Would You Say This Is Just Worn Or Worn Out?

[great white]

I've been cleaning and working on my 10F. I've finally gotten everything freed up, oiled and moving fairly smoothly.

Now I have questions about my lead screw and my cross slide.

First, the lead screw. Here's a pic close up by the headstock:



Probably the same as the day it was cut.

Now, closer to the center:



Would you say that's acceptable wear or should it be replaced? If I don't replace it, is it going to have a negative effect? I would assume it would only make a significant difference in the leadscrew when/if I cut metric as I can't disengage the half nuts? I would think just turning stock the backlash will just be taken up when I start the cut?

Next, the cross slide. No pics, but it has a backlash of 50 on the spindle dial, which I take to mean 50 thou. Is that too much? Seems pretty loose. I can grab the compound slide and "click" the cross slide back and forth. The ACME threads looks pretty good, I'm assuming it's the nut int he carriage?

Thoughts welcome.

 

[pdentrem]

First on the crossfeed. The brass nut is worn a fair bit. There are temp fixes, like partly cut the nut and use a small screw to wedge the nut either apart or close it up a bit to help remove the backlash. It is not a hard part to make, either cut the internal thread single point or make a tap to do the job. Since it is made of brass the tap does not have to be hardened to make it work. Not expensive to buy a new nut but not cheap either!

On the lead screw. You might see some error over a long long thread but how many times will this occur?
Replace $$$$$. Make a new one from a Roton leadscrew stock. There is a posting on this on the site. Flip the leadscrew end for end by cutting off the ends and putting it back together. Now the worn part is at the tailstock end. Mine was worn much more than yours and I replaced it eventually.
Pierre

 

[T Bredehoft]

I gotta admire your re-purposing the dental pick in your second image. I've often wished I had a short supply of them.

 

[great white]

I can usually pick them up in bulk at princess auto (kind of like harbor freight).

I use them everywhere, but they seem the most useful when working on the car for picking up nuts/washers and getting into tight spaces.

 

[george wilson]

There are 3 or 4 different levels of precision that you can buy in acme threaded rod. The more accurate,the more they cost. You probably don't need the most precision variety unless you're doing a some special work using LONG screws. MSC sells these Acme threaded rods.

Turning the leadscrew end for end is also a common option. Needs some machining to do that. But,you can feed the lathe manually to do it if necessary.

As stated though,unless you are making long threads,your present lead screw will be just fine. How many threads over 2" long do you ever make?

Wear on the V ways is the most important factor. On South Bends,a little vertical "cliff" will develop on the top of the V ways when they are getting pretty worn. This happens because on South Bend lathes,in the carriage's V's,there are little "keyways" cut into the tops of the V's. As the bed V ways on the bed wear,they are "Sinking" into those keyways. Hope this makes sense.

 

[NightWing]

This is a common wear issue with machines that use the same feed screw for threading and carriage drive. You could thread all day long for many years before the screw would wear like that. Higher priced machines only use the lead screw for threading. Carriage drive is from a separate unit.

 

[Wreck™Wreck]

I had a Clausing lathe that had wear on the lead screw near the head stock where most of the threading is done, the rest looked unused.
I took it out, sawed off the reduced diameter that went through the bearing at the tail stock end, drilled, reamed and drilled the cross hole that would fit the drive shaft coming out of the gearbox. Turned a 2 diameter shaft, one diameter fit in the old driven end hole and the other fit the end bearing diameter, pinned them together and flipped the lead screw 180º and installed it with the worn part at the tail stock end.

Like so, this may not work on your lathe however. (Someone beat me to it (-: I see)

 

[great white]

That is a neat idea, as mentioned above.

Would seem to be a nice solution to replacing it in the future as well.

My metal lathe needs are modest and the 10F should suit them just fine. As such, I will probably have the lathe for another 20 years or so. That would make a "replaceable " solution seem preferable as I may wear it out again in that time and all I would have to do is source (or make if it fit between centers) an appropriate sized acme threaded rod....

 

[great white]

Found the main source of backlash in the cross slide: the attaching screw had backed off with my noticing.

Backlash is now "15" on the dial.

Pretty sure I can work around that if required.

 

[pdentrem]

15 is pretty good actually for any used machine.
Pierre