Craftsman 618 Half Nuts Disengage While Auto Feeding

I wouldn't have thought a worn leadscrew would cause such large diameter changes when turning (cutting)- I wonder what the
explanation for that phenomena is?
Alas, Ebay is risky but my old screw was really, really bad and the replacement is nearly like new
Mark
 
I have to toss in here that Zamak half nuts, other things being equal, will outlive brass ones. I bought a new set from Clausing a couple of years ago but upon examining the originals (and they are originals, my 3996 is a one owner lathe), I had to conclude that they didn't need replacement yet.
 
I found a decent lead screw on eBay (apparently). The ad says it's like new and I messaged the seller and had him measure it. He says it's .4995" and for the entire length it doesn't vary more than .001". Here's hoping it works! I'll keep you all posted.

An unrelated note, I'm now selling a worn lead screw. :)
 
Just to close this thread out, I got the lead screw and the seller was correct and honest that the lead screw is in good shape. I also measured his same measurement. Installed the leadscrew just now and it works without issue. No popping out.

I did a few boring passes on my aluminum part taking up to .020" and it went nice and smooth. Speaking of the depth, is that too much for my lathe? Other than the motor power, what determines max depth? If my lathe does the pass and finish is acceptable is that ok? Do these little lathes wear out more and it's advised to use light cuts?

Thanks for all the help, much appreciated.
 
On a small lathe like the 6x18, excessive cuts will severly stress the tool post, compound, and cross slide. Early on, I used the lantern tool post and had broken the tool holder. Later on, Clausing sold a tool holder which was much stronger but that just transfered the stress to other parts. Deep cuts are hard on bearings and the lead screw, if you're using power feed. Deeper cuts are also more prone to chatter. As you use your lathe, you will get a feel as to what is an acceptable depth of cut. It will vary with material and with the cutting tool being used.
 
RJSakowski said:
On a small lathe like the 6x18, excessive cuts will severly stress the tool post, compound, and cross slide. Early on, I used the lantern tool post and had broken the tool holder. Later on, Clausing sold a tool holder which was much stronger but that just transfered the stress to other parts. Deep cuts are hard on bearings and the lead screw, if you're using power feed. Deeper cuts are also more prone to chatter. As you use your lathe, you will get a feel as to what is an acceptable depth of cut. It will vary with material and with the cutting tool being used.
Click to expand...

Ok, I figured my question wasn't able to be imperially answered. All that makes sense and I guess I'll just have to gain more experience and comfort.

Thanks for the reply, RJ, I really appreciate it.
 
Unfortunately, I have no experience with the 618 so can't give typical DOC (Depth Of Cut) figures versus material. One of the 618 owners will have to give that.

I do know that chip size/shape varies with DOC. If you are bothered with long curly-ques, if you can increase the DOC they will tend to break off more frequently.
 
I don't know much about the model 618, but does the lathe have a clutch mechanism that disengages if it sees high torque on auto-feeding?
 
You must log in or register to reply here.
Back
Top