Making BA Bolts and nuts

[Dr Jo]

I have been making various small BA bolts and nuts over the last few weeks. One of the things that I keep having to do is to find the correct head height and calculate the correct allowance for the nut (nut height plus one and a half threads) on the end of the thread. So finally this morning I got around to entering the data into a table. If it is of any use to anyone else here goes:

BA Bolt and Nut Dimensions (in mm! ;D)

Size A/F Bolt Head Thickness Nut Thickness Nut allowance on stud
16 1.4 0.8 0.94 1.32
14 1.75 0.9 1.1 1.45
12 2.3 1.0 1.22 1.64
11 2.62 1.1 1.42 1.89
10 2.97 1.3 1.62 2.15
9 3.32 1.42 1.78 2.37
8 3.86 1.67 2.08 2.73
7 4.36 1.87 2.38 3.1
6 4.87 2.1 2.67 3.47
5 5.59 2.39 3.05 3.94
4 6.3 2.67 3.43 4.42
3 7.16 3.07 3.89 4.99
2 8.22 3.5 4.24 5.46
1 9.27 3.94 4.77 6.12
0 10.5 4.35 5.41 6.91

I have also taken a series of photos of making my last batch of 12BA stainless bolts if anyone is interested.

Jo

 

[Mainer]

Of course we're interested! Bring on the photos!

 

[maury]

Y'all, I also use shop made nuts studs & bolts for my engines. I make the studs from SST threaded rod, easy to find in all sizes. The bolts & nuts are made from SST hex rod, available in some 1/16 increment sizes. To get a more accurate scale I'd like to use sizes in increments of 1/32, but have been unable to find a source. Anyone know of a source for SST hex stock in 1/32 increments?

Also, I have access to a screw machine, and can have nuts made to spec. THe downside is the minimum order of 1000 to 2000 per size. If there is some interest in this, post here and I will pursue having some nuts made. Don't have prices, but I'd estimate $.10 to .$.25 each.

maury
www.lonestarengineworks.com

 

[Dr Jo]

Hi Maury,

I gave up with hex as you cannot buy the correct sizes any more. I now make all of mine, including the studs from 303 stainless round bar. For the smaller sizes they are all machined from 1/8" 303 as the smaller diameters bend all over the place and have a nasty habit of breaking off as you run up them with the die :wall:.

Here in the UK EKP will make nuts etc to order but only using off the shelf sized hex, and there is little point ordering 12BA and 14BA bolts from them when they have 10BA heads :rant:.

I will look to dig out the photo's tonight.

Jo

 

[smfr]

I'd love to see some pictures of how to make these.

 

[tel]

That's a handy table - thanks Jo! And yes - bring on the pics.

 

[Dr Jo]

The latest batch of 12BA bolts: they are all 1/2" long. For this set I needed a batch of 8 and I made 9 (one was short by .5mm :wall

These are the basic tools I use on the lathe and materials.

As this is batch work for 8 bolts I machine on both ends of four rods of 303 stainless. I have made myself a second travelling steady especially for these fiddly bolts, nothing special and only has a very small groove filed, with a needle file, which when mounted is lined up with the screw. Tailstock die holder with a slightly oversized 12BA die and the tailstock mount for the die.

Here you can see the set up, the first stage is to only machine the part onto which I am going to cut the thread. I find a simple piece of HSS best for this job.

Now I finish the bolt shank to length.

 

[Dr Jo]

So we now have four rods threaded both ends...

Now we head off to my BCA to climb mill the hex heads on:

The reason for climb milling is to prevent burrs on the underside of the heads.

Back to the lathe, first stage is to measure up the head height (plus .05mm for polishing) and to cut just beyond the flats and to use a needle file to chamfer the heads before parting off. The last photo shows the piece of brass tube I have stuck in an old rug making tool handle which I use to catch the bolts as they part off (sorry it is out of focus) .

 

[Dr Jo]

Now to finish off the bolts, I find holding the bolt in a pin vice is the only option, any nipples can be taken off with a needle file and then polished with what is a woman's nail polisher with various grit papers stuck on. :

If you remember I mentioned that the die was over sized. I intentionally use this one as a finished thread this sized can be damaged by the pressure from the travelling steady. The next task is to finish the thread on my good die. To do this I open up the die, screw in the bolt and then unscrew the bolt, the thread forming on the way out.

Whilst I am working I keep the bolts stuck on a magnet to prevent them going walk about.

As you can see the bolts in this case need to be overlength until the bearings have worn in. In the background you will see my tray of nuts I use when working, I am sure you all will recognise it as a tip holding container.

Jo
(Sorry I cannot work out why photobucket has rotated some of the photo's).

 

[buzbey]

thanks for the info and pics, I do like your travelling steady any rough plans (bogstandard type will do) ?

ken.
:bow:

 

[Dr Jo]

Hi Ken,

The travelling stead is nothing exciting, only a L shape cut out of aluminum with two M6 threaded holes to which is bolted a piece of bronze that has had a slot cut in it. The slot is loose which gives me vertical adjustment, slot length the y axis adjustment.

I have used bolts rather than cap head screws to mount the bronze as I can get nearer to the chuck. Here is a view of this travelling steady versis the original one for this lathe (which I found was no good for this job).

Jo

 

[Dan Rowe]

To do this I open up the die, screw in the bolt and then unscrew the bolt, the thread forming on the way out

Jo, many thanks for posting your methods. I have made a few small bolts of a similar size and I also use 2 dies. One set for an over size cut and one for the final cut. If you open the die to insert the thread for the finish cut how do you insure the die is set correctly for the finish cut?

Dan

 

[Jasonb]

Jo and anyone else using BA fasteners may find the following useful, its a copy of the full British Standard for BA fixings. Happened to come up in a thread on ME forum today regarding washer sizes.

You can now make sure you are chamfering the heads to teh correct spec with your file

http://www.ba-bolts.co.uk/pdfs/BS 57-1951 - BA Screws & Nuts etc.pdf

 

[Dan Rowe]

Jason,
Thanks for the link. I am always looking for hex head steel options in the 1mm to 1.5mm range. If you checked the root of the link they offer BA hex bolts with a one size smaller head. The 10 BA bolts have a 12 BA hex.
http://www.ba-bolts.co.uk/smallhex.html

Dan

 

[Jasonb]

I tend to buy from EKP who actually make the BA bolts for a lot of other suppliers and they also offer the smaller bolt heads and nuts to match. Watch out as they could be nearest metric hex size though from either source.

https://www.ekpsupplies.com/

J

 

[arnoldb]

:bow: Thanks for showing this Jo; you just relieved me from a lot of head-scratching as to whether this method would work. I was thinking along very much the same lines for making little bolts and trying to think whether it will actually work...
And a great tips on threading them over-size to start with and then to size later, as well as the climb milling to not leave burrs on the underside of the head Thm:

Kind regards, Arnold

 

[Dr Jo]

I must say that the boys at EKP are wonderful :-* and they will willingly provide almost everything a woman can ask of them. I was not so impressed when they sold me 12BA bolts with 10BA heads. What can I say....Size matters?

But every cloud has a silver lining and having learnt I now enjoy making my own bolts and studs :big: and they can be as rewarding as building much bigger items.

Jo
------------------------------------------
(Note to self: must try to get out more)

 

[tel]

;D We are a strange breed, ain't we - I enjoy making brass fittings, and cutting gears!

 

[steamer]

Great post Jo! I have a future project in mind that would take hundreds of bolts and studs, a 4 legged marine triple.......I'll pack this post away for future reference.

Thinking out loud......
That little traveling steady and your tool post form essentially a "box tool"...

and any possibility of putting a filing rest on your lathe with a spindle index?....would save a set up on the BCA and would form quickly with no burrs....but maybe too much stock to take off by hand with a 12BA starting with 1/8" stock....maybe rough turn the bolt head portion to near size across the corners?......What do you think?

Dave

 

[Dr Jo]

Hi Dave,

Yes what I am using is similar to a box tool but I use the top slide to turn down the diameter, whilst the traveling steady stays still on the saddle.
---
I have got a filing rest and dividing attachment for my lathe but it takes time to set them up and the work piece would need to stick out far enough to get the filing rest around it, at which point it is likely to start flexing and you end up with tapered hexes.

Making the heads on the BCA is just so quick and easy.

Jo