ER32 collet chuck for lathe...

[John Hill]

ER32 collet chuck for D1-4 mounting...

One would think a suitable chuck would be readily available but I have failed to find one, they were available in the UK but not anymore, apparently.

Nothing to do but adapt something, so I started with a rather too large back plate:


IMGP9441 by aardvark_akubra, on Flickr
...the hole in the middle is too big for the mounting taper on the ER32 chuck so I carefully turned a shallow socket in the face plate to suit the outer diameter of the collet chuck.


Here is the chuck:

IMGP9444 by aardvark_akubra, on Flickr
... it looks nice enough, but take a closer look.  "Germany" is spelt with a "C"!

Because I was mounting this against the face I had machined on the back plate I turned up a stub of scrapbinium and mounted the chuck to that so I could take a skim off the rear surface, I was suprised at how much out of true that surface was.


IMGP9443 by aardvark_akubra, on Flickr


The big excitement of the day:

IMGP9445 by aardvark_akubra, on Flickr
... I am drilling holes to screw the chuck to the backing plate,  this was the first time I had used the pitch circle feature of my mill's DRO,  but I flubbed it somewhat.  The metal of the chuck was quite hard and although my pilot drill went right through OK the larger diameter drills wandered off and the hole positions are not accurate.

"Finished":

IMGP9446 by aardvark_akubra, on Flickr
...the DTI shows .008mm runout which I presume is "OK"?  I hope so as it was really difficult to get it that close, my bolt holes are out of place and I had to turn down the heads of the cap screws to get the necessary 'wriggle' room and the body of the chuck proved to not be concentric with the collet axis which meant my carefully machined socket in the back plate had to be enlarged.  The chuck is now located only by the set screws and I am wondering if I should be worried? Maybe I should put some Loktite under there?  Perhaps drill from the back and put in a couple of dowels?  Maybe not worry about it?

The back plate is rather big for the chuck, I have considered turning it down (that would be a big bin of iron shavings) or trepanning off the ring but thats a bit scarey at the point of break through. I think I will just tell myself that the big backing plate makes a handy handle for turning the spindle etc.

[Stilldrillin]

Nicely done, and shown, John! 

I like how you tell of the problems. The (slightly), out of position holes..... And the reduced screw heads, for wriggle room etc.
Not all of us admit to the necessary extra bodges......   

Don't reduce the backplate dia..... It might be needed for something else, in a few months time.........   

David D

[John Hill]

Nicely done, and shown, John! 

I like how you tell of the problems. The (slightly), out of position holes..... And the reduced screw heads, for wriggle room etc.
Not all of us admit to the necessary extra bodges......   

Don't reduce the backplate dia..... It might be needed for something else, in a few months time.........   

David D

David, I couldnt sit watching TV while it was out there incomplete so I went out and had another try at it.  I turned a step on the bottom of the chuck body so that I had a surface concentric with the collet and carefully turned the socket deeper to match, it fitted quite well and showed 0.008mm on the DTI with the screws done up and no other messing around, I think I can sleep soundly tonight!

The problem with that big backplate is that the excess metal looks like it might be concealing the rim of a big flywheel!

[Stilldrillin]

Don't reduce the backplate dia..... It might be needed for something else, in a few months time.........   
David D

The problem with that big backplate is that the excess metal looks like it might be concealing the rim of a big flywheel!

You were already ahead of me John! 

Suggest you trepann it off using the mill. Small dia endmill, and rotary table....... 

Sleep well!

David D

[John Hill]

The first time I tried to trepan something the piece fell free and moments later it was wrapped around the tool post, the chuck jammed and the drive belt squealing!  I have always kept the motor belt as loose as possible since then!

I trepanned a cast exercise weight by cutting almost through then going around with a cold chisel tapping it into the groove, the bits fell apart quite easily.  Yes, I did take it out of the lathe before starting with the chisel and big hammer.

[Stilldrillin]

Ouch!   

Me too, John....... 




It's a lot easier on the nerves, trepanning with the mill......



David D

[hopefuldave]

[quote

Don't reduce the backplate dia..... It might be needed for something else, in a few months time.........   
David D
 ]
The problem with that big backplate is that the excess metal looks like it might be concealing the rim of a big flywheel![/b]
[/quote]

How about drilling 60 holes around the outer face of the backplate and making up a sprung "finger" to bolt to the lathe bed/headstock, instant indexed chuck, 2,3,4,5,6,10,12,15,20,30 & 60 divisions when you need ;em....?

A second row would give you more choices?

Dave H.

[John Hill]

Good idea Dave, but what about the change gear indexing attachment I made for the lathe?  What about the expensive dividing head I bought for the new mill?  What about the the rotary table I bought for the mill?