very old lathe help please

[stk2008]

Hi all well I got me a very old lathe its an Portass model s :P very old hehe.

Well I have had a play with it and the tool post axis (not sure what the proper term would be) has alot of play in it so I have taken it apart and there I think is an Acme thread and that goes into the bottom of the tool post axis not into a nut so the post casting is worn .

I have measured the Acme thread and its coming out at about 0.390" or 1/32 I have set my vernier the 1" and I am getting 12TPI if this is the way to check?.

What I am looking at doing is getting a nut and drilling out the casting with the worn thread in and sticking the nut in then putting a grub screw to hold it.

This will work BUT can I find a nut can u hell .

Other option is to get 10mm Trapezoidal spindle and nut but I would have to have a lathe to turn the spindle down which I wont have :P.

So any input on this would be great.

I have got no play in the axis that moves the whole tool post up and down the length of the bed as I fixed this with resetting the bronze bush.

I will take photos of it tomorrow if I can.

Thanks all

[Al_The_Man]

Originally Posted by stk2008 Hi all well I got me a very old lathe its an Portass model s :P very old hehe.

Is it the 1922 portable model with the treadle? for £2/5/0.
http://www.lathes.co.uk/portass/page12.html
Al.

[stk2008]

Hi there not far off that age hehehehe its more like this one but with a newer motor ran off the back I will post pics of mine but heres one like mine I have found on the net

http://i47.tinypic.com/292339w.jpg

[stk2008]

Ok here are some pics of my Portass Model S

http://i49.tinypic.com/2dvpz5c.jpg
http://i45.tinypic.com/fxb1gg.jpg
http://i49.tinypic.com/33vf56u.jpg

[M250cnc]

The axis you are referring to is the cross slide.

Looking at your pictures that you posted the one that you say is similar to yours has a slide on top of the cross slide.

This is called a compound slide yours is missing and has been replaced with some sort of spacer.

This type of set-up would be difficult to use as the saddle handwheel is located way over on the right hand side.

As regards the backlash all machines have it but some have ways to control it.

One way is to cut the nut in half and then be able to adjust the two halves together taking out the backlash.

An extreme example is to nuts locked together on a thread they will lock solid.

The alternative is to have someone else machine the parts you require

HTH

[stk2008]

No worry's thanks for the help but I have now got it on Ebay as I have to many problems at the moment to even try to get out in the work shop damn bloody back but maybe when I am better I will get me a lathe that actually don't need looking at tho this one is good I have no time at mo.