A small 5” 6-jaw chuck converted to a 6-jaw adjust-tru chuck

[Tim9]

I’ve been wanting an Adjust-Tru chuck for a while. But I just can’t justify spending as much as 500.00 for a used Buck adjust tru.
So I decided to buy a small 5” 6-jaw Asian K-13 125mm chuck. It’s a Sanou chuck. I then mounted it to the new L00 6” backing plate. That left me with about a 1/2” overhang of backing plate to which I mounted my set tru ring. It’s an exterior set up instead of the traditional set tru.

The ring was trimmed from a 6” steel tube I had picked up from eBay a while back.

 

[Tim9]

I then drilled the ring to accept eight 10-24 socket head screws. Also spaced at 12 o’clock, 3 o’clock, 6 o’clock and 9 o’clock I drilled and tapped 3/8”-24 set screws which are the set tru adjustments.

 

[Tim9]

Then I mounted the ring to the backing plate by drilling & tapping the 10-24 screws. FWIW, THE chuck had already been mounted to the backing plate in the normal way you mount a new backing plate. A backing plate without any set tru stuff. So it’s centered so to speak. And the ring was mounted with a feeler gauge to center it. That little brass piece is a drill guide I made which assisted me getting the socket head screws to fit perfectly into the ring.

 

[Tim9]

Lastly, I trimmed the backing plate…. Removed the chuck from the backing plate and cut the part of the backing plate which had fit snugly into the plain back chuck. This had to go so the chuck can move back and forth using the set screws. I also removed the set screws and turned the inside of the ring because it wasn’t perfectly centered. It was close… but I had to take about 12 thousandths off to make a centered ring.

I also put it on the mill and used a 1/2” round nosed end mill so I could get the wrench into the chuck. All in all it came out pretty good.

The Sanou chuck was 119.00 on EBay. It was out a little over 3 thousandths. I think one of the jaws needs to be trimmed. I’ll probably go ahead and grind that at some point.
That said, with the set tru ring…. I am getting it down to 1/2 of a thousandth. So it’s all good.
The backing plate cost me @89.00 from CME equipment. This is probably the 5th. Backing plate I’ve purchased from them. I’m happy with every one of them and CME has great service.

 

[brino]

Great work Tim.
Thanks for all the photos!
Brian

 

[Aukai]

That was a lot of work, nicely done.

 

[DavidR8]

Fantastic work!