The Retractor

[MrWhoopee]

Well, here we are about a year and half later and today was one of the first times to really use this retractor in a project. I had two sets of threads to cut in mild steel and the first one went perfectly. The second one was a fluke probably due to my pushing the limits of how close to a shoulder this can release. Long story short, on one of the last passes the release tripped as usual but the turning coasted just enough to slam a burr that accumulated at the end of thread onto the insert. I was crowding a shoulder too closely to let it coast and clear the end of cut burr each time. The carbide bit kinda exploded. No other harm done. I'm still proud of the threading job it did.

I do not know inserts and how to identify them, so I need help finding replacement inserts for this. It doesn't seem to be indexable. Help?

DanK

Glad to hear a report, yes timing close to a shoulder can get dicey. The insert is a 16ER-AG60, and it has 3 edges. I've been getting good results with inserts off Aliexpress for around $1 per in packs of 10.

 

[Dan Krager]

Thank you Mr. Whoopee. Imma stamp that on the shank!

Examining the insert before the mishap, for the life of me, I couldn't see how the insert I had was 3 points. One was rounded, and the other presented a point with one side perpendicular to the axis of the lathe. It didn't matter in the end because the insert was shattered into about six pieces! My bad.

DanK

 

[MrWhoopee]

Thank you Mr. Whoopee. Imma stamp that on the shank!

Examining the insert before the mishap, for the life of me, I couldn't see how the insert I had was 3 points. One was rounded, and the other presented a point with one side perpendicular to the axis of the lathe. It didn't matter in the end because the insert was shattered into about six pieces! My bad.

DanK

Did it crash into the shoulder? I've had mine fail to retract when taking an aggressive cut on a fairly coarse thread (10 tpi). I believe that a heavy chip can "trap" the tool due to the positive rake of the insert.

 

[Dan Krager]

No, it didn't crash into the shoulder even though it was mere thousandths away. What did it in was that I was using a stop to trip the retraction so it retracted in exactly the same spot each time. At the instant that happened, I stopped the lathe mid cut so each pass built up a chip instead of exiting the cut creating a ramp. On the last pass, I was not quick enough and the built up chip slammed into the cutter. I was stopping and reversing the lathe instead of opening the thread feed at end of cut.

Now I am confused. In the search for the 16ER-AG60 insert I found this listing which pictures the exact "insert" that was in the tool holder. Note the listing describes it as an insert shim. Should I have installed an insert atop this instead of using it to cut the thread? If so, another newbie mistake.



As in something like this?



DanK

 

[Dan Krager]

Yes, I was using the "shim" as the cutter! Doh. But it worked just fine on several threading ops.....
I know that stopping the lathe and reversing without disengaging the thread feed is not necessary on UNC threads, just metric. So the mishap was a result of a tsunami of events that worked against me. That was due to inexperience and lack of appropriate protocol. So that is part of learning without a tutor.
DanK

 

[WobblyHand]

Yes, I was using the "shim" as the cutter! Doh. But it worked just fine on several threading ops.....
I know that stopping the lathe and reversing without disengaging the thread feed is not necessary on UNC threads, just metric. So the mishap was a result of a tsunami of events that worked against me. That was due to inexperience and lack of appropriate protocol. So that is part of learning without a tutor.
DanK

If your lead screw has backlash, (they all have some, some more than others) it may cut on the way back. Not recommended to keep the cutter in on reverse.

 

[extropic]

Dan,
Based on what I've read here, you're REALLY going to like the way the tool works when you get an insert on top of the shim. LOL
Don't forget to reset the height of the toolholder so the cutting edge is at (but not above) the lathe spindle axis.

 

[RaisedByWolves]

No, it didn't crash into the shoulder even though it was mere thousandths away. What did it in was that I was using a stop to trip the retraction so it retracted in exactly the same spot each time. At the instant that happened, I stopped the lathe mid cut so each pass built up a chip instead of exiting the cut creating a ramp. On the last pass, I was not quick enough and the built up chip slammed into the cutter. I was stopping and reversing the lathe instead of opening the thread feed at end of cut.

Now I am confused. In the search for the 16ER-AG60 insert I found this listing which pictures the exact "insert" that was in the tool holder. Note the listing describes it as an insert shim. Should I have installed an insert atop this instead of using it to cut the thread? If so, another newbie mistake.

View attachment 448842

As in something like this?

View attachment 448843

DanK

That's funny, but you're fortunate to be starting out now with cheap inserts VS back when as at that time inserts were $10-15 each!

I've seen people use the hard shim in a pinch before, so not too bad for a rookie.

 

[Shotgun]

If your lead screw has backlash, (they all have some, some more than others) it may cut on the way back. Not recommended to keep the cutter in on reverse.

From my experience, it won't cut at all on the way back. It will break off the tip of the insert or rip the insert out of the holder. There won't be anything close enough to the material to cut it.

 

[Just for fun]

I'm pretty sure mine doesn't use the insert shim, just the insert. I'll swing by the shop after while and check it out.