Logan 820: How do I lock the cross-slide and compound?

tmenyc

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Having a problem with slop/slippage on my cross-slide, enough that the toolpost bucks at the slightest pressure. The slippage is completely north-south, the filister bolt holding the cross-screw nut is tight, the gibs are cleaned and tight. At the handwheel there's about .015 slop and the whole handwheel to cross-slide screw seems a bit loose. If I lock down the carriage the entire cross=slide assembly will shift, perhaps 1/64". Mikey, who has been hugely helpful to this still-newbie, has recommended that I lock down the cross-slide to isolate the problem but I can't find anywhere how to do that.
Also, this is a problem that has come up recently, after I replaced the two compound swivel bolts. It did not happen before, but clearly, with those two bolts bent I had other problems. Doesn't seem as if those would be the problem since all they do is enable the compound to swivel.
Help please?

Many thanks,
Tim
 
I don't know whether this particular machine has a crosslide lock, but if there isn't one and you just want to isolate the problem, you could tighten the gib to lock the crosslide temporarily.

Sent from my LYA-L29 using Tapatalk
 
Any chance those two new bolts you put in are just a hair long and not drawing the compound swivel down completely? If they're bottoming out beforehand they would probably still prevent the compound from rotating but wouldn't be drawing it tight to the cross-slide. Kind of like a T-nut with too long of a stud.

If I didn't have a problem before changing a part but had a problem after changing a part, I'd look strongly at my new part as being the problem.

-frank
 
292732

Your 820 should be similar to my Model 200. On mine, I was able to adjust some slop out by loosening the outer nut
on the x-slide handle and carefully taking up the slop with the inner nut. It took a few tries, since tightening the outer nut changed
the adjustment but I got it in the end. If you can do this, then any other slop in the x-slide will be the nut at the other
end of the screw that attaches to the x-slide itself. If it has significant wear, it will need to be replaced. Of course the
screw could be worn as well.

Can't imagine why your x-slide would move when you lock the carriage. However, the carriage has gibs that are adjustable
as well at both the front and the back. (At least mine does.). Adjusting them might help.
 
Frank -- my thinking, too, except that the compound is not moving; all the motion is in the cross-slide below it. But yes, it was not present before the bolt replacement. I'll check the bolts out. They were from the Actuator, so I assumed they were milled correctly.
Alternatively, I'm wondering about the cross-thread nut. I had taken it out, cleaned it well, and reinstalled it a good month before the bolt replacement without a problem afterwards. Is there any way it could be in wrong? It is definitely bolted into place, and did not show a lot of wear, although a small amount worn off might not have shown. Would ANY wear be too much wear? I'll take it off tonight and photograph it. The cross-feed screw does not show obvious wear where it is visible, which (the two swivel bolts excepted) is consistent with the whole machine's condition.

NGBack -- I will certainly do the adjustment. With my understanding that "slop" is the looseness of the handle that results in turning the handle without changing the actual position of what the handle turns, my cross-slide handle is loose but does not turn without the cross-slide moving. The .015 slop is longitudinal, on the carriage. Will adjusting the cross-slide outer and inner nuts tighten the handle on the screw AND tighten the mechanism to possibly eliminate the lack of cross-slide rigidity?

Thanks for the help.
 
If you had the cross feed screw out, you would see that there is a gear on it secured with a woodruff key which is sandwiched
between a shoulder on the shaft and the inner end of the bushing that supports the screw. (The bushing is the part I'm
pointing to in the pic.) So, if the handle is adjusted to be loose, that allows some longitudinal movement in the shaft.
Adjusting out that slack with the nuts at the handle eliminates that movement. It's a fussy adjustment: too loose and you
get the movement, too tight and the cross feed handle binds and is hard to turn. Of course, I'm assuming your lathe goes together
the same way mine does, but I'm pretty sure it does. When you perform that adjustment, be sure that the setscrew on the
movable dial is loosened first.

The cross feed nut that moves in response to turning the handle is not adjustable. Slop in that nut indicates wear in the
nut, the shaft, or both. On my lathe, I replaced both parts which I ordered from Logan. The shaft was expensive, the
nut not so much. If you have much (rotational) slop in the handle, changing out the nut would be a good place to start.

And again, I would check the gibs on your carriage as well.


292763
 
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NGB -- many many thanks! If I can get to it tomorrow evening that will be great; if not it will be (ugh) ten days, I have family stuff out of town. Either way I'll certainly report back here. Sounds very do-able indeed, however. I'm hoping the screw doesn't need replacement.

Many thanks again.
Tim
 
OK, I"m back from out of town, itching the whole time to get back here and solve this problem. Tightening down the gibs did nothing except stop intentional movement of the cross-slide. I removed the nut, and as can be seen from the pictures, it looks fine, no apparent wear. Threads are clean, no chunks, only casting marks.

I removed the outer bolt on the cross-feed handle, and the handle, and then discovered that the inner nut cannot come off; there is a widening of the threaded slot, preventing it from moving further. I'm guessing this is wear or damage, but when I tightened the micrometer nut the north-south slop disappeared! Easing back a little bit, it could be turned without creating the slop. Is this the solution?
Is the widened portion a replacement need? It does not seem to get in the way, and I'll see if handle slop returns when I reassemble.
As always, many thanks for the support.

Oh, and by the way, Mikey send me a link to a video of a simple cross-feed lock, which I'll make as soon as I get this fixed.

Tim
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Thread your cross slide nut onto the screw and check the fit at different points across the length of the screw. It will probably fit looser in the center than near the ends. If it's real sloppy in the center, it might be time for a new nut.
 
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