How to use a square broach? (1 Viewer)

nat

Joined
Sep 20, 2005
Messages
1,999
Location
Los Gatos, California
 
 
 
I am thinking I can use a broach to make square corners in a part I want to mill. Do I just drill the pilot hole and press the broach through? Is there an easier or different way? This will be in aluminum.

:cheers:
 

kjohnson

SILVER Star
Joined
Oct 21, 2006
Messages
300
Location
S. WI
 
 
nat, I am not real sure what you mean by ( a part I want to mill) If you are after a square hole instead of a round hole, yes a square broach will work. The broach will have a round pilot on one end, drill your hole so that the pilot will be a slip fit. Keep the broach covered with cutting oil as you press the broach through, nice and slow.

Kevin
 

nat

Joined
Sep 20, 2005
Messages
1,999
Location
Los Gatos, California
 
 
 
nat, I am not real sure what you mean by ( a part I want to mill) If you are after a square hole instead of a round hole, yes a square broach will work. The broach will have a round pilot on one end, drill your hole so that the pilot will be a slip fit. Keep the broach covered with cutting oil as you press the broach through, nice and slow.

Kevin
I am making some parts on a vertical mill, I need mostly square corners.

Broaching seems about what I expect, lots of lube, go slow.

:cheers:
 

kjohnson

SILVER Star
Joined
Oct 21, 2006
Messages
300
Location
S. WI
 
 
nat,
If you are making a pocket say for something to sit in and the corners need to be sharp, consider this:

Use the smallest end mill you have and over shoot your pocket in the corners by the radius of your endmill, in one direction only, either the x and y motion. This will remove enough material in corner to allow you sharp cornered item to fit in it. If it is a pocket you are doing, a broach is not the way to go.

If this is not what you are wanting, I need more info.

Kevin
 
Last edited:

davegonz

Keeping it Weird
SILVER Star
Joined
Sep 15, 2004
Messages
9,047
Location
Austin, TX
 
 
 
nat, I am not real sure what you mean by ( a part I want to mill) If you are after a square hole instead of a round hole, yes a square broach will work. The broach will have a round pilot on one end, drill your hole so that the pilot will be a slip fit. Keep the broach covered with cutting oil as you press the broach through, nice and slow.

Kevin
That sounds like the way I broached some brass a while ago in my college machine shop class. What kind of aluminum is it?
 

nat

Joined
Sep 20, 2005
Messages
1,999
Location
Los Gatos, California
 
 
 
It will be 7075 aircraft aluminum. I am machining some receivers :D the magazine well can't have too large a radius.
 
Joined
Jul 20, 2004
Messages
24,774
Location
Chandler, AZ
 
 
 
It will be 7075 aircraft aluminum. I am machining some receivers :D the magazine well can't have too large a radius.
The shop next to mine makes billet AR15 receivers. They drill the 4 corners with a very small bit first, then machine out the rest, this is for the magazine well.

For one off or low quantity prototype stuff I have had good results with making a broach from a HSS square lathe bit. Machine the hole in the part as close to square as possible. Grind a sharp end on the square bit, chuck in the mill/drill press, move it to just touching the radius, drive it through, move it in slightly drive it down, repeat. With some care very nice corners can be made.:hillbilly:
 
Last edited:
Joined
Feb 19, 2004
Messages
3,371
Location
Pepperell MA
 
 
 
Nat,

You need a new tool for yer shop...a 7" shaper. Atlas made a nice one. Seems to be one or another on Ebay all the time. About the same money as one of those rotary broach deals and can be used for other stuff. But Tools R Us posted the cheapest solution.

Looking forward to seeing the results of your project.

Nick
 

nat

Joined
Sep 20, 2005
Messages
1,999
Location
Los Gatos, California
 
 
 
Wow, I forgot I posted this thread. I machined my lower just fine and my AR shoots good :D

Good info here, thanks again!
 

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

Top Bottom