Need advice regarding turning #4 screws

[Rolf]

The cutter I have use CCMT060204 carbide inserts.  Tried using 8.8 steel bolts.  Started with 6mm (2/8") bolts, they bend and break about 4.5mm (0.057") which is too big for a 4-40 screw.
Tried using 12.9, 8mm bolts. These work sometimes, but 3 out 4 times the steel seems to work harden and stop cutting, even when I change to a new carbide insert.
What type of steel do you use for this size screw?
There are hundreds of types of CCTM060204. The one I'm using was recommended for stainless steel, so I thought it would do the job in 12.9 steel. Can anyone recommend an insert for 12.9 steel?

Best regards
Rolf

[Bob Roller]

We don't know hat 12.9 steel is over here.I use 12l14,an American steel made FOR screws and little else.In my locks
I use a #4 screw which is in inch measurement ,108-.110 thousandths and a 5/32 (.156) head for the 2 bridle screws
and sear screws and the sear spring screw.No need for carbide or any exotic cutters either. 12l14 has lead in it to make
it very east to machine.I don;t know about Norway but maybe the Germans have a Bleistahl listed that is like 12L14 or
very close.I bought the .156 diameter rods and only have to turn them to .110 for a #4 screw.
what are you using these little screws on?Sounds like a lock of some kind.
Bob Roller

[Angus]

What Mr. Rolf is referring with 8.8 and 12.9 is the head stamp on a metric bolt.

Rolf, try using as Bob described 12L14 (a free machining steel) or 1018 (low carbon steel). Should be able to find materials in 2 or 3mm diameters.
Are you using bolts because you want material to make screws with to be robust?

[Clark Badgett]

Rolf, try a CNMG insert with a 1 or 2 radius. I like the gold colored kind. If I don't forget I'll see if I can get the exact numbers at work tomorrow. Bolts are soft enough that they should cut easily.
I only use bolts as a last resort. Get some 12L14 like Bob recommends.

[45-110]

If you are having to use carbide to cut the mystery metal screw blank you will have problems later using a thread die on the hard metal. You may get it done but it will dull the die fast.
kw

[Bob Roller]

I have never seen or had the need for carbide tools to make tiny screws from 12L14 or anything else.
If there was no heat involved I think that material might be machined with your finger nails .
Bob Roller

[Clowdis]

I would try turning the small diameter using a sharp high speed steel cutter arranged exactly on center of the workpiece. I'd also run the lathe at a higher rpm, maybe in the 900-1000 range. If the screw needs to be over 25mm long you may not have any luck with any tooling.

[Rolf]

Thank you for replies. I'll try to answer your questions.
I'm making five left-handed Alex henry style, four screw precussion locks from scratch, no cast parts available. I got the plate pattern and measurements from Bob Roller. Curtis helped me get the pattern for the hammer right.  I've finished the lock plates, hammers, bridles and tumbler blanks. I am trying to make the screws following this tutorial   https://americanlongrifles.org/forum/index.php?topic=39128.0 by Jim Westberg.

I live in Norway and material available is limited. Nobody sells 12L14 rod stock in Norway. I've searched high and low. What I can get is bolts 12.9 and 8.8. I found several US suppliers on the net, but they either won't send abroad or charge 60$ or more for shipping 3 feet of rod.

Clark, I'll try to find a CNMG with a 1 or 2 radius on ebay. 

I have no problems making screws 4mm (0.157") and bigger with 12.9.  It threads easily. It's making smaller blanks that's the problem.

Here is a couple of pictures on the project so fare.

Best regards
Rolf

[snapper]

I am not a machinist, if I were, I would make you some screws and send them to you.   Sounds like that might be easiest and cheapest.

Fleener

[snapper]

Are you making 4 of these locks just because as long as you are making one, why not make a few others?

Fleener

[Bob Roller]

I MIGHT be the most experienced lock MAKER on this forum and these "4 pin" locks ARE labor intensive and the demand is about zero in the USA.Bill Roberts,Jim Westberg and myself are the 3 that made any at all.I used a cast hammer and that was all. i still have the patterns and
drill patterns as well as a half finished one on the bench,a "4 pin" for a rook or boys rifle.I told a man at the CLA Show last Friday I might finish it for $400 and he offered $300.I told him that was my price in 1989.A few years ago while on the LRML forum I was in touch with a man in Wolverhampton who said that there were still a few lock filers he knew that could copy these 4 pin locks and they would cost about $4000 for a pair and that DID include the hammers. . Now at 86 I feel no big urge to make these elegant locks again.
Bob Roller

[P.W.Berkuta]

I go along with what Bob and others have said about using a low grade of steel and a HSS lathe tool. I will also use O-1 tool steel when the need is called for but that is not often. I do case harden my low carbon steel screws for better wear resistance

[Rolf]

Are you making 4 of these locks just because as long as you are making one, why not make a few others?

Fleener

More or less correct. I'm trying to learn lock building before I attempt to put together several cast sets I've accumulated from Blackley, Ron Scott and a few others.  I have to make the "guts" for most of the kits.
If I mess up a cast part, it is almost impossible to replace. If I mess up one of my scratch builds, it's just a chunk of steel.
Also some of the locks I want are not available as kits or finished locks. Often the only option is to build from scratch. Here is a link to my last scratch build. All the screws here are 12.9 , but none smaller than 4mm.
https://americanlongrifles.org/forum/index.php?topic=55741.msg557646;topicseen#msg557646
I thank you for your kind offer to make screws for me, but I have to learn to do this myself. It is a necessary skill in lock building. I plan to keep two of the Alex Henry locks. I hope to send one to Bob Roller for evaluation and trade the rest if the quality is acceptable.

Best regards
Rolf

[snapper]

I dont know if this will help or not, but here is a picture of an original AH lock and hammer. that is on my double rifle.

Might be the picture and it might not matter to you on how close you are wanting to get to an original design, but your hammer with the "C" looks off to me.  Looks to pronounced.

I also included a picture of a Mortimer shogun.   Alex Henry apprenticed and worked for several years for Mortimer I believe.

Fleener

[Bob Roller]

I go along with what Bob and others have said about using a low grade of steel and a HSS lathe tool. I will also use O-1 tool steel when the need is called for but that is not often. I do case harden my low carbon steel screws for better wear resistance

I made lock screws from 5/32 drill rod for years and after I bought the entire stock of 5/32 12L14 from a company that was
shutting down and I still have some of this left over..
Bob Roller

[Rolf]

I dont know if this will help or not, but here is a picture of an original AH lock and hammer. that is on my double rifle.

Might be the picture and it might not matter to you on how close you are wanting to get to an original design, but your hammer with the "C" looks off to me.  Looks to pronounced.

Thank you the pictures, beautiful locks. I copied the hammer that's on the Alex Henry target rifle made by Curtis. He used the kit from Rod England. Here is a link
https://americanlongrifles.org/forum/index.php?topic=55149.msg625875#msg625875

I drew a pattern from pictures he took. The paper pattern was mail to Curtis who then compared it with his hammer and suggested corrections. This was repeated until I got as close I could get. But, I don't claim to be an exact copy, but it's the best I can do. I've done a write up of the building process, like I did on the 1772 pistol locks and will post it when the locks are finished.

Best regards
Rolf

[Bob Roller]

I dont know if this will help or not, but here is a picture of an original AH lock and hammer. that is on my double rifle.

Might be the picture and it might not matter to you on how close you are wanting to get to an original design, but your hammer with the "C" looks off to me.  Looks to pronounced.

I also included a picture of a Mortimer shogun.   Alex Henry apprenticed and worked for several years for Mortimer I believe.

Fleener

These superb locks are EVERY bit as good as a 4 screw tyoe and a LOT less effort.I have made several of these and have even
contemplated using this mechanism in the L&R 900 as an upgrade as I did with 14 Twiggs earlier
Thank you, Fleener for showing these locks.Years ago I discussed these "3 pin"locks with Bill Roberts and he said that
there is no felt difference in this lock and the more difficult "4 pin"types,He knew more about these than I did and I agree with
him 100%.Like Mr.Westerberg,Bill Roberts is deceased for a long time.
Bob Roller

[snapper]

I have purchased just the replica AH hammers in the past from Rod England to retrofit my Roller locks that Bob built for me for my two Don Brown AH kits.

Will be interested in your write up as always!

Fleener

[Bob Roller]

I dont know if this will help or not, but here is a picture of an original AH lock and hammer. that is on my double rifle.

Might be the picture and it might not matter to you on how close you are wanting to get to an original design, but your hammer with the "C" looks off to me.  Looks to pronounced.

I also included a picture of a Mortimer shogun.   Alex Henry apprenticed and worked for several years for Mortimer I believe.

Fleener

These superb locks are EVERY bit as good as a 4 screw type and a LOT less effort.I have made several of these and have even
contemplated using this mechanism in the L&R 900 as an upgrade as I did with 14 Twiggs earlier
Thank you, Fleener for showing these locks.Years ago I discussed these "3 pin"locks with Bill Roberts and he said that
there is no felt difference in this lock and the more difficult "4 pin"types,He knew more about these than I did and I agree with
him 100%.Like Mr.Westerberg,Bill Roberts is deceased for a long time.
Bob Roller
I forgot to say that I made a long run of this style mechanism in Schuetzen locks for a German shop.They called this bridle "Der Kreuzstudel
mit drei schrauben". BR

[T*O*F]

Rolf,
I have #4-40 x 1" and #4-48 x 1" fillister head gun screws.  They are fully threaded and you can cut them to length.
How many do you need?

[bobw]

I make screws down to 1-64 on a 13 inch lathe.  I support both ends, tail stock is a spring loaded live center, and use a VERY sharp, shop made, high speed steel cutter.  Never have a problem.
Bob

[Bob Roller]

Rolf,
Snapper's offer is a solution until you can make your own small screws.Do you have a small lathe of about 150MM or 6 inches.
I have 2 of these and they have a tapered spindle in the threaded end and will take the American number 2 Morse collets like
old style milling machines used.That big 3 jaw chuck in the picture won't work with 4MM rods but a collet adapter could work with
a 4MM collet as used in Northern European machine shops.
Bob Roller

[Rolf]

Thank you for your offer TOF. I have some options to explore first.

Bob, I have an enmco 8 compact lathe, it weighs 80 kg and the largest I can turn is a 12" pistol barrel blank between centers.
There is a supplier in England where I can get parts, but their website is down for maintance at the moment. I'll see if they have a 4mm collect that fits.

Finding a bench grinder for HSS in Norway, now that was opening a can of worms.  I tried Wurth, Tess, Tools and Ashells. These are the major industrial suppliers in Drammen, close to where I live. They can order me a grinder, takes 2-3weeks to get it, and stones are very coarse, 30 and 60, not suitable for HSS. They have tons of turning inserts. Seems sharpening HSS is not regarded as cost effective. I do have lead on supplier who says he can get me a Norton stone for HSS.

I found a few other options for screws. I got a test sample of four 10.9 bolt from a supplier in Kristiansand(way south of Norway). These are softer than 12.9 and I might be able to turn them. The funny thing, is that all the screws I made for the six 1772 pistol locks where made from 12.9 bolts without problems.  I turned them with some "mystery"inserts, got cheap from EBAY. No markings on the box. Wish I could get more of them. All I know is their size code CCTM0604.

Another option is screw blanks. I was able to get a pile of #4 blanks from Brownell. These are very soft, and the head gets messed up easy. The shank is a bit over 2" long. I can thread them by starting in a fixture in the tailstock of my lathe and finishing by hand in a vice. The heads are pre-slotted and to big. The heads 5.7mm and have to be turned down to 4mm. The bridles are counterbored to accept 4mm heads. The tools I have don't cut the steel cleanly. The steel gets mushed instead. Maybe I can cut it with sharp HSS tools.

The last option is to remake the bridles and skip the counterbore for the heads, use the screw blanks and caseharden the heads. As far as know, none of the commercial made locks have counterbored bridles.

Best regards
Rolf

[P.W.Berkuta]

The best grinding wheel I found for grinding and shaping HSS lathe bits is a CBN wheel - here is some info <https://www.actionsuper.com/a-comprehensive-guide-to-cbn-grinding-wheels/>

[T*O*F]

Rolf,
This setup is a poor man's sharpening system for gravers and will handle HSS, Momax, and all the other carbides.  The mandrel is available from Steve Lindsay and the diamond sharpening plates are available on ebay for much cheaper than Lindsay or GRS charge.  The mandrel fits in your drill press.  The plates are available from 230 to 2000 grit.  We usually use a coarse one for roughing out and 400, 800, and 1200 depending on the state of polish required.