Building my first CoreXY machine - facing a number of issues

Hi reprapers, I have built my first reprap - Prusa Mendel i3 last year and has been printing great.

And now I wanted to build a new printer with CoreXY system.
Basically I have done some alterations in the design of CoreXY,
so far I'm facing a number of issues after making the sample out by laser cut sheet metal

Please help to correct me if I'm wrong.

Q1 : The belt in the system are not parellel to each other, will this work ?




Q2 : When belts are installed, the hotend carriage goes little stiff and X/Y Stepper motors are unable to move normally in the X and Y axis
One of the stepper motor at least moves a little but both of them makes clicking noise while moving in X / Y directions
The toothed pulleys are unable to turn and skipping most of the steps
(Are the belts installed too tightly or stepper motors do not have enough torque or Flat cables connecting stepper motors are too thin in radius ?)
How to increase the torque in the stepper motors in a measureable manner, I've tried to turn the little screw clockwise on the X / Y motor driver
How much do I need to turn on this little screw ?

P.S. Stepper motors I've got are 42x42x42 1.8 degrees (Torque claims to be around 0.4N/m)

Q3 : I then removed the belts from the carriage, and the stepper motors seem to turn in the correct directions according to X / Y movement, have not tried moving in diagonal direction. This question may relate to the question above. Again I think my motors do not have enough current to achieve enough torque.

Q4 : I have bought the Reprap Smart Discount LCD2004 from ebay, and wired up it to Ramps 1.4,
Connected all cables just the way it is in my prusa mendel i3, but this time I have installed the electronics, PSU and cables nice and tidily into an ABS box. (Ventilation)
But the LCD very often shows strange characters, I have to press the reset button on the Ramps board every minute to clear the screen.
I have tried to install these magnet shields to all the stepper motor cables and the two LCD cables, the occurance of strange characters has been reduced but this issue still occur every now and then. I'm not sure if I'm installing these magnets incorrectly, I put them straight through one side of the cables, instead of looping the cables around the magnets once on both ends of cable, it is because the inner radius of magnets I've got are too small for the cables to loop round.



Q5 : I'm not sure if this question relates to Q4, but when the LCD shows up strange characters, the auto bed leveling servo on the hotend carriage will turn on randomly at the same time.

Q6 : One more improvement I would like to make, is to find a better replacement for the Headbed MOSFET, I have burnt a few ramps 1.4 board previously, all of the middle pin on the PCB have been burnt, I've read from another post that someone has recommended the following MOSFET.
Please advice which one is the best to solve the overheating problem.

IRLB3813,
IRLB8743,
FDP8870,
AOT240L,
CSD18502KCS

Hello,

1) I don't want to insult you, but I hope this belt path is a joke ...
ALL belts need to be parellele or perpendicular, (except outside one.) else you modify the lenght or the belt at each mouvement (simple trigonometry problem)


The red one are wrong angle, and green white is correct one.

2) Look at 1), it's not current or motor torque or anything problem, only the belt path.

3) Look at 1)

4) I have exactly the same problem when I was putting the 1meter long flat cable, with the 30cm all caracteres glitch have disapper. Try to shorten the flat cable between ramps and LCD.
Magnet shield are useless if not determined correctly by complexe calculus.

5) Yes can be related. Try to correct the 4).

6) I think all of them are correct > 100A which is enough. Have you heatsink on your old one.

Hi Zelogik

Really appretiate your advice here, especially the path issue.

I will do some modifications later.

Many thanks