Davo,
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
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.
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.
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#msg24733which 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#msg24742It 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
