I presume you mean convert to 10-32 UNF as 3/16 BSF is 32 tpi? Off the top of my head your idea should work for this application.

Tony

Hi, some 7/8″ long at arunfasteners

Regards Nick.

MichaelG beat me to the same place.

Buy any 3/16″ BSF fastener with an appropriate length of thread on it, cut off its head with a hacksaw and use the same hacksaw to make a slotted grub screw.

Go direct to this eBay seller’s website or pick up the phone and explain your requirements, and they will assist:

https://www.ebay.co.uk/itm/334554385309

I cite this listing as it notes 3/16 BSF x 1 3/4″ long fully threaded.

—

Edit: turns out the post saying BA was correct all along:

https://www.ba-bolts.co.uk/bsfallen.html

Graham,

BA stands for British Association.  Although derived from a metric thread system BA threads were/are a thread standard used in British industry for threads smaller than 1/4″. Myford lathes were contemporary with Centec mills and Myford used 2BA screws and BSF on their machines. Worth double checking I suggest.

HTH,

Rod

I can hardly believe that I found this on one quick search:

http://www.small-lathes.co.uk/Files/1.663784Centec_2x_Setup_Guide.pdf

… The pictures are unfortunately rather ‘jaggy’ but; might one assume that the grub-screws in question are item 92 [quantity unspecified] ?

MichaelG.

.

On 22 February 2025 at 23:50 Nigel Graham 2 Said:

Buy…

The ‘buy’ part of your post was good:

https://www.ba-bolts.co.uk/bagrubs.html

2BA looks correct from my Centec 2B, though I’ve only pulled one to check, the outermost handle end of the knee, but it appears to be a shade over 1 13/16″ not 1½”. (1.8″)
I wonder if something changed during production, or whether Centec copied something over from a different model in that document.

Measuring the hole depth, from the outer face where the locknut tightens, to where the grub screw meets the gib strip is almost exactly 1½”

Spanner size is 2BA and the thread looks correct, with the first couple of threads turned off, leaving  a flat end.

N.B. do not be mislead by the top scale on these calipers, which read circumference in inches not length in cm.

Macc Models list 2BA studding in steel.

2BA Studding 12″ lengths

Bill

A bit of background may help.

When the industrial revolution started there were no standard threads – everyone did their own thing, so nothing fitted together unless made in the same workshop to do so.    This caused lots of trouble!

Whitworth realised the value of standardising threads for fasteners.   As he was big into measuring, he collected as many nuts and bolts as he could from British industry and averaged their dimensions.   The resulting form,  55° rounded top and bottom, gradually displaced most other UK threads during the early Victorian period, and, when the British Standard Institute was created, they made it 100% respectable.

Whitworth isn’t ideal for everything!   The form is well adapted to soft materials like Cast Iron, less well to steel, which appeared 30 years later.  The original standard only covered coarse threads, so fine threads were added later. The rounded form adds strength, useful in Whitworth’s day, but expensive to make.   In the USA Sellar’s later thread switched to 60° with a flattened form – cheaper.   Likewise, on the Continent, for the same reasons, designers went for 60° and a flattened form, but based on metric pitch rather than turns per inch.  Later threads were designed from theory, rather than Whitworth’s averaging process.   Whitworth is still good for soft materials.

By 1870 another problem with Whitworth had emerged.  The thread came from heavy engineering and isn’t well-matched to light-engineering requirements: clocks, small-arms, scientific instruments, gas meters, and especially electrical.   They call for a different thread form, so the British Association for the Advancement of Science tweaked a Swiss thread to meet the need.   So BA has a 47.5° thread, with a metric pitch, and Imperial dimensions.   BA was extremely successful, used whenever a fastener of less than 1/4″ inch diameter was needed.  Very common in older equipment of all types.

Later, it was found that the standard metric series in coarse, fine, or extra-fine got equivalent performance to BA and were cheaper and more acceptable to foreign customers.  Thus BA gradually withered.

In the 1/4″ cross-over region older British equipment could be BSW, BSF or BA depending on what the designer thought best.

After WW2 Unified Threads arrived causing even more variation.   One car I owned in the 70’s had UNC, UNF, BSF, BSW, BA, and metric fasteners.  Made by a company created by merging US, British and continental car makers, each of whom contributed parts …

Dave

I have relied on Peterborough nuts and bolts (now Sterling bolt and nut co ltd) over several years, for reliable fixings.  I go to epay when possibly lower quality is good enough.