Today I acquired...........

[Screwdriver]

You can indeed move the saddle all that matters is that you re-engage on the same mark of the same turn. If you're feeling brave, you can wind the saddle back all the way to the end of the bed counting the thread dial turns then reverse the lathe until the leadscrew has un-wound those turns and then pick up the same mark, and you'll still be on index. It's a risky venture with a high risk of messing up your turn count, and the only thing to gain is reduced war on the screw and nut, but it works perfectly well.

For short threads it's far less risky. If you divide the number of teeth on the threading dial gear by the leadscrew's TPI the result is the number of inches you can move the saddle without the threading dial even making a full turn, so suppose you have a 8tpi screw and a 24t gear you can move up to 3" and still be on the same turn of the dial. It's easier than it sounds TBH.

FFS. Wind the saddle all the way to the end of the bed?? WTF would you want to do that? Your comment about re engaging on the same mark of the same turn is unintelligible, I don’t know what you’re suggesting. If you are saying just use the TDI as per usual, that is INCORRECT!

I suspect you are answering some other question. This nonsense is ONLY for the circumstance where you are cutting a metric thread in an imperial lathe. You cannot move the saddle with the half nut disengaged and re enter the thread in the correct position.** I know you know better so I am hoping you just misread the question.

** yes there are absurd bodges that machinists might be able to pull but “count the rotation of the lead screw” I mean seriously wtf.

 

[Pete.]

Same turn of the thread dial. Read through my post again properly and try to understand what I'm saying instead of going all rage-faced.

If you stop the lathe and wind the saddle back the thread dial will turn.How far you wind it is completely unimportant. All you have to do is reverse the lathe until you undo those turns and re-engage the half nuts on the same line then you are properly indexed.

 

[roofman]

Same turn of the thread dial. Read through my post again properly and try to understand what I'm saying instead of going all rage-faced.

If you stop the lathe and wind the saddle back the thread dial will turn.How far you wind it is completely unimportant. All you have to do is reverse the lathe until you undo those turns and re-engage the half nuts on the same line then you are properly indexed.

This is my understanding of it too

 

[Bullet2012]

Same turn of the thread dial. Read through my post again properly and try to understand what I'm saying instead of going all rage-faced.

If you stop the lathe and wind the saddle back the thread dial will turn.How far you wind it is completely unimportant. All you have to do is reverse the lathe until you undo those turns and re-engage the half nuts on the same line then you are properly indexed.

All makes sense to me as well.

 

[DAPPH]

Anyway back to the title of the thread
Today much to my surprise as it was a notified 17.00 hrs Sunday delivery by DPD , I acquired one of these after being pointed in the right direction by guys in the brewing section ... many thanks guys . I can at last cap the small single lipped 130 ml liqueur bottles
Will be putting the used twice plier crimper on eBay for a lot less than I paid for it unless someone on here gives me a PM shout for it .

https://www.biggerjugs.co.uk/collec...-top-capper-for-both-26mm-and-29mm-crown-caps

 

[selectedgrub]

but apart from that it's great!

Wait till you get it calibrated.

 

[Screwdriver]

you re-engage on the same mark of the same turn.

This makes no sense

If you're feeling brave, you can wind the saddle back all the way to the end of the bed counting the thread dial turns then reverse the lathe until the leadscrew has un-wound those turns and then pick up the same mark, and you'll still be on index. It's a risky venture with a high risk of messing up your turn count, and the only thing to gain is reduced war on the screw and nut, but it works perfectly well.

This makes more sense

Same turn of the thread dial. Read through my post again properly and try to understand what I'm saying instead of going all rage-faced.

If you stop the lathe and wind the saddle back the thread dial will turn.How far you wind it is completely unimportant. All you have to do is reverse the lathe until you undo those turns and re-engage the half nuts on the same line then you are properly indexed.

This makes perfect sense.

But of course it is a completely absurd way to cut a thread, just to "save wear on the lead screw". Give me a break, it's just to artificially invent a scenario which functionally exactly the same as driving the saddle backwards with the half nut engaged or as I have detailed earlier, re-engaging the half nut (after manually moving the saddle) with a even multiple of turns on the TDI. Be careful arguing with that.

You might disengage the half nut (when cutting metric on imperial) for two reasons 1. to quickly stop the movement of the saddle into a shoulder or the jaws 2. when cutting a longer thread at slow speed so that you can quickly wind back the saddle. "Saving wear" is a bogus excuse for presenting an artificial "argument".

I have explained how you can disengage the half nut then re-engage on the same mark by counting the turn of the TDI. I guess you missed that.

As for the second reason, you might want to wind the saddle back quickly by hand to save time yes but then with this bogus example, you have to drive the lead screw backwards anyway! Otherwise, as I have said a thousand and one times now, you will lose the phase relationship of your threading.

Pete, I fully understand what you are trying to get across and it’s something I do on occasion. The big DSG lathe worked on that principle. It had trip levers that automatically disengaged the half nuts. You then wound the saddle back manually. It even told you with which pitches you could re engage on odd numbers and which were even numbers.

Unfortunately there are certain members on here with little to no real world experience when it comes to machining,but that doesn’t stop them adding their two roubles worth.


I’ve found the best way to deal with silly little people on here that like to sprout nonsense and use uppercase letters…the ignore function works wonderfully…

I fully understand where you are coming from too. Yes we had an argument a century ago when you last made a fool of yourself and yes I can see you like going after me everywhere you can.

But we have met so the personal insult regarding my stature is about as unwelcome as a big fat South African.

You clearly have no idea what my qualifications are and whether I am a trained machinist or not. As it happens, I am. In your haste to dive in with an insult and "prove" me wrong while trying to make yourself look big, you have committed the cardinal error of being completely wrong yourself. You cannot cut a metric thread on your DSG lathe and disengage the half nut "with which pitches you could re engage on odd numbers and which were even numbers". I can see where your confusion is, after all, it is a childishly simple error you are making here.

Anyhow, yes, I had a hissy fit but no, I am not wrong.

 

[Richiew]

Someone needs to invent a digital counting dial thread indicator.

 

[Screwdriver]

Slim fast?

 

[Screwdriver]

Someone needs to invent a digital counting dial thread indicator.

You could use a mechanical counter with the added bonus it would count up and automatically count down but it is a rare situation, really only presented here as a sort of pedantic bodge to argue about whether or not you can (or should) disengage the half nut with metric-imperial threading. Personally I just stop the machine and throw it into reverse.

It's not a very difficult operation but it is repetitive and therefore easy to make a mistake especially if you're doing a large batch. Plus if you're doing a large batch, you really want to streamline your workflow to remove unnecessary operations when there is already a relatively large number of operations you have to do - in strict order.

 

[Pete.]

Engage the half nut as usual to start the threading at a known point on the TDI.
Cut the thread into the relief, disengage the half nut and immediately stop the lathe.
Do not manually wind the saddle(!)
Power the lathe backwards and as the TDI starts turning backwards, re-engage the half nut at the mark. Note because you stopped the lathe very quickly after disengaging the half nut, the TDI has only moved a small amount past its mark. The half nut is of course in the exact same phase as if you hadn't disengaged it SO LONG AS YOU DON"T MOVE THE SADDLE MANUALLY WHILE IT IS DISENGAGED.

If the saddle moves at all while not connected via the half nut, the relationship of its position wrt the thread is lost.

Anyhow, yes, I had a hissy fit but no, I am not wrong.

Well, yes you are. You said, in capitals no less, that you must not move the saddle as if it's some cast-iron rule. It's not even a rule much less a cast iron one.

 

[Screwdriver]

Well, yes you are. You said, in capitals no less, that you must not move the saddle as if it's some cast-iron rule. It's not even a rule much less a cast iron one.

I then went on to explain why. In some detail I might add.

And, as you have probably realised by now, I am not wrong. FWIW I appreciate you know a darned site more than I do about this subject and workshop practice generally. You would be the sort of poster I would go to for advice. But that does not change the veracity of my argument.

I could tell Einstein he was "wrong" about "the cosmological constant" (we are all standing on the shoulders of giants), facts stand for themselves, they do not submit to prejudice or individual merit. You can shift the goalpost and say I am making up a "rule" and that "rule" is wrong. It's called a straw man argument. I have had plenty of those thanks and yes, it is because I am sometimes a bit of an *******.

I am still not wrong.

 

[8ob]

This bun fight is very boring.

Bob

 

[James1979]

This bun fight is very boring.

Bob

A lot of it on here lately. Not just this thread.

Something in the water I think.

 

[The_Yellow_Ardvark]

A lot of it on here lately. Not just this thread.

Something in the water I think.

Well said.

 

[Wozzaaah]

Can’t even blame the heat.
Petty bickering has no place on here, all it ever does is wind people up and drag the overall tone of the forum down.
it’s always the same few members that just have to try and convince us that they’re right and everyone else is wrong. If it carries on then we’ll be making more use of the thread reply ban option as that always seems to get the message across.
Please people, you all say how much you love it on here so just be nice to each other,

 

[The_Yellow_Ardvark]

Its World championship Gravy wrestling day today according to the Radio….Now that’s got to be better than a bunfight

What about a floury bap?

 

[JMS1972]

Someone needs to invent a digital counting dial thread indicator.

They have kind of it's called the Electronic Lead Screw project. You can buy kits on eBay.

It uses a cheap rotary encoder on the spindle to drive a stepper motor on the lead screw. Some simple electronics and some clever software sit between the two. Can cope with reversing and rapid traverses etc.

 

[Blobber]

Its World championship Gravy wrestling day today according to the Radio….Now that’s got to be better than a bunfight

But its not even proper gravy which was a bit of a disappointment!!

 

[daleyd]

Seem to have acquired this little doog as of this morning - our 2 cats are really not sure what to make of her!!