Need advice regarding turning #4 screws

[jsb30]

Brownells sell #4 screw blanks, not threaded.

[Joe Stein]

Dave Kanger beat me to it. I was going to post essentially the same thing. I made my own mandrel in my lathe. It is just a piece of round stock turned to the proper diameter and threaded. I used a nut on each side of the diamond plate, instead of turning a shoulder. I threaded on the top nut and trued it in the lathe so the plate doesn't wobble. I usually start with a 320 grit plate. It will remove material quickly.
I have found the diamond plates for as little as $10.00 on Amazon.
 Be sure to wear a mask and safety glasses. Dust will come off in a cloud. A vacuum cleaner will help keep it down.
Joe Stein

[T*O*F]

I threaded on the top nut and trued it in the lathe so the plate doesn't wobble

I should also mention that these are available at the big box stores cheap.  I bought one and it wobbles like crazy.  Don't buy one of those. 

[Rolf]

Problem solved simple and easy. I got some 10.9 steel bolts. This stuff is hard but turns like a dream with carbide metal inserts I have.
I start with 8mm bolts(0.315").


After one pass, I,m down to 5mm (0.197")


Second pass I am down to 3,4mm (0.134")


After that, I nibble the shaft down to 2,9mm(0.114") and the head to 3.9mm (0.154"). I can cut cleanly shavings down to 0,025m (0.0001"). Have to use a magnifier to watch the cutting.


Threading in the lathe with the tailstock fixture.


Finished screw.


Best regards
Rolf

[P.W.Berkuta]

After seeing what the screw is going to look like when finished I now see why you needed such a large diameter piece of metal rod to start with - odd screw- nice job.

[Bob Roller]

After seeing what the screw is going to look like when finished I now see why you needed such a large diameter piece of metal rod to start with - odd screw- nice job.

He has no good way to do this and no collets available for the 4MM material. I have made these small screws using a Jacobs headstock chuck but to find one now is very hard.Collets are not hard to make and the tapers can be indifferent IF the design of the R8 Bridgeport
is followed.I admire Rolf's determination to make these screws and if that 3 jaw chuck is all he has then what he's doing will work.
I can send him some  12L14 in 5/32 diameter but the set up he has is incompatible with that small diameter rod.
Bob Roller

[bobw]

Now I understand why there was problem.  One cannot use a die the way I cut small threads, when supported on both ends.  These are all cut using a very sharply ground threading tool and the lathes threading abilities, 13 inch lathe using a 3 jaw chuck.  I have the luxury of having a thread mic now, but before that used wires to measure for proper thread size, which is required for a screw to work.  Here are several threads that I cut, #1-64 to 2 1/4-8, with a 1/4-20 bolt for comparison, and you can see the waste end is still on some of them.  All the small screws are for guns or gun sights.

[Birddog6]

I have made allot of things, but screw making will never be one of them. Don't like using
the lathes that much.
I use lathes if I have to, & have 3 out of 4 lathes set up to use, just don't like doing it. It
just bores the H out of me.  I use the little Atlas to make bushings & etc most of the time.
The two bigger ones I never have used.

Other guys say "Oh I love making tiny things with mine."  To each their own I guess.

[Bob Roller]

Making small screws out of bigger ones may be the only expedient available but I would try to
avoid hardened bolts that require carbide tooling.I wonder about suppliers in Europe and think
in the USofA we are spoiled by easy availability of anything and everything with a phone call or
E mail to a lot of places.I use cold finished 1018 for triggers and the bars and it is readily found
from a wide variety of companies High quality end mills,high speed or solid carbide easy to find
and I like 5 and 7 fluted in the sizes I use. Maritool and Kodiak is where I buy them.
Bob Roller

[bobw]

Most of the screws I make are for custom guns and are made to fit specified holes.  Head and unthreaded shanks sizes are usually specially sized compared to standard threaded screws.  Rather than spending time digging through books and on on-line sources and not finding what I need, it’s is easier to just make them.  I have even gone to making my own wood screws because of the poor quality mass produced screws, I really dislike the wide off center slots.  The picture is my shop made Deeley style forearm assembly with custom lathe made wood screws.
Bob

[Elk Hunter]

I use o-1 drill rod for screws. Cheap and easy to turn and thread. I heat treat them like springs.

Just me $0.02 worth.