I need to make a replacement pin for a Russian target pistol (a TOZ-35M
free pistol). The pin is the pivot for the Martini action block.

The pistol has been quite functional for a couple of years using the stem
of a cotton swab, but it looks tacky. I don't think the pin needs to be
hardened, but the official one has a groove in it that a spring detent
snaps into. That will wear over time if the pin is too soft.

I'm going to order some 4mm drill rod, and have the option of A2 or O1
steel. If I don't bother hardening it, is there any advantage to A2? I
can't seem to find any info on what the hardness of the two are in their
annealed condition. A2 has some chomium in it, and I'm guessing it might
hold up a tiny bit better.

Thanks!

Doug White

Go to www.mcmaster.com, put tool steel in the search box, and then click on
more info at the top of the page to get some data tables on steels,
including tool steels. They list the min yield strength of O1 as 50 ksi and
A2 as 51 ksi. For Rockwell hardness, O1 is B85 unhardened and C65 hardened,
and A2 is B88 and C65, respectively. At the bottom of that screen are two
more more info buttons. Hope this helps.

-----
Regards,
Carl Ijames
"Doug White" wrote in message
. ..

I need to make a replacement pin for a Russian target pistol (a TOZ-35M
free pistol). The pin is the pivot for the Martini action block.

The pistol has been quite functional for a couple of years using the stem
of a cotton swab, but it looks tacky. I don't think the pin needs to be
hardened, but the official one has a groove in it that a spring detent
snaps into. That will wear over time if the pin is too soft.

I'm going to order some 4mm drill rod, and have the option of A2 or O1
steel. If I don't bother hardening it, is there any advantage to A2? I
can't seem to find any info on what the hardness of the two are in their
annealed condition. A2 has some chomium in it, and I'm guessing it might
hold up a tiny bit better.

Thanks!

Doug White

On Sunday, November 3, 2013 6:46:20 AM UTC-8, Doug White wrote:

I need to make a replacement pin for a Russian target pistol...

I'm going to order some 4mm drill rod, and have the option of A2 or O1
steel. If I don't bother hardening it, is there any advantage to A2? I
can't seem to find any info on what the hardness of the two are in their
annealed condition. A2 has some chomium in it, and I'm guessing it might
hold up a tiny bit better.

Thanks!

Doug White

Doug:

As Carl posted, A2 & O1 have quite similar properties in the annealed and heat treated condition.
The following site gives some relative machinability numbers for tool steels. A2 & O1 seem to be pretty much identical.

http://www.simplytoolsteel.com/machi...ool-steel.html

I remember from the stone age of my Tool & Die making days that we almost always made our blanking, compound, and progressive punch press dies out of A2... with the occasional die being made out of D2.
The advantage to O1 is that you can torch harden it. If you do
so, be sure to temper it to relive brittleness. If you're not going harden the pin, and there is no significant price difference, you could go with either one.

--
BottleBob
http://home.earthlink.net/~bottlbob

#92
Ways to machine
Some are obscene
Many are routine
A few seem from the Pleistocene

I've made a bunch of firing pins using O1, usually drill rod is closest in size, can be had metric, fractional, letter and number sizes. For flat pins, I've used ground flat stock in O1. Torch hardened on a plate with anti-scale, quenched in oil, tempered in a toaster oven. If you have to have grooves of some sort, make sure you've radiused the corners, you'll have outstanding stress risers otherwise and will be soon making another. I generally polish everything on a firing pin before hardening. Nicks and notches lead to trouble.

Just as a point of information, did the old pin fail at the groove?

Stan S.

wrote in
:

I've made a bunch of firing pins using O1, usually drill rod is
closest in size, can be had metric, fractional, letter and number
sizes. For flat pins, I've used ground flat stock in O1. Torch
hardened on a plate with anti-scale, quenched in oil, tempered in a
toaster oven. If you have to have grooves of some sort, make sure
you've radiused the corners, you'll have outstanding stress risers
otherwise and will be soon making another. I generally polish
everything on a firing pin before hardening. Nicks and notches lead
to trouble.

Just as a point of information, did the old pin fail at the groove?

Nope, it just vanished somewhere in transit. The National's are held at
Fort Benning, and when they unpacked the pistols, the pin was gone. One
thing I need to check is whether the detent spring that is supposed to
retain it is still operational.

Doug White

On Sunday, November 3, 2013 6:46:20 AM UTC-8, Doug White wrote:

"If I don't bother hardening it, is there any advantage to A2?"

Not that I know of. The big advantage of A2 is that it doesn't move like O1 does when it's hardened.

"Doug White" wrote in message
. ..

I need to make a replacement pin for a Russian target pistol (a TOZ-35M
free pistol). The pin is the pivot for the Martini action block.

The pistol has been quite functional for a couple of years using the stem
of a cotton swab, but it looks tacky. I don't think the pin needs to be
hardened, but the official one has a groove in it that a spring detent
snaps into. That will wear over time if the pin is too soft.

I'm going to order some 4mm drill rod, and have the option of A2 or O1
steel. If I don't bother hardening it, is there any advantage to A2? I
can't seem to find any info on what the hardness of the two are in their
annealed condition. A2 has some chomium in it, and I'm guessing it might
hold up a tiny bit better.

Thanks!

Doug White


Can you find a drill bit that's same diameter. use a
grinder to cut off some of the non-fluted shaft.
Chamfer the ends, as needed. How long a pin?

--
..
Christopher A. Young
Learn about Jesus
www.lds.org
..

Stormin Mormon wrote in
:

"Doug White" wrote in message
. ..

I need to make a replacement pin for a Russian target pistol (a
TOZ-35M free pistol). The pin is the pivot for the Martini action
block.

The pistol has been quite functional for a couple of years using the
stem of a cotton swab, but it looks tacky. I don't think the pin
needs to be hardened, but the official one has a groove in it that a
spring detent snaps into. That will wear over time if the pin is too
soft.

I'm going to order some 4mm drill rod, and have the option of A2 or
O1 steel. If I don't bother hardening it, is there any advantage to
A2? I can't seem to find any info on what the hardness of the two
are in their annealed condition. A2 has some chomium in it, and I'm
guessing it might hold up a tiny bit better.

Thanks!

Doug White


Can you find a drill bit that's same diameter. use a
grinder to cut off some of the non-fluted shaft.
Chamfer the ends, as needed. How long a pin?

The problem with using the shank of a drill bit is that a lot of vendors
stamp the size in the shank, which sort of trashes it. The pin is ~
7/8" long, which is pushing it for a 5/32" drill bit if teh shank is
stamped.

I just bought 3 feet of 4mm O1 rod stock from McMaster for ~ $3. A
lifetime supply for about the cost of a hardware store drill bit.

Doug White

On Sun, 10 Nov 2013 02:33:10 GMT, Doug White
wrote:



The problem with using the shank of a drill bit is that a lot of vendors
stamp the size in the shank, which sort of trashes it. The pin is ~
7/8" long, which is pushing it for a 5/32" drill bit if teh shank is
stamped.


Drill blank and reamer blanks are unmarked. McMaster carries both
hardenend and unhardened blanks in several materials. For example:

High-Speed M2 Tool Steel

Hardened Undersized Rods—Precision Ground

Yield Strength: Not rated
Hardness: Very Hard (Rockwell C62)

Also known as drill rods. Straightness tolerance is 0.001". Length
tolerance is ±1/32".Dia. Dia.
Tolerance Drill Bit
Size Lg. Each
0.1520" -0.0002" 24 3 1/8" 3009A236 $2.29
0.1540" -0.0002" 23 3 1/8" 3009A235 2.30
0.1562" -0.0002" 5/32" 3 1/8" 3009A121 2.31
0.1570" -0.0002" 22 3 1/8" 3009A234 2.33
0.1590" -0.0002" 21 3 1/4" 3009A233 2.36

Another source of hard pins in finely graduated sizes is pin gages.
McMaster stock pin gages in 1/2 thou increments. They're usually made
from 52100 bearing steel. Not as hard as the blanks above, but
considerably tougher.

Individual Inch Plug Gauges Go Gauges No-Go Gauges
Sizes Tolerance Each Tolerance Each
Class Z—To Order: Please specify exact size needed in 0.0005"
increments.
0.0110 to 0.0605" +0.0001" 23055A001 $3.48 -0.0001"
23065A503 $3.48
0.0610 to 0.5005" +0.0001" 23055A002 3.10 -0.0001"
23065A504 3.10
0.5010 to 0.6255" +0.0001" 23055A004 4.25 -0.0001"
23065A506 4.25

--
Ned Simmons