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Just a few things I've picked up over my 2-year Machining Studies

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Creating this thread to share some manual mill/CNC stuff I've picked up so far at work/school. Some nice little charts here if you want to print them out. The center drill sizes are basically what I program the controls for depth for each size, because it's tricky finding one that works I've jotted ones that do here. Also the SFM is a bit different, but if you look at the bottom guide it will show you how to use them. This is for milling only. For drilling, I usually use a different chart that I found to be better. Will upload it soon. Let me know if you need clarification on anything. I wanted to use this as a spot for you all to learn and for backup for my notes.

MOST OF THIS IS FOR THE MILLING MACHINE!


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Comments

#2
The general rule for pipe tapping is to leave 3 - 5 threads showing on the tap, The best thing for reaming dowel pin holes is to buy an over and undersize set of dowel pin reamers; it will give you a tight fit for the stationary fit and a snug slip fir for the removable part.
 
#3
The general rule for pipe tapping is to leave 3 - 5 threads showing on the tap, The best thing for reaming dowel pin holes is to buy an over and undersize set of dowel pin reamers; it will give you a tight fit for the stationary fit and a snug slip fir for the removable part.
How about on a die, John?
 
#4
How about on a die, John?
When I am using an automatic die, I just fit the thread to a female fitting; I have made a lot of parts with 1/16" pipe thread, for that I made a thread ring gage with a std. pipe tap and sized it so the finished thread was flush with the small end of the gage, this is the practice with pipe ring gages. With solid dies, I thread the die on until the small end is flush with the die or chasers in a regular ratchet type pipe die. I also have a pipe threading machine, a Toledo 999, same thing with it, open the dies when they are flush at the small end. For making many parts to be interchangeable, best is to have a ring and plug gage. I found the ones that I had on e bay for the most part.
 
#5
Dies I usually go about three threads past the die but it's not all the same with different die sizes you have to Ck the fit. I use to buy a pipe connector in the size needed then Ck on both ends that will put you in the right spot . Most use Teflon to seal connections . Dope or tape.
 
#6
According to the formula, rpm for an 1/8 endmill is like 30,560 in steel. Did you happen to add a zero, or omit a decimal point? Or perhaps I’ve just showcased my poor mathematics abilities. I’ve got (1000/.125)•3.82=30560 rpm

According to the other cheat charts I have, it should be 3056 rpm.
 
#7
According to the formula, rpm for an 1/8 endmill is like 30,560 in steel. Did you happen to add a zero, or omit a decimal point? Or perhaps I’ve just showcased my poor mathematics abilities. I’ve got (1000/.125)•3.82=30560 rpm

According to the other cheat charts I have, it should be 3056 rpm.
The cutting speed in steel is not 1000 SFPM, but more like 50-100 SFPM, depending on the steel, and assuming HSS tools. Also, the formula I use is
SFPM X 3.82
cutter diameter in inches = RPM

80 X 3.82
.125 = 2445 RPM

Using carbide tools, you could multiply the speed (SFPM) by as much as 5 times, ~12000 rpm
 
#8
Thanks Bob Korves. Our math works out the same, except you didn’t use 100 like I did. Which I’m sure you realize. I had considered that the OPs numbers were specific to Cnc milling with insert tooling, but you’ve corrected that as well. Thank you very much.
 
#9
Yeah I guess mine are for insert cutters rather than manual stuff. I believe my max RPM was 2800 on the Prototrak so if it went over that, I just ran it near max and it worked.
 
#10
If you round the 3.82 up to 4, then the equation is simple enough to do in your head. 1/2" HSS end mill on mild steel, 90 x 4 is 360, divided by 1/2 = 720 rpm.
 
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