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Swinging Thread tool
Boucher:
A bit of additional information.
John Stevenson’s post on HSM was the original motivating influence to develop this tool. Evidently his original interaction with the originators of this tool involved his thought that it needed some sort of keying which he incorporated in his tool. He posted a video link that clearly showed that his design worked.
I stated that this was my first attempt to develop a version of this tool. It did not incorporate the indexing key. If that indexing feature is shown to be necessary it can be added with a key or with a side support bar.
Having long ago started my professional career as a Design Engineer in the Aero-Space industry, I really don’t trust designs that seem to work perfectly on the first try. In my experience, designs that go through a development process are much more trustworthy. Health problems have diminished my capacity both mentally and physically so, There may be points of development that are lost on me and do go over my head. I have read all the posts re. Swinging threading tools that I can find. I appreciate the work that is involved in the sharing information in those posts. I am not bashful about disclosing things that I do that don’t work. I posted this because I believed it to have merit. It is food for thought and a worthy candidate for additional evaluation.
Bogs said: It seems that my post about the development of it was totally ignored, or the information just didn't sink in.
Actually the work on this was probably done concurrent with yours and before I was aware of this forum. I later posted it for others consideration and with no intended or implied reflection of your work.
Davo J:
Hi I cannot see any problem with your threading tool. The pivot bolt is below the cutting point and the side thrust is taken by the aluminum block. It would only be left hand threads that it would rely on the washer.
Fair enough for Bog's to get on the soap box in his thread, but I think it is rude to get on it here in your thread with the remarks.
After all, the original design was very similar to your design and worked.
http://madmodder.net/index.php?topic=1276.msg23777#msg23777
Dave
Bogstandard:
Davo,
--- Quote from: Davo J on September 22, 2010, 11:38:51 PM ---Hi I cannot see any problem with your threading tool. The pivot bolt is below the cutting point and the side thrust is taken by the aluminum block. It would only be left hand threads that it would rely on the washer.
Fair enough for Bog's to get on the soap box in his thread, but I think it is rude to get on it here in your thread with the remarks.
After all, the original design was very similar to your design and worked.
http://madmodder.net/index.php?topic=1276.msg23777#msg23777
Dave
--- End quote ---
That is the problem, the original, designed as it was, not only did it only function in one mode, the basic design was flawed for safety reasons.
But of course if you want to follow the route of unsafe tooling, by all means do so, that is your choice.
Am I supposed to leave something unsaid about bad practices and design, with maybe risks to health, purely for the sake of etiquette? I'm sure you would like to be informed if something nasty was about to happen to yourself.
If that is not the case, then I have no business being here, and you should be left to go around injuring yourselves because you don't know any better.
BTW, you are incorrect in your statement about the side loads being taken by the aluminium block.
If you look at the original design carefully, it is using the aluminium block as a pivot, attempting to pull the pivot bolt out of it's hole when cutting right hand threads. Even though small, and maybe wouldn't cause a problem, there is a basic design flaw there.
Even the people who have gone for a single round bar instead of the slot and block have got it wrong. Cutting both ways the tip will attempt to swing around that round bar pivot point, and thus put differing pressures on the pivot bolt. By putting a second round bar, say 1/2" behind the first would solve that problem. The gaps around my swing up piece isn't purely for swarf clearance, that is also there to prevent other forces acting on the pivot bolt, where all pivotting loads are taken by the long block in the slot.
You will find examples of this all thru industry. That is why things mechanically fail just past the guarantee period, obsolescence can in fact be easily built into a product.
That is what is happening to a lot of these modified tool designs people are making. Without realising it, they too are building in designed obsolescence, maybe leading to disasterous consequences.
Boucher,
If you want to know where the original started (as above), I suggest you read my full post on the development of this tool. I have never seen John's post on HSM, as I don't (and don't want to) subscribe to that website.
--- Quote ---This all started a bit back when I saw the post by Andy here
http://madmodder.net/index.php?topic=1276.msg23777#msg23777
From an original idea by Mike Cox.
I will be using his great idea and putting a few of my own mods onto it.
--- End quote ---
John came in at a later stage when I was discussing about ways to prevent sideways movement of the tip, John suggested a tapered block,
http://madmodder.net/index.php?topic=2323.msg24733#msg24733
which I rejected and eventually used a straight version, but I did give John the recognition for sparking the idea to prevent sideways movement.
http://madmodder.net/index.php?topic=2323.msg24742#msg24742
It wasn't from John or myself. I took an (maybe) original idea by someone, and by looking at the problems, came up with a fully functioning and easy to make, safe to use tool. It then progressed from there with everyone and his dog producing different and 'better' ??? versions of it.
But anyway, I don't want to get into a pissing contest about who did what and where, but it would be nice to get due recognition for taking it as far as I did, I am just trying to prevent people from maybe being injured by bad design, with not enough thought being put into their 'new wonder' tooling.
I stated my reasons for my concern, if people wish to ignore them, then on their heads be it.
Bogs
mardtrp:
Got sick and tired of doing it by whipping the tip out and reversing the lathe, then add on that extra bit for the next cut.
Made a few boo-boos along the way and then that bit was scrap.
So, made one of these swing threading tools, wow, what a difference and SO MUCH QUICKER. The boss sort of looked at me like I was a dope when I told him what I was making, but, once I got it going, it was just like a CNC doing the threading, a bit slower, but you can see how quick it is to the normal way of threading.
The lathe is just a Chinese thing with a foot brake and lever start, down for forward and up for reverse. So you start cutting the thread and when cut, just hit the brake, grab the lever and into reverse, whilst it's going backward, add on that bit more for the next cut, when the tool drops into fresh air, brake and hit forward, away you go again, it's slower to type this, than do the job.
Just got one question, now why in the heck wasn't this swing thingy invented years ago ??
Congratulations to all involved in designing and getting this tool to work, it's no longer a "chore" to cut threads for hours now, it's a pleasure.
John Stevenson:
--- Quote from: mardtrp on September 23, 2010, 03:09:26 AM ---
Just got one question, now why in the heck wasn't this swing thingy invented years ago ??
--- End quote ---
Because everyone was going by the text book, only problem is no one has written a new text book in 50 years.
As apprentices I'm sure we all tried winding back in the cut to [1] save time and [2] see what happened. Well because of the slack in the gear train it trashes the thread, this leads to your first lesson in development and testing plus a smack round the head from the apprentice master.
And you are told the first lesson in industry "We have always done it this way"
I thread all the while with a swing tool.
I cut splines and serrations using an electronic Division Master unit.
I cut gears with an electronic hobbing attachment
I cut tapers using a boring head in the tailstock.
Why is none of this in the books ?
John S.
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