Lead Screw Problem - Craftsman 6”

Yeah, I was thinking lead screws as in screws that drive movement (compound and cross) compared to feed screws for threading. The Atlas has one screw for both purposes on the carriage, except the carriage is moved by the handwheel and fed by the feed screw... but it's also a lead screw because the names are somewhat interchangeable depending on who you ask and how many drinks they've had. So disregard anything I said about lead screws, none of that will apply to your feed screw. If you buy the correct threaded rod for your needs, you can still work the ends of the rod as needed on your lathe because the spindle is hollow. Custom precision Acme rod is available for an attainable price in the US. I feel your pain on shipping, I lived overseas for 10 years and had hobbies then, too.
 
Yes your leadscrew is worn out- that's what mine looked like. Not sure about the half nuts but they are probably worn too.
My feeling is that the screw on these lathes should be used mostly for threading; using it frequently for feeding wears it and the nuts much too quickly.
-Mark
 
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Thanks everyone.

Yes that was a typo on the middle number. It’s 101.21400.

I’m glad the consensus is that is worn out. Not that I want to spend the money but I didn’t want to replace parts that were still serviceable.

I got everything taken apart tonight and the rest seem good. I wasn’t able to remove the pin that holds the collar on but from the looks of the replacement part that collar is already installed.

I don’t think there is anything else I need to order form them but the half nuts and the screw. But I will double check before ordering from Clausing.

Has anyone ordered the screw from Clasuing? Just wondered if there is anything I needed to know about it.

I agree and can see the problem using it for feeding as opposed to threading. My thought had been it’s really only good for a final very light finish in pass if used for feeding.

I do remember seeing something someone rigged up with a second screw below it that ran off a drill for feeding so as to not wear out the screw.
 
Voda2000 said:
I wasn’t able to remove the pin that holds the collar on but from the looks of the replacement part that collar is already installed.
Click to expand...

Is this the collar that would not come off? If so, I had the same problem. I destroyed two pin punches and burned a bottle of gas trying to get it free.
collar_north_small.jpg

My lead screw should probably be replaced, as well. I believe I'm going to have to try to drill out pin or cut the collar off with a Dremel if/when I get there.

Craig
 
According to the later 6" parts lists, the lead screw and left-end collar are not available separately. Unlike the 9", 10" and both of the 12" model groups, the 6" lead screw should only be removed to the left. In other words, you do not need to remove the left hand collar in order to remove the lead screw. And spending any time removing the left hand collar would be time and effort wasted. Note, however, that this only applies to the various 6" models.

The half nuts wear more quickly than the lead screw. Especially if you or a PO installed brass ones. Therefore, unless you happen to know that the half nuts have been recently replaced, if the lead screw needs to be replaced, so do the half nuts.

Also, if any of you do the replacements, and follow the standard lubrication instructions, it is highly unlikely that you will live long enough to ever need to do it again. And that is assuming that you don't fall victim to hysteria and cease using the lead screw for routine turning.
 
Hi Craig, ya that’s the one that I couldn’t get off, mine is completely flush. As was pointed out there really isn’t any reason to. The only thing I discovered was I didn’t have enough clearance to the left of my lathe to slide it out so I just unscrewed the bearing from the bed and then took it apart on my bench.

Hi Wa5cab, thanks for the confirmation. I have no idea how old they are (wouldn’t surprise me if original) but I’ll order both the new half nuts and lead screw. Thanks!
 
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Got the new lead screw and half nuts last night. I’ll start the assembly this weekend. Any tips or anything I need to know about putting this back together?
 
Well just to close this up, I finished the install. The replacement parts made it quite clear how much wear was on the old parts.

A couple of words of caution. The new collar on the lead screw is slightly thicker than the original. It doesn’t seem like a big issue initially but when you looks at how close the gears run to it, it can interfere. I chucked it in the lathe and faced it. I don’t remember how much I took off exactly but it was in 0.020-0.030” range. I also had to shorten the the shaft by that same amount to make sure the bolt in the end would snug up again the gear.

I also noticed the bolt in the end of the lead screw had been replaced at some point with one that was too long and they used a stack of washers to make it work. I just shorted the bolt and it worked fine.

Once it wall all reassembled it runs great. Thanks everyone for the help.
 
If the bolt in the end of the shaft (when shortened to the proper length) could draw the gear and keyed spacer up tight against the collar before you took a little off of the collar left face, then you should have thinned the collar from the right face instead of the left.

I would suggest that you call Clausing and report the collar thickness error.
 
I don’t think I explained it correctly. This thread is someone who had a similar problem: https://www.hobby-machinist.com/thr...-atlas-craftsman-6-lathe-from-clausing.32498/

The problem comes down to the clearance between the gear in the photo I’m pointing to and the collar

image.jpg

You are right that if I took some off the right side I may not have had to shorten the end for the bolt but I’m not 100% on that as I didn’t measure it to start with. I seemed easier to take some off the left side when it was in the lathe but I’m new this and I’m sure it could be done the other way. And honestly I didn’t consider that the end would need to be shortened too when it took some off the left side. Live and learn. :)

Regarding Clausing, I’m just happy I could get a part and if I have to do a little fitting to get my clearance right so be it. It’s also a succeeded part number so that may have something to do with the discrepancy in the thickness.

I appreciate the feed back. I did get some practice “fixing it” so I’m a making small steps in my machining knowledge.
 
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