If I recall correctly it’s relates to the speed and torque curve of the steppers. Too slow and the torque drops off…too fast and the torque drops off as well.
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I had a little aluminum part I was cutting on my machine around the parameter. It wasn’t extremely a lot of material but there was sections that had at least over half the diameter of the 1/4 endmill to cut. During the cut the machine steppers skipped and was off location. The endmill didnt break. It didnt load up. I wasn’t running fast maybe around 65 ipm. I still felt that was slow, but after making this cut and it jumping teeth, I was beginning to wonder if my machine could handle aluminum.
I had to rehome the machine and when it went back to Y zero home, the gantry hit the back stops and jumped the same amount in the opposite direction to set it back in the right location. Because of this jump, I have been restricting myself in cutting faster because I feel that my steppers can’t handle the faster speeds my machine should be allowed to handle.
I even had a 3D carving that I sped up to around 160 ipm for a .065" depth of cut on plywood, and the machine glitched the program because I thought maybe the machine was moving faster then the program could be read and so the machine overran the program and crashed the run. Meaning, the machine just stopped running as if the program stopped existing.
I figured that these were just the limits of my machine where it couldn’t handle faster feed rates that pushed the machine past 100 ipm. Then I saw a video posted in here somewhere about the new spindle comparison between the 65mm spindle and the 80mm spindle. The test ran different depths of cut with the ipm feed rate. What I saw with the deeper depths of cuts at feed rates that I couldn’t even touch on my machine because of stepper motor limitations really opened my eyes.
I then started looking into bigger stepper motors thinking that the little stepper motors I have on my Shapeoko 5 Pro were too small. That maybe I could increase the feed rates to a level in comparison to what I saw in the video. Then I realized the person in the video had the same stepper motors as I did. I figured that I must have a faulty stepper motor and until I push my machine hard enough again to find out which motor it was that skipped, I will not know which one to address until then. I am way past my warranty, but that is fine, as long as I can fix the stepper motor issue as soon as I am able to address it.
I purchased the 80mm spindle kit. I now hope that the stepper motors can handle this bigger spindle and feed rates pushing against them. So, if running my machine at too low of speed dropped off my torque enough to cause the stepper motors to skip, then speeding them up would have solved the problem, but then something else happens and cause other issues. Not sure what to make of it, but these two issues might be the reason I have hardly ran my machine much because I feel it will skip or shutdown on me during a program run, especially during a long cycle time. Nothing more frustrating then to run a project that may take 4+ hours and be in 2+ hours of the cutting and then the machine fault out on me and make me have to restart the program from the beginning.
What was your depth of cut ?
I have been contouring the outside of material ( too square it up ). 1/2" thick. 6061 T6.
I used a 1/4" 201 bit at the full depth, but I used the default CC RPM (18k ?) and feed (36 ipm) and stepover (.025 in) without issues. Takes time, but no issues.
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I think I ran the depth of cut to .050" per pass. Some areas of the cut was over .0625", and other areas were in as far as .250". But cutting at .050" should not have been too much. I think I have an issue with the tool I used. Cutting aluminum is best with a single flute endmill, and when I was cutting I used a 3 flute endmill. It might have built up heat and not really sure why it stopped the stepper motor and caused it to jump. I was cutting nicely and then it jumped causing me to have to stop the cut.
I used the CC parameters as the basis. 18k rpm, DOC .015, Feed 36 ipm, stepover 0.025
I have used the single flute bit, and I do use it if I have to ramp in. You only use the tip of the bit.
I have gone to the 201 bit for surfacing and contouring ( not slotting ). The 201 bit is cheaper.
The flat end mill does a better job on surfacing. I can run faster by almost 2x and still look good and not heat the aluminum.
For contouring ( I make a pocket path ), I can use a full depth and walk it in using the CC parameters.
I use a cheap HF infrared device to keep track of the heat.
I am sure I could go faster, but I am trying to be nice the the bits.
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5pro will run 275 ipm firmware limited. You have to change grbl settings to get there.
It has zero downsizes with my 80mm spindle.
I cut 1/2” tigerply edge with a 1/4” Jenny bit every day. Full depth. Slotting. 275ipm.
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You can run your 1/4" endmill on your 80mm spindle at 275 ipm at 1/2" full depth? How the hell is that even possible? If I even try to get up above 150 ipm the machine starts acting up some and can’t seem to keep up with the program. It is like the machine is running faster then the program can be read and processed.
I want to test my machine and see if there might have been an issue with the program version at the time and hope that it might have been fixed. I will start pushing my machine and getting through things much faster under my testing. I figure I will break some endmills in the process, but I need to push the machine to make sure I can figure out what it’s limits are and if I actually have any issues with parts of my machine.
I’ve never had an issue doing it. What brand bits are you using. Cody’s and Amana are sharper and can be run faster than most other brands.
You haven’t messed with any acceleration settings have you? That can cause havoc.
I’m on the edge of how fast a 1/4” 2 flute should go. Just judging by edge finish. But it works. I wanted to try some 3 and 4 flute bits but haven’t had the time.
Plus it loos like the company I’m doing the work for is going another direction since they moved a couple states away so I’m not interested in burning a couple hundred in bits to play.
Most of my bits are from Carbide 3D. I just scared myself when that stepper motor acted up. Anyways, I will start pushing the machine harder once I get my new 80mm spindle attached to my machine.
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$435 for a 1 1/2" 8x4 in the DFW market…
3/4" for $279
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What is DFW Market 
? That’s a great price!
DFW is Dallas FortWorth.
I see about the same from Grimco in ATL if you have a wholesale account.
BlueRidge Sign has it for about $500 of you have a wholesale account. If I remember, you are in NC so those would be closer options.
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Glantz has the 1 1/2" for $400…1" for $300
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Blue Ridge happens to be my supplier 
Sign up for the wholesale account.
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I surely did! They deliver for like $45. Just got 3 sheets. We have been flying through them. 2 large signs on the docket. Stay tuned for requests for help with tiling
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I bought the CIC Workshop Game kit and created a couple sets. I already had the BamCore left from a previous project.
I increased the size from the original plans a bit and put a cribbage game on the lid.
At some point while changing the plans I offset the hinge holes slightly so when I was done with the first one the holes didn’t quite line up. So I offset in the opposite way for the second and ended up with matching pairs. The offset was slight so not really noticeable that they aren’t centered.
Another lesson learned: I tightened up the tolerances on most of the pockets but the second kit I ordered came with slightly larger dice so they won’t fit. I will have to try and find smaller ones.
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You do nice work, congrats
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