Downwards-Counting Cross-slide Dial?

I don't know why I have not spotted it previously but the cross-slide dial on my Harrison L5 lathe counts down, not up when advancing the tool towards the centre.

The top-slide counts up, when winding towards the chuck.

The dials on my Myford ML7, EW and yet-to-be set up "Micro Lathe" all count up towards the lathe axis and chuck.

So, anyone know why the L5 begs to differ?

Funny thing is, I have used that lathe for a good number of years before it became my own, and it was only today that I noticed its dial's nature! And then only because it nearly caught me out.

So you take the first cut, measure the job and set the dial so that 0 is the finish cut position. Then you keep taking cuts working toward that 0 mark. No need to remember where you are aiming at (or mark the dial with chalk or felt pen as i do) and no need for measuring along the way until about the final cut or two. Makes the whole process simpler and quicker. No repeated mental arithmetic along the way.

I think its a great idea. When i get around to making resettabe dials for my Myford i think i will incorporate it in rhe cross slide dial. Topslide i don't see the need so much.

+1 for what Hopper says.

Not only does setting the dial to finish on zero save the mental effort its also an excellent check that what you get is what you set. Doing the stage by stage make a few cuts measure, make a few more, measure again process that neophytes tend to drop into can hide machine issues which are certain to turn round and bite you on a critical job.

I suspect mosts elf taught folk don't properly exploit the dials. Which is a pity as having reliable dials and working to the numbers is both quicker and easier.

Even folks with proper DRO sets probably don't exploit the multiple memories provided for just this sort of thing.

Clive

Without doubt, the best modification I made to my Clarke minilathe was fitting a handwheel to the end of the leadscrew. I bought a suitable wheel, complete with dial, from ArcEurotrade, and because the leadscrew is a RH thread, the dial reads backwards. Initially I thought that this would cause all sorts of problems, but after a couple of operations I adapted to turning the wheel CCW to advance the saddle and reading the dial backwards. I confess, though, that I hadn't thought of using Hopper's suggestion above - I'll give it a try.

It's just another designer's smartypants idea. My Warco counts double the actual movement on the crossslide because it's calibrated on diameter.

I find these 'aids' just a minor irritation - another b100dy thing to remember - but you get used to them.

I'd slightly prefer the simplicity of the Navy method - signal the raw data and leave it to the person on the spot to do the interpretation. Once you put a spin on it, you're as likely to complicate his job as simplify it. That way you don't have to do different arithmetic depending which slide you're using.

Edited By Mick B1 on 03/07/2020 10:17:58

I'm glad I don't have a backward dial, I like to see directly the ammount of cut I'm taking. And I prefer to be reading the exact movement of the top slide.

The dial in question is settable, and I do sometimes use the "aim-for-0" method, but I asked originally because it seemed so at odds with anything else I have seen or used.

It was not how to use the graduations I was asking, but why it counts in the direction it does. The screw itself is LH as you would expect - it's the graduations that are widdershins.

It is of course possible it is not the original dial, especially as its diameter prevents full angular use of the top-slide that the protractor scale would suggest.

'

Still awaiting re-commissioning in my workshop is a small (ish) Denbigh horizontal mill, and that has two of its screws at a right awkward 6TPi, of all things, instead of a binary pitch. Its dials are sparsely graduated and it will be interesting to see what their divisions and count direction are!

My main lathe at work is a Harrison 11". That is to say, a later L5A. The cross-slide dial on that is graduated in the normal way, increasing as the tool feeds into the work. Incidentally, it is also direct reading, radius not diameter. I've cast an eye over other L5's, L5A's, 11"s and 140's over the years, both before buying mine and since and all had a conventiona dial.

My money is on one of two things. Either your reverse reading dial was a option at manufacture, to suit the original purchaser's needs, or a later alteration. Harrison did offer a vertical slide for the L5 and its relatives. Vertical slides often have the dial reverse calibrated. I don't know if the feedscrew and dial dimensions are common, but it's possible that a VS dial has been fitted either during a repair/overhaul or by mistake at the factory.

Mike

.

I remain curious to understand the logic underlying this choice of 6tpi [and 12tpi recently mentioned]

Browsing around, I found this discussion ... which may be of interest to you, Nigel

**LINK**

https://www.practicalmachinist.com/vb/antique-machinery-and-history/1930s-denbigh-h4-horizontal-miller-6tpi-crossfeed-screw-248828/

MichaelG.

Thank you!

Michael H -

Yes, I'm inclined to think it some later modification, whether the reverse dial was intended or by mistake, but it can be confusing to use! It's of rather unusual numbering too, 0-25 X 5s (of thousandths), rather than by 10s with extended 5s lines.

I was using it earlier this evening, to cut two grooves, and used the set-to-0 approach Hopper advises above .

Mike G -

For some reason I was unable to view that reference. The system just told me "This Page cannot be displayed".

I had wondered if 6tpi, which I think is also on the long feed, was to special order, but the only trade I could think of that might work in such fractions is printing (twelfths of inches), so someone might have wanted the machine in making type-galleys.

I've not looked to see what it is calibrated in, but I've tried to work out binary-fraction equivalents for it, and it soon becomes unwieldy:

Calibrate the dial in 12ths and the 8 (3/4 turn) gives 1/8 inch;

In 24ths, 9 = 1/16"; 18 = 1/8"

in 48ths , 9 gives 1/32" ; 18 = 1/16", 36 = 1/8" . 1 would = 0.0035". Very useful!

A decimal dial would not be much better since 1/6" = 0.1666...

.

Good morning, Nigel

No offence taken, but I must mention that you have our names crossed ^^^

I prefer to be called Michael, and presumably MH prefers to be called Mike

.

Now to your 6tpi

Sorry you couldn’t wiew the linked page ...

I guess it was a temporary glitch, as I have just opened it again, with no error message

.

Post #10 makes a very practical suggestion, so I am quoting it for convenient reference:

[quote]

Steve,
Read out is an easy but an expensive option for a horizontal mill. Here is another proposal. Make a dial with 167 divisions, if you assume each division is one thou the error is .000002“ per division. If you index 100 divisions instead of moving the table .1“ you will have moved .0998“ an error of .0002“, plenty good enough for a Denbigh horizontal. If you measure a piece & want to move a small increment for a finishing cut you can forget the error & six turns will still give you one inch of movement.
Ray

[/quote]

MichaelG.

.

Edit: With a pair of interchangeable diials you could work in either system.

... Which might be handy

Edited By Michael Gilligan on 09/07/2020 07:20:01

There was gossip in the machine shops of the 1970s about Russian lathes where configuration was ar$e-about-face - headstock on the right, leadscrews opposite-handed etc.

I've heard nothing of that since, and I never saw any such, so I reckon I'll just leave it there...

Hi Hopper, although this is true, 0 comes round every turn of the dial, which ever the direction it turns and subtraction is just as easy as addition, which is what I do, so you can work towards 0 either way, once you know how much needs to be removed. Of course, if your dials are fixed, you have to keep track by marking with chalk or felt pen.

Regards Nick.

Both Michaels -

Sorry about the mixed up names. I realised my mistake when I posted the message but I don't know how to edit a post. I know it's possible but it's not at all obvious!

The inaccessibility problem might be due to my system using Internet Explorer. I have a sneaking suspicion some web-sites no longer work with it, as appears the case with one of two the materials suppliers on my list.

===

A trick I sometimes use with a fixed dial, whether counting up or down, is to slacken the tool-clamping and ease it into contact on the required dial number. I always measure for the finishing cuts anyway.

Similarly with the longitudinal cuts by top-slide, by adjusting the work-piece in the chuck up against the tool.

(I can never remember if long-ways is sliding or surfacing, so on the L5, which has both feeds powered and reversible and labels the controls by those terms, test that setting with the saddle well clear of the work.)

~~~

I have heard of that tale of Russian lathes, but like Nick, take it with a large pinch of salt. Perhaps there were some made that way for a special purpose. However, I have seen a video of Russian turner using an ancient but decent-looking lathe, otherwise conventional but having cross and long feeds that could be engaged together but geared separately, to generate plain and threaded tapers. He was making large, rapidly-tapered auger-type screws, the business-end of log-splitters for producing fire-wood.

I owned for some years an old IXL-badged but probably Ehrlich-made lathe, on which it was horribly easy when stopping either feed to miss the central neutral-point and go straight to the other direction, in motion. My precaution was simply a loose bolt in the "other" pin-hole.

I rather miss that lathe, which had a T-slotted saddle and comprehensive set of fittings, but home-moving and other space reasons enforced disposal. Following a suggestion from a friend I donated it to the Lynton & Barnstaple Railway workshops - who apparently forgot to offer him his hefty fuel cost for delivering it from East Dorset! Neither of us are L&BR members. I hope they either still have it, or if not, it has a new and loving home elsewhere.

But its easier -- for me -- to add 37 to 0 than to subtract it from 100.

Hi Hopper, fair do's.

Regards Nick.