# Question about collets



## kd0afk (Jun 18, 2013)

I am reading the latest issue of "The Home Shop Machinist" and in the article about collets it shows a 5c collet chuck. The caption reads;"A system used on the 9" South Bend lathe to allow the use of 5C collets. It works when you can't do better."
What does "..when you can't do better" mean? Is 5C not the best choice for a collet system? I don't understand.


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## portlandron (Jun 18, 2013)

It's no so much about the collets but about how they are being held. When collets are being held in a collet holder that is inside the spindle of the lathe they are running as true as the spindle and collet holder allows. For all practical purposes the only deflection would be from the spindle bearings. 

When you mount them outside the spindle, in a chuck, you have more overhang which can equal more deflection. There is also the addition of chuck alignment or run out.


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## rodw (Jun 18, 2013)

portlandron said:


> It's no so much about the collets but about how they are being held. When collets are being held in a collet holder that is inside the spindle of the lathe they are running as true as the spindle and collet holder allows. For all practical purposes the only deflection would be from the spindle bearings.
> 
> When you mount them outside the spindle, in a chuck, you have more overhang which can equal more deflection. There is also the addition of chuck alignment or run out.



So does this mean that my 5C holder that fits in the spindle taper and passes right through the spindle is a better option than fitting a collet chuck? I wondered how accurate it might be and if it could be tightened up crooked.

I have only played with it but I will say that I like the 5C collets and the collet block I got for the mill. I still use ER32 for mill tool holding.


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## Sshire (Jun 18, 2013)

Another consideration about collet adapter vs collet chuck. The carriage travel toward the head is limited. I'm using a Bison Set-Tru 5C collet chuck and the carriage travels under it giving about 6" more travel toward the head. I may not be understanding how the adapters are used, but in a parting cut, where the tool is at 90 degrees to the spindle,the carriage can't move close enough to the head to part off close to the collet nose. Am I missing something here?


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## canadianhorsepower (Jun 18, 2013)

> Am I missing something here?


 
Stan,
              depending witch set up you are using yes you'll run out
of space. Picture one is a common practice cheap but work and you will run out of space. Second picture more money, but you get what you pay for

http://www.mmsonline.com/articles/when-to-use-a-collet-chuck
this is a good article on the subject


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## rhankey (Jun 18, 2013)

Sshire said:


> Another consideration about collet adapter vs collet chuck. The carriage travel toward the head is limited. I'm using a Bison Set-Tru 5C collet chuck and the carriage travels under it giving about 6" more travel toward the head. I may not be understanding how the adapters are used, but in a parting cut, where the tool is at 90 degrees to the spindle,the carriage can't move close enough to the head to part off close to the collet nose. Am I missing something here?


 
I think that potential issue varies depending on the lathe you are using.  For example, on my Hardinge HLV, in which the 5C collets mount within the spindle nose, I still have no problem parting off right next to the collet nose.


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## rodw (Jun 18, 2013)

I have the spindle adapter in the drawing Luc has posted. You need a minimum 38mm spindle to use these so they are not for small lathes. 













From the earlier post, I was not sure if this was likely to be more accurate than a collet chuck. Any comments?



Sshire said:


> Am I missing something here?



On my lathe there is a pressed metal guard attached to the saddle above the leadscrew which also works as a stop to limit forward travel as it contacts the headstock behind the spindle plate.  Removing this guard lets the tooling travel last the spindle plate. I made a mental note that I would need to remove this guard if I was turning say a chuck adapter plate bolted directly to the spindle but even with this guard in place, there is plenty of travel to use the collet adapter right up to the collet. Maybe yours has a similar guard?


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## canadianhorsepower (Jun 18, 2013)

> You need a minimum 38mm spindle to use these so they are not for small lathes.


 
This company sell some 4inch one
http://www.ecolletchucks.com/BISON/BISON-4INCH-5C-MANUAL-COLLET-CHUCK.htm


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## rodw (Jun 18, 2013)

canadianhorsepower said:


> This company sell some 4inch one
> http://www.ecolletchucks.com/BISON/BISON-4INCH-5C-MANUAL-COLLET-CHUCK.htm



That is for a chuck. I was referring to the spindle adapter. Also on that page, there is a collet stop on the bottom right. I can highly recommend them. I have one I got from Little Machine Shop for about $10 or so. It lets you do one setup for multiple parts. It worked well for me in a collet block in my mill.


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## canadianhorsepower (Jun 18, 2013)

[quoteI was referring to the spindle adapter][/quote]

oops:hDe:  Rodw sorry I didn't pay attention


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## kd0afk (Jun 23, 2013)

Metal lathe accessories has a 5c collet chuck foundry kit so when you make it there is little or no run out. My lathe is 4.5' so the loss is ok. I would go with a 3c system but I really need the capacity to turn larger stock.


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## platelayer (Jun 23, 2013)

kd0afk said:


> I am reading the latest issue of "The Home Shop Machinist" and in the article about collets it shows a 5c collet chuck. The caption reads;"A system used on the 9" South Bend lathe to allow the use of 5C collets. It works when you can't do better."
> What does "..when you can't do better" mean? Is 5C not the best choice for a collet system? I don't understand.


 
The problem with collet chucks is that because we are adding an extra piece onto the lathe we are also adding to the tolerance stack, and it is quite lightly such devices will exhibit more runout than the bore of the lathe spindle which have been specifically manufactured to locate collets in the lathe. Beyond that of course with any sort of chuck, overhang of the bearings is increased, and therefore the likelyhood of deflection, however it depends of course on the magnitude of the cutting forces as most of us would simply take lighter cuts to mitigate that problem. We use collets in general as a quick way of gripping work reasonably accurately, but how accurate will depend on the original manufacture of the lathe spindle and the collets themselves. The best lathes (Schaublin/Hardinge for example) when new with new collets may exhibit very little runout at all, indeed I have seen some Schaublin lathes where only the merest flicker of the DTI was apparent. I suppose at the end of the day it depends what the requirements are, and there are other ways of achieving similar levels of accuracy such as using "griptru chucks" or soft jaws that can be machined out to suit a particular job. - It's really horse for courses!


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## platelayer (Jun 23, 2013)

kd0afk said:


> Metal lathe accessories has a 5c collet chuck foundry kit so when you make it there is little or no run out. My lathe is 4.5' so the loss is ok. I would go with a 3c system but I really need the capacity to turn larger stock.


 
The other thing to bear in mind is that collets do not have the gripping force of a chuck, and therefore you may be better using soft jaws bored out to suit the job if you need the accuracy.


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## Tin Falcon (Jun 23, 2013)

Why not go with a 3C system and buy a couple of pot chucks.

Tools for cheap Mass. USA has them for about $30 each. 

available in 2 or three inch so you can bore them to whatever size you need. 
Tin


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## kd0afk (Jun 23, 2013)

Tin Falcon said:


> Why not go with a 3C system and buy a couple of pot chucks.
> 
> Tools for cheap Mass. USA has them for about $30 each.
> 
> ...


This is an option I have thought about. I forgot about the pot chuck. Tools 4 cheap has a 3c system for just a little more than the kit from MLA so I might just do that.
I was under the impression that a collet grips better than a chuck because of the gripping surface area but I guess I was wrong.


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## Tin Falcon (Jun 23, 2013)

> I was under the impression that a collet grips better than a chuck because of the gripping surface area but I guess I was wrong.




Regular 3 jaw scroll chucks  grip at three points 
independent 4 jaws grip at four points. an improvement would be a 6 jaw set true chuck. these are nice but relatively expensive. 

A regular 3 jaw chuck with soft jaws is an improvement also as they can be machined true for a job and they grip segments of circle rather than points.

A pot chuck is also machined to size for the job or can be machined in steps. 
the pot chuck like collects grip most of the entire circumference of a round part . All but the relief slots.   When you machine a pot chuck place spacers in the slots tighten the chuck then machine to size . when you remove the spacers the slots will contract as the chuck is tightened and grip the part. 

you are not wrong the pot chuck is more of a collet than a standard 3 jaw scroll chuck in the way iT works.
Tin


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## kd0afk (Jun 23, 2013)

platelayer said:


> The other thing to bear in mind is that collets do not have the gripping force of a chuck, and therefore you may be better using soft jaws bored out to suit the job if you need the accuracy.


Where do get your information from?


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## platelayer (Jun 23, 2013)

kd0afk said:


> Where do get your information from?


 
Well apart from being a professional engineer, it 's from experience in the workshop and in the workshop and conversations with my peers. If you doubt it think of the mechanical advantage a chuck has over a collet!? Initially there is the gearing, and then the scroll which allows the user to impart significant pressure on the workpiece. It all depends on the requirement. Collets are for quick accuracy within prescribed limits of manufacture.


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## stevehuckss396 (Jun 23, 2013)

platelayer said:


> The other thing to bear in mind is that collets do not have the gripping force of a chuck



Amen brother.  The only time I use a collet is to hold a part without messing up the surface of the part i'm holding. I also like to use them when making valves so the stem and heads are concentric after rotating the part. Chucks are for the heavy cuts.


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## platelayer (Jun 23, 2013)

Tin Falcon said:


> Regular 3 jaw scroll chucks grip at three points
> independent 4 jaws grip at four points. an improvement would be a 6 jaw set true chuck. these are nice but relatively expensive.
> 
> A regular 3 jaw chuck with soft jaws is an improvement also as they can be machined true for a job and they grip segments of circle rather than points.
> ...


 
The other thing worth pointing out is that collets are less likely to damage the workpiece because they grip more lightly over a greater surface area. Circumferential grip is only achieved when the size of the workpiece closely matches that of the collet. Being from the UK I've not come across the term pot chuck. - Perhaps we don't have them here, but is there a picture available on the site.


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## Tin Falcon (Jun 23, 2013)

here is photo of mine in use
I was doing some light milling in the lathe. 
Tin


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## Swifty (Jun 23, 2013)

We must not forget that collets, like 5C style, are designed to hold a specific size of part, vary by a small amount on the diameter being held and the holding pressure will be impacted.

Paul.


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## Tin Falcon (Jun 23, 2013)

true a full imperial set is in 1/64  .015" increments.
Tin


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## kd0afk (Jun 23, 2013)

3C collets are three times the money of 5C. I will probably go with a 3C system though. Thanks for all the help.


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## rodw (Jun 23, 2013)

I thought it might be worth posting up some observations I made of runout on my 6 month old Chinese lathe. The other day I looked at spindle taper and could not see any runout. Today I measured 0.01mm. So here is what I measured. (Difference between high and low readings quoted)

Spindle internal taper 0.01 mm (0.0004")
3 jaw on 3/4" end mill 0.06mm (0.0023")
5C Spindle Collet adapter with 3/4" end mill 0.05mm (0.00197")
4 jaw holding 3/4" end mill 0.01mm (0.0004") same as spindle taper

I have been meaning to remake a collar I need at the back of the spindle adapter. It is possible I will get the collet adapter running a bit better than this when i do. I have also got a Swiss made DTI accurate to 0.002mm on its way so I may revisit these figures. 

Maybe I could have got the 4 jaw better with a bit more practice. But I was able to dial it in to the accuracy of the spindle itself so I am happy with that.

So the message in this for me is the 4 jaw is the most accurate holding device I have. I was hoping the collets would have fared better so more homework required, maybe they will improve. All of these devices exceed my abilities as a machinist.


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## platelayer (Jun 24, 2013)

rodw said:


> I thought it might be worth posting up some observations I made of runout on my 6 month old Chinese lathe. The other day I looked at spindle taper and could not see any runout. Today I measured 0.01mm. So here is what I measured. (Difference between high and low readings quoted)
> 
> Spindle internal taper 0.01 mm (0.0004")
> 3 jaw on 3/4" end mill 0.06mm (0.0023")
> ...


 
Yes the only way one can improve on those it is to acquire a higher quality lathe. Many high precision lathes have the spindle bore and taper finish ground in situ so as to eradicate the manufacturing errors. Watch maker and instrument maker lathes are done that way so spindle runout is zero with the collets held to very close tolerances, and are often better than the spec. sheet would seem to indicate when new. - I have seen Swiss Schaublin lathes with virtually no runout at the workpiece, but there are always ways around these issues without spending pots of money.


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## platelayer (Jun 25, 2013)

Tin Falcon said:


> true a full imperial set is in 1/64 .015" increments.
> Tin


 
It used to be the case that one can order any size of collet within the range from the manufacturer for a specific requirement probably at a premium though. Watchmaker collets are often available in increments of 0.1mm (0.004" approx.)


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## platelayer (Jun 25, 2013)

kd0afk said:


> Where do get your information from?


 
I should say that I was thinking in terms of collets drawn in by a drawbar, however looking at the the collets chucks such as those by Bison the advantage might not be so clear cut as these chucks do have gearing and the thread to wind in the collet giving an improved MA.


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## rodw (Jun 25, 2013)

platelayer said:


> I should say that I was thinking in terms of collets drawn in by a drawbar, however looking at the the collets chucks such as those by Bison the advantage might not be so clear cut as these chucks do have gearing and the thread to wind in the collet giving an improved MA.



Better MA but more runout on the chuck maybe?:hDe:

Still, I think collets are very handy and I have started to breed a bunch of 5C ones in addition to my ER32's. The collet block is very handy. Also look at some of the stuff ArcEuro trade do in the UK. They have ER32 collet blocks and ER32 holders that fit in a 5C collet holder.

Maybe Little Machine Shop has a reasonable priced 3C collet.


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## mu38&Bg# (Jun 25, 2013)

When I added a 5C chuck to my Clausing 4900 lathe with a threaded spindle nose I made a backplate for it and the 5C taper came out at .0002" TIR. I checked it a year or two later and runout had not changed. Modern production lathes use bolted on collet chucks. The method is not the problem it's the quality of the parts. I use collets anytime the material fits.

Greg


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## kd0afk (Jun 25, 2013)

The whole reason for me to get a collet chuck is to have tighter control over the concentricity. Most of what I turn is 1" brass and aluminum. I don't want to use a pot chuck for that so I will stick to my original plan. The bearing play on my spindle is about .005" last time I checked and the collet will be machined in situ so I'm not worried about run out.
The 5C collets are less expensive and the collet chuck itself is less expensive than a 3C setup and for me right now affordability is a deal breaker. I will still have the 3 jaw chuck and the 6" 4 jaw chuck.
I also want to support the kid at MLA, he is doing excellent work and I like the looks of his chuck.
Platelayer- I wasn't trying to infer anything negative about your abilities or experience.


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## platelayer (Jun 25, 2013)

kd0afk said:


> The whole reason for me to get a collet chuck is to have tighter control over the concentricity. Most of what I turn is 1" brass and aluminum. I don't want to use a pot chuck for that so I will stick to my original plan. The bearing play on my spindle is about .005" last time I checked and the collet will be machined in situ so I'm not worried about run out.
> The 5C collets are less expensive and the collet chuck itself is less expensive than a 3C setup and for me right now affordability is a deal breaker. I will still have the 3 jaw chuck and the 6" 4 jaw chuck.
> I also want to support the kid at MLA, he is doing excellent work and I like the looks of his chuck.
> Platelayer- I wasn't trying to infer anything negative about your abilities or experience.


 
Are you sure you mean .005" and not .0005". If you have .005" (5thou) then you need to do something about it as the bearings are badly worn, and would be worthwhile doing something about for much improved accuracy. If concentricity concerns you then sort the bearings out first before testing the runout of the spindle.


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## kd0afk (Jun 25, 2013)

platelayer said:


> Are you sure you mean .005" and not .0005". If you have .005" (5thou) then you need to do something about it as the bearings are badly worn, and would be worthwhile doing something about for much improved accuracy. If concentricity concerns you then sort the bearings out first before testing the runout of the spindle.


Sorry, you are correct. .0005". I'm talking about the ammount of deflection I get when I flex the spindle with a bar. I am a follower of Halligan142 on youtube and I'm referring to his video on adjusting the spindle clearance.


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## kd0afk (Jun 29, 2013)

I've made a decision. When I finally go with a collet system I am going with a 5C.


It has the capacity I need
They are more affordable
The chuck will be machined on the lathe so there will be no runout
I have a 4.5' bed so loss of length isn't an issue
I'm mainly turning brass and aluminum so I don't think that'll be an issue.
It looks awesome!!
Thanks for the valuable input as usual guys. I'll let you know how it turns out.


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## platelayer (Jun 30, 2013)

kd0afk said:


> I've made a decision. When I finally go with a collet system I am going with a 5C.
> 
> 
> It has the capacity I need
> ...


 
Yes well one makes ones choices and pays ones money I suppose, however I don't think the collet chuck is the necessarily the best solution and certainly in the UK typical ones such as the Bison one are not cheap, but I can see it might be an interim solution. Probably the best solution would be to acquire something like a Hardinge lathe in good condition with a collet closer on the headstock. This way the spindle taper and bore should be perfectly concentric, and the collet closer makes for rapid material changes. Of course obtaining a Hardinge lathe in appropriate condition is not easy and never cheap. - I suppose they are more common in the USA, but in the UK good ones are always at a premium. Anyway don't let me dissuade you because I digress. The 5C collets are made by all and sundry, but Hardinge ones almost certainly will be the most accurate providing they are in good condition.


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## kd0afk (Oct 11, 2013)

Here is a follow up. I bought the kit from MLA. Unmachined it weighs a little more than my 4" three jaw chuck and way less than my 6" four jaw chuck, so no change in the deflection department. It gets machined in-situ so it will be concentric to the spindle.
I'm sorry if I disappointed anyone by going with the kit that costs $135 rather than selling my lathe putting several hundred dollars with it and buying a Hardinge. No offence but I think that suggestion was ridiculous.
I have started a thread for documenting the build so any follow-up on this subject will be there.
Thanks for the tips guys.


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