ER Collets

[cfellows]

Any of you guys ever made an er collet adaptor for your lathe spindle? My Logan spindle is a 2.25" by 8" thread and I'm thinking I could make an er40 threaded adaptor for it. Seems like it ought to be more accurate than 5C collets. Or not?

Chuck

 

[BobWarfield]

I can't imagine it being more accurate than 5C. After all, if it was good enough for Hardinge, it's probably good enough for most anything.

ER's are nice for other reasons, mostly having to do with needing fewer collets hanging around. If you get a nice set of 5C's, I'd be surprised if you preferred the ER's, but to each his own. John Stevenson makes some nice products that let you use both (I think?), such as a spindexer. I always thought that was a very clever idea.

The downside of the ER's is the inability for stock to go all the way through the collet and be fed by unlocking the collet.

Cheers,

BW

 

[GrahamC]

The downside of the ER's is the inability for stock to go all the way through the collet and be fed by unlocking the collet.

Cheers,

BW

Actually, it depends on the design of the collet holder. If it is one of the common type with a morse taper on the end then you are absolutely correct - stock will go through the chuck to any appreciable depth. However, if the design of the holder is one that screws onto or bolts to the lathe spindle (such as these: http://www.bealltool.com/products/turning/colletchuck.php or this one http://www.arceurotrade.co.uk/Catalogue/Collets/ER-Collets-Collet-Chucks/ER32-Collets-Collet-Chucks about 2/3rds the way down the page) then stock any length of stock will go through the spindle.

I have one of the Beall chucks and it works very well. I got it for use on my Taig lathe. I also have 4mt style collet chuck for use on my larger lathe and I also have a 5c collet chuck for my larger lathe. I mostly use the 5c collets on the larger lathe now but the er32 collets do have their place especially on the Taig lathe.

cheers, Graham

 

[RobWilson]

HI Chuck see here http://www.homemodelenginemachinist.com/index.php?topic=5843.0
or here http://www.homemodelenginemachinist.com/index.php?topic=6115.0


Regards Rob

 

[cfellows]

Hey, Graham and Rob, thanks for the links, very informative.

Bob, I have a few concerns with the 5C collets. First, they are very limited on the range you can clamp in them. My set only goes down to 32nds. I would have to double it to go down to 64ths. Second, I have trouble getting the 5C collet closer to clamp the work tight enough. I probably need to insert a thrust bearing under the hand wheel I use to tighten the collets. Finally, and this is related to the first concern, as you close the collet, the outboard end closes faster and clamps harder then the the portion closer to the spindle. Not usually a problem except when the work is several thou smaller than the collet.

The thing I find attractive about the er collets, is that they close uniformly along the axis and clamp the work uniformly.

Having said all that, the er collet holder would be a lot of work to make (accurately) and the cost of a full set of er40 collets would not be insignificant.

Chuck

 

[bob ward]

There may be an idea or 2 here for what you are thinking of. This is a 5MT x ER32 collet holder with draw tube that I made a while ago, and the collets can be used as through collets. Feeding the stock and reclamping the collet is a lot slower than a 5C lever arrangement of course, but if you don't need the throughput speed and/or don't have any 5C stuff its just fine.

 

[shred]

I like ER's in a lathe for a lot of things, especially the clamping range. Without a dedicated ER chuck, I end up putting one of my 3/4" shank ER mill holders in a 3/4" 5C collet. That works ok, but as expected runout and through-stock can be a problem, but often its worthwhile anyway. Someday I'll make a real ER chuck-- the complicated part is in the nut, so the chuck is just an inside taper and metric thread.

 

[cfellows]

Thanks for the comments and ideas. Here is what I was thinking about to fit over the 2.25" x 8 threaded spindle. As far as the er clamping nut goes, I can buy those individually on Ebay.

I like the er40 because it can handle work up to 1" diameter. And, since my spindle hole is 1 3/8" diameter, this style of chuck will let me extend 1" rod back through the spindle.

 

[arnoldb]

Chuck, I can highly recommend doing what you propose.

I had pretty similar requirements though on a smaller scale - when I built my collet chuck. It was a bit of work, but very well worth it; in fact it is the chuck I use for the most part now. I can also recommend getting a closer nut with a bearing in for ease of use.

Regards, Arnold

 

[GrahamC]

Thanks for the comments and ideas. Here is what I was thinking about to fit over the 2.25" x 8 threaded spindle. As far as the er clamping nut goes, I can buy those individually on Ebay.

Excellent idea and yes, you can get ER clamping nuts conviently from a number of eBay stores and most any tool supply house - everything for ER8 on up. Had I known what I know now, I would never have bought the 4MT - ER32 collet chuck that I have, I would have bought the clamping nunt and made my own. I haven't quite figured out how to make a proper ER clamping nut with it's offset cam/lip (or whatever you want to call it) with the tools I currently have; maybe I will someday and just make one for the fun it.

cheers, Graham in Ottawa Canada

 

[cfellows]

Just found a 15 piece ER40 collet set with an R8 collet chuck, case and wrench on Ebay for $120 including shipping from a US supplier. Jumped on it so now, all I need to do is make the collet chuck for my lathe and the clamping nut from the R8 adaptor can do double duty between the lathe and the mill/drill.

I have a threaded spindle nose protector for my lathe that rare (never?) gets used. I might use that to start the collet chuck and weld a piece of steel on the front to machine the er taper and collar thread on. I'm a little skittish about trying to cut my own 2.25" x 8 internal threads.

Chuck

 

[Tin Falcon]

I'm a little skittish about trying to cut my own 2.25" x 8 internal threads.

Go for it man it is a learning experience I have the smaller cousin IIRC the 1 1/2 8 on my SB 9" I had to mod a back plate that came with the lathe and had to machine a second one (I cheated and had one of the Guys I used to work with make the dummy spindle nose just a little easier on a monarch IIRC the material that I used because it was available was a bit hard for the 9" to handle) I have since machined dummy spindle nose and back plates for a smaller lathe.
Just take your time and go easy at it especially when you make the dummy spindle nose. Then when you do the internal treads lots of light spring passes as you get close. You need a 1" boring bar any way right??
I hint here for the internal thread put the boring tool and internal threading tool upside down and feed from the head stock to the tail ,cut on the back side of the part that way you are not working blind. Feel less skittish now ?
Tin

 

[Cedge]

Chuck
I bought a full set of ER40 / R8 from Ebay seller 800watt and have been quite happy with the system. I only use it on my SX3 mill since the lathe is set up for MT3. Guess I ought to consider setting things up for the lathe as well. I'll have to do a search for the right taper adapter.

Steve

 

[bob ward]

I'm a little skittish about trying to cut my own 2.25" x 8 internal threads.

If you can single point external threads you can also do internals. Have a play, you will be pleasantly surprised by the results. Main thing is, that before you start threading you need to cut a runoff groove for your cutter which is just a little larger than the root of the thread.

 

[cfellows]

Tin - Guess I'll give it a go. I have some triangular threading inserts that I'll need to make an internal bar for. I have a length of 3" diameter aluminum and the same thing in brass. However, I'm thinking I want to make it out of steel or maybe cast iron. Any thoughts? Maybe 12L14?

Steve - Are you talking about the internal taper on your lathe spindle?

Bob - Thread cutting is always a struggle for me. I can do it, but I don't do it often enough to be very confident about it. I have a retracting tool post I made for external thread cutting. Guess I'll have to do the internal threads the old fashion way.

Chuck

 

[Cedge]

Chuck
Yes... the lathe spindle is MT3 while the Mill is R8. It didn't matter during the purchase since I was already tooled up for MT. Setting up to run R8 on the mill only required buying a couple of R8 arbors and the collets.

Steve

 

[Tin Falcon]

I made a threading stop for my south bend . A fairly simple affair but takes some of the worry and stress out of threading . One less thing to think about lets you concentrate on the more important stuff. Also when working away from the head stock there is less worry of hitting something if you do not react quick enough.
Tin