in very handy in the shop often is angle blocks like these:


Or these.  Or both...


Quick and easy.  I really like quick and easy, though I often do really slow work as well.


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## Aaron_W (Apr 11, 2018)

The collet blocks were what I was really after, but as they initially appeared to be connected to 5C collets they took me down a whole new rabbit hole. Finding the ER32 collet blocks has slowed that down for the moment.


I saw that the 5C allow longer lengths but since I'm usually looking at stock smaller than 3/4" I completely missed that they also go to larger sizes than the ER32 collets.  

I saw the rings included with the collet blocks, but I thought that were related to the lever, I didn't realize they were an alternate to the lever.



I already have a rotary table and a tilting table. I can mount any of my chucks to the table. Does a spin indexer do anything I can't do with the rotary table, or does the indexer just make some tasks easier? 

If I understand it correctly the spin indexer allows one to quickly jump to a new angle vs taking the time to rotate the table to the new angle. 
Doing multiple identical parts I could definitely see that being an advantage. A 60 degree rotation on the indexer would be pull pin, move over, insert pin vs 12 rotations of the handle on my table.


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## Jimsehr (Apr 11, 2018)

Don’t forget you can collet a 1.5 dia x 1/16 thick washer type part in a 5c step collet. Hard to do in a er type collet.


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## Aaron_W (Apr 11, 2018)

Jimsehr said:


> Don’t forget you can collet a 1.5 dia x 1/16 thick washer type part in a 5c step collet. Hard to do er type collet.



I haven't looked too closely at the other options, but yes step collets, expanding collets and the emergency collets all seem like they could prove useful, and offer different options than what I've seen available with the ER type.


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## Bob Korves (Apr 11, 2018)

Spin indexers are also useful on the surface grinder for grinding points, sharpening cutters, making "D" cutters, etc.  Not ideal, but useful.


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## Aaron_W (Apr 12, 2018)

Ok, so these all definitely have a use but it appears I can get by with just the blocks for now. 

I'm just trying to dribble my toy purchases out over time instead of taking a few big bites. So many toys available and it seems like buy one find out about 3 new ones.  

I'm going to need to look more into the angle blocks.

Thanks for the suggestions / explanations.


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## mikey (Apr 12, 2018)

Aaron, just an opinion but I think ER collet blocks are a great purchase for simple indexing jobs. Ever have to make a flat on two ends of a shaft when they both have to be in exactly the same plane? If not, you will. I have both 5C and an ER-40 collet block set and use the ER blocks exclusively now. One thing to keep in mind is that when using collet blocks vertically in a milling vise, especially a tiny vise like a Sherline vise, you have only a small gripping surface to hold the collet block. The rear nut on a 5C block eats up that height so the chances of the block slipping under milling pressure is higher. The ER blocks have no rear nut so are more solidly held; just so you know.

An angle block set, when combined with your tilting angle table and vise, are extremely versatile. They allow you to set pretty accurate angles very quickly, while holding a part solidly in the vise so it doesn't move under milling pressure. You won't use it that often but the combination will allow you to do stuff you otherwise couldn't do. Add to this the collet blocks and you can machine the ends of round stuff at an angle that are held solidly and squarely in the vise. 

I've made Vee blocks, carriage stops, top nuts for QCTP and I can't recall what else but I couldn't do it without that tilting angle table, vise and angle block set. Collet blocks are icing on the cake.


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## RJSakowski (Apr 12, 2018)

One difference between 5C and ER collets is the grip range,  In order to cover the entire range of diameters with 5C , you need collets in increments of 1/32" and preferably 1/64".  A workaround is to use a thin shim around the circumference of the work to build up to a standard diameter.


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## cg285 (Apr 13, 2018)

Aaron_W said:


> Ok, so these all definitely have a use but it appears I can get by with just the blocks for now.



i suspect you will find frequent uses for the collet blocks (and angle plates) while a spin indexer will spend most if it's time on a shelf next to the rotary table.


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## Herk (Apr 14, 2018)

5C collets are also threaded internally and can accept a work depth stop which can be handy.


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## Aaron_W (Apr 16, 2018)

Thanks, I can see that the 5C collets have their own advantages, but can probably wait until I have a need or find a really good deal. They were the most expensive aspect of the blocks which finding a set of ER blocks avoids for now. It seems like one of the major advantages of these blocks comes into play when doing repetitive work.




mikey said:


> One thing to keep in mind is that when using collet blocks vertically in a milling vise, especially a tiny vise like a Sherline vise, you have only a small gripping surface to hold the collet block. The rear nut on a 5C block eats up that height so the chances of the block slipping under milling pressure is higher. The ER blocks have no rear nut so are more solidly held; just so you know.



This is a good thing to know. After I ordered the ER blocks I found an ER 5C adapter and was wondering if I may have been better off buying a set of 5C collet blocks with the adapter. I can see that there will still be an advantage to having actual ER blocks even if if I do later get a set of 5C blocks. They will be complementary not duplication.


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