Hi Chris,

You would be looking at replacement feedscrews and nuts for crossslide and top slide, plus the dials of course. For screwcutting metric threads, a new leadscrew and clasp nuts, plus a leadscrew handwheel, if your lathe has one, plus the relevant changewheels.

You might be better off looking at a cheap DRO setup – then you could switch between metric and imperial as you require?

James

Edited By James Burden on 06/07/2012 12:45:20

Edited By James Burden on 06/07/2012 12:47:13

Aren't the leadscrews and clasp nuts all imperial, regardless of the lathe's metric/imperial status?

Martin.

Any chance of a picture of what you have done John

Not until tomorrow at least.

But, cross slide:

– magnet to apron, square alu section horizontal on magnet.

– dial indicator on square alu section, plunger pointing to centre of lathe, along cross slide, tailstock side (behind toolpost).

– rod, through 2 bushings and thumbscrew so it is adjustable, on cross slide, on the tailstock side of the cross slide, pointing in/out, across lathe axis.

– both dial indicator and this rod are "horizontal". dial indicator rests on end of rod. Thumb screw on rod allows for adjustment. Rod resides permanently on cross slide, dial indicator comes off if required.

compound rest:

– dial indicator on aluminum square section, mounted so dial is flat, and plunger facing headstock;

– "rod" mounted on small magnet attached to base of compound rest, adjusted to hit plunger.

So, both dial indicators are horizontally mounted, dials facing up. Both plunge onto rods on cross slide, or compound rest base.

Because of the magnets, if there is a "crash", the dial indicator comes off with magnet from lathe; so far no issues.

I realize that this is an 1124 lathe; 5-1/2" centre height. However, I have been known to do similar to my Emco Compact-8, so you should have room on a Myford.

Yes, I have only 25mm movement, but that has never been an issue so far.

Yes, a DRO would be better. But the price was right, and it's been great working in metric on this old lathe.

Another JohnS

How can you fit a metric handwheel to an 8 tpi leadscrew ?

And this from Myford ???

John S.

I have a metric super 7. The X-slide and topslide have 2 mm pitch feedscrews. The T/S has a barrel with a mm scale. As I found out to my cost one day, the leadscrew is still 8 tpi! 8 tpi is 3.175 mm, so the scale on the handwheel is calibrated in mm up to nearly 3.2 then goes back to zero! As it doesn't have a zero-settable thimble the graduation is next to useless. Even if it did it would only be useful up to 3.175 mm.

For metric screwcutting, Myford provide tables of approximate ratios that are good for some common metric threads which are just fine for shortish fasteners but obviously if you want to make a metric measuring screw they aren't and you need a 127 tooth change gear (which can only be fitted with some difficulty). However since almost all the threads we cut are for fastening the approximations are not a problem since the errors are almost certainly less than the machine accuracy anyway.

I have converted to CNC so the imperial L/S isn't an issue, it's all sorted out in the software.

J.

Hi,

For the lead screw (8tpi) myford table are usable aproximations

Exact (exeption from your LS error/wear) conversion is obtained with a 127T wheel

A very good translation is made with 47/37 (1,27027) this gear train is more handy

as the big 127T wheel.

By adding this gear train at the end of the lead screw (TS side) you can obtain a

handle rotation 1 turn = 3mm.

Is is also neccessary to graduate the handle with an appropriated graduations

(75,100,150,300)

As the Xslide & topslide are 10tpi pitch for imperial & 2mm pitch for metric, 100 divisions

give 0,001" & 0,02 mm. So the dial can remain the same in both case.

Owner of ML7 Sn° K37512

pm

One unforseen handy thing about a saddle DRO is that once you have set up the lathe for screwcutting you can advance the saddle a set number of headstock revolutions, the TPI of the thread you want to cut, and see if things are going to work right, since the DRO should read 1 inch, 2 inches etc

——

It also occured to me that if you needed a really accurate long thread and your leadscrew was old and worn a DRO would tell you what your best configuration was

A change by a single wheel tooth to a "wrong" setup might actually be more accurate over the full length of the cut

so 20-73/40-60/40-50 would be better as 20-72/40-60/40-50 because of machine issues over the length of the cut

Might only be useful to a real professional btw, but it's still handy to know

Because DRO is an INDEPENDENT measuring system I got options which never occured to me until I fitted it

Edited By Ady1 on 09/07/2012 10:22:19