Cast iron or Aluminium?

Good day all,

I was given a lovely little watchmakers lathe for Christmas and I want to make a little faceplate for it. Should I use cast iron? Mild steel? Aluminium? Brass? Would it make a difference either way? The maximum diameter of the faceplate would be about 80mm.

Many thanks and merry Christmas and a happy new year!

Do you have a bigger lathe to make it on? If so then choice of material is wider, but if you have to make it on the same lathe you might find it easier to use a less resistant material such as aluminium or brass. The Unimat faceplate I have is ali.

I have a myford super 7 so the actual machining will be done on that. I am just making a shopping list for Ally Pally and want to know what I might need to buy!

You can buy a suitable chuck backplate and make it from that.

Martin C

A good idea Martin, I shall see what I can get that is cheapest!

No question, use cast iron. If you use a length of continuously cast bar it'll machine beautifully and be stable. Plus, cast iron has good damping properties.

Andrew

Thanks Andrew, that's basically what I was thinking!

Final machining of the faceplate should be done on the watchmakers lathe to ensure that it is concentric and square to the spindle.

Yep, I thought of that. I do worry about my ability to machine on it though as it didn't come with a toolpost, only a hand turning rest. I might just have to set up with a collet in the myford, or the fourjaw chuck andCdo the best I can with it.

Any chance of setting the hand rest square across the bed, and then locating the cutting tool square to that?

Then hopefully the tool path wood be correct, with the feed being operator dependant.

Howard

If you wanted to face it on the lathe it's working on you could remove the cross slide from the Myford and clamp it down on/next to the small lathe. Use the compound to face it.

Barnabas,

There is a traditional lapping technique, used by 'scientific instrument makers' and watchmakers, that might suit your need to finish the faceplate on the watchmaker's lathe.

Sorry, I can't remember the fancy name for it

Basically, the workpiece [i.e. your new faceplate] is rotated by the lathe spindle, whilst a cup-like lap is rotated on an auxilliary spindle on a parallel, but offset, axis ... the combined effect is to produce a near perfectly flat face, with swirl-lines [like a Catherine Wheel firework] just visible.

This is easily configured using a compound slide, plus vertical slide with a spindle; but I'm sure you could 'jury rig' something to use a Dremel tool, or similar. .... Most of the settings are non-critical: Only the relative alignment of the axes is important, and that can be tweaked 'til you see the right result.

Hopefully this rather laboured description will set you thinking, or perhaps someone will recognise the technique and offer a link to a video ...

Meanwhile; you should find a lot of useful information in this book: **LINK**

http://www.opensourcemachinetools.org/archive-manuals/watch_makers_lathe.pdf

MichaelG.

Hmm. If it's a watchmaker's lathe, and from what you say above, I guess it may not have a threaded spindle but perhaps only a taper for 8mm collets? Whichever, I suggest that the best approach would be to make a dummy spindle nose on your big lathe, possibly forming it on the end of an MT2 blank so you can re-mount it concentric for future operations. Then use that to mount the faceplate blank. If it only takes collets, then make a mandrel matching the taper and loctite it into the blank, rather than a much thinner peg to fit in the collet.

I have to ask though, what do you envisage turning on a faceplate on a small lathe without a tool slide? I believe the main application in watch/clock making is as a "wax chuck", where you use shellac to fix a flat item (such as a wheel blank) on the warmed plate, holding it in place centrally with a centre from the tailstock.. Nowadays you could use superglue and again just warm it to release (smells horrible though). Another way to fix is to use carpenter's knotting (which is just shellac in meths) and let it dry thoroughly - again can be released by warming. For this there's no point in using cast iron, aluminium o brass is just as good.

An advantage of sticking the item down rather than clamping is that you save all the space that clamping holes take up.

Also when you make the faceplate, mark a set of concentric circles on it with a pointed tool to aid in setting up the work.

Edited By John Haine on 04/01/2019 10:50:50

Some cracking ideas as ever guys, thanks!

Michael, the lapping idea is a good one, if I can turn it to within a few 'tenths' then I could lap it flat. I know watch/clock makers use the attachment you are describing for polishing screw heads. I am sure I have seen a YouTube video about making one.

John, the lathe did come with a little brass wax chuck (yes, 8mm with a tapered bore and draw bar) and it is a more useful accessory than a faceplate but there are times when it isn't suitable to stick something down (wood or stone for example) and so a faceplate might be the best option. Also, I just fancied making some bits to go along with the lathe and a faceplate seemed like a good starting point!

If I turn a suitable mandrel to fit the lathe bore and locktite the faceplate to it, then machine it to finished dimensions in one go, it should all be close enough for me I think. I will have to clock it up I suppose and find out once it is finished!

Michael

Did you mean 'engine turning'?

I still think you would be better off making a dummy mandrel for your S7 and turning it on the big lathe with a cross slide. I must say when I bought my Super 7 new at least 10 years ago I bought a faceplate and have used it precisely once! Nowadays I probably use collets most, then the 3 jaw then 4 jaw a distant 3rd.

Good Book link (as usual) Michael - thank you, added it to my PDF reading library... (for Plane & Train use)

Page 79 of said book illustrates what I always think of as a watchmakers faceplate - one with hold-off clamps and 'oles for seeing what's going on behind the workpiece. Barnabas doesn't say what he wants to use his lathe for - it may not be for watchmaking of course.

Regards,

IanT

John has the right idea about making its mounting an 8mm mandrel. Mine (wolfe Jahn) is like that with a 1 in boss to which the plate is held with 3 screws with their heads down and I don't think I've seen a screw on one for a watchmakers lathe.

You could make the mandrel full length of the spindle so it comes out the back where you can put on a thread of your choice rather than using your drawbar.

.

No, David ... I specifically meant lapping

Although, yes, the geometry of the two processes is similar

MichaelG.

.

Exactly so, Ian and the whole of Chapter IV is helpful.

I have a dedicated 'Universal Head' [see Fig.50 for the WW version] for my 6mm Geneva-pattern Lorch; which works nicely on a 'dropped bed' for quite large diameters. ... Light work only, of course !!

MichaelG.