View Full Version : Going Metric

04-26-2008, 11:20 PM
I'm finally giving in and going metric. Where can I find a clear and concise discussion of metric threads. Google left me hanging. Thanks Paul

04-26-2008, 11:27 PM


to start....

For way too much info:


- Bart

Norman Atkinson
04-27-2008, 03:25 AM

04-27-2008, 07:01 AM
Don't give up competely on standard.
Just learn to 'speak another language'
Where I am (east coast) I come across
Just try to learn about them all.
Just this past week I had to make nuts to fit
1.250" with a pitch of 1.5mm
(on a ship of course)
take care

loose nut
04-27-2008, 09:51 AM
. He must have been pretty hard up earlier because he only bought part of the lathe and made the rest out of bit fabricated from spare bits of mild steel.

Another one falls to the metric propaganda machine:( :( :(

Martin Cleeve wrote a whole series of articles on how to improve (his idea of improvement anyway) the Myford ML 7 lathe for Model Engineer magazine in the 70's, I don't know if he made these mod's because he had to or he just wasn't satisfied with the "out of the box" lathe, a lot of these were not available from Myford. These articles are good reading, he had some "different " ideas on feed gearboxes and fine feed drives.

Norman Atkinson
04-27-2008, 12:59 PM
deleted-!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!

04-27-2008, 03:37 PM
Spinrow - All of these sources will help you. DIN 13-ISO 724 is the standard.One thing to keep in mind when working with metric thread designations - if it says M10 , no pitch given , it is ALWAYS the pitch listed under "metric coarse", in this case 1.5mm. If it says M10 x 1 it is metric fine.
Engineering toolbox has it wrong when they designate M10 x 1.5
On the table below they are correct.

04-27-2008, 04:30 PM
"if it says M10 , no pitch given , it is ALWAYS the pitch listed under "metric coarse","

This will save me some phone calls,
but I know I will call 'just to be sure'
take care

loose nut
04-27-2008, 06:58 PM
Oh, I do wish people would research their replies!

Martin Cleeve wrote in the early 1950's and not the 70's.


You are right Norman it would be nice if people research their replies.

Martin Cleeve wrote well into the 70's.

As an example Vol. 143 #3572 Nov 1977 Pg. 1237 titled "A Discussion on Screwcutting" and this was by no means his last article. He did start writing in the 50's, a letter in the Post Bag to start I believe but I'm not positive, but the series of articles on ML7 lathe mods that he was doing, that I mentioned, were from the 70"s not the 50"s.

Norman Atkinson
04-27-2008, 07:26 PM
Deleted-!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

04-27-2008, 07:31 PM
you will probably find everything you will want on Maryland metric's website


They have pages of information on metric fasteners and is always my first stop when I have questions on metric items.

04-27-2008, 11:11 PM
Thanks for the interesting and helpful replies. My question is why did american auto designers use metric threaded spark plugs? Paul

Norman Atkinson
04-28-2008, 03:09 AM
There are two explanations. The long and very detailed one which embraces the development of the internal combustion engine and consequently, embraces all sorts of ideas to fire a charge of combustible gas or fluid. It can be metric or imperial depending on the designer.
The easier answer is that if you only want to go back to the late 20's and 30's it is because the most successful or acceptable methods came from the French and Germans.

I would suggest that you Google for only a fraction of the long history.What you have to realise is that many of us have spent years studying history.
Snappy answers and the truth are unhappy bedfellows!

04-28-2008, 03:20 AM
I've often wondered why Japan went metric, when they were so heavily influenced by the US and to some extent, the UK after WW II, when both these allied nations were heavily committed to an inch (dare I say imperial) system.

Norman Atkinson
04-28-2008, 03:36 AM
I have deleted earlier posts.
Perhaps it is prudent. There are more things in life

John Stevenson
04-28-2008, 04:40 AM
Thanks for the interesting and helpful replies. My question is why did american auto designers use metric threaded spark plugs? Paul

Because at that time the best and most advanced ceramics were German and everyone was forced to use these to progress.

As UK and US manufacturing got to grips with it the die was set for the sizes.

Henry Ford tried to push a 3/8" gas thread plug but it never caught on.

The same applies to the metric bearings in a lot of early American machines, again due to better materials being available from metric based countries.

This is well documented in a lot of early texts.