Crocked/skewed parts and un-flat bed

K8200 3D Printer K8200 - Assembly and user manual
1

Hi,

Both my belt gears that is mounted on the stepper motors shafts are not
centered. Also, the adapter between the threaded rod and the Z-axis
motor is not drilled straight.

All this can be seen is this videos:
http://www.youtube.com/watch?v=K6GEAph2MsI
http://www.youtube.com/watch?v=OtFhZxB2eV0
http://www.youtube.com/watch?v=Imgz2RiFRAw

It is a bit dark in two videos but you can see the problem.

I don’t know yet how big of a problem the belt gears are, not much I think,
but the Z-axes stepper motor is get way to much tension on the shaft I belive.
Is it or could it be a problem?

Also, my bed is not entierly flat, as some others have indicated. I have
put somethong heavy on it for today to see if the buldge will go down,
otherwise, are there any cleaver ideas on how to fix it? It is about 0,5mm
higher in the center then it is in the corners.

Regards,
Jonas

2

all your videos look like my printer, I think just fix safety all bolts of motors and everything is gonna be fine. we have to see after several hours of printing.
For the bed i use a 4mm glass on top to increase flatness

3

[quote=“MOPa”]all your videos look like my printer, I think just fix safety all bolts of motors and everything is gonna be fine. we have to see after several hours of printing.
For the bed i use a 4mm glass on top to increase flatness[/quote]

I thought so too, but i figured I’d ask anyway :slight_smile:

Is the glass real glass or acrylic?

4

real glass 4mm x 215mm x 215mm, and fix on the bed with clamps like this :

take care of the nose path near clamps

5

I will try that and see if it gets flatter.
Do you have any adhesive tape on the glass? Like Kapton? Or do you print directlly on the glass?

6

Yes, that’s true i used “3M” scotch to increase adhesion :slight_smile:

i use this : ebay.com/bhp/3m-2090-blue-tape

the surface state is correct, just pay attention to the connection between the strips of tape

7

It looks like regular painters tape, I’ll see what I can find at the local hardware store.

Lets see if I can get the surface flatter and then print and see how it works with the skewed parts.

Thanks!

8

[quote=“Jonas”]It looks like regular painters tape, I’ll see what I can find at the local hardware store.

Lets see if I can get the surface flatter and then print and see how it works with the skewed parts.

Thanks![/quote]

You’re welcome

yes standard painters tape, easy to find, same for glass and clamps.
Think that you must increase a little the bed temp to 55°C according to the glass.
I try 3mm and 4mm thickness and 3mm seems to be too brittle.

9

I will try this, it cheap and on my way home: http://www.ikea.com/se/sv/catalog/products/60074007/

10

Those are mirrors.
Mirrors reflect infra red and heat.
And it might change the heat flow.

It might cause problems.
Or not :slight_smile:

Vroemm.

11

I’ve seen others use them without problem, and with the tape it should not reflect much I think :slight_smile:

12

[quote=“Jonas”]I’ve seen others use them without problem,
[/quote]

That is a strong argument :slight_smile:
It will propably work fine then.

Vroemm

13

Jonas, The belt gears are not really a problem.

For the Z motor:

This could create Z-banding in your prints. explained here: evernote.com/shard/s211/sh/ … dcdd2d687e
In short: Due to the movement of the motor the height of each consecutive layer is not the same (thicker and thinner layers) and that creates Z-banding.
To alleviate this problem you can make sure (by any means) that the bottom of the Z motor is unable to move. It can handle the stresses that the rod will pose on it. But by making sure the motor is unable to move your prints will have no Z banding.

14

Thanks for the answers, I’ve made a few test prints and I have the problems with Z-banding, and the belt gears does not seem to be a problem.

But now I have problem with not getting the first layer to stick. I’m trying out different techniques to see if something will help.
I’m printing on a glass mirror with different coatings, since the bed PCB is not flat enough, even after modifications…

15

I noticed that support for Repetier Host 0.90 has been verified, so I tested it, with default settings.
Also, after all the post I’ve read about it is not critical that the bed is entierly flat I testet to print on it.

And the print went on almost flawlessly! The first layer did not stick ok on one place, but it fixed it self
during the next round on the perimiter.