Ebay SINTRON Kossel Mini full kit

I have a fair amount of experience with RepRaps. I have a Frankenstein Solidoodle 3, a Prusa I3 rework and an original Prusa (long deceased). My Solidoodle is printing large parts with an E3D V6 with a .60mm nozzle. I needed a fast printer with a finer nozzle for more detailed parts. I Just received a "[SINTRON] 3D Printer Kossel Mini full kit w/ auto level for RepRap Rostock Delta" bought off Ebay for $370. Shipping was free and took about 2 weeks to arrive from China via DHL. I hope the Kossel fits the bill.


Contents as received. Nothing broken or loose.


Bowden extruder pre-assembled.


Genaric Ramps with LCD(?), step sticks (pre-soldered), bunch of cables...


Extruder looks like a E3D V6 clone. Have had some experience with these clones. Generally compatible but nozzles not near as good as original. Time will tell.


Generic 10 amp power supply, a little wimpy. I use surplus HP server power supplies rated at 15 amps.


Extruded parts look pretty good.


Very nice heavy aluminum heated bed. The leads are not attached will require soldering which could be problem for unskilled.


Metal rod ends.

There are no internet links included for assembly instructions or Ramps code. Not a problem as I will find something close and just go for it.

If there is interest and this is appropriate I will continue this post through assembly and commissioning..

Roger

Hi,

i am new and soon i will build my first printer. I have not decided which one. Found this kit today and i' m very interrested whats your impression is on this kit. I think about buying it too.

Always great to have someone put there spin on a build keep it going.

I saw this kit on ebay too, but wondered about the "v-slot" extrusions. They are in fact simple t-slot extrusions.
I hope the rollers for the carrier will survive...

Delta and Mega2560? I hope it will work and not being the weakest part in the chain ( regarding fast printing )
-Olaf

I cannot recommend this kit for a non-reprapper. The corners don't fit and I am going to have to print a new set. This is not a show stopper if you have another printer and don't mind spending 8-10 hours printing new parts. I have spent some time examining a couple of problems with the existing corner design and before I print I will make a couple of modifications including for the drop in t-nuts. Basing new design off file from thingyverse. He provided step files which are much easier to work with using Autodesk 360 (free). I will upload STL and Step files to thingyverse if successful.

Olaf, wheels don't worry me too much as they are extremely hard and I see a lot of similar designs. Mega2560 definitely has limitations with no floating point and square root. Chinese ARM based boards with Smoothieware are reasonably cheap but I haven't taken the time to look at them. Is it as easy as just loading the binary and using a canned ini file on SD?

Roger

Quote
Miamicraft
I cannot recommend this kit for a non-reprapper. The corners don't fit and I am going to have to print a new set. This is not a show stopper if you have another printer and don't mind spending 8-10 hours printing new parts. I have spent some time examining a couple of problems with the existing corner design and before I print I will make a couple of modifications including for the drop in t-nuts. Basing new design off file from thingyverse. He provided step files which are much easier to work with using Autodesk 360 (free). I will upload STL and Step files to thingyverse if successful.

For those in Europe, I can recommend the Mini Kossel kit sold by Think3DPrint3D. I found it easy to build. Currently, it still uses the Mega2560 though.

Quote
Miamicraft
Olaf, wheels don't worry me too much as they are extremely hard and I see a lot of similar designs. Mega2560 definitely has limitations with no floating point and square root. Chinese ARM based boards with Smoothieware are reasonably cheap but I haven't taken the time to look at them. Is it as easy as just loading the binary and using a canned ini file on SD?

There is also ARM-based Duet electronics, which Replikeo sells for $60 + shipping although their build quality isn't the best according to some reports here. Duet is also available from Think3DPrint3D and RepRapPro, and the QC is better but the price higher. On delta printers, the Duet has the advantages of providing segmentation-free delta movement, fast auto delta calibration of up to 7 factors, and you get a nice web interface with fast (10Mb/min) file upload to SD card. As with Smoothie, you download the firmware as a binary and configure it with a file on the SD card.

Edited 1 time(s). Last edit at 08/05/2015 03:44AM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Start rant
Loaded 20/20 STL corner files from GITHUB and then proceeded to waste a lot of time trying to modify them. Freecad could not deal with them (folded surfaces, degenerate edges..), Autodesk Fusion 360 no go, Meshlab and Meshmixer the same. Emailed a copy to a friend with Solidworks. No joy. The change I wanted to make is trivial, I need to remove the rest of the boss behind the T-Nut. I'm a cad user and I'll be darned if I am going to learn OpenScan when there are perfectly acceptable free (Fusion 360) professional tools available. Its a lot like telling Michael Angelo to use a q-tip to paint the chapel ceiling. It amazes me the OpenScad can export bad meshes. I would have thought that this would have been prevented or corrected by now.



I was just trying to flatten the area (circled) behind the t-nut hole to allow the t-nut to fully grip the 20/20.

End Rant

Anyway, the parts printed perfectly (except as noted above) on my FrakenDoodle and I will be back to assembly Friday.

Roger

Keep up the good work.
I am following it and will probably be getting this kit to add to the printer collection as my first Delta.

While you are printing things you might want to print 3 new carriages. The one provided with the kit is for a continuous belt, not the cut belt provided with the kit. I am going with this one.

Roger

Really not worth buying this kit.

BTW: what steppers did you get? 0.4A types or better?
-Olaf

PS: I use NetFabb to repair bad .STL files

Edited 1 time(s). Last edit at 08/07/2015 02:28AM by o_lampe.

I wouldn't necessarily agree that it is not worth buying this kit. For me it is serving its purpose:
1. It was cheap but I didn't expect a BMW at this price.
2. All mechanical and electrical components present without having to figure out what was needed and purchase from multiple suppliers. Plastic pieces a bummer but I have a printer so not a show stopper.
3. I'm unsure of how much better another kit costing a $100 more would be.
4. I get to see for myself, at a low cost in terms of cost and effort, if delta printers are better for me than Cartesian XYZ printers.

As long as people make the decision with eyes wide open it is not necessarily a bad deal. My thought was to fully disclose what I found so others could make an informed decision.

Motor Description:
Step angle accuracy: + - 5%(full step,not load)
Resistance accuracy: + - 10%
Inductance accuracy: + - 20%
Temperature rise: 80deg Max(rated current,2 phase on)
Ambient temperature ----------—20deg ~+50deg
Insulation resistance:100MΩ Min,500VDC
Insultion Strength--------500VAC for one minute
Datasheet(17HS8401,1.8A,78 oz-in or 4.8kg.cm holding torque,5mm diameter shaft)

Not too bad...

Used Netfabb and Instep, did not help. Problem is with screwy geometry the internal database built by CAD programs is flawed and standard commands such as planes, offset, extrude, cut and slice no longer work as expected or at all. If I could afford it or still knew someone who had it Geomagic studio would have fixed it. I printed parts as is and manually modified them. Can't believe other people are not having this problem with T-nuts. The longer threaded boss on them makes it impossible to snug them down with the existing design. Probably works fine with nuts but not drop-ins.

Roger

IMHO, the value of a kit is related to the quality and usefulness ( is that a word?) of the printed parts.
The carrier could be used with cut belts, just make them short enough.

In your special case it is different, because you have access to a working printer.
I´m interested to see, if there are more problems coming up.
-Olaf

Edited 1 time(s). Last edit at 08/08/2015 04:07AM by o_lampe.

I just visited their ebay shop to look for their rods. It seems they use rod ends with 5mm inner hole but you have to use M3 screws for the effector and carrier mounting.
Can you confirm, the metal rod ends are 5mm ID?
-Olaf

Sorry, build was delayed as a friend of mine needed bathroom cabinets and I spent some time making them. Almost finished, will be back full time by weekend.

Last evening I erected the frame, installed the carriages and put together the arms. The holes in the rod ends and the rods are 4mm. The ball ends are very nice. I was worried that the kit did not include include 4mm jam nuts for the rods until I realized that the rods were precisely the same length and the rod ends were carefully machined. On assembly after fully tightening both ends the rods were all the same length. No further adjustment required, amazing and easier than I imagined.

The mounting screws in the carriages are 3mm. The screws are not a bearing surface, they are merely holders. I see two possibilities:
1. Just tighten down the screws with a washer on both sides which will clamp the joint in place. The mechanical load on the balls should be pretty insignificant and if the rods are pulled in the same direction while tightening the effective length of all the rods will be the same.
2. Drill out the carriages and tap the plastic for a 4mm thread. I find that threading ABS works well.

I'm going to elect option 1. I think it will be fine and if not will have to drill and tap some holes. Will report back on what I find.

The wheeled carriages roll very smoothly. The ball wheels provided are very hard and ride well in the 2020 groove. The kit does not use V-Grove but the supplied stuff works well. The extended length of the carriages (as compared to the shorter ones on Thingyverse) makes them very stable. The wheel adjusting screws also work very well.

I was wrong to be concerned about the belt tightening as the carriages provided will be fine after trimming the belt. They were just not what I expected.

The only serious issue I have had with the kit so far is the corners are bad and I had to reprint them.

YMMV

Will continue to post.

Roger

Please continue posting your findings Miamicraft! I've just received my Sintron kit and am going to start putting it together next week. I'm keen to hear about the problems you might have.

Did you notice that on the ebay listing, they haven't installed the belt tensioners at all? Perhaps that's to get a bit more build height.

How does the belt attach to the carriages? I assume you just cut them all to exactly the same length, then slide the ends of the belt into the toothed groove in the carriage. And then tension the belt somehow?


Thanks for posting your experience, I'm finding it very helpful.

Quote
Miamicraft
Emailed a copy to a friend with Solidworks. No joy.
[attachment 59493 BadSTL.png]

I was just trying to flatten the area (circled) behind the t-nut hole to allow the t-nut to fully grip the 20/20.

Do you still need this done? I have Solidworks and im more than capible to help you with this little fix.

Floyd,
Thanks but it seems like the newer Kossel 2020 parts (Link) had recognized this problem and resolved it. My buddy with solidworks 2014 was unable to fix the part. Seems like too many pieced triangles and self intersections. I was ready to just redraw the part in Fusion 360. Openscad makes lousy STL. Anyway, thanks again.

Nebbian,
The belts are tightened by sliding the top of the machine (triangle) up the extrusions. If all the belts are the same length no problem.

Another issue. The Sintron ball ends are very nice but they are larger than the standard Delta ball ends and interfere with one another on the effector (extruder mount). I think I have the problem resolved and will post a fix after testing.

Roger

No worries, figured id throw it out there. Always willing to help out with crappy models and make them useable again.
I cant believe how many crappy things are out there on these githubs!

Quote
Miamicraft
Nebbian,
The belts are tightened by sliding the top of the machine (triangle) up the extrusions. If all the belts are the same length no problem.

Thanks Roger, I understand that already, and was puzzled as to why the ebay listing doesn't show the tightening bolts installed.

I was hoping you could tell me how the ends of the belts are attached to the carriages. Do they just slide into that toothed groove in the carriage, and hopefully stay put?

I'm also interested in the ball joints. From the ebay pictures it really looks like the ball joints are interfering with each other. Looking forward to hearing about your fix. This part might help at the carriage end at least, having an M4 thread and a 3mm hole.

At the moment I'm thinking that maybe I could get mine operational, and then print some upgrades for it (don't have access to a 3D printer yet). Hopefully I can bodge something up for the corner pieces that you were having trouble with.

Edited 1 time(s). Last edit at 08/12/2015 11:25PM by nebbian.

Hey,
So I ordered most of this kit (using different electronics).
Do you have the build guide/PDF that you would have received with this?
I'm using sintron parts, but bought piece by piece.

I have noticed the same issue with the corner pieces not being correct and delaminating on the parts.
Seems likely they will split once I insert the 2020 beam.

So far it's fairly straightforward (was hoping for the guide).

I had missing parts which sucks (some t-slots)


Edit: if you're in Australia and need any parts PM me, I can probably print something up.

Edited 3 time(s). Last edit at 08/13/2015 05:42PM by kingoddball.

Oddball, what was the problem with the corner pieces?

Is it something that can be fixed with a little ingenuity?

@ Nebbian.
The corners are fine as a whole - just the print quality is off.
Delamination on the bottom layers, no support was used so they are drooping and the 2020 slots are not a good fit (far too tight) - they can easily be correct with a file or small knife

A build manual I have been using is: [blomker.com]
You may already have this but it's pretty close - main difference is 2020 extrusion vs open beam.

Edit: @Miamicraft - With the flattening; if you have the printed parts why not just file it down/shave it?
Or two: Drop the piece into TinkerCad and just slide a clear block over the corner, so stress or fuss - group the parts and export.

Edited 1 time(s). Last edit at 08/13/2015 07:47PM by kingoddball.

kingoddball,
The corner pieces can be fixed. I did it but decided to print new ones anyway:

1. Find a heavy rubber mallet (2kg in my case) and drive one of the short 2020 extrusions through the corner.


2. Soak the part and extrusion in hot simmering water. This will allow the part to release from the extrusion (sort of with a little help from the mallet).

3. Tap the both ends of the 2020 extrusion. I think the tap was an M6. Insert a long M6 stud.


4. Place extrusion in corner, add fender washers and nut, Tighten nut to pull extrusion through. When you install the top triangle you will need to do all 3 corners simultaneously. You will also need a ring of some sort (piece of PVC pipe?) so that you can pull extrusion all the way through the top corners plus an additional 13mm for belt adjustment.



That is how you get the extrusions mounted. Before you mount the T-nuts spot the face of the mount holes on the corner with a 6 or 8mm drill. The idea is to drill down a mm or so so the T-nuts will bite down on the extrusion hard enough to hold.

On the effector... If you file about 1.5mm off of the end of each cone where the rod ends mount you will create enough separation so that the rods will not interfere with each other. You will be decreasing the rod spacing from 40 to 37mm which should not affect the geometry. You may also want to relieve the plastic a bit if the side of the rod hits the plastic.I have modified the part by changing the SCAD but have not yet posted, printed or tested the modification. I am still tied up on cabinet detail with she who must not be named.

I have decided not to use the stock extruder. There is nothing wrong with it but I have an E3D V6 clone that I intend to use along with a real Volcano hot end. To that end I am going with a new effector design which is brilliant. Thorpydo even provided Step files so I can use a real CAD program to make any required changes. I will post he SCAD, CAD and STL files on Thingyverse after I'm sure they will work.

Good luck and hang in there. I didn't really expect anyone to try to fix the corners but it can be done. I am going to use the threaded hole on my extrusion for feet.

You may be done before I am. Keep me posted on your progress.

Roger

kingoddball,
Could be that the part quality shifts on each kit printed. Scary. My corners would have taken more than just a little shaving. I required a mighty big hammer and some serious pounding. Plastic shavings from one corner.



Still easier to just print new corners if you can. Had no issues with slump or extrusion fitting on sides of corner.

Roger

Thanks mate,
Great info!
Mine seem to be exactly the same as yours, just too small and inconsistent to use.
I'll see how they go, but want to avoid printing new ones because I paid $45 for these (to save 20 hours printing).


How many T-Slots/nuts did you use?

I'm unsure if I have enough, I've used top and bottom pieces - will I need anymore than this?
8 * 3 for bottom corner
4 * 3 for top corners IIRC.

Will I need anymore of the t-slots/nuts?

Good idea on shaving a bit off the ends of the effector where the ball joints attach, I had considered that as well. You'll have to shave a bit off the carriages as well, so that the rods stay parallel.

The best build log I've found is this one: http://www.think3dprint3d.com/Kossel-Mini-3dPrinter-Kit#tab-product-tab3 Very detailed.

Are either of you considering twisting the belt so that the idler bearing at the top rests on the smooth part of the belt, rather than the teeth? I've read about several people who did this, which reduced noise, vibration and inaccuracy of the print. The Ormerod does this, which seems to be a good idea to me.

Nebbian,
I'm not sure it matters if the rods are parallel as the ball ends should have enough free motion not to bind and I don't see how this could affect geometry. Its late here and I'm too tired to think about this clearly. Would appreciate it if anyone else can jump in on this.

The twisted belt sounds like a great idea. Easy enough to try.

Thanks.

kingoddball,
You missed the T-nuts for the vertical extrusions, 3 on each extrusion, 2 on bottom, 1 on top for a total of 9. Look at the curved face of the corners. I was lucky that my kit came with 100 T-nuts. If you have to pound them together you probably won't need them.

Also... in the probably doesn't matter category I used 10mm screws instead of the 8mm that came with the kit and used washers on eveything. I am lucky that I have a bunch of M3 cap screws from another project and am replacing all of the phillup screws with socket heads.

Good night,
Roger

Guy's

For all you having probs with the Quality of the Printed Corner's have you checked out the Robotdigg Aluminium Corners they are absolutely spot on Robotdigg Delta parts

Doug

Quote
nebbian
Are either of you considering twisting the belt so that the idler bearing at the top rests on the smooth part of the belt, rather than the teeth? I've read about several people who did this, which reduced noise, vibration and inaccuracy of the print. The Ormerod does this, which seems to be a good idea to me.

I´ve printed 22 tooth 10mm inner diameter GT2 pulleys and pressed the bearings in it.
Now the belts run smooth and I don´t need to twist them.
-Olaf

so how is it going? i've ordered the kit last week.