Sear spring mortise........HOW?

John Sabato · 03-03-2011, 08:14 AM

The method used to create the sear spring mortise in the upper receiver has always made me wonder too... obtaining tools that small would not be an issue, but the obtaining the correct internal shapes and surfaces to that mortise are a machining operation that escapes my gunsmith and hobby machinist mentality...

All I know for certain is that the Germans and the Swiss did it MILLIONS of time... and it was perfect every time... An engineering miracle IMHO.

Even the Stainless Steel guns that were produced under several marketing names by the same manufacturer never produced this mortise to the same perfection as the original guns.

sheepherder · 04-03-2011, 08:17 AM

The company I ordered my dovetail cutter from, Harvey Tool, sent me their catalog...Idly browsing through it, I noticed they have very small Woodruff keyseat cutters...

I too need to cut a small "T" slot...I'll be ordering one of these cutters shortly...

www.harveytool.com

TennBill2 · 04-04-2011, 02:19 PM

What a Mother! Having little in the way of exotic equipment, I had to figure out how to mill this little slot. Took a small..3/32(?) broken end mill, ground the broken part off, slowly (Boy, is that thing hard!). Chucked it in the lathe and with a Dremel reinforced cut-off wheel, I ground it into a tiny cutter. Put my 'cutter' in my flex shaft Dremel and Voila', cut the slot I needed. Works just fine for a little sear spring slot.

03-03-2011, 08:14 AM	#1
John Sabato Lifer Lifetime Forum Patron Join Date: Jun 2002 Location: The Capital of the Free World Posts: 10,156 Thanks: 3,003 Thanked 2,308 Times in 1,098 Posts	The method used to create the sear spring mortise in the upper receiver has always made me wonder too... obtaining tools that small would not be an issue, but the obtaining the correct internal shapes and surfaces to that mortise are a machining operation that escapes my gunsmith and hobby machinist mentality... All I know for certain is that the Germans and the Swiss did it MILLIONS of time... and it was perfect every time... An engineering miracle IMHO. Even the Stainless Steel guns that were produced under several marketing names by the same manufacturer never produced this mortise to the same perfection as the original guns. __________________ regards, -John S "...We hold these truths to be self-evident that ALL men are created EQUAL *and are endowed by their Creator* with certain UNALIENABLE* rights, and among these are life, LIBERTY, and the pursuit of happiness..."*

04-03-2011, 08:17 AM	#2
sheepherder Lifer Lifetime Forum Patron Join Date: Feb 2009 Location: ...on the 'ol Erie Canal... Posts: 8,197 Thanks: 1,416 Thanked 4,462 Times in 2,336 Posts	The company I ordered my dovetail cutter from, Harvey Tool, sent me their catalog...Idly browsing through it, I noticed they have very small Woodruff keyseat cutters... I too need to cut a small "T" slot...I'll be ordering one of these cutters shortly... www.harveytool.com Attached Thumbnails __________________ I like my coffee the way I like my women... ...Cold and bitter...

04-04-2011, 02:19 PM	#3
TennBill2 RIP Join Date: Feb 2011 Posts: 101 Thanks: 0 Thanked 17 Times in 6 Posts	Necessity.... What a Mother! Having little in the way of exotic equipment, I had to figure out how to mill this little slot. Took a small..3/32(?) broken end mill, ground the broken part off, slowly (Boy, is that thing hard!). Chucked it in the lathe and with a Dremel reinforced cut-off wheel, I ground it into a tiny cutter. Put my 'cutter' in my flex shaft Dremel and Voila', cut the slot I needed. Works just fine for a little sear spring slot. Attached Images