4Jaw Chuck workholding
Crewmech | 12/09/2010 12:51:09 |
2 forum posts | Sirs
Upon opening the latest copy of ME (#4386) I was appalled by 3 photos in Harold Halls "The Beginners Guide to Building a SteamEngine"
Where oh! where is this great magazine of ours going when it can allow such a dangerous practice of workholding like this shown in photos #30-31-32 of Halls "Guide to "eginners. Publishing a "Top Tip" does not mitigate such a dangerous piece of advice.
In my apprenticeship days if this method of workholding had ever been attempted, I would have been awarded with an immediate "Kick up the pants" followed by an equally quick visit to the Chief Engineers sanctum.
If ME is going to continue publishing advice and help to new entrants into the hobby surely it DEMANDS that SAFE and only SAFE practices are photographed and shown.
Shame on Harold Hall for his advise, and Shame on the Editor for publishing such a dangerous method
Regards
Crewmech |
Ian S C | 12/09/2010 14:25:43 |
![]() 7468 forum posts 230 photos | Crew mech, please explain, my copy will arrive later in the week (hope), and some get MEW and wont see it. Ian S C |
KWIL | 12/09/2010 14:57:06 |
3681 forum posts 70 photos | Ranting does not help, as Ian asks, explain why you consider this to be unsafe. |
MichaelR | 12/09/2010 16:15:05 |
![]() 528 forum posts 79 photos | "Crewmech" please keep us all safe and show and explain the method of work holding which you would use for the operation in pictures 30,31 and 32. |
Stub Mandrel | 12/09/2010 16:44:43 |
![]() 4318 forum posts 291 photos 1 articles | I noticed this myself. Two of Harold's drawings imply holding a long workpiece in just the tips of the jaws of the chuck, and does not show any tailstock support.The text makes it clear tailstock support is needed. I imagine this is oversight not deliberate, but yes I can see it leadinga beginner astray. Neil |
JasonB | 12/09/2010 16:52:47 |
![]() 25215 forum posts 3105 photos 1 articles | Stick the work would have fitted into that 4 jaw with a jaw square to each face so don't see why he held it diagonally, could understand if it were too larege for the chuck.
I've certaily used this method in the past and even the likes of Sparey shows it in his book
Ian if you are a subscriber then its in the digital issues
Jason Edited By JasonB on 12/09/2010 16:55:57 |
David Clark 1 | 12/09/2010 20:36:51 |
![]() 3357 forum posts 112 photos 10 articles | Hi There
I don't see a problem with this method.
It has been used and photographed many times over the years.
Like any machining operation, you use common sense and make sure the component can't move no matter how it is machined.
I have even seen this method photographed in a three jaw chuck.
I think it was holding a flycutter.
regards david
|
AndyB | 12/09/2010 21:20:27 |
![]() 167 forum posts 7 photos | Good evening,
If you look closely, there are round shapes at each end of the casting towards one edge.
Photo 29 shows the 4 jaw used as Crewmech would no doubt advise. The problem comes when reversing the casting for machining of the opposite face.
I, a novice to all this, using common sense, would never mount a casting with a hemisperical face to a chuck jaw! I would certainly copy Mr. Hall's method.
Like our esteemed Editor, I have also seen the same principle used on a 3 jaw and have used it myself, fly-cutting my home-made angle plates. It worked well, except for the fact that I was using too high a speed so chipped my first effort with an carbide tip.
I am using my great grandfather's Drummond, and from what my father remembers, all sorts of weird contrivances were used to carry out work; necessity is the mother of invention.
This is the sort of thing the old boys used to do; from the Drummond book of work carried out on treadle Round Bed lathes;
|
Nicholas Farr | 12/09/2010 23:04:40 |
![]() 3988 forum posts 1799 photos | Hi, If the method of workholding in the said photos is dangerous, then explanation should be made as to why. I myself have used this method many times during my fitting in industry when sizeing keys for shafts. I have never had a problem with this method, as has been said caution, vigalence and common sense when chucking anything before swinging the piece to be turned.
Regards Nick. |
Andrew Johnston | 13/09/2010 22:21:34 |
![]() 7061 forum posts 719 photos | I agree with many of the previous posters; if the technique is dangerous then take the trouble to explain why. Otherwise we don't have the opportunity to learn. If the OP can't, or won't, explain and suggest a better way, then there was little point in the original post. Looks to me like a case of 'rant today, gone tomorrow'. Regards, Andrew |
Axel | 14/09/2010 10:00:16 |
126 forum posts 1 photos | Gawd people are trained to be so safe these days! C´mon let ppl be responsible for themselfs, If one thinks its unsafe, do it another way, don´t insult other peoples inteligence by telling everyone this or that is unsafe. Common sense, you´ve got it or you don´t, and if they dont they probably won´t learn from instructions! |
Bogstandard | 14/09/2010 10:46:52 |
263 forum posts | Axel, I'm with you all the way, but just one thing, common sense seems to be sadly lacking nowadays. You only have to look about when going down the street. I am a great believer in using old tried and tested methods, and if I come across a mounting problem, I refer back to my collection of old engineering hardbacks for inspriration. Those were the days when they didn't have all the modern gizmos, and you just got stuck in and got the job done. Some people nowadays seem to want the job to jump up on the machine and mount themselves, using hundreds of clamps and bolts. In the real world, it just isn't like that. You have to make your own decisions if what you are doing is safe or not. If you are incapable of doing that, there are plenty of knitting patterns knocking about on the web. Bogs |
David Clark 1 | 14/09/2010 10:51:54 |
![]() 3357 forum posts 112 photos 10 articles | Oh, I say.
Don't recomend they take up knitting.
The needles are quite sharp.
How do I know?
My first wife sat on some.
Oh painful.
regards David
|
Nicholas Farr | 14/09/2010 10:58:06 |
![]() 3988 forum posts 1799 photos | Wel David, at least they may get the point.
Regards Nick. |
chris stephens | 14/09/2010 11:47:29 |
1049 forum posts 1 photos | Gentlemen, I agree wholeheartedly about the problems of a cotton wool culture and common sense should rule. The "but" is that common sense must come from experience and knowledge and I ask 'where today are newbies to get that experience and knowledge'? It seems as though cotton wool is self defeating, without risk how are you to know when there is a risk?
chriStephens |
Ian S C | 14/09/2010 14:15:41 |
![]() 7468 forum posts 230 photos | Again Crewmech, tell us why, and how etc. Ian S C |
Richard Parsons | 14/09/2010 15:20:55 |
![]() 645 forum posts 33 photos |
It would have been nice to read my subscription copies of MEWS No 168 and ME No 4386. But they just have not arrived. I suppose that there was a shortage on the print run so the weird (minimal) foreign subscribers were forgotten. Or my subscription has run out and no one has sent me a reminder. But I pay by direct debit so how can that be? Mr Editor there may be another reason which I will E-mail you about. This is not the place for it. As to the problems of safety, a ‘Gnome from the local city’s Elfin Safety’ forbad me to use a hand held graver on my lathe –it was a 6mm Lorch- my reply was “how the h*** did you get in here?” It replied (I could not be sure of its gender) I saw your light in this shed so I came to see what you were doing. Oh it added “You will have to re-hang your gate I took it off its hinges as it was locked. I have the right to go anywhere”. My reply was in Russian well it ended with ‘off’ followed by a call for ‘Ole Alligator chops’ –an old large black mongrel with a set of snappers that would turn a crocodile green with envy. I duly received a visit next day from the rozzers and cautioned about the matter. The idea of trespass went un heeded.. The problem is the idea for the need for absolute safety. Our local Managers (whose job it is to manage the people) must NEVER allow the word ‘Blame’ to appear on their CVs. and they will ignore the rules and laws to to make certain it never happens When we were children if we hurt ourselves we got a clip from our dads and soon learned to use a longer ‘pokey stick’. Mr Crewmech we are not running at ‘production speeds’. What is wrong? Edited By Richard Parsons on 14/09/2010 15:32:33 |
IanT | 14/09/2010 16:57:24 |
2147 forum posts 222 photos | I've just received my ME - and what suprised me - was not the photos mentioned at the start of this post - but photo 24 - clearly showing parting-off using tailstock support.
I was always told NEVER to use any tailstock support when parting off and I have never done so - so I cannot tell you what kind of trouble it might cause you but I am very sure that the old guy who told me this knew what he was doing!
Anyone want to enlighten me?
|
KWIL | 14/09/2010 17:15:46 |
3681 forum posts 70 photos | Just before it parts off it can tilt inwards jamming on the parting tool, instead of just dropping off, it flies off? |
JasonB | 14/09/2010 17:35:15 |
![]() 25215 forum posts 3105 photos 1 articles | But lets look at what he's actually doing
Its a small lathe with a small chuck hence the jaws have been reversed to enable the 1 3/8" bar to be held. This dia is also likey to be the max that the machine will be able to part off.
There is probably a greater risk of the tool jamming in the cut and pulling the work out of the jaws than there is of the parted disc getting caught up so maybe Mr Hall did his risk assesment and decided using tailstock support was the lesser of the two evils?
Jason
No who's going to be first to comment on using double sided tape to hold work or showing a filing machine being used in a series aimed at beginners ![]() |
Please login to post a reply.
Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!
Sign up to our newsletter and get a free digital issue.
You can unsubscribe at anytime. View our privacy policy at www.mortons.co.uk/privacy
You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.
Click THIS LINK for full contact details.
For subscription issues please see THIS LINK.