[trurle]

Its all about Chip Load. Look at GWizard from CNC Cookbook. You can download a free trial and then decide if its worth the cost. Use 2 or 1 flute mills for wood, same as aluminum.

You need to increase the feed rate. Did you even bother reading what was posted?

GW Wizard says: .25 Inch dia 2 flute end mill. .375 Deep Cut 10676 Rpm and 92 ipm feed rate at least.

My most recent settings:
0.125 inch dia 2 flute end mill, 0.04 Deep cut, 9000 RPM, 79 ipm.
The mill starts to veer off course if cut depth is 0.08 inch or higher. The depth of 0.375 inch is actually not cutting by CNC, and breaking bit in manual operation.

[wmgeorge]

My most recent settings:
0.125 inch dia 2 flute end mill, 0.04 Deep cut, 9000 RPM, 79 ipm.
The mill starts to veer off course if cut depth is 0.08 inch or higher. The depth of 0.375 inch is actually not cutting by CNC, and breaking bit in manual operation.

The .125 or 1/8 inch bit is bending and veering or since your running a X-Carve the whole machine is twisting? Try the .250 as suggested in my post and those settings. I have bits I have used on MDF and never have an issue, I don't buy the $100 ones, nor the cheapest usually around $20 or so for .250. You are trying to cut, correct? I cut an 8 hour job with one bit in MDF using a Hitachi router motor I think was rated at 1 + Hp on 120 volts.

[trurle]

The .125 or 1/8 inch bit is bending and veering or since your running a X-Carve the whole machine is twisting? Try the .250 as suggested in my post and those settings. I have bits I have used on MDF and never have an issue, I don't buy the $100 ones, nor the cheapest usually around $20 or so for .250. You are trying to cut, correct? I cut an 8 hour job with one bit in MDF using a Hitachi router motor I think was rated at 1 + Hp on 120 volts.

The problems with veering off always start at X-axis, which had only 1 belt-driving stepper as opposed to 2 steppers on Y axis and screw-driving stepper on Z axis. Therefore, likely the problem with depth of cut is under-performing stepper. May be because i try to run 120V AC machine at 100V AC outlet.
Regarding bits, i actually try to use bits in the range $1 - $5 per 1/4 inch bit (this is direct buy from China - likely corresponds to $20 per bit in US retail). The last batch is completely destroyed by now, and need to buy a new one.