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rohart
03-23-2012, 05:49 PM
Well, now I know what a left hand end mill would be wanted for.

I did it another way, in the end, not being in possession of said article.

The liner on the rear flank inside my car's boot (trunk) has lost those ridiculous plastic studs. I was left with six holes, 8mm square. So I thought I'd take 6mm nuts, and cut a lip so they would click into the 8mm square holes. Then I would glue or weld them in position.

So, tap 6mm into a small block, allthread welded into the hole, block in the mill vise with the thread sticking up. Screw each nut down on the stud and mill around. Now, this is where I needed a left hand end mill. If I used a right hand, the normal variety, it would unscrew the nuts all the time. Well, just once would be too often.

In the end I made the inserts out of strip, in the same way you make t-slot nuts.

So, my question is, does anybody use a left hand end mill, and what for ?

mitsue
03-23-2012, 06:18 PM
They work great on my old manual mill that only has power feed one direction. no more climb milling on the old girl

oldtiffie
03-23-2012, 09:52 PM
It works well on the side/end of a thin strip that is clamped to the mill table as it tends to drive the strip down instead of lifting it up (which a right-hand cutter tends to do).

Toolguy
03-23-2012, 10:44 PM
When running a mirror image part on a CNC, you can use RH for the original part and LH for the mirror part and climb mill both sides without changing the program except for spindle direction. Also, surplus LH are cheap on eBay and they cut just as good as RH if the spindle is turning the correct way.

Budz100
03-23-2012, 11:50 PM
When running a mirror image part on a CNC, you can use RH for the original part and LH for the mirror part and climb mill both sides without changing the program except for spindle direction. Also, surplus LH are cheap on eBay and they cut just as good as RH if the spindle is turning the correct way.


Hey toolguy, that's pretty cool. I never ran a cnc with a mirror option, at least not that I know. The wire edms I run have that but I rarely use it. Neat bit of info.

becksmachine
03-24-2012, 12:06 AM
It works well on the side/end of a thin strip that is clamped to the mill table as it tends to drive the strip down instead of lifting it up (which a right-hand cutter tends to do).

I guess I am not convinced that the "hand" designation determines this.

Can't a right hand spiral be downcutting as well as upcutting depending on whether the cutting edge is on the top or bottom of the flute? Same scenario for a left hand spiral?

Dave

ak95xj
03-24-2012, 12:28 AM
They use them at my work as well, for the mirror/climb milling reason stated above..half the endmills there are left hand..

rustamd
03-24-2012, 12:39 AM
I guess I am not convinced that the "hand" designation determines this.

Can't a right hand spiral be downcutting as well as upcutting depending on whether the cutting edge is on the top or bottom of the flute? Same scenario for a left hand spiral?

Dave

It can be, but those down cutting ones are much harder to find then just regular left hand end mills

macona
03-24-2012, 01:35 AM
Left hand bits are used when you take off too much material and need to put some back on. Just run the program in reverse.

Toolguy
03-24-2012, 11:42 AM
On the down cutting ones, the common spec is LH spiral, RH cut. In this case the spindle turns the normal direction but the flutes are pushing down. The opposite is possible too, but not as common.

Black_Moons
03-24-2012, 12:47 PM
I guess I am not convinced that the "hand" designation determines this.

Can't a right hand spiral be downcutting as well as upcutting depending on whether the cutting edge is on the top or bottom of the flute? Same scenario for a left hand spiral?

Dave

Correct. Both left and right hand mills can be up or down cutting. It depends on the direction of the helix compared to the direction of rotation.

If need be, you can lend your mills to evan. hes got a tool ( http://ixian.ca/pics9/hammerdrill.jpg ) that can turn them into left *and* right helix drills. ( http://gallery.pipandphil.com/d/33688-1/twirlywurlydrill.jpg ) :rolleyes: