Denford Software & Machines

hi help needed i have a 1980s viceroy 250 lathe and the cross slide brass nut has been lost does any one know where i can buy one or the screw thread used thanks very much

I'll measure the thread on my synchro this weekend for you William. I will be able to give you the pitch but I don't know much about the forms used though having th epitch is a start. When I get a motor I could try to turn you a thread.

Here you go William:

EDIT: PLEASE DISREGARD THE PREVIOUS INFO.

Basically I assumed that since the dial was marked as .100"/turn and the screw thread was .500" OD they must have used an imperial screw. TUrns out that four turns of the dial moves the cross-slide 9.98mm so now it looks like we have a screw with imperial OD and metric pitch. It COULD be that a 1/2" x 10TPI nut would work but right now who knows. All you can do is measure your screw OD with a vernier and then try to measure the pitch too or take a chance and buy a tap from RDG for a tenner and make a test-nut from ally. If it winds on the thread of the screw then you at least can make a brass one to make the machine useable. I've left the drawing up of my 280 nut as a guide.

Pete.

...see above

Pete. wrote:...see above

thanks very much pete that looks like the part i need is the one in the pic for sale or is it being used thanks for you time to reply to me

Hi William.

The truth of the matter is that I am no longer sure what the heck they have produced for a cross-slide screw. I'm still working on it. My gut feeling is that it's an imperial screw but testing with a dial suggests otherwise.

First question is - is your lathe imperial or metric? Does it have dual-scales on the dials?

Pete. wrote:Hi William.

The truth of the matter is that I am no longer sure what the heck they have produced for a cross-slide screw. I'm still working on it. My gut feeling is that it's an imperial screw but testing with a dial suggests otherwise.

First question is - is your lathe imperial or metric? Does it have dual-scales on the dials?

hi pete i dont know as i am new to this hobby it does have a hand wheel and a knurled wheel behind i think for fine movement the lathe is from 1980s is this is any help will the owners manual tell me the information you need but looking at the part you emailed me it looks to be the correct shape and fitment type thanks william

The handwheel is for moving the cross-slide. The knurled wheel is for zero-ing the dials. You hold the handwheel tight and turn the knurled part to line up 0 with the pointer.

On the scale it should tell you the graduations, it will be either 0.001" or 0.02mm. Knowing this will help.

Pete. wrote:The handwheel is for moving the cross-slide. The knurled wheel is for zero-ing the dials. You hold the handwheel tight and turn the knurled part to line up 0 with the pointer.

On the scale it should tell you the graduations, it will be either 0.001" or 0.02mm. Knowing this will help.

hi pete thanks i will have to check the machine thank you very much for helping me

william crosby wrote:

Pete. wrote:The handwheel is for moving the cross-slide. The knurled wheel is for zero-ing the dials. You hold the handwheel tight and turn the knurled part to line up 0 with the pointer.

On the scale it should tell you the graduations, it will be either 0.001" or 0.02mm. Knowing this will help.

hi pete thanks i will have to check the machine thank you very much for helping me

hi checked dial and it displays starts at 0 then 0.1 to2.4 and on a plate on the slide says 1div=0.25mm does this help thanks william

It was common on Denford lathes and Tom Senior mills to have a metric pitch leadscrew with and 'imperial' diameter (0.500" dia x 2.5mm pitch) - to keep common first op machining wherever possible.

Pete - I expect your 4turns = 9.98mm is purely down to wear.

Admin - can you scan & post up drawings ML100/512D (cross-slide feed nut), ML100/501 and ML100/501B (cross-slide screws).

I'm not sure which drawings will show english, metric or both variants.

Andy

Sorry, could only find ML100/512D, its here:

viewtopic.php?t=1922

william crosby wrote:

william crosby wrote:

Pete. wrote:The handwheel is for moving the cross-slide. The knurled wheel is for zero-ing the dials. You hold the handwheel tight and turn the knurled part to line up 0 with the pointer.

On the scale it should tell you the graduations, it will be either 0.001" or 0.02mm. Knowing this will help.

hi pete thanks i will have to check the machine thank you very much for helping me

hi checked dial and it displays starts at 0 then 0.1 to2.4 and on a plate on the slide says 1div=0.25mm does this help thanks william

Metric lathe. You need to find someone who can make a nut to that draeing. If you do, I will have one too as a spare - the one in my pic is the one fitted to my lathe.

I often use this site to identify threads. Very usefull.

https://www.gewinde-normen.de/en/specifications.html


The only 10tpi 1/2" thread I could see was-

https://www.gewinde-normen.de/en/knuckle ... n-405.html

The thread could be entirely non-standard though! I guess I could cut one on my CNC if I had an internal tool small enough- and if I could set it up for the correct profile, if we knew what that was...

I think the safest bet is to find a length of cross-slide or compound-slide screw and grind it to make a tap, then use that to produce a nut. That way we can guarantee having the right thread form. I've been on the look-out for such a thing without any luck so far.

I've been looking at this today and my new best-guess is that it's an Acme thread.

https://en.wikipedia.org/wiki/Acme_thread_form

So the options would be, buy a tap or grind a lathe tool to the correct profile. There's a possibility of using a single point tool to cut the trhead, but I'd probably go for making a tool.

When I get some spare time I'll make a rough tool and turn a thread in alu. that you guys can test.

The drawing says 'modified squareform'. The nut doesn't look like it has a square thread hence my guess at Acme.
Perhaps the mod is from 2.54 pitch to 2.5 pitch?

A closeup pic of the leadscrew might prove usefull.

Andycnc wrote:I've been looking at this today and my new best-guess is that it's an Acme thread.

https://en.wikipedia.org/wiki/Acme_thread_form

So the options would be, buy a tap or grind a lathe tool to the correct profile. There's a possibility of using a single point tool to cut the trhead, but I'd probably go for making a tool.

When I get some spare time I'll make a rough tool and turn a thread in alu. that you guys can test.

The drawing says 'modified squareform'. The nut doesn't look like it has a square thread hence my guess at Acme.
Perhaps the mod is from 2.54 pitch to 2.5 pitch?

A closeup pic of the leadscrew might prove usefull.

thanks for been very helpful i will email you a pic of the screw thanks william