Steel type and source for a mini mill

Mark1958

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I just finished milling a part out of A36 steel using my Sherline Mini Mill and the mill seemed to be on its limit (or a little over it) while doing so. I was using a new HSS cutter. Does anyone have a suggestion regarding a more machineable steel (plate form as opposed to round bar)? Within reason, strength isn't a real issue with anything I make. 12L would probably be ideal but it does not seem to be available in plate form. 1018 looks to be easy to find but it appears to have the same machineability rating as the A36. If you do have a suggestion, could you please provide me with an internet source for the material? Thank you.
 
Need to up grade your mill.

A-36 can give you havic sometimes trying to machine it. The mill scale can be an issue too. Grind it off if you can. The edges, if not saw cut can be tough to cut into. Get some cutting oil like Mobilmet 766 or any high sulphur content cutting oil to help.
 
Mark, see if you can find some 1117 or 11L17 plate. It has a high sulfur content (the 11L17 has lead to improve machinability) so it cuts well (machinability of 91%) but does not weld well due to the sulfur. I tried some round once and it cut nice but I know they make plate from this stuff.

1018 is easier to machine than A36 but it finishes ugly. I HATE 1018.

What are you making? I sometimes us precision ground low carbon steel for projects and it cuts nice but it is expensive.
 
Mark, check this website for some good info. : www.usa.arcelormittal.com then in their search box type free machining steels. You will get more than enough sound info. here in PDF form. Also 12L14 but not in plate but it can be had in square up to 3"x 3"x ?. I had a Sherline mill and yes A-36 and the mill did not get along too well together.
 
Need to up grade your mill.

A-36 can give you havic sometimes trying to machine it. The mill scale can be an issue too. Grind it off if you can. The edges, if not saw cut can be tough to cut into. Get some cutting oil like Mobilmet 766 or any high sulphur content cutting oil to help.
 
Thanks for the reply 4gsr, I will try the cutting fluid you suggested.
 
Mark, see if you can find some 1117 or 11L17 plate. It has a high sulfur content (the 11L17 has lead to improve machinability) so it cuts well (machinability of 91%) but does not weld well due to the sulfur. I tried some round once and it cut nice but I know they make plate from this stuff.

1018 is easier to machine than A36 but it finishes ugly. I HATE 1018.

What are you making? I sometimes us precision ground low carbon steel for projects and it cuts nice but it is expensive.
Thanks Mikey. I just got the mill so I haven't made much yet and most of what I have made has been made from aluminum. The A36 steel piece was a plate to attach to my aluminum mill plate so my magnetic indicator base will stick to it. What is precision ground low carbon steel and how does it machine compared to 12L? My fantasy is to find a steel material that will machine on the mill as well as 12L machines on my sherline lathe.
 
Mark, check this website for some good info. : www.usa.arcelormittal.com then in their search box type free machining steels. You will get more than enough sound info. here in PDF form. Also 12L14 but not in plate but it can be had in square up to 3"x 3"x ?. I had a Sherline mill and yes A-36 and the mill did not get along too well together.
Thank you FLguy, I will check out that website.
 
You are not going to find steel plate that machines like 12L14, Mark, but if my experience with 1117 rod is any indication, then 11L17 plate will be very nice to machine. Online Metals carries some: https://www.onlinemetals.com/merchant.cfm?id=1703&step=2&top_cat=197

Low carbon steels is available as precision ground stock. I use Starrett brand steel and they say it is a silicon-killed steel similar to 1018 but it finishes much better than regular 1018. I made a Graver Tool Rest from this stuff and it machined easily. Keep in mind that "easily" is relative; it is steel after all. But this stuff does cut readily with end mills and leaves a nice finish.
 
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