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MEW 237 Three Jaw Chuck Mount

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Kiwi Bloke08/01/2016 09:53:16
408 forum posts
1 photos

What a lot of cumbersome maths!

The easy way is to look up in an engineers' reference book the relationship between pitch circle diameter and the distance between vertices. This is typically used when one has to set out the vertices by co-ordinates. This is usually given in the books for many regular polygons. For an equilateral triangle, the PCD multiplied by 0.86603 gives the distance between vertices, to a good-enough approximation.

If we are to be treated to a mathematical tutorial extending over two pages, let us at least have an elegant solution. A little geometric insight shows that the PCD = 4/3 X Square root (3/4 X D^2), where D is the distance between vertices. No need for a calculator with trancendental functions!

This type of trivial and badly edited article does MEW no favours. The mathematical approach is clumsy and makes the subject intimidating for novices. For non-beginners, there is no need for articles teaching Grannie to suck eggs, either. (The triangle is equilateral, not isosceles and the plural of 'apex' is either apices or apexes, not apeces, as printed. I was pleased to see evidence of apparently improved proof-reading under the new editor, but standards seem to have slipped dramatically. In a publication with an international readership, it is important to maintain high standards of English usage, spelling and punctuation. Sadly, the correct use of the apostrophe seems to be a vanishing art...).

MEW seems to be becoming an an organ for entertainment, rather than authoritative information. It may be interesting some to learn how the editor mucked about with welding equipment, but an article telling us how to do it properly would be infinitely more useful. Please can we have no more articles of the "Wot I did on me 'olidays" type?

Lambton08/01/2016 10:07:19
694 forum posts
2 photos


Has Kwil contributed any articles to MEW, ME or EM?

Edited By Lambton on 08/01/2016 10:21:51

KWIL08/01/2016 10:13:08
3220 forum posts
63 photos

Does it really matter if "he" has not? The points made may be carping but there is some substance! Anyway, no Personal Profile so maybe not a real Kiwi.

Edited By KWIL on 08/01/2016 10:13:59

Roger Provins 208/01/2016 10:17:55
343 forum posts

It's fine as is for me. I wouldn't want a journal just full of learned articles. I do enjoy some lighter content amongst the more serious stuff. Plain facts are easy enough to find on the web.

What I would like is the forum cranky software sorted out!

Edited By Roger Provins 2 on 08/01/2016 10:18:25

Martin Kyte08/01/2016 10:44:59
1808 forum posts
33 photos

It was the long way round to do it. The PCD is just the pin spacing divided by Cos30. Or just multiply by 2/root3.


Kiwi Bloke08/01/2016 11:08:44
408 forum posts
1 photos

Thanks Martin for pointing out that the expression I derived can be simplified - much more elegant! So I too am guilty of cumbersome maths! Also, I am guilty of a typo in the third-to-last line! (Couldn't edit the post once it was posted and I noticed the error - too late!) Mea Culpa. I'll go away and sulk, whilst remembering not to throw stones in glass houses...

(Real) Kiwi Bloke.

Edited By Kiwi Bloke 1 on 08/01/2016 11:14:11

ega08/01/2016 11:25:18
1633 forum posts
140 photos

Kiwi Bloke 1:

Nor should we throw stones in glasshouses (sic)! We all make mistakes from time to time.

I emphatically agree with your "In a publication with an international readership, it is important to maintain high standards of English usage, spelling and punctuation. Sadly, the correct use of the apostrophe seems to be a vanishing art...)" but even this may contain an internal contradiction. Look at the actual usage - I'm afraid it's "it's" when it should be its all over.

I also agree with KWIL's points.

PS Just wondering, where is the neither to go with my nor?

David Clark 108/01/2016 11:44:51
3357 forum posts
112 photos
10 articles

I don't think there was much wrong with the proof reading of the old editor (me). You will never get it perfect but there were not many errors.

David Clark 108/01/2016 11:48:03
3357 forum posts
112 photos
10 articles

Hi Lambton. KWIL did several articles for MEW but I am not sure if he did any for ME. But what has KWIL got to do with this thread which appears to be about Kiwi Bloke 1?

Lambton08/01/2016 11:58:22
694 forum posts
2 photos


Sorry I confused you with Kiwi Bloke. I originally addressed me remarks to Kiwi then edited it to read Kwil - evidence of my advancing years and diminishing powers.

John Stevenson08/01/2016 12:34:15
5068 forum posts
3 photos

Wot's wrong wif using a blind transfer punch and a big 'ammer ?

If U want to get reel tecknical then use a copper 'ammer

David Clark 108/01/2016 12:41:16
3357 forum posts
112 photos
10 articles

If you read my article on this site, there is an easy way to drill chuck back plates.

jason udall08/01/2016 16:29:33
2023 forum posts
41 photos
Look the process to establish the pcd is simple ..once you have done it.

The article shows an individual's route to that state.
If this helps someone who hasn't seen the ( various) idea (s)..
Then it serves a purpose.
And of course the transfer punch method works even if the original weren't regular ( in the geometric sense)...but not every one has punches or has seen that technique anymore than the pcd derivation.
Dinosaur Engineer08/01/2016 17:49:33
145 forum posts
4 photos

Haven't seen MEW 237, but if the backplate holes are to be clearance on the screws then the old timers solution was to very lightly smear a very then coating of grease where the holes would approximately be and then sprinkle some chalk dust down the chuck holes and fit the backplate over the chuck. The assembly would then be turned over and given a sharp rap with a mallet/lead hammer. Upon separation the hole positions would be clearly shown with chalk circles. It is surprising how accurate this process is as the center-punching of the chalk circles by eye is quite easy . Ultimate precision is not required as the chuck should only be located by the backplate register and not the holes. The old timers didn't waste time in making precision holes where non was needed & making transfer punches but just got on with job.

Edited By Dinosaur Engineer on 08/01/2016 17:50:09

Neil Wyatt08/01/2016 18:58:59
17740 forum posts
697 photos
77 articles

That would have made a useful contribution to scribe a LIne..

Not sure how I missed 'apeces'? Mea culpa, but in my defence this issue was produced in half the normal time - we expected three weeks, but due to Christmas the deadline was brought forwards another week the last minute.


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