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Accusize 5" 3-Jaw Chuck Fitting
- Thread starter ChazzC
- Start date
- Joined
- Jan 4, 2021
- Messages
- 3,305
Finally Had a Project Where I Needed My 5" 3-Jaw!
Most of what I have been doing lately has used the ER32 collet chuck, but while taking photos for an upcoming post about my Sherline RT & tooling, I realized that the threaded adapter – 1"-8 male to 3/4"-16 female (3/4"-16 is the Sherline standard, but I got a 4" self-centering 4-Jaw from TAIG 3 years ago ($20!!) that had a 1"-8 back and wanted to use it on the RT) – didn't fully engage on the Sherline mount due to the 3/4"-16 female threads being recessed about 1/4".
No problem, just chuck it up and face off 0.200". Not with the 4" 3-Jaw: center hole won't take the 1"-8 portion, and I wasn't going to hold the adapter by the threads. Yes, I do have a 25mm ER32 collet, but 25mm is its absolute max. Fortunately, the 5" 3-Jaw will pass 1.180", so I mounted the chuck on my 7x16 Mini-Lathe, inserted the adapter, using three 1/8" dowel pins to space it off the face of the chuck (remembering to remove the pins after the jaws were snug), checked that the face was square and proceeded to face:
Generic DCMT 21.51 Insert, 1,650 RPM, 0.015" DOC, hand feed = lots of blue chips; I used a HSS bit to chamfer the ID & OD. The vacuum helped, but I needed the auxiliary shield to keep from burning the backs of my hands as I was advancing the cross slide. Overall, I'm pretty pleased with the results:
I used my Scotch-Brite (-ish) deburring wheel to clean up the wrench flats on the end of the adapter:
Yes, a lot of stick out, and I wouldn't run it on a Sherline (or TAIG) lathe, but it will be fine on the RT. And if I get up the courage to single-point a 1"-8 thread on an MT3 arbor I could use it in the Mini-Lathe without the adapter.
Most of what I have been doing lately has used the ER32 collet chuck, but while taking photos for an upcoming post about my Sherline RT & tooling, I realized that the threaded adapter – 1"-8 male to 3/4"-16 female (3/4"-16 is the Sherline standard, but I got a 4" self-centering 4-Jaw from TAIG 3 years ago ($20!!) that had a 1"-8 back and wanted to use it on the RT) – didn't fully engage on the Sherline mount due to the 3/4"-16 female threads being recessed about 1/4".
No problem, just chuck it up and face off 0.200". Not with the 4" 3-Jaw: center hole won't take the 1"-8 portion, and I wasn't going to hold the adapter by the threads. Yes, I do have a 25mm ER32 collet, but 25mm is its absolute max. Fortunately, the 5" 3-Jaw will pass 1.180", so I mounted the chuck on my 7x16 Mini-Lathe, inserted the adapter, using three 1/8" dowel pins to space it off the face of the chuck (remembering to remove the pins after the jaws were snug), checked that the face was square and proceeded to face:
Generic DCMT 21.51 Insert, 1,650 RPM, 0.015" DOC, hand feed = lots of blue chips; I used a HSS bit to chamfer the ID & OD. The vacuum helped, but I needed the auxiliary shield to keep from burning the backs of my hands as I was advancing the cross slide. Overall, I'm pretty pleased with the results:
I used my Scotch-Brite (-ish) deburring wheel to clean up the wrench flats on the end of the adapter:
Yes, a lot of stick out, and I wouldn't run it on a Sherline (or TAIG) lathe, but it will be fine on the RT. And if I get up the courage to single-point a 1"-8 thread on an MT3 arbor I could use it in the Mini-Lathe without the adapter.
Last edited:
- Joined
- Jan 4, 2021
- Messages
- 3,305
Fix One Issue & Create a New One!
Was very pleased with how the adapter turned out, and it fits on the rotary table much more securely. However, I created anotherproblem opportunity: in reducing the unthreaded portion of the 3/4"-16 hole, I also reduced the width of the wrench flats. I knew that was going to happen, but thought I had a thin open-end or adjustable wrench – wrong. I can get my thin-ish adjustable in just enough to break the adapter free, but it's not good.
I figured I'd have to buy a thin open-end wrench, but like everyone one on the Forum I dislike acquiring tools. I checked and found that I have a pin C-Wrench that would work, so over to the Mini-Mill, clamping the adapter by its flats and placing an adjustable parallel on the other side of the vise to balance the pressure. Then put a jack under the 1"-8 end to provide support during machining:
Centered the adapter using a 10mm edge finder:
This edge finder has a ceramic tip and is the only one I have that would reach; I could have centered using the jaws, but didn't trust that the slots were equal (and ended up just rotating the adapter to do the other hole without checking that it was still centered).
After moving back 15mm from the end of the adapter, I milled a flat using a 2-flute 3/16" end mill:
Spotted the hole:
Then drilled 3/16" x 4mm deep to accept the pin wrench:
Spotting before drilling was overkill as the 3/16" stubby drill bit is shorter than the spotting drill. I rotated the adapter in the vise and skipped spotting on the other side, just milling a flat. Deburred and cleaned the adapter up, and now it's done:
Was very pleased with how the adapter turned out, and it fits on the rotary table much more securely. However, I created another
I figured I'd have to buy a thin open-end wrench, but like everyone one on the Forum I dislike acquiring tools. I checked and found that I have a pin C-Wrench that would work, so over to the Mini-Mill, clamping the adapter by its flats and placing an adjustable parallel on the other side of the vise to balance the pressure. Then put a jack under the 1"-8 end to provide support during machining:
Centered the adapter using a 10mm edge finder:
This edge finder has a ceramic tip and is the only one I have that would reach; I could have centered using the jaws, but didn't trust that the slots were equal (and ended up just rotating the adapter to do the other hole without checking that it was still centered).
After moving back 15mm from the end of the adapter, I milled a flat using a 2-flute 3/16" end mill:
Spotted the hole:
Then drilled 3/16" x 4mm deep to accept the pin wrench:
Spotting before drilling was overkill as the 3/16" stubby drill bit is shorter than the spotting drill. I rotated the adapter in the vise and skipped spotting on the other side, just milling a flat. Deburred and cleaned the adapter up, and now it's done:
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