Clausing 8520

[PointFive]

At the Community College, our instructor gave us conservative startup guidelines for using a Bridgeport mill. Example: 3/4" end mill, take maximum 3/8" passes (overlap= 3/8"). The depth of cut should not exceed 3/4". Set spindle rpm using SFM chart. The feed should start out slow and watch the chip colors. No blue/black chips.

Now I am trying to apply those guidelines to this new to me Clausing 8520. The head is trammed-in. The end mill is sharp (new). The spindle has no measureable movement on a .001 DTI.

How much must I scale down these quidelines for the Clausing 8520?

What would you recommend for the following metals using a 1/2" HSS end mill?:
Pass Overlap Depth of Cut
Mild steel

Aluminum

Thanks for any suggestions.

Paul

[Griff]

I have never used a Clausing mill but have quite a bit of milling experience both manual and CNC. There are two schools of thought on metal removal. One is to take max radial and depth cuts with slow fee rates and the other is to take light depths of cut(.050 -.100) at 1/2 to 3/4 cutter dia overlap at a faster feed rate.
The second option is much better on small millers and CNCs with small taper tool holders as it cuts down on vibration, allows the heat of machining to be carried away in the chips and prolongs the cutter life. With a 1/2 cutter I would start out in steel with a .100 depth of cut and a .2-.25 overlap for roughing
and would feed the cutter so that you felt no vibration in the machine (dependent upon the rigidity of your setup). Start out at 300 sfpm and creep it up if you don't get any chatter.(go down if you do). Looking at pictures of the Clausing I think it might be better to use 1/2 Dia for Alum and drop down to 3/8 for steel. We do a lot of machining with Fanuc CNC ROBODRILs and have found that we can get better total metal removal rates with smaller cutters in the harder materials than with the larger ones.
In general terms you can run Aluminum 3 times faster RPM than steel but I would still stay with shallow depths of cut and faster feed rates.
I hope this helps
Regards
Griff