# Lathe ER40 Collet Chuck



## thestelster (Nov 6, 2022)

I love the ER collet system.  I have ER40 and ER11 for the milling machine.  I have a full set of metric collets and 8 Imperial collets (1/4"-1") for ER40 and full set of Imperial for the ER11.  I love the versatility so much, I used an old 10" 3-jaw chuck, ground the jaws to accept the shank of a straight shank ER40 collet chuck.  And it worked perfectly well for years.  Runout was good enough, a couple thou'.  But that chuck was heavy.  I'm no spring chicken anymore!  So I decide to get a 5C collet chuck.  What a mistake!  It's decent enough, Accusize, but the 5C collets are designed to use nominal round stock, within a thou' or 2.  That's fine if you've got drill rod, and doing production work, but when you do 2nd operation work, they won't work.  So then I got to take it off and put a different chuck on. PITA!!  

I decided to make an ER40 collet chuck for my lathe with Set-Tru style adjustability.  I already had a back plate, D1-5, which I was using for a different application, which I no longer use.  Previously I had welded up a  plate onto the back plate.  But because of the heat during welding, things warped a bit, quite a bit.  So I had to scrape the backplate face and tapered section to fit my spindle properly.


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## thestelster (Nov 6, 2022)

Next I had to make a mandrel which would hold the ER40 Collet chuck so that I can turn its body true with the axis of my lathe.  I couldn't use my tool post grinder because I had recently switched over to the Multifix QCTP, so I hadn't adapted the TPG yet.  The collet chuck is hardened, a file would slide across, barely grabbing, so I just turn the outside with my carbide inserts, and see what happens.  Especially since the collet chuck has two flats, so not only is it hard, its also interrupted cuts.  But it worked fine.


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## thestelster (Nov 6, 2022)

Next was to make the plate which would hold the ER40collet chuck, drill and counterbore.  Put the backing plate on the mill to drill and tap to accept the front plate.  I made the center bore and screw holes app 0.050" larger so that I have adjustability for dialing in run-out.


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## thestelster (Nov 6, 2022)

Next step was put the back plate on the spindle, and take a facing cut.  I used my carbide tooling and then checked the face, and it was slightly concave, 0.0006" over 1.5", which I thought would be ok.  Better concave than convex!  But I decided to use HSS to face it to see if there was a difference.  Yup!  0.0000".  So now to bore the center hole which will hold the collet chuck.  1" deep, almost 2" diameter.  Bored it out to 0.002" smaller, then used a round India stone to clean up the tooling marks, and then wrapped some 280 grit sandpaper to polish smooth.  It's now about 1/2 a thou' away.


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## thestelster (Nov 6, 2022)

I had previously drilled the front plate to accept a securing screw for the flat on the collet chuck to prevent it from spinning.  I forgot to make a dog point on the set screw, and there was no way I was going to take off the new collet plates from the lathe until everything was done.  So I used the milling machine.


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## thestelster (Nov 6, 2022)

So, we're still about a half a thou' from the exact diameter of the body of the ER40 collet chuck.  So, with a little bit of heat from the heat gun blowing on the face, while the lathe is spinning.  Of course I stopped and measured and the bore had expanded to about 1 thou' larger than the body.  Started the lathe back up, continued to use the heat gun for a little while longer.  Stopped, and inserted the collet chuck body being super carefull to go straight,  and quickly.  Pushed it all the way in, tightened the set screw, while rotating the collet chuck body, to make sure the set screw was fully seated properly to the flat.  Took  a small whack the the face with a wooden mallet to make sure the collet chuck body was fully inserted, and tightened the set screw.  Let everything cool down, chucked a gauge pin, and adjusted run-run out.  All is good.  I'm a happy camper.  This chuck will be almost permanently mounted on my lathe, until I need to chuck anything larger than 1"


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## Susquatch (Nov 6, 2022)

Wow, Lotta work on that ER40 system of yours..... But very nice job.

Didn't know you had a D1-5 too. I could have sworn you had a D1-6.

I should make something similar. Prolly ER32 though cuz I don't have ER40.

FWIW, I've managed just fine with C5 Collets on my Lathe using a Bison C5 Collet Chuck. Sorta like you said, a collet chuck is what lives on my lathe. I had the same problem you encountered when I first got my C5. The steps are just too big even with a wide variety of collets. So I use home made shims. Most are just slices cut from a pop can with tin-snips. For some reason popcans have great consistency.

I keep a box of shims beside the lathe and just use them as needed - all different diameters and thicknesses.

You will miss the C5s when you need to work on something long that has to stick into the spindle.

Think shims next time you do.


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## thestelster (Nov 6, 2022)

Susquatch said:


> Wow, Lotta work on that ER40 system of yours..... But very nice job.
> 
> Didn't know you had a D1-5 too. I could have sworn you had a D1-6.
> 
> ...


I bored out the ER40 collet chuck, to 1.050", so I can put any dimension up to 1" and any length!!

I'm still keeping the 5C collet chuck.  You can never have too many chucks!

Shims....you crack me up.


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## Susquatch (Nov 6, 2022)

thestelster said:


> Shims....you crack me up.



Dead serious. Works great. Thick Card Paper works pretty good too as long as it's consistent thickness.






My C5 collet set is not complete but it is pretty much every 32nd with a few 64ths thrown in for good measure.

Most pop cans, are around 5 thou, so 10 thou total. 1/64 is 15.5 thou. 1/32 is 31. So a pop can shim or two gets you tweeners. Never had one slip yet.

Try it!


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## Proxule (Nov 7, 2022)

Very nice, good detail, Hats off to you


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## PeterT (Nov 7, 2022)

Good job @thestelster 

Back when I got my 5C collet chuck setup, ER's were not quite as common for lathes & Set-Tru capability was even less common. Maybe that is still the case, I haven't checked. I blew my fun money on a euro Set-Tru 5C chuck & 1/64" incremental 5C set. The price of both has since gone through the roof. ER-40 spans 0.188-1.024" & wider range per collet. 5C spans 0.046-1.125" but takes a whole lot more collets to accomplish that. Shimming is an option as @Susquatch mentions. One downside is smaller diameters it becomes fiddly IMO. 5C also offers square & hex profiles which I thought would be useful additions, but in reality have never had enough need to justify purchase. 5C also offers ID holding profiles & blank/machinable (emergency) collets, again great work holding devices but comes at cost. At the time 5C plugged into spin indexers whereas ER was rare, but now I see them.

I guess its one of those tradeoff things, really depends on the work I suppose.


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## Dan Dubeau (Nov 7, 2022)

Your lathe has got a big dose of functionality lately, Nice job.  

IMO both collet systems have their place.  5c is great with a lever closer, and bar fed style, or 2nd op work.  ER is great all round general purpose 2nd op stuff with oddball diameters that would cause you to take out a 2nd mortgage to cover with 5c collets.  Er is certainly cheaper to get into for the coverage range than 5c.  The big downside to ER is the grip length.  You "need" to grip over the entire length of the collet in theory.  In practice you can get away with a little more than half, or even less but you're taking chances with accuracy.  2nd ops sometimes don't allow that, so you must back pack the collet which is a pita.  Also not being able to use hex collets, or make your own emergency collets.  See, you really need both .


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## thestelster (Nov 7, 2022)

Proxule said:


> Very nice, good detail, Hats off to you


Thank you.


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## thestelster (Nov 7, 2022)

I agree, and I do have both types of collet chucks.  And I also have have an ER11 straight shank collet chuck.  So I can chuck that chuck in the chuck so I can grip smaller parts.  I have an ER40 collet chuck on the mill as well, so the collets serve double duty.


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## Susquatch (Nov 7, 2022)

thestelster said:


> So I can chuck that chuck in the chuck



Sounds reminiscent of:

How much wood can a wood chuck chuck if a wood chuck could chuck wood. 

Repeat 15 times as fast as you can. No drinking allowed before, after, or during.


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## Dan Dubeau (Nov 7, 2022)

thestelster said:


> I agree, and I do have both types of collet chucks.  And I also have have an *ER11 straight shank collet chuck.* So I can chuck that chuck in the chuck so I can grip smaller parts.  I have an ER40 collet chuck on the mill as well, so the collets serve double duty.


I bought one of those a few years ago to make a toolpost grinder/drilling/milling spindle for the lathe from it.  It's currently sitting on my desk at work in the "where projects go to die" pile.  I'll get to it.  Someday.   In the meantime I've used it for holding tiny pins in the lathe, and tiny drills for long reach extended stickouts in the mill.  Might have to buy another one for the spindle lol.


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## thestelster (Nov 7, 2022)

Dan Dubeau said:


> I bought one of those a few years ago to make a toolpost grinder/drilling/milling spindle for the lathe from it.  It's currently sitting on my desk at work in the "where projects go to die" pile.  I'll get to it.  Someday.   In the meantime I've used it for holding tiny pins in the lathe, and tiny drills for long reach extended stickouts in the mill.  Might have to buy another one for the spindle lol.


Yes exactly!  Sometimes on the mill  using a 1/8th end mill, the ER40 collet nut totally obscures the line of sight.  Throw in the ER11 holding the endmill and perfect.  I also use it for holding 1/4" solid carbide boring bars on the lathe.


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