upside and reverse
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Last edited by Schutzhund; 04-01-2006, 04:25 PM.
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For those of you that dont get it (new to machining, etc.), he turned the toolbit upside down and ran the lathe lathe in reverse, so that the threads could be cut with the carriage moving away from the chuck rather than toward it.
My only question is: Is this safe to do with a threaded spindle? There are two chuck retention "clamps" that "bite" into a groove on the spindle on this type of lathe. Is this considered adequate enough to keep the chuck from spinning off the spindle? Or would this be considered a risky operation?
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Originally posted by SchutzhundFor those of you that dont get it (new to machining, etc.), he turned the toolbit upside down and ran the lathe lathe in reverse, so that the threads could be cut with the carriage moving away from the chuck rather than toward it.
My only question is: Is this safe to do with a threaded spindle? There are two chuck retention "clamps" that "bite" into a groove on the spindle on this type of lathe. Is this considered adequate enough to keep the chuck from spinning off the spindle? Or would this be considered a risky operation?
This is about the ONLY way I ever do threading. So much easier and you don't have to worry about pulling it out of gear at the last second before the tool slams into the chuck or uncut workpeice.
But there ain't no way I'd do this on a screw-on chuck though!
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I was thinking about this on the ole Craftsman. If the threads are clean and in good shape, the last "sling" holds the chuck darn tight. With light cuts it shouldn't be a problem. I thought about modifying the backing plate for a chuck to use a t-shaped sleeve and draw bar setup. That would hold the chuck on but limit through-chuck capacity. (Like collets)
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Originally posted by BillHYour also putting more stress on the whole carriage and compound. Instead of everything being in compression, your in tension.
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upside and reverse
Unfortunately, I ran into computer problems with " Machining Forum" and after a lot of effort from many very worthy guys, Adrian manage to fix my problem going through his " network". It was at the time when I was trying yet again to mention that this "thread" is being constantly repeated in both Forums. It was at a time when I was feeling a bit peeved because readers fail to accesss the real gems from other contributors.
Not me, I am only repeating the findings of other people but what appears to be pretty original research from others. I'm not clever like that.
To try to come back in- so to speak- might I suggest that "digging in" to these vast wads of information is something to be cultivated. It is part of the learning pattern and is to be encouraged. Only in recent days did someone post that he had followed my words and music- albeit a year ago when I wrote. That he was finding this upside down lark on the lathe and things so useful and so on. Again, I got a nice E-mail from a bloke in the UK who thanked me so something or other. Frankly, I'd forgotten except that he had come over as a fine guy.
Please have a go at researching information and mention where you get your sources. If you disagree with some of us, again tell us what you discovered wrong and how you corrected the problem. Few of us know a fraction of the answers but respecfully, detail your experience for others.
Again, learn to thank contributors for their help- and apologize for being a crusty old so and so. Like I am being now?
Norm
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upside and reverse
RustyB and all
Many of us in England own Myfords which a 7" swing lathes with a threaded nose.
If a Myford is run in reverse the odds are that the chuck will come off.
Parting Off-which is primarily what I was prattling on about- is best done with an upside down tool at the rear of the saddle.
Again, if any operation is carried on, the whatever will be on the floor with a bit of toe attached. Clearly, the screw in spindle and the reverse on the motor are for removal of chucks- and toes.
A screwcutting tool is theoretically no different to any other lathe tool and for all practical purposes operates from the front of the saddle- with screw in chucks.
Having said all that, screwcutting does present difficulties to some.
Books have been written solely on this ie Screwcutting in the Lathe by Martin Cleeve- TEE. This directly relates to someone who had a screw nosed lathe.
Again, George Thomas wrote up screwcutting in his Model Engineers Workshop Manual- again TEE. Again, George was a Myford user and went on to publish drawings for two retracting tools in which the cutting action could be disengaged at the flick of a lever. Furthermore, he published a mini parting off tool. All in one book!
As you will appreciate it is impossible to condense the writings here.
Again, going on( as usual), this is what I hinted at a post or so ago about publishing what was found to be useful to other readers.
Buy the books, you may not agree but they are my "Bibles" on the subject.
As a sort of word of caution( RustyB), removing a stuck chuck uses words that ought not to be printed here. I once had to machine a backplate off.
Regards
NormLast edited by Guest; 04-09-2006, 01:29 PM.
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I do this all the time (threading in Reverse) on a 1943 Logan built lathe with a threaded spindle. I run it in Intermediate Back Gear when threading 'cause things happen so quickly once the half nuts are closed. Since I am only taking off about .010" or less at a pass, I do not see that enough pressure is being put on the chucks or faceplates to cause them to un-screw. If I were cutting or boring on a production basis and needed to make deep cuts, I don't think I would try it.
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When I run mine in reverse I always make sure the tailstock is brought into play. Forrest mentioned something to that affect about a year ago and it stuck. Thanks Forrest.- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Thank you to our families of soldiers, many of whom have given so much more then the rest of us for the Freedom we enjoy.
It is true, there is nothing free about freedom, don't be so quick to give it away.
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