Kossel K800 from China??

Hey all,

I just got a "Kossel K800" assembly kit from a seller on Amazon..it was stupid cheap ($375 with free shipping) seller is really nice and it got here within one week. 3DHubs recommended this seller so I thought it should be reliable.

However the actual producer is a Chinese company and it's a slightly altered version of Kossel mini. Many parts are different (for example it doesn't use rails for vertical carriages, but rollers) and instructions are not readily available online.

The problem I'm running into right now is that the vertical carriages are sort of askew when rolling up and down (because the rollers are trash) and the 6 carbon rods are not necessarily the same length

I wonder what impact will this issue bring to the calibration stage (e.g. will the software accommodate potential errors? )

I wonder if anyone has tried out the same kit and can give out any advice?

Edited 1 time(s). Last edit at 09/07/2015 07:53PM by brettgao.

It sounds like it might be similar to the one sold by Sintron (apart from the carbon rods). We've got a good thread going here:
[forums.reprap.org]

which might give you some ideas on how to get your machine up and running.


The best idea is to spend some time getting all your mechanics totally perfect, as best you can, when you're building. It's a lot easier to sort it out at this stage than by spending days endlessly printing calibration objects and noticing that they are a bit off. With the rods, use a jig to glue them all to be exactly the same length.

The K800 is the one I have.

I have made some comments about it on this forum and one other user with K800 experience has also pitched in. We both have a very negative opinion.

At the end of the day, what ruins this printer is the way the magnets are on the effector (the part that moves around and put out plastic) - At certain angles the magnetic force is just not big enough to overcome the forces and it loses contact and ruins the print. This is especially a problem if you make the carriages stiff - Which you need to do, to get good prints. As you have already noticed the "per factory" carriages are crap - See below threads for my fix.

Maybe it will make sense if you read this:

[forums.reprap.org]

and this

[forums.reprap.org]

Besides these issues, the issues that you mention with different rod lengths is unacceptable and will impact your printer performance very negative and certainly increase the chance that the rods will disconnect from the magnets. You must make sure that they have the same length. You can use the thread on the steel balls to adjust a little.

For building you might also want to read:

[forums.reprap.org]

The same user also have a thread on google groups but he discontinued it before he got to commissioning the printer so it is not really worth reading if you already have assembled your printer. I also disagree with some of the things that he has done so be careful following this blindly.

[groups.google.com]

I have actually started the rebuilding of mine with a new effector but it is not ready for publishing. Also it is not all bad. I did manage to print enough parts with mine to build my CoreXY. Just it was never a good experience because so many prints failed for all sorts of reasons. One day it is one problem, next day another. The problem with the magnets was the final showstopper but had maaaaany others.

I think also looking at the peoples experience with the Sintron kit and other chinese kit experiences I would say to anyone reading this, who have not purchased anything yet - Do not purchase the Chinese Deltas - The delta tolerance requirements are just too big for them to make it super cheap.

Delta k800

This is instructions for a k800 I was thinking about buying a while back. Not sure if it is the same as yours but might be some info there to help those trying to assemble.

the k800 is a rubish machine. i have seen it personally with a lot of people here ( beijing ) and nobody is happy. the only way to fix it is change the rollers to actual derlin rollers meant for v-slots . and as for the magnets there is a lot of variation in the socketed magnets have a lot ov variation and it is impossible to calibarate the machine manually .. so you would need a probe and do auto calibration.. I almost bought this machine but when i saw it in a trade fare i just dropped the idea !!

Omg I wish I had done more research on this. What will be a better version kossel to buy?

Thanks! this is very helpful.

Quote
LarsK
The K800 is the one I have.

I have made some comments about it on this forum and one other user with K800 experience has also pitched in. We both have a very negative opinion.

At the end of the day, what ruins this printer is the way the magnets are on the effector (the part that moves around and put out plastic) - At certain angles the magnetic force is just not big enough to overcome the forces and it loses contact and ruins the print. This is especially a problem if you make the carriages stiff - Which you need to do, to get good prints. As you have already noticed the "per factory" carriages are crap - See below threads for my fix.

Maybe it will make sense if you read this:

[forums.reprap.org]

and this

[forums.reprap.org]

Besides these issues, the issues that you mention with different rod lengths is unacceptable and will impact your printer performance very negative and certainly increase the chance that the rods will disconnect from the magnets. You must make sure that they have the same length. You can use the thread on the steel balls to adjust a little.

For building you might also want to read:

[forums.reprap.org]

The same user also have a thread on google groups but he discontinued it before he got to commissioning the printer so it is not really worth reading if you already have assembled your printer. I also disagree with some of the things that he has done so be careful following this blindly.

[groups.google.com]

I have actually started the rebuilding of mine with a new effector but it is not ready for publishing. Also it is not all bad. I did manage to print enough parts with mine to build my CoreXY. Just it was never a good experience because so many prints failed for all sorts of reasons. One day it is one problem, next day another. The problem with the magnets was the final showstopper but had maaaaany others.

I think also looking at the peoples experience with the Sintron kit and other chinese kit experiences I would say to anyone reading this, who have not purchased anything yet - Do not purchase the Chinese Deltas - The delta tolerance requirements are just too big for them to make it super cheap.

Thanks! this is very helpful.

Quote
LarsK
The K800 is the one I have.

I have made some comments about it on this forum and one other user with K800 experience has also pitched in. We both have a very negative opinion.

At the end of the day, what ruins this printer is the way the magnets are on the effector (the part that moves around and put out plastic) - At certain angles the magnetic force is just not big enough to overcome the forces and it loses contact and ruins the print. This is especially a problem if you make the carriages stiff - Which you need to do, to get good prints. As you have already noticed the "per factory" carriages are crap - See below threads for my fix.

Maybe it will make sense if you read this:

[forums.reprap.org]

and this

[forums.reprap.org]

Besides these issues, the issues that you mention with different rod lengths is unacceptable and will impact your printer performance very negative and certainly increase the chance that the rods will disconnect from the magnets. You must make sure that they have the same length. You can use the thread on the steel balls to adjust a little.

For building you might also want to read:

[forums.reprap.org]

The same user also have a thread on google groups but he discontinued it before he got to commissioning the printer so it is not really worth reading if you already have assembled your printer. I also disagree with some of the things that he has done so be careful following this blindly.

[groups.google.com]

I have actually started the rebuilding of mine with a new effector but it is not ready for publishing. Also it is not all bad. I did manage to print enough parts with mine to build my CoreXY. Just it was never a good experience because so many prints failed for all sorts of reasons. One day it is one problem, next day another. The problem with the magnets was the final showstopper but had maaaaany others.

I think also looking at the peoples experience with the Sintron kit and other chinese kit experiences I would say to anyone reading this, who have not purchased anything yet - Do not purchase the Chinese Deltas - The delta tolerance requirements are just too big for them to make it super cheap.

Thanks! this is very helpful!!

buy a kossel from robodigg or t3p3(uk) i am not aware of us vendors. The robodigg machine is bullet proof ( literally ) all metal machine .. ( i have nothing to do with them fyi )

Edited 1 time(s). Last edit at 09/11/2015 01:43AM by ekaggrat.

Quote
ekaggrat
the k800 is a rubish machine. i have seen it personally with a lot of people here ( beijing ) and nobody is happy. the only way to fix it is change the rollers to actual derlin rollers meant for v-slots . and as for the magnets there is a lot of variation in the socketed magnets have a lot ov variation and it is impossible to calibarate the machine manually .. so you would need a probe and do auto calibration.. I almost bought this machine but when i saw it in a trade fare i just dropped the idea !!

Why can´t it be calibrated manually? Firmware restrictions or unreliable homing switches?
I´ve built my delta from scratch with 400mm wide and 800mm high extrusions.
Mine has optical endstops and Traxxas joints, but the same crappy rollers. When I change something on the printer, I can now calibrate it with marlin and pronterface in less than 30min.
Those m665, m666, m428 commands are very helpful, no need to flash the firmware every time.
-Olaf

Edited 1 time(s). Last edit at 09/11/2015 03:41AM by o_lampe.

it can be just u will spend a long time doing it.. the arms are unequal .. the mag joints are unlevel. the rollers are wonky ...

First of all, don't despair. Just take one problem at a time. For now, get the correct length on the rods . Make a jig that you can try your rods in, to make sure they are equal in length. Maybe you are not going to make big beautiful Yoda heads every time with this printer, but you can get it to print. Remember that the 3d printer community has been up for some years now, so if you have a problem that you can not solve in 30 min, try a google search as someone else has probably had that before. If you, even with the help of google, can not solve your problem in another 30 min, then just go ahead and make a post here on the forum about your problem.

Just at what stage of the assembly are you now???


Regarding;

Quote
brettgao
Omg I wish I had done more research on this. What will be a better version kossel to buy?

There are many kits out there, but I do not have the experience to tell you the best one. The Kossel Mini Kit is a proven design it seems.

What I am pretty confident in telling you, is that there is no DELTA kits out there, that works for ~400 USD. The ones Ekaggrat mentions comes at 730$ before shipping and extras.

I think, and this is a controversial topic, that for a cheap and first printer, you should look for the cartesian printers.

For example Andrew here on the forum is trying to put together people for Prusa I3 Steel which from what I read, seems to be a very stable printer; [forums.reprap.org]
Buying his parts will cost you 130 € ( 150$) and then you just need the rest from China (~150 USD) and then you have a printer with very strong support, in its 3rd revision and a proven simple design.