Set true ER32 collet chuck for my SB wide 9

mattthemuppet2

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Next up on the list, an Er32 collet chuck for my South Bend.

I bought an 80mm er32 chuck off Amazon so that the current lack of metric threading on my lathe didn't hold me up. Also got a cheap HHIP cast iron back plate to cut up.

Started with the back plate,
IMG20230515154216.jpg
trepanned out the bit I wanted
IMG20230515155212.jpgIMG20230515155418.jpg
Faced and bored
IMG20230517124245.jpg
Badly threaded, thread gauge fits but won't fit on the spindle:(
IMG20230517150930.jpgIMG20230517151030.jpg
 
Well crap to that, so a quick rummage through the scrap pile found a piece that was almost exactly the right diameter and plenty long enough
IMG20230517152651.jpg

So, get started with that :) Don't know what material it is, but it's a little tough to cut and produces a BEAUTIFUL finish without much effort. Mid carbon steel I guess.
IMG20230517171723.jpg

Turned and faced
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Lots of beautiful blue and purple stringsIMG20230517174302.jpg

More in a bit, got to get on a flight
 
Drilled a 3/8 pilot hole, then a 1-1/8" biggieIMG20230517181105.jpg
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Threading went a lot better this time (no pics unfortunately). Spindle gage fit
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and then I flipped the chuck around and tested fit on the spindle itself.
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It fits!IMG20230517192927.jpg

I later figured out the mismatch between the gage and the spindle was because I had the compound set at 60.5 degrees, doh!
 
Next up on the list, an Er32 collet chuck for my South Bend.

I bought an 80mm er32 chuck off Amazon so that the current lack of metric threading on my lathe didn't hold me up. Also got a cheap HHIP cast iron back plate to cut up.

Started with the back plate,
View attachment 448517
trepanned out the bit I wanted
View attachment 448518View attachment 448519
Faced and bored
View attachment 448520
Badly threaded, thread gauge fits but won't fit on the spindle:(
View attachment 448521View attachment 448522
That's a shame. Do you know what went wrong with your internal threading in the cast iron? I machined a back plate from scratch and amazingly it came out ok, despite myself. Must have been beginners luck. I used a left handed bar and threaded away from the chuck.
 
Parted off the excess and turned the back plate down to the final size. The stub is 1/4" high and around 10 thou smaller than the id of the chuck
IMG20230518155719.jpg
Then I realized I couldn't get the back plate off the spindle (doh! #2), so made a C spanner (or flogging spanner as they call them in Oz!)IMG20230518161936.jpgIMG20230518210429.jpg
It worked!
IMG20230519130107.jpgIMG20230519130120.jpg
 
I take it that your original CI can't be salvaged? Cast iron absorbs vibration better than steel, so it would make a better back plate.

I later figured out the mismatch between the gage and the spindle was because I had the compound set at 60.5 degrees, doh!

Here's where the "measure twice, cut once" phrase comes into play!
 
Parted off the excess and turned the back plate down to the final size. The stub is 1/4" high and around 10 thou smaller than the id of the chuck

The diameter of the stub should be almost exactly the same size as the ID of your mating chuck. Any extra will lead to excessive runout.
 
That's a shame. Do you know what went wrong with your internal threading in the cast iron? I machined a back plate from scratch and amazingly it came out ok, despite myself. Must have been beginners luck. I used a left handed bar and threaded away from the chuck.
Two reasons - one big one was that I had the compound set to 60.5 degree. It later clicked that the thread slopes weren't symmetrical because I had the compound set wrong. Even worse, I learned that I can't set the compound to 29.5 internal the way I had it, as the cross slide bolt gets in the way.

Second, the cast iron was crap. I couldn't get a clean thread, even with sharp for alu inserts. I was planning on remaking it anyway, I just got a kick start on the process when it didn't fit :)
 
I take it that your original CI can't be salvaged? Cast iron absorbs vibration better than steel, so it would make a better back plate.



Here's where the "measure twice, cut once" phrase comes into play!
It probably could, but the material wasn't very good so it didn't seem worth the effort to pick the threads up. I hear you in the measure twice thing. First time I've done id threading on this lathe and I didn't realize you can't swing the compound round far enough on the back side to get 29.5deg. it has to be swung to the front towards the chuck
The diameter of the stub should be almost exactly the same size as the ID of your mating chuck. Any extra will lead to excessive runout.
You'll just have to wait and see (or read the title :) )
 
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Now to work on the chuck side of things. I needed to drill and counterbore 4 holes for M6 bolts plus some wiggle room
IMG20230519154707.jpgIMG20230519174504.jpg
Then drill and tap four 10-32 holes around the circumference of the chuck for set screws
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Got a great education on using my new to me rotary table :)

Then drill and tap four M6*1 holes in the backplate (actually fine between the second and third pic above to avoid disturbing the set up)
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And finally drill four #11 holes in the circumference of the chuck so I can hold it without screwing up the set true adjustment
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Spent some time with a 0.625" gage pin and a dti and got it within a half a thou. I need to open up the front bolt holes and counterbores a little just to make sure the bolts are not being constrained.

I think it looks rather pretty
IMG20230521161633.jpgIMG20230521161639.jpg
 
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