BA Bolts

Recently bought some 8Ba bolts - small head. Being ignorant, I bought these presuming that small head meant a smaller than specification Ba size. On closer inspection, they turn out to be 3.25mm A/F. Now I know Ba dimensions are based upon metric sizes converted back to imperial, but I do think suppliers should state "Metric headed Ba bolts".

Anyone know of a good supplier of small spanners to fit these metric headed bolts ?

A quick lick with a file/stone will take the 0.003" off the spanner jaws if they are a tight fit.

You will start to find this issue more and more as BA hex becomes harder to obtain.

J

Edited By JasonB on 10/09/2012 16:00:39

This looks a good place to start looking

Knupfer

MichaelG.

There are some interesting goodies there, will have a better look later but looks like their spanners are either 3.0 or 3.5mm though they do have a 3.2mm nut spinner.

Thinking about it you could just file up a spanner from some MS plate or even gauge plate if you wanted to harden it.

J

Edited By JasonB on 11/09/2012 10:22:11

As Jason says, buy a cheap 1/8" spanner and take out the 3 thou (0.003" ) if needed using a warding file or thin slipstone.

Terry

... or, for the sake of 0.0015" per face, you could take the opportunity to finiish the bolt heads nicely.

MichaelG.

Hi again,

If you don't want to take Michaels excellent advice, a 9BA head is only 0.002" (approx) larger than your 8BA so a 9BA spanner should fit well.

Terry

P.S. Hemingway generously provides ample detail of Edgar T Westbury's design for a Filing Rest, here.

Sadly BA bolts with metric heads is all too common.

Which is one of the reasons I now make my own (the other being that mine are now all 303 stainless).

Jo

I think its quite fitting for a copy of a metric design.

Steve Larner

Incidentally ... I just found this rather useful site

which includes handy look-up for dimensions.

MichaelG.

I agree that the Knupfer link provided by Michael Gilligan looks interesting, but does anyone know if it can be translated to English?

Benard

I could not get it to translate and I have my computer set to automatically convert German to English as I quite often visit a few of the German ME sites.

Just need to pick out the odd words and translate them in a separate window and you can get the jist of it.

J

It's a rather convoluted route, but Model Motorcars Ltd. [in the USA] has some of the Knupfer parts listed, in English.

MichaelG.

some years ago there was an excellent tool emporium in nottingham permanent market. there used to be a large bin of small BA spanners (chrome vanadium, and ex WD) for sale for pennies each! i bought up quite a few including a selection of metric spanners in the same bin. i have found the metric spanners to be invaluable for BA bolts that turn out to have metric hex heads and are a permanent part of my running kit for my locos. i also often turn up steel BA bolts that are supposed to be BA hex but often arent, so again these spanners are invaluable. also the small hex socket sets (see the market stalls again) are often metric and cost very little. so from my point of view i dont see a problem. the spanners and sockets you need are available! 8, 9, 10 and 11BA seem to be the problem with the trade selling 'BA hex' that is usually metric. for some odd reason i seem to have tons of 12BA hex that i will probably never use up completely!

cheers,

julian

I have several sets of simple, punched out, BA spanners (including the large sizes W^D set) but I find the Chronos nut spinner set invaluable.

Neil

I usualy enter the site url into google search, then in the results you will see a "translate" link next to the results. When you click said link you may need to tell it - via drop boxes at the top of the page - which language you want it to translate from, if it doesn't do it automatically.

Edited By Ian.T on 13/09/2012 03:09:21

Bernard,

Ian's method seems to work very well on the Knupfer site.

... Thanks Ian; I had not realised that 'translate' would handle the menu structure.

MichaelG.

Here is a table of BA head sizes. "One size smaller" BA heads means that 8 BA will have the same head size as 9BA. Although the sizes are quoted to 3 places of decimals there obviously is a tolerance on the actual A/F dimension so do not expect accuracy to the last thou. Also a spanner of any size must be an easy fit over the bolt head.