| Gallery, Projects and General > Project Logs |
| Swingup external threading tool |
| << < (22/29) > >> |
| Artie:
I hear whAT YOU ARE SAYING BUT AT THE SPINDLE SPEEDS AT WHICH SINGLE PPOINTING IS CARRIED OUT, THIS PROBLEM IS PRETTY UNLIKELY...oops sorry damned caps lock..... :doh: Btw, thanks to Bogs, this item is HIGH on my list of tools I need to make .... Cheers Rob T |
| troup:
--- Quote from: Artie on May 16, 2010, 05:31:46 AM ---I hear whAT YOU ARE SAYING BUT AT THE SPINDLE SPEEDS AT WHICH SINGLE PPOINTING IS CARRIED OUT, THIS PROBLEM IS PRETTY UNLIKELY...oops sorry damned caps lock..... --- End quote --- It happened at only 250rpm or thereabouts on my lathe, which is well within the single pointing speed range for a fine thread, even on a totally manual lathe without any fancy bits and pieces. And it happened emphatically. not tentatively, although I reiterate that the chuck was empty. I'm puzzled you would say that in any case; the only reason single pointing on manual lathes is done so slow is the human factor. From a process (and particularly finish) point of view the traditional speeds are woefully sub-optimal, especially for carbide. To me the main attraction of this flip-up tooling idea is single pointing at speeds more like CNC than manual lathe practice. This in turn is the main reason CNC threads (particularly in gummy materials like mild steel or alu) are so much shinier in their finish, and when I saw that fantastic video of John Stevenson's I suddenly realised we mortals could have that too ! Check out the finish on John's photo, also (not the crummy material from the second, LH thread (?) test, but the first. It's my hope, which I'm a few more hours of spare time from of testing, that (providing reversing is accurate and automatic) it should be perfectly feasible to single point at speeds unthinkable on any manual lathe short of a Hardinge HLV with a highly sophisticated single tooth dog clutch. This is dedicated to providing an adjustable, reliable and automatic reversal cycle, specifically for singlepoint threading, even up to a shoulder. The manufacturers cheerfully suggest this facility should not be used at over 800rpm, or 1000rpm, I forget which... A new Hardinge is about USD50,000, or 15,000 for a Taiwanese copy. Compare this with: Flip up toolholder: a few hours or days of work, depending on sophistication Auto reverse sensing/switching and trip dogs: if you already have a VFD: maybe the same In my case, I need to make a 'Dead man's pedal' for control and safety reasons (the inverse of a foot brake), and that's just about done. I'd like to say a huge thank you :beer: to the people who blazed this trail; to the guy from another forum (Mike Cox?) who revived (or independently reinvented) the idea, to the guy who brought it here, to the intrepid early adopters who so generously and inspiringly and thoroughly documented their investigations and implementations, including Darren who brought the good news from Ghent to Aix (ie posted on the PM forum, bringing it to a new audience again, myself included.) I'd even like to thank the muppet who took umbrage at a perfectly reasonable response to his plea for drawings -- for having the decency (or truculence, or whatever) to leave the field before his hissy fit could give rise to any temporary tensions in the exemplary public-spiritedness of this forum. |
| Bogstandard:
I have now finished reading the rest of this topic, and it seems to have generated a fairly large following and comments on other sites as well. But I have noticed there are people who think nothing of changing the basic design and calling it OK to work with, then calling it their own 'new' simplified design. I am not boasting, but I have had a very deep grounding in basic engineering design, which it seems a lot of people haven't, and in the unshown background, while developing this tool, lots of calculations were used to make sure the original design I did turned into a simple build exercise, where almost anyone with a bit of machining knowledge could make one, and get a tool that would work, and last almost indefinitely. What has been done by other people, is basically doing away with the little block under the nose of the tool, the one that stops the tip of the tool swinging side to side, and are relying on a large washer around the rear pivot point instead. WRONG. Little would you believe it, that little block is one of the most important bits of the whole setup. Without going into deep calculations about moments and stresses, and to explain it in easily understandable terms. The block is there to take all the load of the side cutting action, and not allowing those loads to reach the pivot bolt. By doing away with it, that side load is instantly and drastically increased by the moment of the length of the swing arm and cutting tool, and is very likely going to cause the pivot bolt to break at the shoulder where the thread screws into the main block. Maybe, with dire results. The things I show usually do take a lot more thinking about than you ever see, plus also I do try to simplify things so everyone can understand it. So please, if you are going to change the design, look to the possible consequences that might happen before doing so. I don't give a rat's arse about someone taking a design of mine, or anyone elses, but what I do object to, is people taking a proven and safe design, and modifying it to where someone just might get injured. Bogs |
| Boucher:
I don't give a rat's arse about someone taking a design of mine, or anyone elses, but what I do object to, is people taking a proven and safe design, and modifying it to where someone just might get injured. -------------------------------------------------------------------------------- If you don't try it, you will never know if you can do it. Somehow these two statements seem to be in serious conflict. I have no personal intrest in turning left hand threads and I doubt that the key is needed for right hand threads. As stated, "If you don't try it, you will never know if you can do it. For a really simple swinging tool a dedicated tool post rather than the quick change holder appears to hold the advantage in simplicity and rigidity. The description and detail of the cutting the quick change holder is very well done and should be preserved as a separate stickey for others to copy. John Stevensons inverted design and the way he makes the tool blocks in long strips makes one think about doing that for these tool holders as well. This swinging thread tool is one of the best work saving shortcuts that has come down the road in a long time. If your machine has the features to use it you should try it. |
| 75Plus:
--- Quote from: bogstandard on September 21, 2010, 08:03:36 AM --- But I have noticed there are people who think nothing of changing the basic design and calling it OK to work with, then calling it their own 'new' simplified design. Bogs --- End quote --- In all honesty John, I believe you took Mike Cox's design and made your "New and Improved " version to satisfy YOUR tastes. Not everyone feels the need for a "Rolls Royce" model so they build themselves a "Ford" which serves their need. It should be their choice and, if they choose to post their results, that should be OK also. Joe |
| Navigation |
| Message Index |
| Next page |
| Previous page |