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Interested again in my barrel weight project. I'm going to be using a 27/32" 2 flute HSS ball end mill to mill 2 opposing grooves into a piece of metal approx 7/8" x 7/8", leaving approx .090 to .100 metal b/w the 2 grooves (this is the easiest way to state what i'm going to do, I lost the pic or that would make this make sense).

At any rate, I can't decide b/w using brass or 12L14 steel. I know brass will probably be a little easier to machine, but won't look as good since i can't blue it, and its going to be alot more expensive. Whats the comparison b/w the 2 materials as far as machinability, feed rates, depth of cut per pass, tool wear, ect?
 

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Ian.. 12L14 is very easy to cut.. and it finishes well.. Your biggest problem here is the 2 flute ball end mill.. If you went to a 4 flute it would cut like butter.. The 2 flute needs a higher speed and slower feed to finish well.. Brass will always have less wear on a cutter than steel. Hope this helps..
 

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I agree with what PBB said, and will add that brass cuts easily on a mill and you can take about as much as you feel comfortable with in each pass with it. When I was making my comb hardware out of brass, I was taking .100" to .150" each pass with a 3/8" end mill. Brass is also very forgiving on surface finish. Good luck, Josh.
 

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With brass you can run the machine about as fast as you want, with the 12L14 you need to keep the cutter speed under 280 surface feet per minute, if you are using tool steel cutter with coolant, with out coolant I would keep it down around 150 to 200 sfm.

surface feet per minute = cutter diameter x rpm x .262


I hope this helps!!


tony
 

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Thanks guys. This might be an easy choice in favor of brass, which I have already found a potential supplier for, having trouble finding 12L14 in the size I need in flat stock, everything is round or hex, i need 7/16x7/8 or 1/2x1, any thoughts? Have a request for quote into Southern Steel right now, but thats about the only lead i have at this point.
 

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CS: brass-200
RPM=CSx4/d
RPM=200x4/27/32 rpm=948

CS: mild steel-100
rpm=100x4/27/32 rpm=474

chipload .005-roughing
.001 or .002- finishing

brass feed rate= chipload x # of flutes x speed
FR=.002 x 2 x948 fr=3.7 ipm

steel= .002 x 2 x 474 fr=1.8 ipm

I would say brass, polish it when your done might look better then blued steel, and easier to machine.
 

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Hey Skeet_Man,
I use a lot of 12L14 and it cut's like butter, also take's a nice blue. If you want to blue then go with it!
I get most of mine from Speedy Metals.
Yes, brass cuts easier, but if you want carbon steel then go with your 12L14. You won't be disappointed.
I'm building a Rail Gun right now and all metal is 12L14 and 416L stainless.
Sounds like you have a milling machine so go for it.
Mike C.
Groveland, CA
 
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If using brass, remember it "sucks".
literally..
run the locks on the table slightly snug,
because at times,especially coming out of the mat'l.,
any backlash in the leadscrew, and the table will jump out all the backlash.
I've broken small endmills on cheap mills this way.
another tip,if you have a good supply of cutters,
rough most of the material out down to just shy of radius centerline
with a regular endmill, or even better,a roughing endmill, then just use the ball endmill to finish,no sense removing all the material with the ball E/M.
 
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