Novice SB 10L power feed question

First, let me say I've got no real experience running a lathe, so I apologize if this is a stupid question.

I've been getting acquainted with my 1957 10L, and I noticed that the power feed and the power cross-feed run in seemingly opposite directions. In forward, both the half nuts and the power feed run the carriage towards the chuck. The power cross feed backs the cross slide away from the center. Is this for some particular reason, or just something that is a happenstance of the design?

Useful in my opinion. Think of turning toward a shoulder that you want to be square. On your finish pass, you feed toward the chuck, flip the feed to the cross slide and face the shoulder.

On many larger and newer lathes, you can reverse the feed at the apron. Since you can't on the heavy 10, the arrangement used makes the most sense to me.

Teryk

IMO its that way just in the interest of simplicity...when you are toward the center of a part that is when your feed should be at the highest and as you get toward the outside feed should slow down to get a really consistent finish...SFM and all that.

the feed rate is much finer on the cross feed than the long feed on most SBs, which is less than ideal, so most guys I think feed by hand when finishing facing work.

one of the things that endeared my Sheldon to me was the fact the cross and long feeds were about equal and the cross fed inward(opposite of SB).
since I parted at turning speed it let me turn and then part off under power without shutting down to change my feed.

Still a bit of the SFM issue but a bit more workable for me.

I will always contend the SB is a feel machine.

Not entirely sure what the fact that the reversing lever has to be changed has to do with SFM rates. I get that the speeds need to change, but I'm not quite understanding what you're saying about that being related to the feeds running in a seemingly opposite direction.


Related to feed rates though, does the chart's feed rate indicate movement of the carriage in thou per spindle rev, or movement of the cross-slide in thou per rev? It doesn't actually say and I honestly don't know. I know it'll run down to .0007 per revolution in the slowest speed (wide ratio box) but I'm not sure which moves at that rate. I don't currently have a mag back indicator and its a bit cumbersome to set up the indicators I have in a manner that would tell me that.

*most* SBs cross feed rates are 1/3 of the long feed, so if you turn a part to size it is in too fine a feed to just flip the lever, unless you have a lot of time, so mostly easier to just hand feed in the case of turning to a shoulder and facing outward.

The rest was just a comment on the inconvenience of having to turn off to go from turning to parting for the stuff I did.

ok, now I understand.

The manual cross-feed is fine enough that I can do that by hand and not have it get all screwed up. The long feed, not so much. One thing with that wide ratio box, you can slow it down so much that its almost not moving. Gets awful boring to watch.

So basically it is how it is, because thats how it is. Just didn't know if that was a "all machines are like this because X" thing or what. No experience with other machines, and barely enough with my own to know if it makes sense. I only really noticed it because I went to part something off after turning it, and the handle was running the wrong way.

It's pure and simple happenstance. Or to put it another way, it's a consequence of the simplified
apron gearing for the SB lathes.

I also find it annoying to have to change the reversing tumblers between feeding (towards headstock)
and crossfeed (inwards, which I prefer).

You get used to it, after a fashion. =)