have you considered using a parting off tool ?

H

Playing around with small ba screws/studs requires some dedicated tools /jigs one of which is the lantern chuck which will repay you many times over for a wet days work. Small parallel shaft ER collet chucks come into their own for jobs like this especially ER8 size. You will find things a lot easier with the turning and parting if spindle speeds are increased quite dramatically. I have a little Peatol lathe which has a top spindle speed of 9000rpm, this makes the machine bit of the job a doddle. Best of luck.

If you’ve not got too many (whether 40 is too many is up to you), then a bit of say 5mm flat with a 6 ba hole near one end, then a sawcut through the hole and continuing a fair way beyond will help you nip the stud/bolt in your vice for cutting/filing. I keep meaning to do something better as shortening bolts is really boring

I use these crimping pliers which can shear a selection of small metric threads. They will shear off 6BA studding easily enough, then clean up the sheared face with a file in the lathe.

On 22 May 2024 at 18:32 JasonB Said:

I would saw them off. At 6BA it’s a toss up between junior hack saw or piercing saw for me. Then into the lathe and use a file on the end while rotating to put a neat concave end on it.

+1  though I think you mean convex not concave.

Mike

I use a piercing saw a lot for this job. Lantern chucks if you are being fussy.
It’s also possible to make your own cropping tool. Couple of circles of gauge plate with extensions for handles. Device clamped through the middle of the circular bit with a nut and bolt. Drill and tap a circle of BA (or whatever) holes for all the sizes you use. Separate and open up one of the pair to clearance size. Harden and temper.
You can then screw in your bolt to depth and operate the tool by squeezing the handles. Crops cleanly enough to use the bolt without further work.

regards Martin

What mor edo you need?

Bit of 7BA studding I’ve had laying about for years. Held in small vice and sawn with piercing saw, length to rule. Into the lathe and a few strokes of a file while twisting it in your hand and job is done. Nice domed (convex) end and no burrs

Seems to work Ok

I recall Myford Boy making a load of meccano screws from threaded rod on his lathe – oversize nut held in chuck to feed the rod through, second nut as a jam to hold it at length, feed out to a stop and part off, looked very neat and quick. He also cut slots (slits?) in the heads with a slitting saw.  There’s a video on Youtube if you search.

As I said earlier I would usually thread my own but as the OP was intending to use studs or cut the heads off screws that is what I went with😊

Well actually on such small studs that are often holding things that are no thicker than 1 x their diameter it is hardly worth leaving an unthreaded section in the middle that may only be 2mm or less long, at least that is what I tend to do. If it were say a stud for a valve chest and cover then not worth the time threading the whole length.

But just for Andrew 😍

Although the nut method will break off a burr it can still leave a sharp corner. The doming by filing method will remove any sharp edges and the file size should be adjusted as the stud gets larger, for something like M10 then a 10″ lathe file would get the job done a lot quicker than that small file I used in the video.

If it is more of a functional item rather than a steam engine that should look nice then a larger stud can always be faced and if positioned correctly the same tool used to cut a chamfer on the corner

Usual warning when filing on the lathe, use a handle, roll up sleeves and if you have one use a collet chuck as they don’t hurt as much as a chuck jaw. If you want to be really safe hold the file backwards and offer it up to the underside of the work.

Not the same as acting left handed.

The option I describe will draw the file away from you should it get hit by a chuck jaw or part of the work as it is in contact with the parts that are rotating AWAY from you.

Left or right handed with the file on the top of the work which is rotating TOWARDS you if the file hits something it will get pushed back towards you hence why a handle should be used as that is better than having the tang pushed into the palm of your hand.

The OP only wants to use the threaded shank of the screws as studs, so no need for fancy jigs or tooling.