@JoergS5 Thanks for helping out! You are correct on how the linkage work (point 1-4). The platform is tilted a bit, but the tilt does not change when moving (it does a tiny bit but that's because of sloop in the system, i did not have all the right fasteners at hand). I am working on a updated version that uses Capstan-Drive system. I would like to get this working first.
here's a fusion 360 link to the cad model
a360.**/42M19T2

in using 1.8degree steppers and total gearing is 51,8 (5,18:1+200:20)

@JoergS5 Do you have access to a 3d printer big enough for printing my design?

@JoergS5 No problem.

1 is the first actuator / this is correct. If I add a rotating base to the robot does the rotating base become axis1? Or does it not matter?
2 is the second one. Together they define through the parallelogram the blue arm and the lower end position, lower hinge / This is correct. the link between 2 and the blue arm only moves the motor position down to the base, it has the same effect on blue arm 3 as if it was mounted in connection point between 1 and 3 (edit, the last bit is not correct, its only true if you add correction, ignore that part)
4 (the second arm in back of 1) is unclear for me: is it just to stabilize or has it a movement function? this is correct, arm1 and arm 4 is mechanically the same and can 4 is only strength
5, 6 and 7 define the upper endpoint in respect to the lower endpoint through parallelism /correct,

The basic setup is verry similar to a abb irb660 (specially now that i have added the rotating base).
I cant post url links here for some reason. but add youtube. com to the url below to watch a irb660 in motion.

watch?v=8LJOLwr5Wck

I have added a rotational axis nr1 to the base.

@JoergS5 My plan is to use this robot to reload my resin printer, so the final version should be capable to handle about 1.5kg. it will be mounted on a linear rail. Repetability will be more important than absolut precision.
I do own a cnc mill and the final version might be in aluminium or laser cut plywood. But its 3d printed for now

@JoergS5
Here is a better drawing. Is there som cad format that you prefer? I can export to most of them. would you suggest any changes to the geometry?

@JoergS5 Ok. I will wait for your test bin files then. here is some dimensions of my arm

@JoergS5 Sounds great! Is there some "hack" to force the D values for now? Or is the robot firmware on github not working?

@JoergS5 Thanks for helping out! You are correct on how the linkage work (point 1-4). The platform is tilted a bit, but the tilt does not change when moving (it does a tiny bit but that's because of sloop in the system, i did not have all the right fasteners at hand). I am working on a updated version that uses Capstan-Drive system. I would like to get this working first.
here's a fusion 360 link to the cad model
a360.**/42M19T2

in using 1.8degree steppers and total gearing is 51,8 (5,18:1+200:20)

@Nakcam This is a old picture, it does have motors and move. But not with Inverse kinematic

@JoergS5 Thanks for the reply. I have now found the robot 4 axis pelletized section of the duet3d documentation ( duet3d*/User_manual/Machine_configuration/robot_4_axis_palletized), this sould be a perfekt fitt.
I have uploaded the "github*/JoergS5/RepRapFirmware_robot" firmware to the board and run the firmware update. But now im stuck with :

M669 K13 B"axisTypes=PRRRp"
currently only CoreXY5AC and CoreXY5BC are support

and it wont take the D values

=== M669 K13 current config ===
numOfAxes 5 axisTypes �������� chain ���������������������������������������� (normal �������������������� special �������������)
axis � ori: -0.00 0.00 0.00 point: -0.00 0.00 0.00 angles min/max/home: -0.00 0.00 0.00
axis � ori: 0.00 0.00 0.00 point: 0.00 0.00 0.00 angles min/max/home: 0.00 0.00 0.00
axis � ori: 0.00 0.00 0.00 point: 0.00 0.00 0.00 angles min/max/home: 0.00 0.00 0.00
axis � ori: 0.00 0.00 0.00 point: 0.00 0.00 0.00 angles min/max/home: 0.00 0.00 0.00
axis � ori: 0.00 0.00 0.00 point: 0.00 0.00 0.00 angles min/max/home: 0.00 0.00 0.00
Screw values:
reference angles/positions: -0.00 0.00 0.00 0.00 0.00
endpoint axis X: -0.00 -0.00 -0.00
endpoint axis Y: -0.00 -0.00 -0.00
endpoint axis Z: -0.00 -0.00 -0.00
endpoint point: -0.00 -0.00 -0.00
abSign: 0 (A/B angle preference: 0 take >=0, 1 take <= 0, 2 don't change calculation
cache used: -1 maximum: 200

Mine is the same as yours with one arm fixt to the base (mine is to the right seen from behind)
I do have a fysikal protorype. config (1).g