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

mikey

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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.
 

tmenyc

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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

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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.
 

wa5cab

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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.
 

tmenyc

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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
 

wa5cab

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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.
 

tmenyc

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Robert,
thanks, really helpful.

Tim
 

Nogoingback

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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.
 

tmenyc

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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
 

tmenyc

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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
20190512_202017.jpg
 

mikey

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Tim, I've only replaced 4 gib strips so I am by no means an expert at this but I will offer what advice I can.

New gib strips often come without the locating holes predrilled; that is a good thing because every lathe is different and it is better to drill them yourself. If you do some reading, you will find all sorts of opinions on which shape of screw point is best - round, conical, ball bearing, etc. Personally, I prefer the angled cylindrical insert that Emco uses because it spreads the forces from the screw over a broader area; whether this makes a difference, I am not sure but it makes sense to me. With that said, 3 of the 4 lathes I replaced the gib strip on used conical screw tips like yours and they seemed to work fine.

You will need to trim the gib strip to length. I suggest cutting to fit the length of the cross slide instead of matching the length of the old strip. Be sure to deburr the ends and all corners of the strip lightly, then sand the working faces with 400 grit wet/dry sandpaper laid on a surface plate or flat glass plate. You are just looking for a uniform surface here so go lightly and evenly.

Clean the dovetails of the saddle and cross slide really well. Get up in the corners with a knife and get all the crud and debris out of there. Also make sure there are no burrs on the inside of the dovetail where the gib screws enter and clean the screw holes out really well.

You are going to drill the four holes for the screws into the gib strip. Personally, I use a file to gently shorten and gently round the tip of each gib screw so that the sides of the tip bear on the gib strip hole, not the point. This spreads the forces out over a broader area. I use a spotting drill that is slightly wider than the included angle of the screw tip to drill the holes in the strip. Because the tip of the screw is cut back and blunted, the sides contact the hole instead of the very tip of the screw. Hope that makes sense. I use a spotting drill because it is short, rigid and only the point cuts. The flutes of a spotting drill are not sharpened so they do not cut; this eliminates the risk of damaging the threads in the saddle.

Once the dovetails are cleaned and the screws are prepped, take your drill and pass it through the gib screw hole. You only need to drill about 1/3 of the way into the strip for each screw so pass the drill through until it is in far enough to give you that 1/3 depth and mark the drill on the outside with masking tape or a Sharpie; you will use this as a depth gauge when drilling.

Now you can put the gib strip and cross slide into place on the saddle. Pull the cross slide tight to the saddle, trapping the strip between them, and then clamp the cross slide in place if I can. On all the ones that I did, I was able to use blocks and clamps to do this. You are not trying to apply a lot of force; only enough so the strip cannot move. Look at the strip to make sure it is not cocked and then you're ready to drill.

I prefer to drill the first hole, the one on the operator side of the strip. You are using the threaded hole as a drill guide and if you use a spotting drill, this works well. Shoot some cutting oil into the hole and drill to the depth of your marker. Once done, use compressed air to clear the chips and install a gib screw. Snug it down lightly; now the strip cannot move and you can drill the other three holes. Then take the whole thing down and clean all the chips out of the holes and gib space. Deburr the strip if needed and recheck to make sure no burrs were raised inside the threaded holes. Now you're ready to install the gib strip.

Most gib screws are long enough to allow a locknut to be used on the outside. If yours are too short for this, some Blue Loc-tite works well and allows you to adjust as needed without the screw vibrating loose. If you use Loc-tite, use it sparingly.

Oil everything up and install the cross slide and gib. I use machine oil for this. Install all four screws and gently thread them in until they just touch the strip, then back them off a tiny bit. Now you can adjust them. What you are trying to achieve is a smooth sliding fit with zero play. Since the saddle/cross slide assembly already has some wear, some screws may need to be adjusted more than others but you should be able to accommodate that wear.

Using just moderate hand pressure, push the cross slide away from the gib strip so it fully contacts the dovetail on the other side of the saddle. Now you're going to adjust the screws and the easiest way is to work from the center on out to the ends. I adjust all the screws until they just touch the strip; this is enough to feel drag when you turn the cross slide handle. I fractionally back off all but the second screw from the front and turn the cross slide handle; you will still feel some drag. Adjust the screw just until the handle turns freely; this may only be a tiny fraction of a turn. Then I bring in the third screw until it touches just enough to cause some drag. I adjust that one until the handle turns freely. Repeat with the first and last screw, each time feeling it cause drag and then adjust until the drag just disappears. Once you are done, the cross slide should move freely but there should be zero side play when you firmly push across the cross slide with your hand.

Done.

Hope this helps.
 

wa5cab

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I doubt that the 1/4" difference in length will matter. But the gib should have the four flat bottom holes cut at a 30 degree angle. Without them, the gib will walk out. Also the new gib screws appear to be threaded to the end.

This is mostly tongue-in-cheek, but I wonder whether Logan and Clausing are using the same machine shop. Two or three years ago, I bought a new carriage gib for the late Atlas 12", mainly to confirm that they were still steel and not plastic like the compound and cross slide ones had become.. It was also missing the flat bottom holes. So were about 12 out of 13 on the shelf in their warehouse. The sent me the 13th one and had the remaining 12 sent out for completion.
 

tmenyc

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thanks, Mike and Robert.
I wrote to Logan this AM to ask, based on Robert's response, if sending gibs undrilled is standard, on the chance that they'll do it for me. Otherwise, I have to beg some time with a friend with shop to use his drill press. Somehow I don't think this is a job for an unmounted DeWalt. Mike, thanks for the instructions; I'll definitely use them.
Assuming I'll have to take it to my friend, I'll take advantage of the occasion and drill the cross-slide for the lock as well.

Late-breaking news: return email notes "must be drilled after assembly".

best,
Tim
 
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wa5cab

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Then you need to write back and get them to send you the drawing showing where the holes go, size, shape and depth.
 

tmenyc

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Robert,
Mike's note, #41 above, seems to cover the ground, no? Although the hole difference from 820 to 820 can't be great, the only way I'd know it was correct is by using my cross-slide's holes.

Tim
 

wa5cab

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Well, yes and no. In the first place, Logan should never have sent you the gib without instruction on how to make it usable. You've figured out, because you have asked, that you are expected to have to do something in order to make the gib usable. But you still don't know how deep to make the holes, what diameter of drill bit to use, what the included angle on the nose of the bit should be (yes, that is a variable), and whether or not you should locate the hole positions with a spotting bit just small enough to go into the tapped holes and then finish them with a larger bit (which will require being able to hold the gib at an angle).

I don't approve of doing gibs this way. It was only done to save the manufacturers a few cents. The chances of ruining one of the holes while modifying the part and later during routine maintenance are pretty good.
 

mikey

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Late-breaking news: return email notes "must be drilled after assembly".
I have only done the gibs on two machined cross slides and two cast cross slides and it seems to me that the gibs for a machined cross slide could conceivably be pre-drilled. For a cast cross slide, I think it would not be practical to pre-drill them unless the maker used a consistent datum that is consistent for all their models. Bottom line is that it is probably more accurate to drill the gib holes yourself. I use a hand held drill for this - Makita, not Dewalt, but it works fine.

You only need to drill into the gib deep enough to center the cone of the gib screws. This ensures the gib cannot walk. As long as the conical sides of the screws provide the pressure instead of the point, this should be sufficient. If you use the gib screw holes as a drill guide and use a spotting drill then the angle of the holes should be close enough to be correct and you won't mess up the threads in the hole. In a properly functioning gib set up, the screws do not put a lot of pressure on the gib; they only adjust the space between the sliding components that ride on an oil layer.
 

tmenyc

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Well, that's reassuring! But, it will be a DeWalt...

Robert, I see your point. I also see Mike's. And, probably, you're both correct. I don't know, and don't know if anyone knows, how alike one 820 is to another 820, but it's easy enough to get it right myself. Instructions would have been nice, for sure, but I have your and Mike's guidance, which is sufficient. I learned a long time ago in my world of vintage pen restoration that instructions for the brand and model and born-on-date don't necessarily fit the pen; I'm learning now that the lathe is a whole lot larger but the tolerances are a whole lot finer. With pens, with some exceptions one generally shaves a bit here, adds a bit there, which is both the beauty and the challenge. With the lathe, the challenge is getting it right to get it at all. I'll certainly post when it's done.
Many thanks to you both.
Tim
 

wa5cab

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Pretty much all of the vintage American iron that gets discussed in these Fora originally came with flat bottom holes in the gibs and bull-nose gib screws. The only reason for changing them would be to be able to make it cheaper. And think about it - if the company building the lathe couldn't manage to get four holes to line up with four other holes, how could you expect any machine that they built to be able to produce decent parts?

I'm sure that the cheaper gib they sent you will work OK after you finish making it. But this is an example of what happens when the bean counters get the upper hand. :alien:
 

Nogoingback

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It certainly would have been nice if the gib had the holes in it. But, let's keep in mind, the company that built the lathe
no longer exists, and hasn't for many years. Scott Logan told me that he doesn't possess the original drawings for the older
machines, and so he may not know what the hole spacing is on that gib. I suspect that has more to do with it than "bean
counter" shaving pennies. I could be wrong, but my impression is that there aren't any bean counters involved and that
Scott makes all the decisions. He supplies the parts he can, but they're parts for 75 year old machines that went out of
production decades ago. If this lathe were a Sheldon or South Bend, the conversation would be about how to make a
gib from scratch.
 
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wa5cab

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OK. I guess that I am too used to dealing with Clausing where, if they no longer stock the part, they almost always have the original drawings (at least for the lathes - less so for the mills and shapers).

In that case, the first thing to do would be to check the angle on the tip of the Nylon Patch or Nylon Rod gib screws that he was sent. Be sure that it is the same as on the spotting drill and that the spotting drill just fits through the tapped gib screw holes in the side of the cross slide.

I would suggest acquiring a roll of 0.005" and 0.010" shim stock and cutting enough strips to approximately center up the gib top to bottom in the slot that it fits into. Shim both below and above the gib. Use three round nose set screws to lock the gib immobile in the slot. Spot drill the first hole, move one of the screws to that hole and drill the second one, and so on. Then move the gib to the drill press and use a drill bit the diameter of a body drill for the screws and with the same included angle on the cutting end to enlarge the spot drilled hole to the diameter of the screws. Use a depth stop to get all four holes to the same depth which, absent instructions to use something else, I would make around the depth for the body drill to be cutting to the full diameter.

To pre-position the gib vertically for getting the gib screws into place, I would use the shim pack that was under the bottom of the gib for step one above.
 

Richard White (richardsrelics)

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Tell me if this make sense...

Step 1.png Step 2.png

So drill and ream the first hole, then drill and ream the second so the 2 holes intersect at 90 degrees, size is dependent on just how big your lathe is.
The second hole, from the side drill and ream thru an inch or so, and then thread the first 3/8 of an inch or so.

Next step take dowel pin, grind one end on a 45 degree, then make it so that the high side of the 45 degree end it fits at or near the top of the line of the horizontal hole. Make a second dowel, again with a 45 degree end to go in the side hole, the 2 angles meet and the screw applies pressure to the lathe making a nice stop. Get fancy and create a step in the vertical pin to allow a small spring to pull the pin from the base making it spring back up off of the main lathe. Personally, I have this on the wrong end of the cross slide as being on the back side is best. The front could allow the pin to drop out if the slide is brought too far back.

Yell at me if I messed up..
Regards

Richard
 

TomKro

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Tim,

I've been away and just looked thru this thread.

I have some spare Logan parts and noticed that the cross slide from a Logan 210 uses a gib locating pin and the same style conical screws that Logan provided you. This particular gib has no seats cut into it (but dimples on the back side from contact with the adjustment screws), and just one through hole placed to match a 1/8" gib locating pin mounted in the cross slide. Here's a pic.

InteriorView.jpg

There appear to be quite a few different ways to locate and apply pressure to the gib plate.

One other thing - I inadvertently used long screws at the two locations for the cross slide screw cover plate (you can see the bottom of the tapped holes on the left side of the cross slide in the pic). If those screws happen to contact the carriage casting, it can cause travel and gib adjustment troubles. Not sure if this has been mentioned. Easy to fix with a few washers.

Good luck with the troubleshooting.

TomKro
 

tmenyc

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TomKro,
That's interesting. I don't think the chip cover screws go through but I'll certainly check tonight.
thanks,
Tim
 

Shiseiji

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Tim, just checking, are you aware there is a Logan group Scott moderates? Also several members there who have been working on the 200s & 820's for decades. There are a couple of recent discussions on the cross slide dials that cover the little adjustment possible with the two nuts. I don't recall any gib discussions in the past couple of years, but they could be some in the archives. I can't get the link thing to work, but it's groups.io/g/lathe-list
 

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Shiseiji

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[QUOTE="ThinWoodsman, post: 665157,

Out of curiousity, for people having trouble getting links to work, is that when using a phone on this page? I've never had a problem with the little "insert link" button (the two-link chain).
[/QUOTE]
Yes. And trying to balance turning the JS on and off. Not bad here, but on another site it can take literally 2 min for a page to load.
 

tmenyc

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Shiseiji, TW -- thanks, yes I know the Yahoo forum and have new topics come into my email. But I had not thought to search it! It's interesting that the yahoo boards are what the internet used to be...one forgets so easily. And, it's also interesting that this is where Yahool started, and where it's ending...
Tim
 

wa5cab

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Quite a few of the Yahoo groups have moved to groups.io because of no tech support on Yahoo since 2016. Most kept their same base names except that any underlines in the names were replaced with hyphens as groups.io doesn't allow underlines. Which is actually good as most email managers underline links . So the underlines don't show up.
 
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