Hello,

I apologize for the length of the post and what I'm sure are dumb questions!

I am relatively new to machining and use a PCNC 770 with the ATC, enclosure and flood coolant. We machine 6061 Al parts < 4"x4"x2". I have been getting back up to speed after a hiatus and realized that I still have these lingering questions. I was hoping to get input from more experienced folks:

1.Breaking bits
We use Solidworks CAM and have been letting it pick the F&S. I find making deep pockets with anything but big mills problematic, and I just broke another bit recently. I was trying to make a 20mmx20mmx15mm pocket with a 3/16 4FL flat end mill, it was one of the HSS China millsets. The flood coolant was active all times aimed at the tool tip. The center pocket was about 15mm deep, and due to previous issues I made the entry a spiral and limited the cut to only 1mm, which seems like it should be safe. The machine got pretty far in(~10mm) and then the bit broke. Here are my thoughts so far, I would love to hear what others suggest:

The first thing I remembered while researching is that I should be using a 2FL bit for aluminum, so I am planning to try a similar feature with a 2FL 3/16 cutter.

When I look at the very tip of the broken bit, it looks like there is a small amount of melted aluminum stuck to the end. I thought maybe the chips did not get cleared despite the flood coolant, so on the next test I will try compressed air as well.

2.PCNC 770 Spindle speed/power
We have our belt in the 'low' setting. I find I have to dramatically slow down the feed on any plunge/spiral because the spindle easily gets bogged down. This has been hard to predict and I've been mostly experimenting with what works without breaking a tool or making the work incredibly slow. I was wondering if others have the same issue. I've been wondering if we should move our belt to the 'hi' position and maybe higher RPM will solve this issue.

3.Coolant system
I find that during every part, the coolant flow starts getting weak and I have to pour more coolant in to restore the flow. We did have leakage issues with the enclosure but we have fixed those, so I can only imagine the coolant is evaporating or sitting in the chips. We have a bunch of containers with mixed coolant and every part it feels like we are just sitting there pouring coolant into the thing. Is this normal?

4.Tool length error
We use the Tormach ETS, and usually set it on the mill table and touch-off the entire tray before starting. Despite this, I find that I cannot use 2 tools on one face. For example, often we will want to rough with a big mill and then switch to a small mill to contour out boss details. If we do that, we can see a significant 'step' between the features. The step is large enough that it cannot be removed with the typical vibratory tumbler processing we do(we use the green pyramid media). We have several theories.

One thought is that our ETS is just sitting on the table or work blank, and the Tormach ATC somewhat 'slams' back and forth, possibly slightly moving/bouncing the ETS. We are wondering if a bolted down ETS is a necessity, it is on our list to try.

Another possibility is that this is just inherent to the accuracy of the ATC system and if we want a fine face finish, then it must be finished with 1 tool.

We also thought the tools might be sliding in the collet, but we have tightened them on a vise and anything further seems excessive.

5.Tool comp question
I spent a lot of wasted time getting up to speed because when I exported g-code from Solidworks CAM, the paths were incorrect in PathPilot. After a lot of diagnosing, it seems the default state of Solidworks CAM has the CAM computing the actual tool path(with the tool size taken into account), but it also defaults to having 'cnc compensation' (G41/G42) enabled. This was resulting in gcode that is compensated twice for the size of the cutter. I still don't understand how can this be the default state and keep thinking it must be some sort of user error, any thoughts on this?

6.Mill setups in g-code/pathpilot
We have multiple mill setups for each face of the part. If we just post the code in one file, PathPilot errors saying that the coordinates are outside the maximum range, because it doesn't seem to know that the different mill setups involve part flips. We have been working around this by posting 4-6 separate files, one for each face. Is this what everyone else does?

7.Carbide mill bits
We are considering getting carbide mill tools if we move the belt up to the 'high' position. Can someone recommend quality sources/tools for making 6061 mostly prismatic parts on this 1hp machine? We find a lot when searching but we don't know what the best tool would be. Our goal is to make the parts faster and also break fewer tools although I'm not sure carbide is going to help with that.

Thanks in advance, and thanks for taking the time to read!