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Kossel Alt - 20mm extrusion - 8mm smooth rods

by Crashoverride, published

Kossel Alt - 20mm extrusion - 8mm smooth rods by Crashoverride Sep 22, 2013
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I've been using my Prusa Air printer since over a year now and I have decided to try delta type printer. Kossel is a really great design but as I had some 8mm smooth rods and 20mm extrusion laying around I wanted to use them instead of precision rails.. I've found Zam's Kossel files but after printing them out I've noticed that belts are not aligned with the carriages. I had some older stepper motors probably from an old printer(?) with gt2 pulleys pressed on the shafts and I couldn't remove them.., anyway I thought that it would be better to have belts running exactly between the smooth rods.. So instead redesigning carriage I have redesigned frame.. Carriage was taken from here http://www.thingiverse.com/thing:30611
Dry test http://youtu.be/RXFzkHzH564

UPDATE: 01/02/2014
As it was noticed by Senormeow http://www.ohmpie.com/delta_printer/, the 8mm rods are not sturdy enough for this height. I will be uploading stl files for 10mm rods version soon which should help to make it more rigid. If you decide to use 8mm rods anyway then I would advice to use shorter extrusion lengths for the columns or lower top frame by 10-20cm. Bear in mind it's still work in progress ;), thanks


for the frame use:

  • 3 x 800mm - 20mm extrusion for columns
  • for the top and bottom frames use either 9 x 300mm - 20mm extrusion or 3 x 300mm - 20mm and 3 x 300 20x40mm extrusion

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How heavy is a kossel built like ?

come si fermano le linee guida alla struttura?

Comments deleted.

You can share source files

i would appreciate them too

Hi I Download Thing Files and printing but I have not found how Rod Carriage. Can you give me? Thanks

Hi bro

How i can find dimension correct for DELTA_SMOOTH_ROD_OFFSET
My arm are 213.5mm i am using 15x15 version Zam Kossel 15x15
Can you help me?

Hi bro

How i can find dimension correct for DELTA_SMOOTH_ROD_OFFSET
My arm are 213.5mm i am using 15x15 version Zam Kossel 15x15
Can you help me?

Any chance for a 30x30mm with 10mm rod. Thinking a stronger frame for 1000mm high will be needed?


what is the highest succesfull print speed ? :)

Could Rostock stock carriages be used? I am planning on building this using my Rostock first version parts. Thank you!

phenomenal! work! I wil ABSOLUTELY build one, 2 if there is any chance for a 1515 remix. i have an openbeam mini kossel rail stock kit, but would love to use this as the parts kit for it! I also have optical distance sensors that would work great on this! i have several sizes, but the best for the 1515 is very small measuring 8mm in dia for the 1515, and 12 mm in dia for the 2020 version. i am also interested in experimenting with the sharp distance sensor, its TINY and on a polou carrier. Pololu item #1134. Sharp distance sensor GP2y0D810z0f. if you remix in 1515, i will send you one for free!

how did it went with sharp sensor? Iam interested in thatone too

Where is the Rod Carriage ???? This is not fair... Where we gonna use without carriages ????

I have changed my arm to be 265mm, still not getting it right we my end effector at the edge of the heated bed (200mm round bed) the effector tilted a bit and not 90 degree, I measured dozen of time the frame are sound and correct lenght I'm running out of ideas lol, I'm going to print a new carriages with double LM8UU and double check my Pulley tooth,


Double Vertical carriage for Rostock with Kühling's LM8UU holder

These may help for sure.
Not saying you not to try your solution, but to let you know, i tossed my sliders (told you they were bad anyway ^^) and replaced them with rollers from openbuilds, for a total amount of around 110€ (had to buy the 20mm extrusions, mine were not V-slots) and all my problems are gone forever, perfect fit, adjustable pressure, and no more tilting at the bet extremes, since there is absolutely no play.

I can only advise one to go with a good roller solution.
If you're interrested in the one i choose, you can save 3*8.53€ by printing http://www.thingiverse.com/thing:69004
and order the rest at http://openbuildspartstore.com/.
What i ordered was :

The shipping is a bit expensive since there are taxes included, and if you're interrested, check for other stores that may be closer to your country, there are many selling V-slot, but not all have the stock or parts you're looking for...

Hope this helps, cheers ;)

OpenBuilds V-Slot™ Linear Actuators

I ordered from openbuild before I still I have a 1000mm 20x20 vslot with 4 delrin roller in a box, that make me missing out 2x 1000mm 20x20 and another 8 set of roller lol, yeah it will be expensive to get it shipped to my country and I have really no luck finding nearer distributor for this, the previous order was for my CNC machine which It end up never happen :D

I guessing If I get another 1000m v-slot 2020 and a few more delrin wheel, I have myself a new rail systems :)

what size of the enccentric space you use 6mm or 1/4"?

I went with the metric system, since I can't stand the imperial one ^^, so 6mm
You can avoid paying for the excentric spacer (if the 6mm spacer is still provided with the wheel, but it doesn't seem so, mine were 2 weeks ago) and save 3 wheels by printing one of the adjustable pressure carriages, you'll find plenty : http://www.thingiverse.com/search/page:1?q=kossel+carriage&sa=

My printer has been sitting on my desk doing nothing as I still failed to get to calibrated, and lack of funding for part slowing down the project even more, I positive default setup should works as it should as I can see many other people & the creator successfully run their, I gonna disassemble my stepper motor to make sure my pully are correct specs :)

Hi guys,

My rod is 250 after configuring 3 point pass paper level I can't get my Z center to touch the bed been trying everything anyone using Repetier can share their config? Been following all the video no luck getting this to level

Hi, the issue you are encountering is a standard for delta printers, to correctly compute the positionning, you firmware needs values that are not always the same as the real ones. You need to increase/decrease the printer radius to lower/raise the print head at the center, but this link will explain it better than i can : http://minow.blogspot.fr/


I have been following those but none of them really helped me, I just printed a new arm Jaw going to extent my arm to 265mm as I noticed the effector are not level when it reach end of my build plate (210mm round build plate) it fall out short maybe longer arm will made a different

these are my reference:


been trying all of them since Saturdays, I think I flashed the firmware more than 30 time now :) I guess I need more flashing to do

Hi, Sorry it seems we are in very different time zones :)
If by "not level", you mean that the end effector tends to tilt in any direction while approaching the exterior of the bed, apparently you are facing the same problem i had with my printer since i got it working, and the answer is :

  • Arms may be too short (the tower for which arms are almost horizontals has no more authority to hold the effector, and you can move it very easily by hand while in this position)
  • Too much play on your carriages (not your arm linkages) (My 10mm smooth rods were too long, and since the carriages are always approx at the middle of the smooth rod, it maximizes the bending effect, i could tilt the effector a lot while bending only 1 or 2mm the smooth rods). So i gave up on smooth rods, and tried sliders, more play, even with adjustable ones, and one year after the initial assembly, i'm about to start investigating rollers ;)

Hi Kert,

I suspecting the same too, arm to short, I printed a new arm going to extent it to 265mm as the author setup, but looking back at rostock original setup the dimension are the same, I reduced the hight of the actual printer my max height is now 275mm which roughly I raised the bottom vertex around 50mm or so, wanted to use slider not can't find any slider used rostock style carriages most of them are kossel slider carriage with traxxas ball bearing arm, I'm using rostock original U joint printed ball and Jaws

I remixed the sliders i'm using, they were for 1515 alu extrusions, and had the carriage type built in i made them for 2020, and removed the carriage to put anyone on a basic 4 screws system. But as i told you, there is quite a lot of play to my taste...
I can upload them if you want, and maybe even adapt the classic U-joint to them ;)

Appreciated if you can upload them, or perhaps email them to me at idzuwan (@) gmail.com :)

Working on it

awesome thanks!

Here you go, take your time to inspect the part and make sure it suits your needs, made for 2020 aluminium extrusions, U-joint, with belt clamp, I let the endstop screw at the same place as it is on the classic U-joint, but you may not need it, or else where. Don't hesitate to ask for any change if you need!

2020 Aluminium extrusion adjustable Slider with U-Joint carriage
by kert

awsome thanks! will need to reroute all my wiring of I'm going to use this :D

Were the original CAD files ever mad available. I really like this version but want to tweak a couple of things.

I also need them,too.T T

Hi, did you ever get the 10mm version online. I looked for it and did not see it.


Hi, just look in the remixes, i uploaded the parts there ;)

finish printed mine, part does not include Z end stop mount? it seem you using traxxas ball join are you using auto leveling? I'm using rostock original carriage need to figure out where to put the z end stop

Hi, Crash.

Looks like the J-HEAD groove mount is broken. I tried netfabb, no results.
I tried both Slic3r and Pronterface to fix it, but no luck.

Can you help?

Crashoverride news on the 10 mm rods version?

Don't you like my remixe? :P

Hi, are you know z-probe design for your platform?

tried to make up one but because of the frame is wider no way to auto deploy the probe like kossel mini did

I have just made 8mm rod version kossel.
I got Crashoverride's marin firm but couln't work well
I uses reptier host to do dry run.
It's difficult for me to understand the difference of repair's parameter and marin's parameter
Would someone please give reptier-host firm to me?

Hi, once you know that repetier has an online configuration tool, it is therefore extremely more sympatic ^^
Here is the link: http://www.repetier.com/firmware/v091/http://www.repetier.com/firmwa...
Just chose delta type printer and follow the step by step. You even can upload your old configuration file in order not to start from scratch.
Hope it helps

Hi, kert
Thank you for nice advice.
I'll try to do it
But some parameters are difficutlt in online repteir-host firm.

Which ones? The diameters?
In fact just throw a value barely close to it, anyway you'll have to tweak around to adjust it.
Once your printer is ready, just follow this video it greatly helped me for the calibration : https://www.youtube.com/watch?v=XmP9JQPAlr4https://www.youtube.com/watch?...
And at the end of it, if you see your nozzle following a bowly curve (nozzle closer to print bed at the center, but higher when close to the edges/towers), then adjust the diameter (through experiment will do the job, i don't remember if bowl = decrease or increase diameter...)

Thank you for letting me know useful video for making and tuning delta.

Hi Crashoverride,
I thing this is the best desingn for delta 3d printers.
I build the frame but few questions, please help me.

  1. What should be the size of the rods?
  2. Are you have a Marlin firmware?
    If yes, are you share the configuration.h
    If no, are you share this values?
    thank you.

Hi Phenomen,
my rods are about 265mm long, and yes I'm using Marlin. I can share my configuration.h file if you want but it's more or less standard. here are the values you asked for from my config file:

define DELTA_SMOOTH_ROD_OFFSET 204 // mm

define DELTA_EFFECTOR_OFFSET 33.0 // mm

define DELTA_CARRIAGE_OFFSET 22.0 // mm

you may need to make small adjustments to them.. good luck with your build! Best

Hello again,
First, thans for response. And yesterday I prepared rods for 265cm :) I'm lucky. I'm waiting the ramps card and very excited for first calibration process. I have a question, are you know a good guide for calibration?

Here you go: https://www.youtube.com/watch?v=XmP9JQPAlr4https://www.youtube.com/watch?...
If you wanna use repetier, just follow step by step what he does. If you want to stick to marlin, then it all can be done the same way, just with a bit more pain...

Very thans Kert.

I like your design, nylon carriages should work better than the smooth rods, but just wondering how long they will last for.. please give us some feedback when you finish your tests.

New idea very simple to mount delta delta Kossel and Rostock aluminum! ... :-) (supporting parts in the engine and Abs)

Hi Crashoverride,
Thank you very much for this design as I would build this as my first 3D printer.
Just hope you could let me know how many % of fill you would suggest to print the parts?
Thank you very much

Hi Okaydoke,
I work on updating this design, I would advise you to wait for revision 2 files which will address some of the issues with frame stiffness etc. but if you really want to build current version then.. I printed my parts with 80-90% infill as I remember. Are you going to use ABS or PLA? Thanks

Thank you very much for your advice, I'll wait for the new
version. I'm going to use PLA and hope the whole set of printed part could
weight under 350g which I could afford to order it from the print shop. I
wonder if I could use Kossel mini’s suggestion to printed 50% filled with 3
perimeters and 2 top/bottom solid layer. I could lower the top frame to increase
the stiffness, right? Please share your thoughts. Thanks.

How do I fix the 608zz idler to the 8mm version top frame?

I printed it but space is very narrow and I couldn't install it in the place where are aligned on belt clamp of carriage.

I want to thank you a lot because i printed your effector in order to build a derivative of the Kossel using belts in the alu profiles, with a magnetic plate and "reversed" rods (with static extruder and hotend). I have reversed the effector and have put magnets ont it with glue. The bed is a mirror with magnets. Your effector is very very well designed for M3 screws : congrats and thank you. My first printer works !

Has anyone had any trouble with the 2020 holes? The replicator I used made parts that fit the 1515 like a glove, but the 2020 is too small by about half a millimeter. Really weird.

Hmm, that's really weird as all the holes for 2020 extrusion are actually slightly bigger than 20mm x 20mm. You will have to investigate your CAM software settings.. I'm using Slic3r for generating gcode and Repetier host and I've never noticed any issues with re-scaling models .. try to slice stl again and check dimensions in you host program before printing. Let me know in case you can't fix it and I will try to help..

Comments deleted.

Very nice job. I like this version the best. Can you release the source so I can make some tweaks to my needs? I am trying to use 2060 extrusions for the bottom. I found them at Misumi and they are very cheap. They don't have 2040 for some reason.

sure, I will upload sketchup files tomorrow.

Can you still upload that nice Sketchup file? Thanks in advance.

What was the length of the M4 screws you used to fasten the structural 3d printer parts to the aluminum?

I have used 8mm long screws as I remember but just in case get some 10mm as well

Hi Crashoverride. How are you?

My structure is mounted.

Profile 2040 down and 2020 up and in columns.

Now I've put the engines and came across a difficulty.

How did you tighten the screws of the engines?

Any special tools?

Thank you,

Hey, I had to use hex key set with ball ends like this one http://www.fatspanneruk.com/includes/resizeimage.ashx?src=pics/products/ALLEN_KEY_SET_LG.jpg&width=265http://www.fatspanneruk.com/in... but in the worst case you could use small pliers to tighten those screw. I'm glad to hear that you build is close to finish :),

What size of bolt do I need to assemble main frame?
m4 or m3?
I downloaded some files and I found that holes for bolts were about 4.05mm dia.
Is it different from the kossel legacy that use m3 bolts mainly ?

You should need M5 bolts, i assembled it over a month ago,
Are you sure about that measurement? Usually the T-nuts used on 20mm profiles are M5.

I downloaded Kossel_Rav_Alt_bottom_frame_20mm_V3 and then measured a hole placed in the center using 3d cad.
However, hole size is 4.2mm dia.

it really depends on the aluminium profile, the one I have used has 6mm slot and the t nuts are M4

Have you had any wobble issues with the 2020? Have you heard of anyone having success with 1515 (which I have on hand :/ )

not really, it has been working quite well with 2020 so far but 1515 won't work I think, you could down size the frame and instead of 300mm use 200mm? and 550 high? then it could work..

Since the arms are 250mm I assume this machine has the same dimensions and specs as the original rostock am I correct? Either way I can convert my Rostock into this model easily.

you are right. I have used slightly longer arms but 250 should work just fine.

Would you mind posting your delta section of your firmware or your configuration.h?

sure, sent me a message with your email and I will forward it to you. hmm I'm not quite sure how much plastic you need as I didn't check that. If you slice files with Slic3r it should calculate how much plastic you need for each part.

Hello Crashoverride,

I could not find the vertical carriage stl's, could you upload or mail these? The rest is already printed.

I am planning to build your design, it looks great!

sorry for late reply, I'm quite busy at work currently. I have used 0xPIT design for carriages http://www.thingiverse.com/thing:41743http://www.thingiverse.com/thi... as I'm using traxx ball joints

Rostock Carriage: Ball Ends, Screw LM8UU Mount and Belt Retainer
by 0xPIT

So if i read it well....3 lengths 2040 extrusion for the bottom and 3 lenghts 2020 at the top and pillars?

Or is it also 2040 at the top. ??
I like to be as rigid as possible. I am scaling to 1meter height and 360 mm triangle lenghts.

As for the linear guidlers i am going for the grabercars v rollers.... nice and quiet.

you are right, 3 lengths of 2040 for the bottom and 3 lengths of 2020 for the top. then 3 lengths of 2020 for the pillars.
for 1 meter height you will have to use a bit bigger extrusion like 25mm or 30mm or add some extra cross support between pillars.. it really depends what speeds you expect to print with..

I am in the process of designing something very similar, and ran across your project. I am trying to use 15mmx15mm extrusions from Openbeam. Would you be willing to release the original design files or collaborate with me on creating a set of files suitable for 1515 extrusion? Many thanks in advance.

I'm not sure about releasing original design files as this is still work in progress.. if you want I can make main frame elements compatible with 15mm open beam but will need few days to update files as I'm currently quite busy at work.

I would like a 1515 compatible design, too :)
Yours looks great!

That would be fantastic. Thanks!

Wow. Just a thing. I am in France. Any idea where i can find 800 mm smooth rods at a good price in order to try to build and launch this rocket ?

sorry but I'm not sure where to get them in France, I'm got mine from http://www.zappautomation.co.uk/fr/http://www.zappautomation.co.u... you will have to check shipping cost. I'm sure you will find some good deal if you look online for a shops specializing in selling products for automation etc.

I thank you a lot : i received my extrusions, i hope this will be the first printer i build entirely from scratch :-) Because it is beautiful :-D

Hi. Great Work.

What type of nuts you used in the profile?

You know the amount of nuts?

Do you have any link where to buy?


Aren't 8mm linear shafts wobble?

they should be fine with bowden. I made some prints and so far I couldn't find any issues, platform/hotend mass is divided between all 6 rods.. of course 10mm rods would make it more rigid. I will post some photos of printed parts soon.

I'm just starting the build, still waiting for most of the parts, but went on a 10mm design. Will post results and remixed parts once it prints ;)

fantastic work. i will make one too

thanks, hope you will enjoy building it :)

When calibrating start with DELTA_SMOOTH_ROD_OFFSET 195, for 300mm profiles at the base. Towards it's first print...

I have used ~204 for testing. it looks like you will get it to work before me hehe :). I'm just installing led's lights and testing hotend made by myself but not really happy with bowden performance.. I got airtripper running but I will to swap it back to wades..

I ended up with DELTA_SMOOTH_ROD_OFFSET = 200, not perfect but i'm checking out some prints. With 0.3 first layer, the "higher" center was ok. The test print sticked well on hairsparyed kapton.

it looks great! I just did my first print as well with 204 and all dimensions are fine.. will try with 200 now.

Could you provide 10mm smooth rod holes?
I'm not really used at fiddling with .stl files.


Nvm, I did it myself with Blender.
Was easier than I thought it would be.

Thanks a lot.

Sorry :) I was about to upload them.. anyway I will include one set for 10mm rods, thanks

Hi. In STL Platform_traxx_ball_joints. Which model of ball joints? And at the other end of the arm is any printed piece? And what kind of arm you used? thank you

hey, ball joints are Traxxas 5347, and the rods are mode of 4mm carbon fibre rods (I found both on ebay). ball joints have 3-.3.5mm holes for the rods but I hand drill them to 4mm so they fit together quite nicely even without the glue. I'm making small changes to the platform.. stl's should be available soon. thanks

Hello, how the length of the tubes of carbon fiber?

Great work, i just disassembled my original rostock and started yours. I noticed that the access at the motor's screws is pretty hard. Maybe 4x4mm holes (some spacing also) across the bottom part won't affect it's robustness.
Also 8mm holes for 608 bearings on the top frames would be nice as a choice.
I hope i'll get this working in the next week with more feedback.

Another note that came to mind, use profiles cut at 300mm or either 340mm (20x20) so that they can be used in other builds like mendelmax 1.5, or adapto.

I'm happy you like it. I noticed the issue with not having enough clearance to use allen key on the motor's mounts and I fixed that already.. I will upload most recent versions of all stl's at some point during the weekend . I can make top frame with 8mm holes.. current version is for use with 624zz and the idler pulley generated from http://www.thingiverse.com/thing:16627http://www.thingiverse.com/thi....
It could be quite good idea to use 340mm extrusions for the frame, more universal.. thanks for pointing this out..
I'm open to any suggestions :)

Parametric pulley - lots of tooth profiles

Hi. Do you have BOM file ? 20mm extrusion is 6x 300mm and 3x800mm. It´s ok ?

Hi, I'm still building/redesigning it so don't really have a BOM file yet.. you can build it either with 20mm extrusion which will require 9 x 300mm for the top and bottom frames and 3 x 800mm for the columns or use 20x40 extrusion for bottom frame, then you will need 3x300mm (2040), 3 x 300mm (20mm extrusion) for the top frame and 3 x 800 mm for columns.. I would advise you to use 20x40 on the bottom frame as it will make it more rigid.. there is a basic set for 25mm extrusion as well. I'm planing to update all stl's at some point during the weekend.

Thanks. I will use 3x300(2020) / 3x300(2040) / 3x800 (2020). Thank

Hey Crashoverride! Nice work. I'm in the process of printing a set of parts out to have a play. Have you got any updates for this? Or anything I should watch out for? Normally I wouldn't ask but this is still a work in progress =)

Hey Slip, if you will print them in pla then all should be fine I think... I printed mine in abs with 30% infill and the bottom parts have cracked a bit on the sides because they are quite large and abs is shrinking a bit.. I just finished assembling the frame so will have more feedback after the weekend.