Meccano bolts

I guess this is the right newsgroup for this one. Its not quite Sieg v Myford but you can't get more uk.rec.models.engineering than meccano.....
My 7 yr old has one of the (French manufactured) meccano sets. Alas, he is having difficulty because the nuts and bolts keep coming undone - and its turning him off it.
I don't seem to remember having that much trouble 45 yrs ago when i used to be an avid fan. Its not just him - even when i tighten them, they will still work loose with ordinary handling.
The bolts are different from those I remember - these are allen headed black things (diameter outside thread 3.5mm - sorry haven't got a thread gauge). The nuts look similar to my youth - square not hexagonal but i remember them as marginally thicker. There are many more bolt length options than I ever used to have as well.
There are some nyloc nuts in the set and I have also locknutted the critical ones and tried the old varnish trick on the thread but none of these are a sensible solution. I did ask the chap with all the Army Meccano models at Brighton exhibition earlier this year but he didn't have the problem.
I guess the nuts or bolts are cheapo with too much clearance and I would be perfectly happy to buy him some good ones if it means he xxx we can get on with the big crane with motor - but what do I get and where from - and would normal hexagonal nuts be Ok for 7 yr old fingers?
Ken
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Sieg v

meccano.....
Alas, he is

and its

used to

will
headed black

gauge).
remember them

I ever

critical
these are a

models at

problem.
would be

get on

and would

They should be 7/32 Whitworth. Here are some on ebay:
http://tinyurl.com/yr9w32
AWEM
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Thu, 28 Jun 2007 19:53:58 +0100, "Andrew Mawson"
wrote:

You sad bastard knowing that...................... -- Regards,
John Stevenson Nottingham, England.
Visit the new Model Engineering adverts page at:- http://www.homeworkshop.org.uk /
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

i
they
thread
than
the
I
can
from -

Sad bastard I agree! However all I did was google Meccano bolts, find the ebay ad which told me the size, post it into TinyURL, and reply to the O/P - took all of 15 seconds. I knew that they were a none preferred Whit size but not which <G>
AWEM
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Andrew Mawson wrote:

Sad - and wrong! They were, and still are, 5/32 Whit, not 7/32.
http://cgi.ebay.co.uk/5-32-BSW-machined-brass-nuts-quantity-20_W0QQitemZ270115529693QQihZ017QQcategoryZ25644QQrdZ1QQssPageNameZWD1VQQcmdZViewItem
-- Peter Fairbrother
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

undone -

when
find
reply to

http://cgi.ebay.co.uk/5-32-BSW-machined-brass-nuts-quantity-20_W0QQitemZ270115529693QQihZ017QQcategoryZ25644QQrdZ1QQssPageNameZWD1VQQcmdZViewItem
Odd as if you look at that url I posted it would seem to be an original Meccano packet (from Binns Road in Liverpool - now THERE'S a sad bastard!!!) which distinctly says 7/32", though I agree 7/32" at 5.5 mm seems a tad large.
Have another look:
http://tinyurl.com/yr9w32
AWEM
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Andrew Mawson wrote:

[...]
http://cgi.ebay.co.uk/5-32-BSW-machined-brass-nuts-quantity-20_W0QQitemZ270115529693QQihZ017QQcategoryZ25644QQrdZ1QQssPageNameZWD1VQQcmdZViewItem
7/32" long?
-- Peter
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Nuts:
http://www.mackay.co.uk/webstore/acatalog/257.html#a22451040-257
5/32 bsw
Bit expensive, but ...
-- Peter Fairbrother
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Well, I had a firm recollection that they were 5/32 BSW, so I just went and checked dome of my Meccano bolts (even sadder bastard!) and sure enough, 0.1485 - 0.1520" - a slightly loose 5/32 - x 32 tpi.
The ones from my childhood (early 60s) were brass cheeseheads, the more recent ones are a mixture of CH and RH types, mostly chromed.
I always found lock-nutting worked well for moving parts, certainly within the limits of what you could expect of Meccano structures.
David
--
David Littlewood

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

David
I can't challenge you in the "sad bastard" competition as I have very little Meccano and nothing more recent than the early 60's. As my life at the moment consists of rushing up and down the M4 caring for ailing relatives, I took the opportunity during yesterdays visit to venture into a very dark recess of my fathers attic. The quest was to find a box of Meccano which had been packed away since my childhood, green and red vintage with brass cheesehead bolts. I can confirm your 5/32" size and also as part of a long forgotten assembly I see that many of the bolts have been lock-nutted so that must have been my preferred method of 40 years ago. The bloody nuts still hurt my fingers when I tried to undo them as no spanner was to be found! I packed the box away again for the next 40 years although I suspect it won't be me that opens it next time.
Regards
Keith
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
jontom snipped-for-privacy@hotmail.com writes

Yep, they are hard on the fingers. The 1960s nuts were IIRC all square, which made them marginally easier to do/undo with the fingers -but not lock-nutted ones of course! The spanners (two were supplied) were cheap stamped things with one end cranked to get into tight corners.
David
--
David Littlewood

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
writes

The USA "Erector" sets used 8-32 round head slotted screws and square nuts. I still have some of the screws and nuts in my "8-32" hardware drawer. These date from the 1930's and 40's.
Don Young
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Is 3.5mm not a common(ish) metric size, and given that it's french, it's highly unlikely going to be imperial.
And a 7yo, is more likely to manage normal hexagon nuts of that size far better then you!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
moray wrote:

It's still the same 5/32 bsw thread - but the new French stuff has slightly smaller holes than the old meccano.
However m4 nuts and bolts will fit in the new holes, albeit needing a gentle squeeze sometimes if the paint is too thick. With m4, you have a complete range of nuts and bolts readily available.

yep! But get him some box spanners too.
-- Peter Fairbrother
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
moray wrote:

It's still the same 5/32 bsw thread - but the new French stuff has slightly smaller holes than the old meccano.
However m4 nuts and bolts will fit in the new holes, albeit needing a gentle squeeze sometimes if the paint is too thick. With m4, you have a complete range of nuts and bolts readily available.

yep! But get him some box spanners too.
-- Peter Fairbrother
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
pete wrote:

You could also try american 8-32 nuts. I don't know for sure whether they will work though.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

You mean the french have not modified something they never came up with? Shame their vehicle designers couldn't try the same philosophy!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

They were whitworth of some sort, and yes they should be fine for 7 year old fingers, IIRC I was 5 when I got my first meccano set, a big yellow crane, for xmas :) I dont remember having problems with them coming undone, and meccano takes the stresses *much* better than technic lego ;)
Dave
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I was a Meccano kid (red/green era) and the screws and nuts were always coming loose on anything powered. On the other hand if you locknutted joints it was a real pig to undo the nuts (the pain!)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
May be this helps: http://www.usmeccano.com/pdf/newmeccanoscrew.pdf Dirk

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.