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

Let us hope that a new gib and screws resolves your issues, Tim.

This is an opportune time to make and install your gib lock. I suggest you make it in two parts. The part that goes into the hole and contacts the gib will not be rounded. Instead, I would use a piece steel round stock turned to just slip fit into the threaded hole you make and cut the tip at an angle that matches the angle of the gib strip. Be sure to deburr all edges well. Insert it into the threaded hole with the long end of the slanted tip pointing down. Then make a threaded locking screw that bears on the back of the first piece so that when you tighten the screw, it simply pushes on the first part to lock the slide with very little pressure. This type of locking mechanism is smooth, locks and releases well and does not cause excessive wear on the gib. I would avoid using a ball bearing for this kind of lock; it will eventually dimple the gib and cause alignment issues.

Once you have the new gib strip and screws in hand, maybe we can all go over our method of adjusting the gibs. There is more than one way to do this so a discussion might be a good idea.
 
Mikey,
That makes a lot of sense; the ball bearing in the video did as well but I hadn't considered the wear it would cause. So the inside (against the gib) side is the matching angle and the outside (against the screw) is perpendicular? Is a 1/8" hex bolt about the right size? Or should I go up to 1/4"? Since it will be a small piece, does it get ground to the angle and then parted off?

Many thanks for sticking with me on this.
Tim
 
Mikey,
That makes a lot of sense; the ball bearing in the video did as well but I hadn't considered the wear it would cause. So the inside (against the gib) side is the matching angle and the outside (against the screw) is perpendicular? Is a 1/8" hex bolt about the right size? Or should I go up to 1/4"? Since it will be a small piece, does it get ground to the angle and then parted off?

Many thanks for sticking with me on this.
Tim

You're welcome, Tim.

Yes, the part touching the gib is angled to match and the other end is flat, to match the tip of the screw that bears on it. I would size the locking screw so it is similar in size to the gib screws.

First drill and tap the hole for the gib lock. Then find a rod that is a close slip fit in that hole. Grind the end of the rod to match the angle of the gib as closely as you can, then stick it in the lathe and part it off so it occupies about 1/3 the length of the threaded hole. Deburr all edges and you're good to go.
 
Tim,

It may be my eyes playing tricks but those gibs look like just flat bar. The thin edges should be milled at an angle of 30 degrees to the wide sides. And the flat bottomed holes should be made at a 30 degree angle to the wide faces of the gibs. The flat bottom holes would then be made with an end mill such that the holes would be parallel to the machined edges. And the three gib screws that don't have the bevel on the tip look correct. Not the one with so much bevel on the tip that it is almost sharp.
 
Robert,
I'm sure it's my photography, not your eyes. Cell phone cameras don't do depth of field well. The gib is absolutely slant-sided, and the holes do have sloped sides. I'm hoping to get the new gib and gib screws in this week, so will see what a fresh set looks like. On close inspection, there are other differences as well, so I have to wonder if these screws were pulled from a box o'gib screws at some point.
Tim
 
OK. Just making sure.

Although I don't recommend using it as one of the four gib screws that remain in the machine, I do recommend keeping the bevel nosed screw as part of your maintenance tools. Or bevel the noses of the other three screws only not quite as much. First confirm that the holes are deep enough so that the full diameter of the nose does get into the holes, or at least across top quarters it does. Then when you get ready to install the new gibs, start with the beveled one in the in the rear position. With the bevel, it will be easier to make sure that you have a hole aligned with the screw. Run it down just finger tight and then back it out just a few degrees. Then start a new screw into the front hole and use something that will slip under the bottom of the gib to lift the front to align the hole with the screw, using only your fingers to turn the screw. Then get the rest of the screws into the holes in the gib, replacing the rear beveled one with the last unbeveled one last. You may also have to push on one end of the gib or the other to align the screw noses with their holes. It can be a little ticklish getting all of the screws into place. The compound gib will be easier to align with the compound off of the cross slide and inverted. For practical reasons, you can't do that with the cross slide one.
 
Robert,
thanks, really helpful.

Tim
 
Well, I got the UNF die nut, straightened out the threads, got the nuts and handle off ok. Cannot seem to get the screw out completely, is there a woodruff key in there somewhere? The cross-slide is much better now, much less slop. BUT, the original problem of the tool not holding a DOC is still present. It seems to buck off a facing cut and just move away from a turning cut. And, there is still this small amount of south-north movement in the entire cross-slide assembly that won't go away. Iglesias it to check for wear.
Appreciate your continued help.

Tim


Hi Tim, sorry I didn't respond sooner, but I've out of the country and unavailable. If you pull the carriage, you'll see the gear is pressed onto the the shaft and secured with a woodruff key. If you insert something between the gear and the casting, you should be able to get it out with light taps with a compothane hammer. Before you consider that, you can check some things first. Screw the nut onto the shaft and wiggle to check for wear. Even new parts have some play, but if there's lots you need to consider changing the nut at the very least. Check for slop where the shaft passes through the bushing screwed into the cross slide: it has a bronze bushing pressed into it that could be worn.

The replacement gib screws that Logan sells don't require nuts since they have captive plastic inserts in them. I find they're easier to adjust. When installing the gigs pay attention to orientation and ensure that the tips of the screws fit
into the indented spots in the gibs. When you adjust them, snug them up evenly, and then back them off only enough
to allow movement in the cross slide. It takes very little rotation of the screws to achieve this.
 
Thanks! I'm waiting to hear from Logan re buying the new gib and screws. Acting on the theory of doing less before doing more, I"m hoping hoping that the gib screw issue will be my problem's resolution. So, since I got a lot of the play out of the handle just with the nut adjustment, I won't take it apart now.
Tim
 
Nogoingback, WA5CAB, Mikey -- I just got back to town, and the replacement gib and screws had arrived from the Logan Actuator. Yes, the screws have no nuts, and I can see the captive inserts. However, the gib itself does not have indentations! Can this be correct, or should I reach out to Scott Logan?
Many thanks for the directions for getting the screws in correctly. I won't try, however, until I know that the gib is correct without indentations. It's also 1/4" longer, is that a problem?

best, Tim
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