coreXYU (i think?)

Slzer

HI,

So i've decided i want to upgrade my current corexy rig to an idex as i'm fed up with the second print nozzle getting in the way etc. when not required but don't want to lose the capability (or have to assemle/re-assemble the nozzle into it when i want to use it!)

I found this kinematics diagram which i thought would be pretty easy to implement in hardware terms (using mostly my existing parts plus a long steel rod).

Is this the default coreXYU option? or will i need to manually create the M669 command - i had a go at it and i think this correctly represents the kinematic equations?

M669
1.00 1.00 0 0
0 1.00 0 0
0 0 1.00 0
0 1.00 0 1.00;

theruttmeister

No.

If you haven't already check out this thread:
https://forum.duet3d.com/topic/14362/rat-rig-v-core-pro-corexyu/57

This Dual X by Haqnmaq is not going to mimic the coreXY/H-bot kinematics or the CoreXYU. Its going to need to be based on the markforged matrix.
The kinematics on the image are not actually correct, which doesn't help.

▲Y != ▲A.
▲Y = ▲A + ▲B1 + ▲B2

If you only drive A, the printheads will move diagonally.

it should be
▲X1 = ▲B1
▲X2 = ▲B2
▲Y = ▲A + ▲B1 + ▲B2

Its a bit of a complicated setup. Although I admit I'd probably copy it if I was building a dual head and I didn't need a full IDEX. Well... I'd copy the kinematics, not the mechanical layout though.

Slzer

@theruttmeister thank you for the feedback. I will need to take some time to process that.

Just one question for now what do you mean by if you didn't need a full idex?

theruttmeister

@Slzer
IDEX
Independant Dual EXtruder.

The design above shares a Y axis. So its not IDEX.

You could be supper fussy and and say that most IDEX designs out there (not that there are very many) share a Z axis as well...
But then you are trying to build an Esher printer... Which is very cool, but even more niche than IDEX.

Slzer

Ahh yeah I understand, it's not truly independent.

Haggan90

I've built a printer using this kinematics.
After some updates to the firmware it was quite easy to get working.

Slzer

@Haggan90 How did you find the kinematics itself? did you see much of a racking issue? any advice on making the implementation work well or pictures would be appreciated!

I'm torn between this and proper coreXYU with 4 motors

zapta

@theruttmeister said in coreXYU (i think?):

The design above shares a Y axis. So its not IDEX.

I believe that it's common for IDEX printers to be independent only on one axis.

Haggan90

@Slzer I found them on probably the same place as you found them, on Hackaday
As far as I've seen it this kinematics prevents racking very well as the two belt paths constrains it.