The Firing Line Forums

Go Back   The Firing Line Forums > The Skunkworks > The Smithy

Thread Tools Search this Thread
Old June 20, 2018, 06:40 AM   #1
Senior Member
Join Date: January 5, 2013
Posts: 215
4140 steel 80% 1911

Has anyone used a 3/32" end mill to cut the rails on a 4140 steel frame? I have done some milling over the years on my 3 in 1 mill/drill/lathe but never with this small of an endmill. HSS with flood cooling? Carbide dry? Or is a key way cutter the best way to go? My equipment is all manual.
Hdonly is offline  
Old June 20, 2018, 09:21 AM   #2
Senior Member
Join Date: January 20, 2009
Location: Amity Oregon
Posts: 646
Keyway (Woodruff) would be the way I would do it. Cut both sides in one setup.
BillM is offline  
Old June 20, 2018, 09:26 AM   #3
Senior Member
Join Date: March 5, 2009
Location: NY
Posts: 228
I know your particular task but have never done it. Have done many like it... No clue as to the rigidity of the equipment you have but I personally I like the idea of the key seat cutter with coolant. Any size EM can pull to one side unless you are taking multiple light passes on one side at a time.
tango1niner is offline  
Old June 20, 2018, 10:04 AM   #4
4V50 Gary
Join Date: November 2, 1998
Location: Colorado
Posts: 20,148
Key cut it. Automatic feed set on slow with lubricant.
Vigilantibus et non dormientibus jura subveniunt. Molon Labe!
4V50 Gary is offline  
Old June 20, 2018, 03:17 PM   #5
Senior Member
Join Date: February 13, 2006
Location: Washington state
Posts: 13,459
Keyway (Woodruff) would be the way I would do it.
Never try to educate someone who resists knowledge at all costs.
But what do I know?
Summit Arms Services
Taylor Machine
Scorch is offline  
Old June 20, 2018, 06:07 PM   #6
Senior Member
Join Date: February 25, 2013
Location: Broward County, Florida
Posts: 2,945
I would use a keyseat cutter but could probably be done with an endmill. Either way it will be key to have very accurate set up with regards to cutting the rails square and parallel with the rest of the frame.

Carbide is more rigid and resistant to heat but is less forgiving on making a nice finish if you're not pushing the speed. HSS is more forgiving in this regard but you'll have to be more careful with the heat. If you don't have a flood coolant system, I would use a heavy cutting oil like the Vipers Venom offered by PTG
Over the next 25 days, I am raising money on Kickstarter for a Historical Firearms Coloring Book. If this interests you and you would like to see the project completed, please consider pledging or simply sharing the project.
dakota.potts is offline  
Old June 20, 2018, 07:03 PM   #7
Senior Member
Join Date: January 5, 2013
Posts: 215
I have an older Shoptask 3 in 1 and a smaller tabletop milling machine. I was wanting to do it on the smaller machine, but I am limited to 1/4" collet. I have 3/32" endmills in 1/4" but I see mostly 1/2" shank key slot cutters. Guess I should do the job on the Shoptask with 1/2" x 3/32" key slot cutter. I have mist cooling setup, but it will flow pretty wet with the right settings. Thanks for all the good information.
Hdonly is offline  

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

All times are GMT -5. The time now is 03:36 PM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
This site and contents, including all posts, Copyright © 1998-2018 S.W.A.T. Magazine
Copyright Complaints: Please direct DMCA Takedown Notices to the registered agent:
Contact Us
Page generated in 0.06655 seconds with 8 queries