[RotarySMP]

Why did you choose 100 ozin motors? High speed Keling 387 ozin motors only cost about $40 and would give you much faster rapids, assuming the drivers match them.

[ipmmiller]

Hi Chris, just found your build thread and i'd say if your going to retrofit a cnc5 that would be the one to do, early machine.Keep your DC spindle motor if possible ,its a great unit.If you hav'nt already you'll want to check and or polish the ball screws on it,i use an old shoe lace and some mothers mag polish followed by some acetone,do not oil the screws or acetone the ball nuts.Oil will capture chips and chips will enter the ball nut,no wipers on these,....not a fun day but if it happens you'll have to remove the screw while not allowing the nut to get anywhere near the end of the screw,if it comes off the balls come out and your SCREWED,put a zip tie,wax or something on the end of the screw to prevent this, now you can spend the afternoon working the nut back and forth cleaning chips off the threads as they come out until its smooth again...told ya..not a fun day .As far as steppers go i think 100oz will be more than enough, im still using the....25 year old..."weak" factory steppers,same as yours, on my f1 mill and i cut mild steel everyday and sometimes o1 tool steel and 304 stainless with no apparent loss of steps and it stays in spec all day.Hmmm...since there are so many of these machines still in service...ya think Emco knew what they were doing?My F1 was used in its "adult life" in a busy machine shop cutting cast iron pump parts all day if that tells you anything,of course these guys took correct care of it,sharp tools,skill,lube etc,(Mobil Vactra 2 reccomened).My thinking is really fast rapids do nothing in the home shop but wear your ballscrews etc. prematurely,these are rolled not precision ground and quite small,if something is going to break or "give" you want it to be the stepper,they're cheap compared to the ballscrew which is unobtainium..They'll last forever if taken care of and not overstressed or "whipped" by insane rapids.You'll be suprised how much work these machines are capable of with sharp tools and correct feeds and speeds and i'd reccomend insert tooling if you hav'nt looked yet, i've found tialn coatings to be the best on hard stuff, cuts stainless like butter with no flood needed, i just vacumn chips behind it.Although i've used the gold Tin coatings with success on the lathe and mill the variable helix endmills with Tialn coatings,a dark gray color coating, from Maritool turned the f1 mill into a monster,you truly do get what you pay for sometimes and you'll find a sharp cutting tool is THE most important part,without it your lathe is a hammer.Best of luck with your refit,let us know how it goes,Kevin