Hi Arthur,

You will probably find the nut is badly worn in the cross slide. You can either make a new one or slit the old one and add a screw to make the nut sort of "pinch" the thread to reduce the backlash. However you may find the screw is also worn. New screw can be made or the old one chased (threads made thinner, removing material just enough to take the thread to a uniform state same size as worn part) and a new nut made.

For a spanner I suggest finding a bit of gauge plate (oil hardening tool steel, ground flat both sides, sold by tool suppliers) and hacksawing / filing out the opening to fit the nut, to make a spanner. It may work fine without hardening if you leave enough "meat" beside the opening. 10" or 250 mm long would probably be fine. Wrap the end in electrical tape for good grip and to protect your hands.

You could also buy a thicker spanner (maybe 12 mm ) at a pound shop or cheap imported tool dealer and grind the sides to fit.

Two sources of thin spanners to use for this kind of thing, or modify for such use, are the old Terrys tappet spanners or those sold for adjusting cycle hub cones, etc

Sounds like you are running the lathe much too fast.

Typical countershaft speeds for machines of that era would be in the region of 250 to 350 rpm. Generally the spindle oiling arrangements for these simple plain bearing headstock machines aren't up to handling speeds above 600 rpm.

Concerning identification the inverted rack with teeth pointing upwards provided for driving the saddle is very unusual. Coupled with the extremely skimpy saddle apron and left hand operated half nut lever for screw cutting it ought to be possible to identify it. I'm fairly sure that a machine with similar features was added to the list at **LINK** sometime in the last 4 or 5 years. I have a horrible suspicion that machine had its feednut cut directly in the saddle casting. If so it will need to be bored out and new nut fitted. Which may be difficult as space will be limited.

I'd undo the two screws holding the handle assembly to the cross slide then wind the screw out so you can see whats going on and, hopefully discern how it's all put together. On a machine like that expect some creative simplicity to minimise the number of parts. With the screw assembly removed pull off the cross slide too so everything can be examined and given a proper clean.

Clive

11.3-11.4mm a/f is 3/16" Whit. or 1/4" BSF spanner size. The nut won't be too tightly done up. A piece of 3mm mild steel flat, a hacksaw and a file wil soon produce a spanner.

If you need to remove the handle(s) they are usually held in situ on these older machines with a taper pin. These can be a bit of a sod to get out if they have been fitted flush both ends, and will have corroded a little so won't come out without a fight. Carefully clean off any grot and polish the handles boss, then use a magnifier and you should just be able to detect which is the 'thick' end and which the 'thin'. Get / make a proper sized drift sized for the 'thin' end, support the other side of the boss and tap away.

Dont go too heavy, a little heat may help. If you're too enthusuatic you will sort of 'rivet' over the thin end and it will be almost impossible to get out without drilling.

£10 for a lathe like that Arthur? You're obviously like one of those Lucky people I see on the Antiques roadshow on tv who buys a piece of costume jewellery from a charity shop for 50p and it turns out to be Faberege worth £1000's! If I spent 50p like that I'd usually find out that it was only worth 20p! Happy turning!

Edited By Mike Hurley on 28/12/2020 09:59:57

For a machine of that vintage, the nuts are very likely to need Whitworth or BSF spanners, not Metric or A/F..

The threads wiil probably be BSW or BSF, with possibly BA for things like gib adjusters.

You need to distinguish between slack and backlash

Backlash is wear between leadscrew and nut, and unless there is provision for reducing backlash, such as split nut, short of making new parts, there is not much that you can do about it. You just learn to take out the backlash as you use the machine. (If you overshoot, back off by more, at least twice, than the backlash and then advance to where you want to be )

If there is play between the handle and the cross slide, if possible the handle can be moved along the Leadscrew to close the gap. If the position of the handle is fixed, by a pin, the space can be filled with one or more washers, or even better, a custom made spacer. Which you can make on the lathe!

For this lathe, if Imperal, as it seems to be with a 16 tpi leadscrew, you need to work in inches and thous, to make life as simple as possible. Try putting on a cut of 0.02 mm using a dial with 125 graduations, let alone 62.5!.

If you want graduated dials, you will have to add them. (Whjch means making, or finding some kind soul in your Model Engineering Club who will make and fit them for you) You certainly won't find any "off the shelf".

A dial for a 16 tp[i leadscrew will need 62.5 graduations to give 0.001" increments. "And a Half"?

Yes! I made one for my Adept Shaper. It looks a bit odd with 62 evenly spaced marks and then a half size gap, but that is what it takes, unless half thou graduations turn you on. For those you would need a larger diameter dial to accommodate the 133 marks with a sensible spacing. The wider the spacing, for a thou, the more accurately you can estimate lesser parts.

Probably essential on a machine with plenty of backlash.

Howard

.

Set your calculator to divide by 25.4, or better still set up a spreadsheet to calculate all the dimensions for you.

Bet that the dimensions will be whole mm, leading to some strange Imperial decimals, unless they have already been translated from the original Imperial to a Metric (possibly the nearest ) dimension.

Good luck

Howard

The problem that I envisage is that the original drawings were possibly done in 1/64. Someone converted 64s to nice decimal dimensions.

Then along came someone else who calculated the Metric sizes and probably rounded them up or down to nice round numbers.

End result is likely to be 1/2" becoming 12.7 mm "so lets call it 13 mm". If you are lucky. 3/8" became 9.5 mm

End result something which which is even further away from being a true scale model to become something which may begin to look a little odd and out of scale.

That might even be a benefit. But you may not know until the model is well on the way to completion

Shades of "Send reinforcements, the battalion is going to advance" becoming "Send three and fourpence, the battalion's going a dance"

Meccano Ltd used to make Dinky Toys from actual manufacturer's drawings, but with slight modifications to keep the model looking true to scale! They didn't always succeed.

Howard

Hi Arthur,

If you make your own drawings then you are master of your own fate.

You are spared the inconsistencies that arrive after several people have applied their brains, slide rules and calculators to a machine.

The tables at the front of Zeus charts take some of the pain out of changing measuring systems

Otherwise, as you say a "crib sheet" containing the relevant dimensions and their equivalents is a must have.

Now that you have removed the "slop" from the lathe you are all set to go!

May your cuts be clean and the right size

Howard

PS Have you tried a Tangential Tool for turning and facing? Easy to sharpen, only one face to grind.

My favourite scale is one I came across recently when reading a 1920 book describing how to design an electric tramway:

"… use squared paper divided in millimetres. On this, taking as a convenient scale 1 centimetre to a furlong, the line is marked off…"

By the way, I find a useful rule-of thumb for conversion is to say that 1 mm = 40 thou. It's really 39.6, but 40 is close enough for roughing out and I find it easy to visualise.

George B.