The past week I’ve been busy testing the maximum acceleration of the machine.
I already did this in the beginning but wasn’t really happy with the result. Last week (after months of mailing back and forth to China) I finally received the full spec sheet of the stepper motors. Turned out to be a good thing to keep requesting it until I finally received it. The motors turned out to have a max peak current of 4A (approx. 2,85A RMS). The machines stepper drives where however set to 3,41A peak.
After rasing the peak current to 3,97A I had to retest. At first with a simple endurance test with a lot of abrubt and fast movements to “torture” the machine a bit. With this test I got a max. acceleration of 1750mm/s2 instead of the previous maximum of 75mm/s2!
A quick example: When the machines max. speed is set to 50mm/s or 3m/min like on my machine and max. acceleration is 100mm/s2 it takes the machine half a second to reach full speed (max speed/max acc.).
So in my case this was 50/75=0,67s before raising the peak current and 50/1750=0,029s after!
After the test to find the maximum I started testing irl on a few projects that I had planned. This showed that finding a maximum is one thing, but it being usable is another 😉
A short movie:
http://www.youtube.com/watch?v=GPjYvDqBtls
Since MDF is quite cheap this was an ideal project for testing some settings.
I routed the pockets on 3m/min and 1240mm/s3, that went crazy fast 😀 but resulted in quite some vibrations in the machine.
After this I roughed the base shape at 2m/min and 750mm/s2 and that went a lot better, but stil some slight vibrations on the complex parts.
The finishing pass (seen in the movie) was done at 2m/min and 250mm/s2 and all vibrations where gone, but as a result the machine was a bit slow on the complex parts.
So I’ll need to find a “base” setting somewhere in between.
Simple G-code (straight lines, squares and circles) can be done at a higher setting, more complex pieces will need a little lower settings.
Just to show you the end result:
