[Geof]

I don't have any comments about the GR machines to add to what I have already posted in this thread. But I do have a question: You are working with 16 to 10 ga. material; i.e. your thickest material is around 0.1". Why do you need 24 inches of Z travel?

And actually I do have a(nother) comment/(question). Have you tried machining the galvanized steel with a 3/8 two flute at 100 ipm. My limited experience cutting some 11 ga steel was something of a disaster. The d****d stuff would not cut. Granted I was running a four flute cutter but it built up a huge burr in front of the cutter and the material eventually started to glow red. By slowing things down I managed to finish what I was doing but it was not one of my most efficient operations.

[JSH6318]

24" Z axis being considered for future use to machine taller formed parts ( again made from sheet metal raw material ).

However , weighing that need out against the machine's ability to cut my steel sheet product. Thinking the 5000 RPM 20HP higher torque spindle may be the ticket . ( as you give up the 24" Z axis with this 5000 RPM spindle option ).

Any insight as to how the 5000 RPM spindle will then peform on the easier to cut aluminum sheet material ? Or do I need the 10,000 RPM for optimum aluminum cutting ?

[Geof]

If you wanted to poke 1" diameter drills through thick steel plate the 5000rpm high torque spindle may be useful. In my opinion the GR machines, especially with the long Z axis, are not rigid enough to take a big cut in side milling or facing to use the extra torque from this spindle. Also the lower speed would certainly slow down the cutting of thin aluminum sheet.