Logan 200 Saddle/cross Feed Screw Question...and Some Others

expressline99

expressline99

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So I'm baffled by this and I'm sure it's simple. Turning the cross feed handle clockwise bringing it towards you. Where is the load placed that holds the cross feed screw in place? Obviously the cross feed nut is moving the carriage... but looking at the diagram I don't see what keeps the screw in place. The reason I'm trying to figure it out is because I can see and feel my cross feed dial move in and out slightly. When I'm bringing the carriage towards myself it seems to be binding slightly as if the cross feed bushing (LA-689) is pushing on the cross feed dial. Should it be doing that? It's driving me bonkers that there could be any load on a dial.
 
ex,

The carriage only moves left-right. The cross slide moves toward or away from you.

According to the Logan 200 Series Operator's Manual & Parts List (copy in DOWNLOADS, when advancing the cross-slide (moving it away from you), the cross-feed screw is held in place by a shoulder on the screw which bears against the far end of the Oilite bushing which is pressed into the nose of the cross-feed screw bearing (which is screwed into the front of the carriage). When retracting the cross-slide (moving it toward you), thrust is taken by the 3/8"-24 hex jam nut which bears against the dial which bears against the near end of the cross-feed screw bearing (or the bushing in the near end of it). Note that the parts list actually calls bearings bushings and bushings bearings.

Early Atlas machines were the same way.
 
Thanks I meant cross slide. (Carriage lefty righty got it.)

Mine doesn't have the jam nut between the dial and the handle. Only the nut on the outside of the handle. My handle does thread onto the screw is that how they all are?
The movement I'm seeing must be the dial moving trying to snug against the back of the handle. Seems like the steel bushing against a steel dial would eventually get grit in it and cause an issue. But I'm picking at something that probably shouldn't bother me. But then again I did take the dial off at one point and hand polish the back of it up to 1500 grit. My Horrible OCD that day I suppose.

I have another question about the lead screw collar. Should the lead screw collar be set tight against the support so that the lead screw cannot move at all? Or is a little bit of movement OK? Mine will move if I engage the half-nut (power off on the machine) and lightly move the carriage handle. When I say a little bit of movement it's about 1/8".
 
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ex,

I've never seen an internally threaded crank or handwheel on a lathe. The 200 Series manual that we have shows smooth bore with a broached keyway. Maybe yours isn't original. If the cross-feed screw has a Woodruff key seat cut in the proper location, and if it were mine, I would bore out the threads, broach a keyway, and assemble it the way that the manual shows.

On your final question, assuming that you are referring to the LA-169 Collar that can be moved against the right end of the LA-166 bracket (located on the front of the bed below the headstock, 1/8" clearance is excessive. Although some of the carriage movement will also be due to clearance between the half nuts and the lead screw threads. And some from clearance between the half nuts and their guide. Nothing that you can do about that. Loosen the set screw. Use something like a .003" to .005" feeler gauge as a spacer between the collar and the bracket and move the collar against the spacer which is against the bracket, with the lead screw pulled hard to the right where its movement is stopped by the LA-167 Bracket, and tighten the set screw. Then pull out the spacer. With the screw gear temporarily removed, the lead screw should turn freely with minimal end float. But don't get it too tight.
 
The hand wheel I replaced myself. But the old one was internally threaded also...but I broke the handle off of it. The new one had an insert in it that I had to drill out and thread to fit. I only did that thinking that's how it fit. My cross-feed does have the seat cut in it. I don't have a press or broaches so I can't fix it the proper way.

Yes that's the suspect collar. I'll get out in the garage tomorrow and get that adjusted with the feeler gauges.

Also, how tight are all of the nuts/bolts on the front of the apron supposed to be? Frequently several of mine loosen the point of finger tight. Are there any torque specs anywhere? I realize that's a stretch of course.
 
ex (you need to set up your Signature),

I haven't seen any torque specs for various threaded fasteners on the Logan (or on any other machine, for that matter). Sometime earlier than 1973 (when I moved to Houston) I bought a pocket reference handbook that has several generic tables for various types and grades. I just scanned and cleaned the torque spec pages and uploaded it. It is in the Charts and Tables category, currently first file in the list. If you aren't familar with navigating DOWNLOADS, read the instructions posted at the top of this Forum.
 
Robert, Signature fixed.

I adjusted the lead screw collar and it actually quieted the gear rack some. Probably from my gears actually being closer to aligned. As well that slack in the lead screw is good now. Thanks for that.

I still have to go and look at all the bolts to check grade and torque as needed. The chart is just what I needed on that.

There maybe some slippage in the engagement of the half nut as well. Not sure what I'm going to do about that. The lead screw doesn't have noticeable ridges in it..?
 
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I've decided that the inherent dragging/resistance between the dial and the cross-feed screw bushing is going to drive me nuts. So I am going to turn down a replacement bushing just enough to fit a very small(5/64ths) roller thrust bearing between them. It appears to me that this will get rid of the "drag" I get when drawing the cross slide towards me. I'll get some type of result one way or the other.
Paul
 
Roller thrust bearing = bad idea. That just bound up on me. So I guess a plain oilite bronze thrust washer... something has to help.
 
installing a oilite bronze thrust washer between the dial and the cross-feed screw bushing did the trick. It took a little fiddling to get it adjusted just right. But it is wonderful. nice and smooth operation. As soon as I get the the Bridgeport rebuilt I'll be making new feed nuts.
 
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