Ebay SINTRON Kossel Mini full kit

The ball joints don't fit on the sliders, there is not enough clearance for the larger ball joints. . The solution was to print a 4mm spacer to put between the 2 pieces of the carriage. This in itself isn't an issue if you happen to have a RepRap or laser hanging around (have both). The the potential larger problem is that this affects the machine's geometry.





CarSpacer.stl

Sintron's customer support is customersupport@sintron-hk.com . I made them aware of the corner and ball joint clearance issues and sent them a link to this thread.

Roger

I opened my kit today, and had a look. The printed parts seem OK, although there is a bit of stringing and looks like they will need to be cleaned up a bit.

Also thanks to Miamicraft for the investigation work, I've ordered some Traxxas 5347 ball ends. These should screw onto the metal pushrods after tapping with a 4mm tap. Hopefully these will alleviate the packaging issues that the larger metal ball joints have.

Letter from Sintron:

customersupport
9:42 PM (21 minutes ago)

to me
Dear Roger.


thanks a lot for informing us , and our aim is to improve them to better quality , so your opinion is really important to us !!

1. The corners do not fit the extrusions. You should be able to open one of your kits and slide one of the 2020 extrusions into one of the corner pieces. You can't, they don't fit.

i've checked all the article you posted , and we do have our own assembled , so actually i didn't quite understand about what you mean for this.
but here we are double checking and will do as your instructions to test , will keep you informed again .


2. The ball ends on the rods are very nice but don't work with the extruder platform. They are larger than most and cause interference with one another.

we do understand about your concern .

and please don't worry , you can check our picture here :

[www.dropbox.com]

although it seems a little bit jammed to each other.

but after you start to use it , you can figure out they actually won't touch each other ( due to 3 axis )

hope this is clear for you .

( or if you still think it is an issue , please let us know again )


--

and by the way , could you help to post these document for us , as i think these should make others easier to use:
( the firmware is also adjusted to fit our models )
--


please check here to download the instructions for Kossel mini .

[www.dropbox.com]

password : Sintron_Technology


--


firmware :

[www.dropbox.com]

Marlin for Kossel mini (with 2004 LCD )

software :



for windows :

[www.dropbox.com]

slic3r for windows x64 ( 64 bits )

[www.dropbox.com]

slic3r for windows x86 ( 32 bits )

[www.dropbox.com]


printrun for windows


for Mac :

[www.dropbox.com]

slic3r for mac

[www.dropbox.com]

printrun for for Mac

--

thanks.

james.

Nebian,
My corners sure didn't fit. Much more than just cleanup. Did you try sliding in an extrusion? Sintron says no problem so maybe mine was just a bad kit.

Roger

I wonder if Blomker Industries realise that Sintron have totally ripped off their instructions? Pretty funny when Sintron's instructions show the belt tensioners installed, but their eBay listing shows no such tensioners.

Also pretty funny that they say that their rod ends aren't touching, when clearly they are.

I guess it's a case of caveat emptor, we're getting enough parts to build a printer as long as you know what you're doing, and are willing to make some modifications as you go.

Roger, am at work now but will start test fitting various parts tonight.

Edited 1 time(s). Last edit at 08/18/2015 11:17PM by nebbian.

At least you got an reply.
You didn´t ask them about the rod ends and carrier problem. Would like to see their answer.
4mm is a lot...you have to add it to the DELTA_CARRIAGE_OFFSET
-Olaf

I did in a followup. They sent me back this picture of their machine from the front view and said see, there is no problem.



The picture I sent them:



A lot of things have changed in the month since I ordered this kit. There appears to now be better choices on Ebay for about the same cost. A month ago that wasn't the case. It is possible that I just got a bad kit, but I don't think so after messaging them. The corners can be reprinted, and I will order the Traxis rod ends. Just because I can fix the machine doesn't mean I should have to.

Don't buy this kit.

Roger

Hm... I ordered (still in transit) Sintron's kit from Aliexpress for $315. And just found this thread. It will my first experience with assembling of 3D printers and I should prepare to have a deal with all these issues, as I read. That's a pity. But for this price...

As for belt clips, I asked the seller also:
> On the picture from description I see belt clips for closed loop belt. But the package contains open belts. How it's supposed to work? Because belts from the package are incompatible with this clips.

And the answer was :
"when you receive it , it's open belts.
but on the plastics , there's a place to put the belts , and then it will be connected together as closed loop .
so don't worry , it's actually quiet easy when you see it ."

So, if I cut belts exactly to length required, and then put the each end to half of clip, it would work. But it' s still needed to fix the ends there somehow.

Edited 1 time(s). Last edit at 08/19/2015 03:37PM by GrAndAG.

Hey!
So, my corner pieces were not that bad.

I placed the 2020 on the top of each hole and used a small (2.5lb/1kg) hammer [cardboard to help, hhaha!] and they went in fairly well.
Nice, tight and straight (enough??).
Pretty much one of each piece is poorly printed. I may need to reprint some.

The tops pieces, same way but REALLY gently tapping them down - do top of top corner, take off and do bottom - now they are a nice fit.

the arms - well these ends are just crap. very big and I feel they will get in their own way eventually and a few have rough movement.
I have not installed these to the runner/sliders yet so I'm worried I'll have the same issue as Miamicraft's slide/runner.

I'll order some traxxis parts and then I'll upgrade to carbon fiber magnet kit ($40).

I need some new allan keys as I have no ball end ones and its taking AGES to install motors - so I'm stuck for the moment until I get down to the shop.

On a side note; I like the wheels, does anyknow know what these are or where I can find them (ebay maybe)?


Edit: Decided to order Traxxis rather than use big chunky metal ends!

Edited 1 time(s). Last edit at 08/19/2015 08:37PM by kingoddball.

Wow, it's great that there are a few of us all at the same stage, able to help each other out

I did some test fitting and cleaning up of parts last night, and as expected I had to bash the extrusions through the corner pieces with a mallet. No biggy, they are a very snug interference fit which is fine by me. The detailed instructions I posted a while ago prepared me for that step. Anything that increases rigidity is a good thing.

I weighed those metal rod ends... 120 grams. Yowzers. The whole point of the Kossel design is that you keep your effector light... using those rod ends will mean 60 grams of weight on the effector just in rod ends. When you consider that the total weight of the effector itself is something like 150 grams or thereabouts, an extra 60 grams would be noticeable as lack of precision in fast moves. There really isn't a lot of load on these rod ends either, so I don't see the point of speccing a part that is totally overkill. Not to mention the fact that it simply doesn't fit. My Traxxas ends are sitting at the post office waiting for me, so I'll get on with using those, along with the metal pushrods. Metal pushrods are heavier than carbon fibre, but I think they'll be OK.

Kingoddball, these look like the wheels you're after:
[www.dhgate.com]

Yep!
Should be good, communal help is wonderful thing.

Has anyone found the correct STL files for the magnet upgrade that will work with these pieces?
I have not found the parts that will work; found effector but not slide/runners...

If anyone in AU (or wherever) these are the cheapest Traxxas I found:
[www.ebay.com.au]


Carbon rods with magnet - Maybe not the cheapest but seems to be easier all in one kit; cut to size and nothing extra to find:
[www.ebay.com.au]

Edited 1 time(s). Last edit at 08/19/2015 09:56PM by kingoddball.

Kingoddball,
The Sintron carriage is not a standard Kossel part so you won't find anything "off the shelf" that will work. I wonder if you sent a note to customersupport@sintron-hk.com asking for the STL of the two carriage pieces if they would send them. If they provided the STL I could modify them to work with 10mm balls and springs. There are effectors on Thingyverse that will take care of the lower end and I happen to have a set of the threaded balls.

I don't think they want to hear from me.

Roger

Thanks mate,
I have sent a request (via ebay message).
Told them one of their printed pieces is not usable -- one I have the hole is gone. sagged pla.

That would be great if you are able to add the magnet parts!!

I dont think they make this piece themselves, its bound to be somewhere.. I'm checking thingiverse for now then i'll move onto other GitHubs.

Found it - or at least extremely close!
As soon as I saw the word "Cheap". hahahhaa

[www.thingiverse.com]


Extra: Printable roller wheels for that ^^^^ (above)!
[www.thingiverse.com]

Edited 1 time(s). Last edit at 08/19/2015 10:41PM by kingoddball.

If anyone in Australia wants some ball ends NOW (ie in your hands within 24 hours) then this place is pretty good:
[www.perthrc.com.au]
Yes they are expensive, and $10 for shipping is daylight robbery, but you do get the parts the next day.

I've also ordered a set of these:
[hobbyking.com]
which may or may not work.

We'll see.

@ Miamicraft:
Sintron have sent me the STL they use.
Attached.

Let me know if I can help

Steed ball = 10mm
magnet ball joint = 12mm


Edit: It's the same piece I linked to above
Comparing these and they are the same.

Just like the "Borrowed" build guide! hahaha

Edited 1 time(s). Last edit at 08/20/2015 01:35AM by kingoddball.

Ha ha I asked for the STL models and they sent them to me as well. I don't think they know why there was a sudden rush for those files. I also doubt they're prepared for an onslaught of determined printer builders

Also weighed the Traxxas ball ends... 18 grams for 12. So by using Traxxas joints you'll save over 50 grams at the effector (not to mention that things will just fit without lots of modifications). The balls also have a 3mm hole, so you don't need to drill/tap the effector or carriage. Win win.

Question for those more experienced, how do you know if the parts supplied were printed in ABS or PLA? From the warping on one of my corner pieces I'd assume it's ABS, but don't really have a good way of telling. Do they burn with a different coloured flame? Is there an easy way to determine melting point?

Ta

Hey,
Parts are printed in PLA.

PLA feels smoother, shiny and doesnt have much flex.

ABS feels much lighter - all my replacement parts are in ABS.

Edited 1 time(s). Last edit at 08/20/2015 03:40AM by kingoddball.

Cripes. Shouldn't the effector at least be printed in ABS? Now I'm worried about the hotend falling out!

My parts are ABS as acetone affects them? Don't think acetone affects PLA?

Roger

Hey,
Correct acetone has no affect on PLA (or none I know of).
My parts are 100% PLA.

PLA strands are also extremely hard compared to ABS (ABS feels softer, if that makes sense).

If you need an effector in ABS let me know.
I havnt made the megnet effector yet, only one I found was 10mm socket, the parts I ordered are 12mm

I'm reprinted intricate parts in [clear//verbatim brand] ABS but for frame I'm using the big red ugly parts

It's more than possible they have changed in recent times?

Kossel Mini Plastic Printed Parts for RepRap Rostock Delta 3D Printer, PLA Red (Copy and paste of the ebay listing)

Edited 1 time(s). Last edit at 08/20/2015 06:32PM by kingoddball.

btw if anyone's ordering Traxxas rod ends, be sure to order two packets.

I had to put together 15 before I had 12 good ones (without slop). Strangely enough all the bad ones were marked "C". I think this mark shows which part on the injection molding tree it is. All the good ones were marked other letters and numbers.

If anyone has only ordered one packet of rod ends then you might be lucky and not get any sloppy ones, but if not then let me know and I can mail you out some good ones (still got a few that are surplus).


When putting them together you have to do a couple of steps:
1) Put the balls in a bath of ice, water and salt
2) Hold the plastic part in boiling hot water for 30 seconds
3) Using tweezers, quickly take the ball out of the ice bath, rest it on a wooden board, and place the plastic part on top of it. The plastic part has two different sides, one is wider than the other to allow assembly. Remember to put the side with the shiny ring towards the steel ball.
4) Quickly press the plastic part onto the ball using your fingers. You will feel the two parts tightening up after assembly as their temperatures equalise.
5) After a minute, hold the assembly by the ball. If the plastic part is free to dangle and rotate then it's too loose and you need a new one. If the plastic part doesn't slip on the ball then you've got a good one.
6) Tap the plastic with an M4 tap
7) Screw the rod ends onto the steel diagonal arms.


So using 4mm thread to adjust these, you're going to be able to get your rods to within 0.35 mm of each other (worst case). I don't know if this is close enough, my gut feeling is that there is going to be more flex and slop than that elsewhere in the system so I can't see how 0.35 mm will make a difference. I mean that's a difference of 0.18%... I challenge anyone to even accurately measure a difference of 0.35 mm over 200 mm using normal tools. Bear in mind that a 3mm bolt has some slop inside the ball anyway, I haven't measured it (not sure how to, tbh) but you can definitely feel some clicking.
If they have to be closer than 0.35 mm then I guess you could heat up the thread with a blowtorch (gently!) and pull the thread in the direction it needs to go, which would melt the plastic of the rod end. Again I struggle to know how you would do that accurately. I also think that there would be more flex in the effector, carriage assembly and wheel contact patch than 0.35 mm...

I guess we'll see if there is binding in the finished article.

@nebbian Sorry for OT, but could you put the sloppy Traxxas joints in cooking water for 10mins. and let them cool down in it?
We used to do that with all plastic parts back in RC-Car days...
I´d like to know, if the slop is gone by the treatment..
THX
-Olaf

0.35mm would be the same difference as with the original joints, plus they have 4mm holes in the ball ( IIRC ).
Would it be possible to drill one traxxas per rod to 4mm and glue it to the rod while it´s length is fixed?
-Olaf

@o_lampe,

Good call on the cooking water for 10 miuntes, I'll give that a go.

Regarding the 0.35 mm, drilling and gluing, that's certainly an option. My issue is that I'm not confident that at the end of it I'll have joints that are any closer than just by using the threaded rods and cutting threads into the rod ends.

To visualise this I got out my calipers and measured 0.35mm. In the old language this is 3/5ths of 5/8ths of f..k all I mean how would you measure this?

The only way I can think of is to get a 3mm rod (from where? You can't use a 3mm threaded bolt as this is less than the diameter of the hole in the ball), somehow permanently attach it at exactly 90 degrees to something solid, get another 3mm rod, somehow put this on a sliding trolley so that it stays at exactly 90 degrees to your solid object, put yet another 3mm rod at something like 220 mm from the first one, slide your diagonal arm onto the first two rods, and measure from the second to the third rod with calipers.

And be sure not to pull too hard on any part, as this will deflect everything more than the distance you're trying to measure.

Yeah not easy.

Would 0.35 mm actually make any difference to the geometry anyway? I've tried drawing parallelograms and triangles in the same dimensions as the rod arms, which is just confusing me more.

Maybe I'm overthinking this.

Quote
nebbian
@o_lampe,

Good call on the cooking water for 10 miuntes, I'll give that a go.

Regarding the 0.35 mm, drilling and gluing, that's certainly an option. My issue is that I'm not confident that at the end of it I'll have joints that are any closer than just by using the threaded rods and cutting threads into the rod ends.

To visualise this I got out my calipers and measured 0.35mm. In the old language this is 3/5ths of 5/8ths of f..k all I mean how would you measure this?

The only way I can think of is to get a 3mm rod (from where? You can't use a 3mm threaded bolt as this is less than the diameter of the hole in the ball), somehow permanently attach it at exactly 90 degrees to something solid, get another 3mm rod, somehow put this on a sliding trolley so that it stays at exactly 90 degrees to your solid object, put yet another 3mm rod at something like 220 mm from the first one, slide your diagonal arm onto the first two rods, and measure from the second to the third rod with calipers.

And be sure not to pull too hard on any part, as this will deflect everything more than the distance you're trying to measure.

Yeah not easy.

Would 0.35 mm actually make any difference to the geometry anyway? I've tried drawing parallelograms and triangles in the same dimensions as the rod arms, which is just confusing me more.

Maybe I'm overthinking this.

Best way is to get some tube that is 4mm bore either aluminium or Carbon Fibre cut to length and use some M4 Grubscrews in the traxas ends and then Epoxy them into the Tube ends that way you should be able to get to within 0.05mm of them all being the same.

IMHO getting the rods all the same is imperative if not you effector is going to tilt in all manner of ways as it track across the bed (I had this problem which is why I have gone to all metal parts on my Kossel variant in an attempt to reduce any of these in accuracies).

Doug

I was goingto use ball ends and springs as I had on hand. I modified the Sintron carriage to take the ball end by cutting the ears off of nice ball carriage and joining them to the body of the stock extruder. The result looked pretty good but my concern is how far the ball ends ended up being from the track. It would affect he geometry. The assembly can be found here and can be opened and modified using the free Autodesk Fusion 360.

I am just going to wait for the Traxis.



SintronBallCarriage.stl

Roger

Hey,
That piece looks brilliant.
I'm a little confused what goes into what piece.

What I see is that there is a flat (curved one side) piece that goes into the carriage and balls are on the rods?
Is it possible to turn the round pieces into the flat disk shape?
My pieces have not arrived yet but the way they are designed is:

Disk > steel ball on rod | steel ball > disk.

I'm going to print one out now and see what it comes out like. Pics will follow

Edited 1 time(s). Last edit at 08/21/2015 07:46PM by kingoddball.

So,
I've taken a look at started a quick redesign to accomodate the cylinders rather than balls.
I think I need to change these to 12mm over the current 10mm.

I'll upload once I print and see how it feels.

Is this carrier meant for magnetic balls or what? What are the vitamins I´d need?
-Olaf
Forget it, I just read the instructions.

Edited 1 time(s). Last edit at 08/22/2015 03:16AM by o_lampe.