I have just finished building my K8400 and I am having issues with slipping with the belts as they approach either end of their travel. When I tried to ‘auto home’ the printing head to the (rear right - I just want to confirm this is correct) corner it started making a horrible clicking noise, so I turned it off. Please can someone describe to me what should happen when I use the ‘auto home’ feature?
Here is a list of things I’ve tried:
[ul]• Tensioning the short belts by moving the motors to the bottom of their slots.
• Ensuring the crossed metal rods are the lengths specified in the instructions.
• Ensuring the beams are parallel using a vernier calliper. The maximum discrepancy was 0.2 mm. I can’t imagine this is too high, but if it is please provide details on how to reduce such a small value.
• Oiling the metal rods.[/ul]
I can’t see how to fix the problem as everything seems as straight and true as possible. The only other thing I could think of would be that the case panels are not straight, but the air gap at the corners is very small and the many bolts and joints should make it as good as it can be.
On another note, my X/Y/Z end boards shine red LEDs normally. Is this constant or does this change depending on what is happening?
There are many possible reasons for your issue but the main one is a misalignment of the X/Y rods : actually it often happens that the distance (as per the manual) between the clamps is too short.
Check the [color=#408040]Wiki [/color]about that.
[quote=“raby”]There are many possible reasons for your issue but the main one is a misalignment of the X/Y rods : actually it often happens that the distance (as per the manual) between the clamps is too short.
Check the [color=#408040]Wiki [/color]about that.[/quote]
Thank you for the advice. I have looked at the wiki page and I have managed to get the X axis to glide smoothly, but the Y axis is still problematic. I have tried changing the distance between the clamps by removing a rod and twisting them out, as well as knocking them with a hammer. Any changes I made did not seem to improve the situation, so are there any other solutions you could suggest?
Also please could you detail how the ‘auto home’ feature and axis end boards operate?
When moving the axis by hand, check if the lateral rods tend to bend inward or outward (if the clamps are to close they will draw the rods towards the center and vice versa).
Other causes : the Y rod is bent (but then the rubbing is more noticeable near the center of the axis).
The diameter of the rod is not constant (normal should be a bit less than 8mm).
The auto home function moves the head towards the rear right corner until it hits the end-stop (always lit). Then it stops, moves slowly away and then again slowly towards the end-stop.
[quote=“raby”]When moving the axis by hand, check if the lateral rods tend to bend inward or outward (if the clamps are to close they will draw the rods towards the center and vice versa).
Other causes : the Y rod is bent (but then the rubbing is more noticeable near the center of the axis).
The diameter of the rod is not constant (normal should be a bit less than 8mm).
The auto home function moves the head towards the rear right corner until it hits the end-stop (always lit). Then it stops, moves slowly away and then again slowly towards the end-stop.[/quote]
Thank you for the information. I got to a stage where both axes were moving smoothly without the belts, but as soon as I add belts to one axis (using a spacer the ensure it’s perfectly parallel with the other beams), the other is no longer smooth.
From what I can tell the rods don’t appear to be bent, but I am not certain.
It is normal that the motion is less smooth with belt than without but there is a distinct difference between the smoothness of well calibrated rods and unaligned ones. Please test your setup when they are driven by the steppermotors. Also do not forget to lubricate all the rods with fine machine oil.
[quote=“SlowFoot”]Then something might be blocking the nozzle, usual the build plate is too close so no filament can be extruded. You can also have too high feed rate, the default value in the Vertex slicer is way off. Setting the feed rate to somewhere around 60% usually works.
Or you can have very high friction somewhere in the feed line after the extruder. Miss alignment between the hot end tub fitting and the isolator guide for instance. Too low printing temperature will also make it hard for the extruder.[/quote]
This has actually happened when building models that have a low surface area. For example I was printing a model with a few spikes on it and as they got smaller the extruder snapped the filament as described.
I managed to stop all the resistance by loosening the belts, but they slip off very easily now. What I did to fix this was put cable ties around the clamp pieces so it can’t slide all the way off. I’m sure I could design a new piece with a flange on it to fix the problem in a nicer way.
I’m still getting the issue with PLA snapping though, so if anyone has any suggestions on that, please let me know.
[quote=“SlowFoot”]There should be flanges on all belt pulleys, like the pictures in the manual. If not ticket Velleman for new pulleys support.velleman.eu/open.php[/quote]
Apologies for the ambiguity, but I was referring to the belt clamps, not the pulleys. For good operation they only need to be tightened very lightly, but then vibrations caused by rapid movement of the print head can cause them to shake off. Can I get an STL model of them to change slightly to make them more reliable?
[quote=“Jean D”]http://www.thingiverse.com/thing:691419
This one make a decent job[/quote]
Thanks for that link. That will be suitable for modification. I will post it as a remix once it’s done.
[quote=“SlowFoot”]Ok! Just check that you still print round circles, they tend to get square-ish if the belts are too slack.
As for the STL models, most can be found here. There is another website too but I lost the link.[/quote]
Thank you very much for that link. I can add some flanges to the part I need and print it off to fix the problem without cable ties (as they risk catching on the bolts on the case panels.
As for the quality of circles, I printed the slug file from [color=#0000FF]this[/color] and it seemed fine, but I’ll check it with a vernier gauge when I get back to my printer in a couple of weeks.