SB13 Cross slide oil hole - incorrectly drilled??
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  1. #1
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    Question SB13 Cross slide oil hole - incorrectly drilled??

    I'm working on the cross slide on a 1971 SB13. Not surprisingly on a 50-year-old machine, somebody has worked on this mechanism before me. My lathe has the late model version cross slide screw with 2 bearings. However, when I disassembled the cross slide I found 1 bearing and 1 solid shim taking the place of the second bearing. I did find a replacement bearing and seem to have the shaft assembled correctly now, so that's not my problem. I just mention it so you understand that additional "modifications" could have been made since the lathe left the South Bend factory.

    The problem I'm having is to do with the "C. F. Bushing" (part #PT63T3). This is the housing that the crossfeed shaft runs through, and it screws directly into the Saddle. It also happens to be the part that has the "0" mark which is the index for the crossfeed dial. When I screw the C. F. Bushing fully into the Saddle the "0" index mark comes right up on top where you would expect. What's confusing me is there is a hole cross drilled through the C. F. Bushing that looks to me like it should line up with the hole in the Saddle marked "oil". This is one of those tiny little oil ports that is normally plugged up by a 1/4-20 set screw. It looks to me like that hole was drilled in the bushing so that oil will get inside and lubricate the shaft. Otherwise, it seems like any oil you put in that hole really can't go anywhere. Anyway, the problem is that the hole in the C. F. Bushing ends up 90 degrees from the hole in the Saddle. It seems wrong, but I have a hard time believing that SB drilled the hole incorrectly 50 years ago, and I'm the first guy who has discovered it. It seems much more likely that I'm misunderstanding something about the situation and the parts are made and drilled correctly. If it weren't for the "0" index lining up as expected, I might just put a little shim on the C. F. Bushing so it tightens up at a point where the holes align, but with the index mark aligning correctly, I have to think that the C. F. Bushing must be threading in the expected amount. I wonder if anybody on the forum has an idea what I a doing wrong or thinking wrong here?

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    I know nothing of SB details, but having a feed hole to an undrilled Oilite bushing works fine. The light oil diffuses through the bearing as needed. Is the bushing Oilite?

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    There should be a groove in the bushing that lines up with the tapped "OIL" hole on the top of the saddle. The groove should allow the oil hole in the bushing to receive oil no matter what orientation it winds up at as the threads bottom against the front of the saddle.

    If the groove is missing, the oil would not drop when you fill the oil hole up. If it drops as you fill the tapped hole, the groove is doing its job.

    If the groove is missing, that's a manufacture error.

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    Thank you, Jim - you are right. There is a groove in this area so that the orientation of the drilled holes in the C. F. Bushing is not important. I also see that the same situation exists with the Compound Slide Bushing. It's drilled 90 degrees from where the "0" index is, but there is a groove there too, so the oil will flow where it needs to go.

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    Sometimes the oil doesn't look like it's dropping when you put it in there, sometimes the setup tends to get a bit air-locked. I find that putting the oil in at the very side of the "OIL" hole lets it flow in a bit better because the air can get out the other side.

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    Quote Originally Posted by jim rozen View Post
    Sometimes the oil doesn't look like it's dropping when you put it in there, sometimes the setup tends to get a bit air-locked. I find that putting the oil in at the very side of the "OIL" hole lets it flow in a bit better because the air can get out the other side.
    I use a large syringe with a large needle to oil from the bottom of these oil holes. Getting an air-locked oil hole is a common problem. The syringe really makes the oiling a smooth operation.

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    Quote Originally Posted by SLK001 View Post
    I use a large syringe with a large needle to oil from the bottom of these oil holes. Getting an air-locked oil hole is a common problem. The syringe really makes the oiling a smooth operation.
    Agree. One issue though is that syringes with plastic plungers tend to jam up in contact with oils. I use a glass barrel one for lube oils. Tough to find these days.


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