Personally I would say use the thread dial for imperial threads (if imperial screw) that way you can easily reposition internally.
Why would you not use the thread dial for metric threads then.
Personally I would say use the thread dial for imperial threads (if imperial screw) that way you can easily reposition internally.
You can't if the leadscrew is imperial and you are cutting a metric thread. Well not 100% true as on some lathes you can but I think they have a different dial for that. I am not 100% certain as I have never had a lathe with an imperial leadscrew, but I think the iopposite applies if you have a metric screw and are doing imperial threads.Why would you not use the thread dial for metric threads then.
You can't if the leadscrew is imperial and you are cutting a metric thread. Well not 100% true as on some lathes you can but I think they have a different dial for that. I am not 100% certain as I have never had a lathe with an imperial leadscrew, but I think the iopposite applies if you have a metric screw and are doing imperial threads.
Il remember that.If you are new to threading and want to choose a random thread to practice here's a great tip:
Choose a thread that is a multiple of the leadscrew's TPI, then you can literally engage the half-nuts anywhere without having to worry about the dial or getting it wrong. So, if you have a 8tpi screw, choose 8, 16 or 32 tpi thread. Impossible to mess up.
For metric threads choose the pitch, half-pitch or quarter pitch. So if you have a 3mm screw choose 3mm, 1.5mm or 0.75mm. Again, it's impossible to get wrong you can close the half-nuts anywhere anytime.
Il remember that.
Haven't cut a thread yet. Missing most of my changewheels.
Next year's project is gutting this and making a case to fit it on my lathe.
View attachment 203692 View attachment 203693
Precisely why I'm going to try and retrofit.I wish that my lathe had cogs like that, I have to unbolt/change mine over, looks like it's going to be a pain in the rear end.
I wish that my lathe had cogs like that, I have to unbolt/change mine over, looks like it's going to be a pain in the rear end.
What's your lathe? What does the change-wheel area look like?
Sometimes some fairly simple modifications can make swapping gears a lot easier (see for example the one I made for my mini-lathe: https://www.cgtk.co.uk/metalwork/minilathe/threadingbanjo). It'll never be as nice as a gearbox of course.
Interesting link, my lathe is an Amadeal one, very similar I guess.
In that case, open up the change-wheel housing and take some photos and some measurements of the distances between the first change-gear shaft and the leadscrew shaft. If it looks like it's the same as my SC2, I'm happy to post you both of my home-made threading banjos (as shown in the pictures on the website). I've got the M250 with its gearbox now, so I can't imagine ever wanting to cut threads on the mini-lathe again.
On a positive note, if your lathe is the same, it's got a flange-mount chuck. That means you can safely run it backwards with an upside-down tool and thread with the tool moving away from the headstock. That makes for a much more relaxing threading experience and is pretty much the only way I ever do it these days. No worrying about crashing the tool into the workpiece as it just runs off the end into free space.
Well done on cutting your first thread
But if you keep calling those gears cogs I'll have to send someone round - and it won't be Santa, it'll be his evil twin Satan
The blanks in the indicator table are where it won't work...
There had to be a mathematical relationship between leadscrew pitch, thread pitch and indicator gear (14 / 15 / 16 teeth) for the indicator to synchronise the leadscrew with the spindle and tell you to engage the halfnut in the right place.
Dave H. (the other one)