New to me: Craftsman 101.27440 lathe.

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L6-38 was only used on three models, 101.07403, 101.27430 and 101.27440. The 3996 (final 12" model built) uses 10D-38. If you look at the parts lists for 101.07383 back to at least 101.07381, you will see 10D-38. The reason that the flat isn't visible on the drawing of L6-38 is that it would be hidden by the disk on the inner end of the scroll. But why your machine has 10D-38 in it instead of L6-38, I have no idea. As you discovered, without the flat, you can never engage the cross feed with the plunger installed. It's even possible that an unscrupulous PO installed the wrong scroll so that a buyer couldn't engage power cross feed and discover that it did not work. As to why the sheared off key left no sign, if it happened long enough ago, it could be worn smooth.

Yes, if the tumbler is set to run the carriage toward the headstock, it will back the cross slide out toward the operator untill the cross feed screw backs out of the nut. As I said some time ago, the later 12" machines do not have the interlock. My guess is that whomever was at Sears in 1939 who insisted on the interlock had probably either retired, gotten fired, or died by 1957 when the new 12" was being designed. o_O
 
Hello everyone and thank you for replying to this post, again. LoL

Robert, I got the feeling that you are probably correct about the miter gear. I remember telling you in one of our PM's, that when I was taking the carriage assembly apart. That I noticed the miter gear (10F-83) was stuck and did not move. And I mentioned it to you because I couldn't get it out to clean it. We ended up figuring it out and I was able to remove the stuck miter gear and clean it. And now it is working fine. But that was most likely the problem, and because of it being stuck it probably snapped the internal key in the (10F-82A) miter gear a long time ago.

As for the Scroll, I decided not to mill a flat on the round area for the Plunger to drop into. Though I really didn't want to cut the end off the Plunger. It was easier than trying to remove the Plunger from the apron. Because I would have had to remove the pull knob for the cross feed and I didn't have a drive pin small enough to punch out the little pin that holds the knob. I just thought it would be easier to cut the end off the Plunger. And yes I kind of regret it now, but I can always make a new one when I get the Lathe running. LoL

And the reason I have a (10D-38) instead of the (L6-38). Who knows at this point with the Lathe being so old. One thing I did find was a old receipt from back in the 70's. Whoever owned the Lathe at one point bought new half nuts (10F-12) and a (10F-36) cross feed slide screw and a (10F-19) carriage slide nut. Now I know that the (10F-12) half nuts need replacing every once in awhile, so that is a good thing. But what has me wondering is the purchase of the (10F-36) which is the AMCE screw for the carriage cross feed. The other part, the (10F-19) would be a replacement nut for the (10F-36) cross feed screw. So something must have happened that might have been pretty bad or they just wore out to have them replaced? Again, who knows what might have happened that long ago.
 
True. Although I have seen people replace the cross feed screw and nut and then complain that that didn't fix the backlash problem at least in part because they didn't understand the system. Any time that you think that the screw and/or nut need replacing, you should first crank the cross slide nut off of the screw and measure the screw and crank end float. This should be about .001 to .003". Then pull the cross slide back against the end of the screw and crank it back to the area in which it usually runs. Then measure the backlash using the dial on the screw. anything under 0.010" is OK. New parts would not improve it significantly. Plus as a practical matter, if you get used to the practice of never approaching the position for OD turning or threading by turning the crank CCW, backlash doesn't affect accuracy anyway. It's just annoying.

Also, the half nuts don't wear out that fast, unless maybe if you are only using the machine for grinding. I bought my 3996 in January, 1981 and although I already bought a replacement set, I haven't yet changed them.
 
Hey Robert,

Now that you mention it, when I bought the mill and lathe. I got several cigar boxes full of miscellaneous tooling. But in particular was a couple of boxes of grinding wheels. That at the time I didn't know what the previous owner had been using them for. Now you got me wondering if the previous owner was using the lathe for grinding on something? I was told by the person who sold me the mill and lathe that the previous owner was a old gunsmith. And I don't know anything about gunsmithing, so it kind of makes me wonder what the guy would need grinding wheels for?

Maybe someone can enlighten me on this gunsmithing and why the use of grinding wheels?

And about the replacement parts for the carriage assembly. I didn't realize that the parts on the receipt I found were to the cross slide. I looked at the receipt a couple of times and knew about the half nuts that they ordered. And just figured that the screw and nut were just that, a screw and nut. Until last night when I was looking over the receipt again and looking at the PDF file. Figured I would see what this screw and nut really were and where they went. To my surprise they went to the cross slide!!! And Robert, you are correct that the cross slide on my Lathe does not have any backlash.

And the half nuts, yes they look brand new. Like they have never been used before. I thought it was kind of weird that the whole Lathe was covered in grease and saw dust. But the half nuts were completely clean with no wear on them when I started taking the lathe apart.

And on a parting note, I finally got the Lathe together last night!!! Now I don't have the motor on yet, but I might get that done tonight. After I get the motor on then I need to start thinking about getting a link belt. I already know what you guys are going to say about link belts. But I have a couple on my Atlas horizontal milling machine. And so far I don't see any unusual wear on the pulley system. But then I only have about 8 to 10 hours of run time on the mill. LoL

Thanks again everyone for all your help, it is truly appreciated!!!
 
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