I need RPM settings please

I got one of these and it has been great. A tachometer that can give RPM or SFM (Surface Feet per Minute). Like you said you need speeds for the different diameters. This tachometer tells you exactly what speed you are turning by measuring it from the spindle and you look up the SFM from a chart based on the metal and diameter. With the tachometer going and data from the chart you know for sure you are optimal speed.

I think it would be helpful especially for someone new to machining. With experience people will tell you that you can just know and feel what the speeds should be.

http://www.machtach.com
 
I had a go last night on a scrap 6mm diameter aluminum rod. it worked ok at 100rpm. Altho I couldn't seem to part it off completely. I got to about 75% in but it wouldn't cut anymore. I'm guessing my tool is not aligned and either too high or too low. Also I was using just a cheap 3 in 1 oil..and my lathe doesn't seem to like it. I was parting off better when it was dry.

Can anyone please tell me what cheap oil I could use?
 
wd40 would work. Dark tap fluid from a box store. You are likely to high. As the OD gets smaller you are running out of material to cut as your cutter is over center. If you were to low it would part through the work but it would leave a square tit holding the two.
 
Thanks. I only gave it a quick go last night as I was in between helping my wife with out 7week old baby.
I'll give it a try again tonight and will make sure the pointy end of the parting tool is at center.

I'll keep you guys updated. :)
 
Thanks! She's definitely a joy but definitely taking up most of our time!
Thanks for all the help so far!
 
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