[Newbie] Dual readout Cross/Compound slide dials.

[DELBOY52]

Hi,
As a 'NEWBIE' to Hobby engineering, although I have watched others doing lathe work, I would like to ask a question regarding Imperial and Metric machining.
I believe that most Imperial lathes have their 'Slide' screws threaded in an ACME size, usually 10 TPI, thus allowing the dials to be calibrated with 100, or even 200, divisions. Thus 1 Division would give a 1 thou travel of the slide. However, does a Metric machine (Lathe) have its 'Slide' screws cut with a Metric Pitch, i.e 10 threads per 1 CM ? If so, would the dial still have 100 Divisions, or does it have 10 or 20 divisions?
Also, are there any dials that are calibrated in both Imperial and Metric, which are not the really expensive geared dials? Could a dial be obtained with 100 Imperial divisions and also 25.4 Metric divisions?

I ask this as I am attempting to help a Disabled colleague restore his Mini Lathe. That lathe was originally Metric, with the compound slide having an unusual threaded screw sleeve running along one side of the slide. There is no provision for a Central type screw nut. The problem that we have hit is that the screwed sleeve, together with the Slide screw, are both badly worn. The Compound slide screwed sleeve does not have enough meat on it to insert a bush in order to re thread it to its original Metric size, although it could be bushed in order to accept a smaller Imperial size. The cross slide is not so much of a problem, as a New screw and nut could be made, although we would like to make both screws in exactly the same sizes.

I realise that the above questions may seem a little weird, but any advice would be greatfully welcomed'
By the way, I am in the UK.

Many thanks,

 

[Tony Wells]

One of my lathes has a crossfeed screw that is Imperial, and a dual dial (fixed) that can be used in either the Imperial or Metric system. Honestly, I haven't used the Metric calibrations, but I'm sure it must fall on some odd number of mm.

And btw, the proper way for Metric threads to be described or specified is not in "threads per cm" but in a pitch "length" as in the distance between the threads along the pitch line, a measure from that point on one flank to the corresponding point on the next thread. For example, a standard pitch for an 8mm diameter would be called out as M8-1.25, signifying a diameter (nominal) of 8 mm and a pitch measurement of 1.25 mm from thread to thread.

 

[Sparky2432]

Hi, delboy52, many of the mini lathes I have seen in the uk have parts available. I feel that metric is easier to get accessories for ,but if imperial is required a lot of the mini lathes have conversion kits available.what make and model is the lathe?someone here might know of a conversion or have spares.all the best with the restoration ,mark.

 

[Ghoulardi]

You ain't seen nothin until you've seen the dial on the Y screw on my mill. It has 72 divisions. Weird. What's more is that they are meaningless. When I firs got it I couldn't translate that into metric or english so I got out the JO blocks and found that one rev was .0625. Oh well figured to put DRO's on it anyway. The X dial is english with 62&1/2 divisions. Go figure.

 

[DELBOY52]

Hi, delboy52, many of the mini lathes I have seen in the uk have parts available. I feel that metric is easier to get accessories for ,but if imperial is required a lot of the mini lathes have conversion kits available.what make and model is the lathe?someone here might know of a conversion or have spares.all the best with the restoration ,mark.

Hi Again,

My friend's Mini lathe is probably some 70 to 80 years old, and certainly isn't a modern type lathe. We believe that it may be Danish/Swedish, as the lathe has a sellers name plate showing his name and 'Stockholme'. The lathe itself is very similar to the 'DAMACO' as shown on the Lathes.co.uk web site.

The lathe has no dials whatsoever, but we believe that the original Cross slide screw had a Metric thread. As mentioned earlier both screws are extremely worn. If a Metric screw with a pitch of 8mm x 1.00mm, or 8mm x 1.25mm is made, how many divisions should be shown on the Cross feed dial?

If anyone is using a Metric lathe, how many divisions are shown on your lathe's dials?

Thanks,

 

[7HC]

Hi Again,

My friend's Mini lathe is probably some 70 to 80 years old, and certainly isn't a modern type lathe. We believe that it may be Danish/Swedish, as the lathe has a sellers name plate showing his name and 'Stockholme'. The lathe itself is very similar to the 'DAMACO' as shown on the Lathes.co.uk web site.

The lathe has no dials whatsoever, but we believe that the original Cross slide screw had a Metric thread. As mentioned earlier both screws are extremely worn. If a Metric screw with a pitch of 8mm x 1.00mm, or 8mm x 1.25mm is made, how many divisions should be shown on the Cross feed dial?

If anyone is using a Metric lathe, how many divisions are shown on your lathe's dials?

Thanks,

Sounds like an ideal candidate for a DRO.


M

 

[mekanix48]

Hi Delboy
For what its worth; I have a Warco 250V-F vari-speed (metric) & its dials have a hundred div' on the cross slide but dial is is marked to indicate up to 4.0, so that ea div' = 0.025mm but actually is 2:1 ratio, resulting in double the amount taken off the dia. so be sure you replace your leadscrews with direct configuration. Have attached pics of my crosslide configuration with digital setup to confirm what ea.div actually reads, if you get my drift. The stamping indicates that ea div will take off 0.04mm off dia. not what ea div actually is, intially confused me when I checked diameters on test runs until I twigged ! :thinking:.



Cheers
George

 

[Sparky2432]

Hi again, I have an emco unimat with dials about 1inch diameter with 20 divisions on a thread with 1mm pitch this gives .05 mm per division,when I am working in imperial this works out to be .0019685 inch I call this two thou. Per division.it is as near to two thou. As I can measure. If you could make a dial slightly larger 40 divisions would be easy. 20 divisions with a pitch of 1.25 mm gives .625 mm. Or .00246063 inch per division. 1.5 mm gives .075 mm or .00295275 per division Rounded off this all gives. 2, 2.5 and 3 thou per division with metric threads . Personally I would keep the lathe as standard as is possible and keep it metric just convert on the dials. All the best. Mark