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Hello, All,

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We seem to be talking a lot about ELS, so I thought I would mention something about rigidity.? John has found that the better the lathe rigidity, the better the ELS performance.? I know, you are going to say, "Hey, that's true with manual machining!? It's not a special requirement of? ELS or CNC!"? This is true, but apparently it's even more important with automated operation.? This is because most of us quickly learn the quirks of our machines, and can compensate for weaknesses quickly.? I have heard various stories of professional machinists in the primarily manual days who would know that to take off an extra .0005 inches, they would have to press on their tailstock just so, or hold onto this lever during part of the operation.? If I see an uneven cut, I can immediately check to be sure my carriage is sufficiently rigid and adjust if before I continue.? Unfortunately, the dumb computers that run automated systems don't know anything about that, and so can't compensate this way.

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There are several modifications worth making for both automated and manual operation.? These are also quite important with a gear reduction unit, as you probably implemented the GR unit to make heavier cuts, which puts more load on the lathe carriage system.

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1. Replace the carriage gib strips with an improved system?

2. Replace the compound with a riser plate

3. Improve the cross-slide gib adjustment system

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There are other mods that, IMHO, are worth making, such as changing to tapered roller bearings, but I think they have been discussed ad infinitum, so let's focus on these three.

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I have made all three of these mods, and I can say that they do make a big difference to rigidity.? (I abhor people taking credit for someone else's work, so I have to point out that items 1 and 3 were John's design.? Item 2 I designed myself, as I recall.)? I've attached photos of these changes below, and will discuss them in more detail in future posts.? The carriage gib strip replacement was the most complex, and the most different from the numerous other fixes commonly available online.

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A few words about the carriage gib strip replacement, which I refer to as a "tensioner".? First, a modification is made to the carriage that allows the gib strips to be adjusted from above.? The existing holes are tapped through, and several new ones added.? Set screws (grub screws, if you are from the UK) are added with a nut attached permanently to the far end.? I silver soldered mine, but any technique that fastens them permanently is fine.? These are threaded in from below with the nuts down and the hex cutout up, and now you can adjust from above.? It seems that locking nuts are not needed here, but Loctite or fishing line in the hole can give some additional anti-vibration protection if you find it's needed.? This change alone allows the existing gib strips to be adjusted with much less difficulty than the originals.

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The tensioners themselves differ from the usual solutions because they contact four areas of the way undersides; i.e., they are not continuous.? The problem with the continuous strips that come with the lathe is that the underside of the ways is not perfectly flat.? Even if they were, the ways wear because the carriage spends most of its time near the chuck.? The tensioners have a half countersink on the end opposite where they contact the way underside.? A set/grub screw with a conical tip fits this countersink and is used to do the rough adjustment of the front or back two tensioners.? The final adjustment is made by the set/grub screws with the nut pulling up the ends of the tensioners where they contact the way underside.? Hopefully this description will supplement the photos.

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