aluminum mini kossel kit

stonewater · Post by **stonewater** » Wed Jul 22, 2015 1:19 am

athoughts on this product? seems like its a good buy.... has all a luminum corners and uses 80/20 so it theoretically could be made larger at some point

http://www.robotdigg.com/product/406

I am getting a max V2 soon but wanted something for my son to build for himself.

Tom C

Polygonhell · Post by **Polygonhell** » Wed Jul 22, 2015 2:23 am

Where do you see 8020, the description as far as I can see states 2020 Openbeam which is a product that doesn't exist.

OpenBeam which the original Kossel design is based on only have a 15x15 extrusion, the problem with it in general (and any other 15x15 extrusion) is the lack of torsional stiffness, the kosell design gets around this because linear rail is bolted to the inside of the uprights and dramatically increases stiffness.

FWIW assuming it is actually OpenBeam 15 mm extrusions to go much bigger you'd have to move to 20mm extrusions, then the corners wouldn't fit, and the linear rails wouldn't fit.

Doesn't look like a bad price, it's hard to know for sure without seeing it in person, RAMPS is OK but you'll have to mess with trim pots which can be annoying, they don't mention which hotend they supply, it could be junk, no heated bed and adding one will likely require a new PSU. I'd assume they cast the corners, rather than machining them, which means accuracy is likely a crap shoot. The one thing to be aware of if you build a delta where the arms are not preassembled (which it looks like here) is that the assembled arms MUST be very close to the same size, make a jig and make every arm on the same jig.

I built a Kosell a while ago, the only think I don't really like about the design is like many repraps because of the variety of available electronic packages, little thought is given to packaging of the electronics and wire routing, so often getting a clean build can be challenging.

Jimustanguitar · Post by **Jimustanguitar** » Wed Jul 22, 2015 8:45 am

I've ordered from RobotDigg a few times. It seems odd that you "checkout" only to wait for an email with your actual total, but Derek always comes through. My last order arrived in 8 days, I was shocked!

Anyway, I don't have any experience with this kit. It looks pretty. I really like the aluminum corner extrusions. I would expect it to be of average "China quality" and require some deburring and elbow grease to make it perfect. The China linear bearings tend to have junk in them, so clean them out with an untrasonic cleaner or something like that and put grease without grit in them.

They weren't ordered from RobotDigg (it was an Ebay mystery special) but a friend just received an Arduino Mega clone and Ramps board that both had cold solder joints and didn't work out of the box. You've got to find the right line between high value and authentic quality to end up with a machine that works in the end. Sometimes it's a roll of the dice.

Let us know what you end up doing. I'd love to read a build log on one of these blue deltas. Good luck!

Eric · Post by **Eric** » Wed Jul 22, 2015 4:41 pm

Polygon is right that the official trademark Openbeam only comes in 1515. But Robotdigg seems to have borrowed the term and they sell "2020 Openbeam" which appears to be your normal 2020 aluminum extrusion. The aluminum corners are sold separately as well, with better pictures.

2020: http://www.robotdigg.com/product/183/20 ... for+Kossel
Corners: http://www.robotdigg.com/product/395/Me ... 0+OpenBeam (the price is comparable to what a plastic set costs, so reasonable!)

It looks like an extrusion sawn to length for top or bottom corners. Going on that theory, I quickly found an indication of where Robotdigg probably gets them that confirms it's an extrusion: http://www.aliexpress.com/store/product ... 26083.html. See the pictures.

jesse · Post by **jesse** » Wed Jul 22, 2015 6:09 pm

Folgertech sells them too: http://www.ebay.com/itm/Folger-Tech-Kos ... 4d28cf84b7

teoman · Post by **teoman** » Wed Jul 22, 2015 6:44 pm

Why the price difference between the two?

Also the last ebay link, is that even properly assembled? The endstops and the rails look like they have been assembled too low.

stonewater · Post by **stonewater** » Wed Jul 22, 2015 7:16 pm

yea it's not 80/20... I am used to building with it so it came out in the typing..... I just thought it might be a fun build, not committed to it..... at this point in time it may be just be a bunch of stuff from Brian, steppers from Robotdigg, and a smoothie.... I must admit linear rails seem a real nice touch for rigidity... I have had to adjust my cheapskates 2 times, and will need to replace the bearing covers soon. when its all said and done matrials will be a bit more than a V2 but it will be a commercial production level printer

Tom C

Polygonhell · Post by **Polygonhell** » Thu Jul 23, 2015 1:08 am

FYI I just saw this on the reprap forums http://forums.reprap.org/read.php?4,534882
Not the same seller, but looks like possibly the same parts supplier.

teoman · Post by **teoman** » Fri Sep 04, 2015 7:24 pm

I have contacted robotdigg over skype and sent a link to that thread. I asked them if they also had that problem of the frame being stressed and robotdigg replied:

"We have No such problem"

I am in need of a 3d printer kit to get my students to assemble for a robotics class. After that they will use that 3d printing robot to build a robot that prints on a whiteboard using a pen.

If anyone does not have a better recommendations or big NoNo's i shall be purchasing this printer.

stonewater · Post by **stonewater** » Mon Sep 07, 2015 11:45 am

Looking forward to your build teoman. think my son is getting one for Christmas!!

Tom C

teoman · Post by **teoman** » Sun Oct 11, 2015 4:40 am

Half of it arrived. The other half is stuck in customs. I will get it tomorrow.

Anyone have a link to a good manual or such for a kossel. I dont expect a manual the quality of the rostock...

When i asked the vendor they said they have no manual or guidelines. Which would make it a very bad choice for a first printer.

Polygonhell · Post by **Polygonhell** » Sun Oct 11, 2015 1:36 pm

There are a couple of assembly manuals floating around, but none of the ones I've seen a have exactly the same set of parts as Johan's original design, I like this one http://blomker.com/Kossel_Mini_Assembly_Guide_V1.0.pdf but it has some changes to the design.
I would also use a single jig for all of the arms when you make them, getting them all the same length is critical.
I used CA glue to secure mine, rather than epoxy or gorilla glue and they've been fine, and it has the advantage you can make a complete set of arms on a single jig in one day.

teoman · Post by **teoman** » Sun Oct 25, 2015 3:29 pm

I finally got all the parts. I only got stung about 20 usd at the customs.

I was assured by the aliexpress seller that it would have a heated bed but it didnt.

All the parts in the box are well wrapped. And the machining on the aluminium parts looks very good.

The box smells a lot like machine oil and i go some on my hands.

KAS · Post by **KAS** » Sun Oct 25, 2015 6:35 pm

I'm building the OpenBeam Kossel RepRap with old parts from the v2. Using the same guide for the most part, although some of the sections don't match up with the OpenBeam design exactly.

Did your kit include the metal slides that the arms attached to? Like this found on ebay: http://www.ebay.com/itm/3pcs-Metal-Koss ... SwBahVVGar

Just curious if they are the same width as the printed versions I'm using for the openBeam Kossel.

teoman · Post by **teoman** » Sun Oct 25, 2015 6:53 pm

Yes. They were nicely machined.

KAS · Post by **KAS** » Sun Oct 25, 2015 7:06 pm

Could you please measure yours? I'm showing 36mm on my printed ones. If it's the same ( or damn close) I'll order the aluminium ones.

teoman · Post by **teoman** » Sun Oct 25, 2015 7:48 pm

If your calipers touch the screw holes, then that dimension is 40.2mm on the parts that i have.

teoman · Post by **teoman** » Sun Oct 25, 2015 7:57 pm

Sorry for the large pics. It is 2 am and the wife is sleeping close to the computer so i am sending via mobile phone.

teoman · Post by **teoman** » Sun Oct 25, 2015 8:00 pm

The machining marks are not so evident, with current lighting they are more pronounced.

KAS · Post by **KAS** » Sun Oct 25, 2015 8:02 pm

teoman wrote:If your calipers touch the screw holes, then that dimension is 40.2mm on the parts that i have.

Just checked again, I didn't zero the calipers (I'm at 41mm).

I guess I need to print the effector and see what that comes out at.

Thank you!

teoman · Post by **teoman** » Sun Oct 25, 2015 8:03 pm

They also sell the effector platform aswell. Micht be a good idea to get the set.

KAS · Post by **KAS** » Sun Oct 25, 2015 8:04 pm

teoman wrote:They also sell the effector platform aswell. Micht be a good idea to get the set.

you have a link?

teoman · Post by **teoman** » Sun Oct 25, 2015 8:11 pm

http://www.robotdigg.com/product/396/En ... for+Kossel

KAS · Post by **KAS** » Sun Oct 25, 2015 8:26 pm

Thank you, I'll check it out.

Post by **Eaglezsoar** » Mon Oct 26, 2015 5:09 pm

The Folger Tech on Ebay looks to be the best buy. IMO

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