Checking stepper temperature frequently while cutting

In the quest for more reliability and accuracy, I’ve started checking stepper temperature periodically mid-job to get a feel for what is normal. If I see an unusually hot reading, I plan to try to find the cause. The steppers rarely get over 40C and I’ve not yet seen a reading over 50C, even on long hard jobs. I use this cheap pistol-style non-contact temperature sensor. An amazing value for $17.

I’m also trying to use this method to check bit temperature while milling aluminum. Not sure yet if the readings are meaningful on such a small spinning target object. Hoping to detect the chip welding before it occurs, perhaps pausing the job and adding a bit of oil.

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Quick question in your setup-what rpm can you run with that spindle? Is it water cooled? If so, please provide some details. Your obviously cutting lots of aluminum.

I typically cut 6061 aluminum at 18-20 krpm (24k is max for this spindle) using a three tooth 3/16" Viper cutter from Destiny tools. Usually run .04" stepover and .04" depth-of-cut with feed rates between 20 IPM (for holes) and 80 IPM (for roughing). And use the climb milling direction. I’ve stiffened x, y, and z axes. Have upgraded steppers to 269oz-in NEMA 23s. I use Fusion 360 to generate toolpaths. Lots of learning required in F360, to keep material removal rate up without welding chips.

The spindle is not water cooled. It doesn’t even get close to being overloaded. Machine flexibility and steppers are overloaded way before the spindle is.

I do blow an air jet continuously the cutter, for cooling and chip clearing. Sometimes I pause the job and add a drop of oil if the bit seems to be gumming up, but really prefer to cut alum dry.

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How do you pause the job? Are you sending the programs with UGS?
How fast (or slow) are you running the spindle? I tried to get a router speed control to lower the rpm for aluminum sheet, but neither of the 2 I bought worked.
I’m cutting (well, trying…) to cut 2024, .012 thick, with a single flute bit. On my cnc machining center it cuts great. Here, on the X carve, not so much…

Matt, I know this isn’t why you started the topic but can you tell us a little more about the spindle? source, model and price maybe?

Also, what kind of z axis stiffening did you do?

Here’s a post on the spindle and VFD that I use. The spindle cost $360 and the VFD was $300.

I use ChiliPeppr to send gcode files. I have sort of a love-hate relationship with ChiliPepper, but it seems to be the only sender with all the features that I need. ChiliPepper has two pause buttons. One to pause buffering gcode and one to pause the job immediately.

I usually pause by pressing the pause button on X-Controller, which is super cool! It responds instantly and lifts the bit to a safe height. With the ability to pause and to drive bigger steppers, X-Controller is probably a key ingredient in my aluminum milling recipe.

Here’s a link to what I did for the z-axis.

I also switched to running the z-axis with 1/8 microstepping, which seems to have been a good change. Although I haven’t really tried to quantify that.

Thank you Matt for posting that info again!