I don’t understand how anyone can manage on a lathe without power feed.
Aside from wanting a more consistent finish am I just lazy?
Oooo look at you Dr 58K on Stack, well done!I've just added a new section to my website with some generally useful (to me at least) metalworking-related data. As part of this, I included a table of distances to feed a tool in when cutting threads on the lathe. I have a print-out of this permanently next to the lathe as I do quite a lot of thread cutting.
Since it seemed relatively topical, I thought others on this thread might be interested in the in-feed distance data.
I hope it's useful to others. Comments/corrections/abuse on a postcard to the usual address...
https://www.cgtk.co.uk/metalwork/data/threadinfeed
I've just added a new section to my website with some generally useful (to me at least) metalworking-related data. As part of this, I included a table of distances to feed a tool in when cutting threads on the lathe. I have a print-out of this permanently next to the lathe as I do quite a lot of thread cutting.
Since it seemed relatively topical, I thought others on this thread might be interested in the in-feed distance data.
I hope it's useful to others. Comments/corrections/abuse on a postcard to the usual address...
https://www.cgtk.co.uk/metalwork/data/threadinfeed
You have not really been using either although probably closer to sharp tipped.
Sharp tipped I will assume refers to the likes of a ground piece of HSS. they can be used for different pitches but will not properly form the root or the crest.
Full profile refers to a carbide insert (although could be fully ground HSS) which has the full thread profile and will form the root and crest profiles correctly, they are limited to a single pitch.
The ones you have are partial profile, they will cut any pitch within the range, say 0.5mm to 3mm , they will cut the correct root profile only on the minimum pitch they are designed for and will not cut the correct crest on any.
From that Sanvik PDF I linked to earlier.
Full Profile
View attachment 204129
Partial Profile.
View attachment 204130
Looks great, but I have a question,...... what's the difference between a full thread form tool and a sharp tipped tool? And which one have I been using??
Sorry but sometimes more information poses even more questions especially for us novices.
There's a knob on the carriage that you pull out for facing, push in for to/from the chuck. Takes about 1 second to switch between facing and turning.
The 'trouble' with mine is that when the feed is set to work towards the chuck as you use 90% of the time when you pull the knob to switch to facing the direction is in my eyes backwards - instead of facing from the outer inwards it goes from the centre outwards which usually isn't what you want. It's easily changed by reversing the drive direction at the headstock, but this means stopping the lathe.
The only time it works as you want it is if you're turning the diameter down and then at the end want to face out on your final cut to the finished, clean length you just pull the knob and power feed out.
That’s weird my m250 works the other way turning towards the chuck then pulling the knob to switch to facing doesnt require a direction change it travels from outer diameter inwards.
That’s weird my m250 works the other way turning towards the chuck then pulling the knob to switch to facing doesnt require a direction change it travels from outer diameter inwards.
Ditto mine (although it's also an M250, so that's not surprising). I guess it's another one of those things that vary from lathe-to-lathe. I must say I can see the advantage of the way @Bill Edwards' lathe works (although I think I would find the need for a direction change frustrating overall). I have on a couple of occasions set up for a turning cut but not realised that the knob was set for a facing cut. With my lathe, the tool plunges into the work-piece; with Bill's it moves safely away.
Probably a sign I need to be more careful...
The Colchester Triumph 2000 I have has two push/pull knobs on the saddle, one for reversing direction, whether that be feeding or surfacing, and the other for changing between feeding and surfacing. If you just change from feed to surface then it will move out the way so you have to pull one and push the other to change from feed to surfacing in the way.Mine is an L5 so a good few years older than your M250's! Obviously at some point they changed things.
There certainly are times when it's a good thing to have it as my lathe is, but more often than not I'd rather it was the same setting for turning to the chuck as well as facing.
The Colchester Triumph 2000 I have has two push/pull knobs on the saddle, one for reversing direction, whether that be feeding or surfacing, and the other for changing between feeding and surfacing. If you just change from feed to surface then it will move out the way so you have to pull one and push the other to change from feed to surfacing in the way.
The Colchester Triumph 2000 I have has two push/pull knobs on the saddle, one for reversing direction, whether that be feeding or surfacing, and the other for changing between feeding and surfacing. If you just change from feed to surface then it will move out the way so you have to pull one and push the other to change from feed to surfacing in the way.
.....with a centre position that is the half-nut interlock so yiu can engage the leadscrew and feed together.