Had some fun today and wanted to share it with the rest of the class.
As a lot of you know we sell what we call a hard sear. It is 56 ish Rc. hardness.
Over the last 12 years we average less than One failure per year.
This includes a sear some nice rocket scientist stoned to a point and returned to brownells. and another that the half cock had beaten a dent in the sear. It takes quite a bit to dent 56 rockwell tool steel by the way.
So we went along with a failure rate of less than one sear in 1000 per year, That is alarming but considering we always ask for the broken ones back and half of the returned ones have strange things going on. The other thing we have to take into account is Many of our sears end up in competition guns that get shot a TON.
We went out looking into a new tool steel this year to improve from our 0.05% failure rate.
SO how do you break a sear?
first choice was take a demilled frame. install a 23# main spring
mill the hammer down and move the notch in .030
this leaves the hammer fall and smack into the half cock notch.
OUCH!
We than releived the half cock notch so it could get a longer running start.
Next we dry fire the hammer into a sear and stop on the half cock each and every time. (ok it was not a pretty sound.)
after 100 repeats we found the old sear had a shiny surface where it hit the hammer but no peaning.
Plan B
We wanted to get a sear to fail to test against another material.
Caspian sent us some blank bar stock we use around the shop for fixtures. a nice block of 4140 at 41 rc.
the block is 8" long .935 thick and 1.7" high
a Chunk of steel
next we drilled a pin hole in a plate and milled a slot to hold the sear. We drilled and tapped the steel bar to make a pivot point.
And we dropped this chunk on the sear. A much uglier sound
3 smashes later the sear tip broke off.
My first thought was wow, a sear is pretty darn tough!
100 times falling squarely on the half cock. and it didn't touch it.
KooL
So we pulled out another sear and 3 smashes and it cracked, on the fourth smack it parted with the point.
next we tried the new tool steel, unobtanium (you can only get it from us )
it went 8 hits with the sledge. Again this was tested in the frame smack test also before the test fixture. On all these tests the sear pin bent long before the sear gave up the Ghost.
The other interesting thing that came up recently was about manufacturing. We close the shop one day a year for a field trip to our Yearly tool show. Speaking with one manufacture they mentioned they sold a machine to Kimber.
What struck me is they sell over 75k guns a year. Imaging making 60,000 bushings. (it was mim it failed and they went to bar stock fact) It was a turning center with a live tooling Z X C and Y axis and a live pick off spindle. The machine makes a bushing in about 110 seconds. They have to run one machine all year to make Bushings for a gun. One part for a 1911.
Think about WW1 or 2 making 45's at the rate they did. and all from forgings extrusions, and bar stock ONE at a Time on NON cnc machines. Now conside Today with our CNC mills and turning centers that Darn few manufactures do it the old fashon way. From bar stock or even from Castings.
Who wants to make 1500 firing pin stops, Sears, Hammers and thumb safetys a week. Mim is here to stay. It costs less.
geo
As a lot of you know we sell what we call a hard sear. It is 56 ish Rc. hardness.
Over the last 12 years we average less than One failure per year.
This includes a sear some nice rocket scientist stoned to a point and returned to brownells. and another that the half cock had beaten a dent in the sear. It takes quite a bit to dent 56 rockwell tool steel by the way.
So we went along with a failure rate of less than one sear in 1000 per year, That is alarming but considering we always ask for the broken ones back and half of the returned ones have strange things going on. The other thing we have to take into account is Many of our sears end up in competition guns that get shot a TON.
We went out looking into a new tool steel this year to improve from our 0.05% failure rate.
SO how do you break a sear?
first choice was take a demilled frame. install a 23# main spring
mill the hammer down and move the notch in .030
this leaves the hammer fall and smack into the half cock notch.
OUCH!
We than releived the half cock notch so it could get a longer running start.
Next we dry fire the hammer into a sear and stop on the half cock each and every time. (ok it was not a pretty sound.)
after 100 repeats we found the old sear had a shiny surface where it hit the hammer but no peaning.
Plan B
We wanted to get a sear to fail to test against another material.
Caspian sent us some blank bar stock we use around the shop for fixtures. a nice block of 4140 at 41 rc.
the block is 8" long .935 thick and 1.7" high
a Chunk of steel
next we drilled a pin hole in a plate and milled a slot to hold the sear. We drilled and tapped the steel bar to make a pivot point.
And we dropped this chunk on the sear. A much uglier sound
3 smashes later the sear tip broke off.
My first thought was wow, a sear is pretty darn tough!
100 times falling squarely on the half cock. and it didn't touch it.
KooL
So we pulled out another sear and 3 smashes and it cracked, on the fourth smack it parted with the point.
next we tried the new tool steel, unobtanium (you can only get it from us )
it went 8 hits with the sledge. Again this was tested in the frame smack test also before the test fixture. On all these tests the sear pin bent long before the sear gave up the Ghost.
The other interesting thing that came up recently was about manufacturing. We close the shop one day a year for a field trip to our Yearly tool show. Speaking with one manufacture they mentioned they sold a machine to Kimber.
What struck me is they sell over 75k guns a year. Imaging making 60,000 bushings. (it was mim it failed and they went to bar stock fact) It was a turning center with a live tooling Z X C and Y axis and a live pick off spindle. The machine makes a bushing in about 110 seconds. They have to run one machine all year to make Bushings for a gun. One part for a 1911.
Think about WW1 or 2 making 45's at the rate they did. and all from forgings extrusions, and bar stock ONE at a Time on NON cnc machines. Now conside Today with our CNC mills and turning centers that Darn few manufactures do it the old fashon way. From bar stock or even from Castings.
Who wants to make 1500 firing pin stops, Sears, Hammers and thumb safetys a week. Mim is here to stay. It costs less.
geo