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Swingup external threading tool

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bogstandard: Andy, I had already looked at your solution, and unfortunately, rejected it. That was due to two things, the first could be fixed, and that is the bolt head protruding from the side, but the second bit couldn't, and that is putting a fairly substantial side loading onto the pivot, I wanted to do it so that the pivot is only used in a rotary motion with no or very little side loads onto it. Friction is going to be the killer on this job. John, The way you have shown is a fairly easy fix, and is much easier than the ways I have thought about up to now. Only one problem with it, with any side loads, I suspect it will try to make the two tapers ride up on each other, it might only be a tiny amount, but could a problem all the same. Plus although fairly easy for me to make, others might struggle with it, when they try to replicate the design (if it works of course).   But by using a straight sided plate in there, and a couple of brass faced screws, one from either side, I think it could definitely be a main contender for curing my problem, and I think it wouldn't cause too much trouble for people wanting to make one. If you hadn't brought up your problem in the first place, it would have easily been done and dusted well before now :lol: I would like to thank both of you for the trouble you have taken in making suggestions. As I have said before, I can't be expected to know solutions to everything, and I really appreciate a bit of input like this to get me moving again when I hit a problem. I will see what can be done if I can get in the shop later. John

Ned Ludd: Hi Mr. Standard, Can you not have the toolpost at, say, 45 degrees and have a canted swing up part to hold the threading bit, in a similar way to some parting tool holders. That way you should be able to get it nearer the chuck and if combined with JohnS's taper seating, rigidity should not be a problem. Although for most purposes the design, as you have it, will be quite usable. Why not prove the concept before worrying about niceties, there is always room for the Mk2! or in my case Mk3 Mk4 Mk5 etc :D May I again say I am a great fan of your work, writings and style. If only there were more people with a lifetimes worth of experience willing to share their knowledge with the "youth of today". This really is the best forum for "light" engineering fans. :mmr: Ned Ludd

bogstandard: Ned, Many thanks again, I had already thought of the angled bit, but nowhere near as much as you are suggesting. I didn't want to complicate matters from the outset, because as you know, if it does eventually work, the simpler the method, the easier it is to reproduce for the masses. A couple of my rules to making things, what isn't there, can't go wrong, and always try to make things as simple as possible, life is complicated enough as it is. As was mentioned before, this isn't my idea, but a follow on from a suggestion, and I am sure, if I can get it to it's simplest state, and working correctly, I think we will both be very happy chappies. I hope that my ramblings help a few people along the way. We seem to be a bit of a dying breed, with all the latest technology coming along and taking most of the 'hands on' enjoyment out of it, so we need all the help we can get. I would like to point out, even though this looks like a 'light engineering' site, it is a site for almost everyone to enjoy, and we have on here many artisans showing their work that isn't metal engineering orientated. John

andyf: Bogs, I'm speaking as one of the newbie masses and this isn't meant as criticism, but might it be best first to continue along the original line with a relatively simple Mark 1 device for RH threading only, to see if that works before considering LH threads and the complexities they bring? My worries are: (a) that if the first one you make is the complex version and it doesn't work, you will be discouraged from making the simple one where there is much less to go wrong, and (b) that it's essentially a device which might appeal mainly to those as inexperienced as me. We might find it hard to reproduce the fine standards of fit around the tenon which the complex one needs if the toolholder is to flop nicely down but have minimal sideways play when in position. Andy

bogstandard: Actually Andy, a little bit too late, I have already done it. It seems that your post didn't highlight when I checked the site just before I went into my shop late afternoon, so I just went ahead as I had planned. But no problems, if it does work as planned, and it proves that it will work, then there is nothing wrong in making a very simple design from what you can gather from what I am doing. This isn't a slavish 'copy as I am doing post', but my ramblings captured in text and pictures as I progress along a development route, and if the concept doesn't work, then it will be recycled and forgotten about. But if it does, then it opens up a whole new idea to threading that could benefit a lot of people. So at this time, I am running with a modified suggestion that John Stevenson came up with. Because I am going down the route of a fully machined up tool holder, I have caused myself a problem for access to one area I need to cut a slot into. If you made a much simpler version than this, say with an 'L' shaped backplate, then you would be able to get a normal cutter in. I had to use a woodruff cutter to solve my problem, so I made a few quick calculations. Then set to work. In no time, I had the two slots that I needed. This is how the two slots lined up. The uppy downy bit then got a dose of reshaping. You will notice that I have gaps all over the place with this tool, and I have mentioned this before. This tooling will be working in a swarf producing environment, and unlike normal fixed tool holders, where it wouldn't cause a problem, because this tool is moving, swarf could get in and disrupt the nose setting of the tool and cause major cutting problems. These gaps are to try to give somewhere for the swarf to settle into without affecting the correct operation of the tool. A quickie calculation gave me the size of block that will be required to give me the gaps I want. I had certain scoffs when I first mentioned that I used a mini vice, but for jobs like this, they are indispensible. I was able to hold the small component very accurately while I swung the big cutter around, hacking the block down to size. The block was machined to thickness so that it was a tight fit going into the swingy bit. The block was then cut to the correct outside dimensions and I got out my secret weapon. A piece of what must be ten year old very worn out fine W&D paper. The block side face was then gently rubbed on it until it fit perfectly into the swing holder slot, with no side play but a nice smooth sliding fit. It took only a couple of minutes to achieve that state It was then loctited into the main holder. So very close to being finished. A bit of lathework, a few holes to drill and tap and it will be ready for first trials. Another point of interest is that the swing block protrudes slightly in front of the main block. This is another one of my attempts to keep swarf out of the operating bits. I have been reliably informed by the better half that I need a haircut, I told her that I didn't, but you can guess who won. When I argued that things like that don't trouble her, 'cos she ain't got any at the moment, I was told it was either haircut or no shop time. So to get this finished off tomorrow, I am making a great sacrifice and dragging my weary bones to the chop shop. I just hope it is all worth it. Bogs

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