The Plan

October 2014

OK, so everything was now in pieces, mostly clean, boxed up and stacked around the garage. Taking it all apart had shown me where things were worn or broken so I had a list of things to do or get done, and a few decisions to make.

Bed Regrind

The ways are quite badly worn, no doubt about it. So I made enquiries about having it reground; there are a couple of places who do it and it didn't seem like it would be a problem. I was quoted £650 pounds for a regrind of the bed and saddle to match. Asking about how this affects the leadscrew (as the saddle drops, so the apron drops, so the screw is no longer lined up properly), the chap said that the way he normally sorts this out is by taking an equivilent amount off the mating face for the saddle / apron - thus bringing the apron back up. It was something I'd thought about myself, but wasn't sure how this would affect the drive gear which protrudes from the top of the apron and meshes with the gear on the crossfeed screw. Apparently there is normally enough spare clearance that this is not a problem, though in a few cases he's had to shave a bit from the outside of the gear.

So this all seemed pretty reasonable. But looking at it practically, the bed is actually very flat up near the headstock, and in 5 years I have never turned anything which required a constant diameter for more than a few inches. The wear will only actually be noticable when turning a very long shaft with a constant diameter; as long as each section is only a few inches long it will never matter. So if I were to get it reground, would I actually notice?

Suddenly it started to look like I'd be spending my £650 + vat + shipping, probably a good thousand quid all in, for accuracy I might never use. I wrestled with this for ages, as I really wanted to do a good job for the sake of doing a good job; but ultimately, I decided I couldn't justify that sort of cash if it wasn't going to make a noticable difference. So I decided against it; it's not like it will prevent me doing it later if I change my mind.

Headstock Bearings

I need to get these back into spec, my experiments with the rear bearing lead me to believe that I can do this with what's there, so that's just work to do when I get there.

Crossfeed Screw and Bushing

The Crossfeed has masses of backlash, is missing a thrust bearing, and I'm not convinced that my bushing repair is quite concentric. As mentioned previously I had a new screw and nut made by a very nice chap in the USA called Tom Ross, who trades on ebay as TROSS96586. When I refit it I will sort out a new thrust bearing and see if the bushing is ok; if not I will try to make a new one when it's all back together.

Compound screw and Bushing

Again, very worn and loads of lash. Tom made me a new one of these as well; I will definately try and make a new bushing as there is loooooads of play in the old one.

Leadscrew

Another major part which is badly worn. I rang a few specialist companies and was quoted around £4-500 (+ vat, + shipping of course, so probably around 700 all in) for a new screw with the journals machined on the ends. Again I really wanted to do this for the sake of doing a good job, but again I had to consider that actually, I've only used the threads once; while I want the capability, it's not something I will be using very much at all. However in this case I think I have a middle path I can follow. Leadscrew stock is actually pretty cheap - about £110 for the length I need. So I could buy a piece and machine it myself, what with having a lathe and all. The only slight problem is that the gearbox end has a larger-diameter collar section, and I'd need someone to machine the long keyway for me. But I think I will look into that as a project for next year sometime. I'd probably have to make the gearbox part as a separate section and fix the screw on the end, then hopefully find someone local with a milling machine who can cut a keyway. Should be quite a nice little project.

Handles

The various winding handles are pitted with rust, particularly the crossfeed and compound. The chrome on the main round apron handle is getting tatty, and the tailstock one is similarly looking pretty bad. So I've sent all four of these off to be chromed. Only the main apron handle was originally chromed, but the others get most of the use so it seemed sensible to do them; they're also the ones which were most damaged by the rust. For the rest, I'll file them back to remove any pitting and polish them back up; ideally I'd chrome every handle, but some of them are parts of larger assemblies and I can't easily get them apart (they're mostly riveted/hammered together).

Apron Drive Key

I need to make a new drive key for the worm gear in the apron as the old one is very worn.

Reverse Tumbler Axle

One of the axles holding the top gear in the reversing assembly is a horrible bodged affair, I need to turn up a replacement.

Electrics

I need to fit a new start/stop switch as the old one doesn't always work, which is not what you want on an emergency stop. I've had it apart and improved it for a time, but it's gradually getting worse again and I can't have that. I also want to fit a reversing switch to make cutting threads easier.

Missing Gear Teeth

There's the one gear in the headstock geartrain which is missing two teeth. Ideally I'd replace it, but I'm having trouble finding a spare - unfortunately it's not a simple flat gear, it has a small gear and larger one as a single piece. If I can't find a spare, I'll do what I did on the Union Drill - build up the missing teeth with weld, and file it back to shape. Highly time consuming but short of getting a new one made from scratch, which would be rather expensive, probably the best I can do.

Tailstock Quill Repair

The quill is very badly scored, so I will recut it with a morse taper reamer. I also need to repair and cut a new thread on the end of the screw shaft as it is somewhat graunched. I'll do this when the lathe is up and running.

Cosmetic bits

A few tarting-up things to do, like refurbishing the brass plate for the gearbox. I'd like to get replacement dials for the crossfeed and compound but can't find anyone who does them; so I will probably just have to clean them up as best I can. They're both a bit pitted and worn.

Oils

Previously I'd done a bit of research into the oil to use, and ended up with Esso Nuto 32 for the spindle, and have been using 68 grade pretty much everywhere else. I didn't know so much and there wasn't that much information about at the time, or I couldn't find it. But in the intervening few years, there's been a bit more written about it.

Though different people say different things about how much difference it makes, I figured I'd stick with the recommended lubricants as much as possible. Southbend refer to Oils as "A", "B", and "C" grades, which are of increasing viscosity; then there is a separate oil for the slideway. They are all readily available, but often only in bulk - the trick is finding someone who will sell you a litre or 2 rather than a 20 litre drum. There are a few on ebay, obviously buying the bulk packs and splitting them out to sell in smaller amounts, which'd be easy enough to do if you could be bothered. A, B and C are available as Hydraulic oil, the consensus of opinion is that this is fine for use in lathes. I've bought a stock of each type so that I can rebuild everything with the correct grade.

Southbend Grade	ISO grade	Comments
A	22	Very thin oil for use in the spindle. In the uk, mostly available as Sewing/Knitting machine oil in small amounts, otherwise can be found as hydraulic oil.
B	32	Used in the gearbox and apron, amongst other places. Readily available as ISO 32 Hydraulic Oil, or NUTO 32.
C	68	This is pretty thick stuff and used for "everything else". It's the same viscosity as slideway oil, but without the additives Again most commonly found as hydraulic oil.
Slideway	68	For the beds, crossfeed and compound slideways. Basically 68 grade oil with "tackifier" additives to make it stick to surfaces better and not run off. I've used Mobil Vactra 68 before, this time just some generic stuff from a reseller.

The Rest...

...is "just" stripping, cleaning, painting, putting new felts in and rebuilding everything as well as possible.