New Lathe

George; you can also scratch a new zero marking at 10 degrees, makes live a little easier. Niko.

Edited By speelwerk on 30/10/2013 13:54:35

On a lot of lathes the pin or stud about which the topslide rotates is not designed to be a precise fit or reference point so the degree scale can be variable even if you make a new 'zero'. At some stage you can make a genuine vernier scale to add to the degree scale if the above does not make it pointless.
If the toplide has a flat side face that is also accurately parallel to its movement you can set that against a square held against the face of the chuck. Another method is to set a centered holed bar between centres as a reference.

Another point is that on some lathes the whole saddle can twist slightly on the bed anyway. This does not happen on top v-beds but does on round and flat beds, including those with the v slope underneath a flat top.

In the end, if it is something important, you still need to check with a test indicator.

In many ways if the lathe has a leadscrew that can be disengaged from the saddle then it is just as well to deliberately keep the topslide offset to avoid temptation.

If you set your top slide at an angle then you can get a finer control of the in feed for those times that you need to remove half a gnats whisker from the work. For example you can set it such that 1 division on the top slide dial advances the tool 1/2 thou. ( or any other amount depending upon the angle that you set). To find the angle you need you will need to revisit those maths lessons where trigonometry was on the menu. ( See they SAID it would come in useful one day!)

N

Sorry for the confusion its the protractor gauge I am referring to its way out. It needs to go in the bin.

The book I was advised to buy arrived in the post this morning I will give it a coat of looking at before having another go at turning expensive silver steel bars into scrap.

Hi Dave,

The original measurements you quoted would equate to an error in the topslide setting of just under half a degree. That seems to be a reasonable error for the degree scale on this type of lathe. That scale would usually be used for things like 45 degree chamfers or feeding the tool in at an angle for screw cutting. Anything requiring accurate tapers would need setting with a dial gauge, a reference taper, or a sine bar.

Enjoy the reading.

Russell.

Edited By Russell Eberhardt on 31/10/2013 21:07:15

I have started reading the book I think its going to be a uphill struggle there is more to this machining business than meets the eye. I have loads of projects I would like to start but I am realizing there is a huge learning curve to get over. Thanks for all your input much appreciated.