VC3.1 500 issues. FMMM and Extrusionless X
I have recently built my second VC3.1 500 and have added FMMM and an extrusionless X. My resonance and accelerations are quite a bit lower than the first machine I built and I'm scratching my head as to why.
The tool head doesn't move at all when I manually move the gantry forwards and backwards, the belt does walks up and down a bit on the pulley but it doesn't seem to be chewing it up. Checked all bolts and tried to keep the umbilical cables tight. They're in a nylon sleeve with 1mm piano wire. The machine is sitting on a table but it's pretty sturdy... I will try and put it on the floor and test but anything else I should look in to? Thanks!
14 Replies
i bet its y flex, the upper and lower rails are not bonded, jsut screwed
even if your belt tension graph looks good, the max accel for y is way below a normal v-core, should be arround 5k
conscious-sapphire•16mo ago
Could you clarify what you mean by that - is the assembly of the 2 rails on the X flexing as the Y moves back and forth? Has this already been discussed between others that have done this mod?
its an assumption
your x input shaper graph is perfect
all the unwanted vibrations and peaks you see in the belt tension graph are located in the y axis
you can see that by comparing the x and y shaper graph
so either something is loose or the blocks and rails allow some flex
conscious-sapphire•16mo ago
Okay I understand what you're saying, thank you for the input. The other machine I built has typical accelerations for a 500 and really the only mechanical difference is that gantry. Interesting.
I didn't see much difference in y-acceleration on mine.
One thing you definitely should do is tie that ADXL cable down near the ADXL
you have too much free length pulling on the ADXL
conscious-sapphire•16mo ago
Securing the cable didn't have much of an impact. I tried tightening and loosening belts, but still coming up with low Y accel. I am going to try and reprint the joiners, there is a small chance that I printed them too light. Aside from that and putting the machine on the floor... I'm going to run out of ideas.
did you fasten the screws that go through the letters?
and use 2 M5 bolts through the middle holes?
could be that the extra length on a 500 allows more flex
I made an alternative design to mount rails to both sides of a 12mm tube for extra stiffness
conscious-sapphire•16mo ago
I did use those and I made sure those, and the M5 are all snug. Do you have a picture of the 12mm tube design? I'll do some more testing and hopefully and report back.
conscious-sapphire•16mo ago
Looks pretty damn stiff. what was your motivation behind making that change from aluminum blocks?
conscious-sapphire•16mo ago
conscious-sapphire•16mo ago
Reprinted joiners and reassembled hot end to make sure everything was tight. reduced y resonance a bit but still low accel.
Going to stiffen up the table or put it on the floor and try again.
I got lighter rails that are less stiff and I cannot talk about yet
conscious-sapphire•16mo ago
With the machine on the floor instead of a table the results are the same. I'm curious if anyone else who's tried a similar extrusionless set up on a 500 is showing similar results.