I need a complete list of fasteners (bolts, nuts and washers) for the Sintron Kossel.

Has anyone bought this kit, and knows the answer, or knows where this is documented?

A complete list would be great, but in particular, I need the dimensions (M2.5/3/4/5? and length) and quantity of the bolts (and nuts) which:

  • fasten the PCB mounted mechanical switches to the PLA rectangular end stop spacers/holders, and;
  • fasten the PCB mounted mechanical switches and the PLA rectangular end stop spacers/holders to the extruded 2020 aluminium.

I have:

  • Searched the web, but to no avail;
  • Read the product page, which states only "screws and nuts provided";
  • Contacted Sintron, but not had an answer;
  • Obtained the Sintron build manual but there is no list contained therein, nor contains details about the fasteners relating to the endstops, and;
  • Obtained the Blomker manual, from which the Sintron manual is copied, but that also has no list (as well as not being relevant with respect to the endstops).

Note that I am only interested in the fasteners specifically for the Sintron Kossel and not the Kossel in general. The Sintron uses the PCB mounted mechanical switches (with four holes), and not the simple barebones mechanical switches (with two holes), and uses 2020 aluminium1, not 1515 OpenBeam:

Endstops and PCB mounted mechanical switches for the Sintron Kossel

Why? Because I purchased only the 3D printed parts from Sintron, and I am sourcing the rest of the parts cheaply, either locally or from Chinese suppliers on eBay.

1 In my particular case, there is an additional complication. The profile of the non-standard/non-"European" 2020 extrusion that I am using, does not take T-Nuts, only M5 hexagonal nuts (it is unbelievably difficult to find the standard 2020 extrusion in Bangkok). Combine that with the fact that the Sintron kit uses only M3 nuts and not M5 (I only discovered this after purchasing the printed parts kit (see the email from Sintron, in my answer below) - not through lack of research, but because there is no available list of fasteners), then I have the problem of finding a nut to use (see Fat hexagonal M3 nuts, with outer diameter greater than 6 mm).

Here is a photo

Four pieces of 2020 Aluminium extrusion

  • 1
    $\begingroup$ The Sintron build manual clearly states what fastener is used for each location. Every picture has the size and length on it. $\endgroup$
    – tjb1
    Jun 1, 2017 at 13:19
  • 1
    $\begingroup$ For the endstops you're just going to have to measure what you have for parts and buy as needed. I'm not even sure how they use all 4 holes as it looks like 2 of them may block the connection. $\endgroup$
    – tjb1
    Jun 1, 2017 at 13:30
  • $\begingroup$ Also, many wire cutters/crimpers have bolt cutters built-in near the hinge that are more than capable of cutting M3 screws - a.co/dew90MR so you could just buy the longest length you can find that are fully threaded and cover everything below. $\endgroup$
    – tjb1
    Jun 1, 2017 at 13:43
  • $\begingroup$ @tjb1 - Unfortunately, the SIntron build manual does not state it clearly for the endstops. Blocking the connection - yes, it is a pretty crappy printed kit, to be honest, FolgerTech is superior, although I only paid $20 for the PLA parts and $20 for the 2020 aluminium... Cutting bolts to length. with wire cutters, tends to damage the thread of bolt. A Dremel will do though, I suppose, but I would prefer, in order to keep costs to a minimum, to order the correct length of bolts, as the longer bolts cost more... Not by much I know, but I'm building these for people on extremely tight budgets. $\endgroup$
    – Greenonline
    Jun 1, 2017 at 15:38
  • 1
    $\begingroup$ You may want to simply make square "nuts" to suit your extrusion with flat stock, a saw, a drill, and an M3 tap. That's what I'd do, anyway, if I couldn't find ones to purchase. $\endgroup$
    – Ecnerwal
    Jun 1, 2017 at 17:58

3 Answers 3


I found two lists for the Kossel mini (the documents you referenced are for a mini, so that is what I am assuming you got). One as a Google Doc and one as an order sheet

Both seem to list all the fasteners.

Here is a Sintron mini carriage assembly and it lists the hardware included

I found an ebay listing for the Sintron 2020 Rails. The recommended screws are M3x20mm and here is the infor on the required t-nuts.enter image description here

Happy building.

  • 1
    $\begingroup$ Note: I don't have a Kossel; so, no guarantee the lists are complete. Anyway, it is a kit; so the parts you need is a bit "flexible". I built a Tronxy X3 kit and the parts supplied were mostly complete; but, several build steps called out parts that weren't in the kit. I am glad I have a pretty good selection of screws and nuts in my shop. $\endgroup$ May 31, 2017 at 20:48
  • $\begingroup$ Many many thanks, but unfortunately, they are not for the Sintron kossel. I have seen those links (see my (confused) blog Kossel 3D Printer. However, the Sintron Kossel, whilst having many common features with other Kossels, is a bit of a particular/peculiar beast. W.R.T. the endstop holders, the Sintron uses the PCB mounted types (with four holes), and not the simple barebones mechanical switches (with two holes) that the TriDPrinting/Google docs uses. I'll update my question to be clearer. $\endgroup$
    – Greenonline
    Jun 1, 2017 at 0:42
  • 1
    $\begingroup$ @Greenonline Well that is complicated. I'll see what I can find and add it to my answer. $\endgroup$ Jun 1, 2017 at 6:07

For the M3 t-nuts, could you use this printed solution. You are just attaching a PCB; so, it you wouldn't need that much strength.

Another excuse to use your 3D printer. ;)

  • $\begingroup$ That is a good tip, but I need them, principally (along with other reasons), for attaching the extrusions to the vertices, so they need to be strong and in metal really... $\endgroup$
    – Greenonline
    Jun 1, 2017 at 19:49
  • $\begingroup$ But, why can't you use M5 for the other locations? (Note: Use of "But," is a homage to your English Post $\endgroup$ Jun 1, 2017 at 19:55
  • $\begingroup$ All of the holes in the Sintron printed parts are M3. I considered reaming the holes to make them M5, but i don't want to lower the integrity of the parts, i.e. weaken them, nor have (slightly) misaligned screw holes, etc. $\endgroup$
    – Greenonline
    Jun 1, 2017 at 20:04
  • 1
    $\begingroup$ @Greenonline, I will add the comment to you engineering post; but, IMHO, it is providing you with a different option for one of the parts to use (so, an alternate parts list). $\endgroup$ Jun 2, 2017 at 17:00
  • 1
    $\begingroup$ Another option would be to purchase some 4mm x 5mm bar stock and tap your own holes. All you would need is a drill press and an M3 Tap. That would be as strong or stronger than someone else's t-nut. $\endgroup$ Jun 5, 2017 at 19:44

After examining the guide (Kossel mini instrution by sintron technology_v2) and the printed parts kit, I came up with an 99.9% complete parts list. The lists relating to the effector and autoprobe mount maybe slightly incorrect:

##Parts List

###Listed by Printer part/section:



For each:
10 x M3 x 8 mm
10 x M3 nut (T-nut)


For each:
5 x M3 x 8 mm
5 x M3 nut (T-nut)

1 x M3 x 35 mm
1 x M3 nut
1 x M3 washer


For each:
1x M3 x 25 mm
4x M3 Washers
1 x M3 Nut
2x F623ZZ


For each:
2 x grub
4 x M3 x 8 mm
1 x 16T/20T GT2 pulley


6 x M3 nyloc nuts
6 x M3 x 25 mm

4 (5?) x M3 x 16 mm <<==, or
2 (3?) x M3 x 16 mm <<==
2 x M3 x 20 mm <<== For the auto probe, if mounting the autoprobe directly on to a collar, above the hotend, and not on to the flange on the Sintron PLA collar

4 (5?) x M3 nuts <<==

2 x M3 x 8 mm <<== fan mounted to Sintron PLA collar
2 x M3 nuts <<==

1 x PC4-M6

Note: Some additional bolts are required for the mounting of the hotend. It is unclear what these are. See link.


For each:
2 x M3 x 20 mm


For each:
2 x M3 x 10 mm
1 x M3 x 25 mm
3 x M3 nuts
3 x M6 x 25 mm
3 x M6 nut    
2 x M6 washer (optional)


For each:
1 x M3 x 8 mm <<==
1 x M3 nut (T-nut)
3 x M3 x 8 mm <<==
3 x M3 nut


6 x 625-2RS Bearing (or 625zz)
5 x M5 x 20 mm
1 x M5 x 25 mm
6 x M5 nut
6 x M5 washer
(or 7 x M5 washer – there is a discrepancy between the kit (7) and the manual (6))
3 x M3 x 8 mm ?
3 x M3 nut (T-nut)


1 x M3 x 40 mm
1 x M3 x 8 mm
1 x M3 x ?? mm <<==
2 x M3 nut (T-nut)

1 x PC4-01


Note: This is optional

2 x M2.5 x 12 mm
1 x M2.5 x 12 mm
2 x M3 x 8 mm <<==  If mounting the autoprobe on to the flange of the Sintron PLA collar (if mounting directly on to a collar, above the hotend, then these are not required, and 2 x M3 x 20 mm replace 2 x M3 x 16 mm on the effector)
2 x M3 nuts <<==  If mounting the autoprobe on to the flange of the Sintron PLA collar (if mounting directly on to a collar, above the hotend, then these are not required)

Safety Pin 2.5 mm
Spring 23.5mm

Terminal Block
1.5mm Allen key

Note: Some additional bolts are required for the mounting of the autoprobe, as well as the hotend. It is unclear what these are.


3 x M3 x 8 mm ?
1 x M3 x 20 mm
4 x M3 nut (T-nut)


Note: This is optional, as mounting on the top will interfere with the spool

2 x M3 x 35 mm
2 x M3 nuts
2 x M3 nuts (T-nut)

###Total Parts:



Size, Length, Quantity
M3, 25, (1×3)+(6)+(1×3) = 3+6+3 = 12
M3, 8, (10×3)+(5×3)+(4×3)+(4x3)+(3)+(1)+(2)+(3) = 30+15+12+12+3+1+2+3 = 78
M3, 16, 5
M3, 20, (2×3)+(1)+(2) = 6+1+2 = 9
M3, 10, (2×3) = 6
M3, 35, 3
M3, 40, 1
M6, 25, (3×3) = 9
M5, 20, 5
M5, 25, 1
M2.5, 12, 3


Size, Quantity
?, (2×3) = 6


Size, Quantity
M5, 6
M6, (3×3) = 9

M3, (10×3)+(5×3)+(1x3)+(1×3)+(5+2)+(3×3)+(1×3)+(3×3)+(3)+(2)+(2)+(4) = 30+15+3+7+9+3+9+3+2+2+4 = 90


M3, (1×3) + (1×3) + (5+2) + (3×3) + (3×3) + (2) = 3+7+9+9+2 = 33
M3 T-slot nut, (10×3) + (5×3) + (1×3) + (3) + (2) + (4) = 30+15+3+3+2+4 = 57


Size, Quantity
M3, 6


Size, Quantity
M3, (1x3)+(4×3) = 15
M6, (2×3) = 6
M5, 6 (or 7)


Size, Quantity
F623zz, 6
625-2RS, 6
625zz, 6

####Printed Parts



3 x 2020 x  750/600 mm
9 x 2020 x 360/240 mm


1 x Arduino Mega 2560
1 x RAMPS 1.4
5 x Stepper drivers
3 x PCB mounted mechanical switch
3 x Stepper motors
1 x Extruder stepper


3 x 16T/20T GT2 Pulley
GT2 belt (5 meters)

####Other Parts

Safety Pin 2.5 mm
Spring 23.5mm
Terminal Block
1.5mm Allen key
9 x Delrin wheels
9 x 696zz bearings

1 x PC4-M6
1 x PC4-01


The fasteners required for the following parts is, as yet, unclear

Effector/Hotend mount
Autoprobe mount
Additional Extruder holder screwpoint


Hotbed frame mounts (assumed to be M3 x 8 mm)
Spool frame mounts (assumed to be M3 x 8 mm)
Endstops (four M3 x 8 mm are used, not just one)

See also Kossel - Sintron parts list.

I have a partial answer from the suppliers:


Good Day !

thanks for your contact.

we use M3 bolts + T-nuts .

i suppose the problem is , you don't have T-nuts , right ?

T-nuts is used for 2020 extrusion.

with warm regards.


I replied for a clarification of the length required:

Many thanks for the reply.

I have two types of 2020 extrusion, with differing profiles: one that takes T-Nuts, and; one that takes regular hexagonal M5 nuts.

For the T-nut extrusion I have both M3 and M5 T-nuts.

However, the second type of 2020 extrusion takes regular M5 nuts. Regular M3 nuts will not stay in place, unless I can find some M3 nuts with a larger outer diameter, greater than 7 mm.

With respect to the M3 bolts, what are the lengths required? Are two lengths used? One length to secure the endstop switch and holder to the 2020 extrusion, and then another length to secure the remaining three holes? Looking at the diagram in your build guide, it seems as if only one bolt is used to secure the endstop switch and holder to the frame, is that correct? Are any other bolts used to secure the PCB mounted switch the the endstop holders.

I thank you in advance.

Best regards

I followed this up with a second email

Hi again James,

Following on from my previous reply.

Firstly, I have found that flanged M3 nuts will work perfectly, in the extrusion that will not accept T-Nuts.

Secondly, what I really am looking for is a list of the lengths (and dimensions) of the bolts used throughout the Sintron build. In particular the endstop bolts. Rather than having to iteratively deduce each bolt, a list of the bolts used would be very handy.

I thank you again in advance for your kind consideration.

Best regards,

I received a second reply from Sintron

Hello Friend.

for endstop . it's M3*8mm .

i am collecting the list of them for you soon.



  • $\begingroup$ As a friend of mine said "sounds like a lot of data; but no useful information". I added some info on the t-nuts and screws to my answer above that may help. This is another solution that might work. $\endgroup$ Jun 1, 2017 at 6:46
  • $\begingroup$ @markshancock - The particular 2020 aluminium extrusion, which I am using, will not accept regular T-Nuts, although I am not sure about the slim half T-Nuts. See Fat hexagonal M3 nuts, with outer diameter greater than 6 mm. Flanged hex M3 nuts seems to be the way to go. $\endgroup$
    – Greenonline
    Jun 1, 2017 at 6:52
  • $\begingroup$ @markshancock - I love the idea of 2830 pieces of fasteners... :-) Unfortunately, upon further thought, flanged hex M3 nuts aren't a solution, after all. They would have no purchase on the sides of the slot and would spin hopelessly upon being tightened. Seems like I will have to get standard extrusion, that will accept T-nuts, and use the non-European extrusion for a different set of printed parts that use M5 nuts. $\endgroup$
    – Greenonline
    Jun 1, 2017 at 12:43
  • $\begingroup$ I am really surprised you are having so much challenge with the t-nuts fitting the extrusion. The extrusion you have must have an non-standard profile. If you buy more 2020 from eBay, I recommend you buy the t-nuts as part of the set. $\endgroup$ Jun 1, 2017 at 15:20
  • $\begingroup$ Here is the offering on eBay where I got the profile. I dislike linking eBay offerings since they are temporary. I'm including it separately so I can deleted it later if the link goes dead. $\endgroup$ Jun 1, 2017 at 15:21

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