Recap :
Kossel Mini build : Part 0 – a brief explanation of intent and also sources where I got the parts
Kossel Mini build : Part 1 – building the top triangle frame, as it seemed like the simpler of the 4 main components
Kossel Mini build : Part 2 – built the diagonal rods by leveraging parts used on the bottom triangle base
The epoxy was properly hardened when I checked, so I removed them from the extrusions. The 6 x 240mm extrusions are for the bottom base of the Kossel Mini, so I put that aside as I continued on.
This part, I used the following components
- 3 x carriage rails
- 9 x M3x25mm screws
- 3 x M3x15mm screws
- 2 x M3x16mm screws
- 2 x M3x20mm screws
- 7 x M2.5x12mm screws
- 6 x M3 nylon nut
- 6 x M3 nut
- 1 x effector
- 1 x euro connector
- 1 x allen wrench(came with nuts and bolts pouch and it meant to be used in autoleveler)
- 1 x retractable housing
- 1 x j-head hotend
- 1 x pressure fitting
- 1 x micro switch
In addition, I needed to get the following parts:
- 40 mm PC fan
- a safety pin
- a compression spring
- a metric tap and die
There appears to be several different revisions of the rail carriage piece – the piece I got does not resemble the ones in Blomker’s site, nor the current one available from the creator’s github page. This is the reason for using 15mm screws with 25mm screws for this build.
The effector is an interestingly looking piece and it is the platform that the hotend will be attached to.
I had put about 3 or 4 screws and nylon nuts together when I hit a problem. The nylon nuts seem to lock onto the screw prematurely. Normally, a little bit of force would get them going again, but this time the nut started to rotate, chipping away at the plastic.
So I went out and bought a metric tap and die kit and spent some time threading the nylon nuts. It turns out most of the nylon nuts needed to be tapped with an M3 tap. I also had to rethread the screws.
Well, that was a bit unexpected.
Anyway, the opposite end of the rods are screwed into the effector, basically the platform for the nozzle with the heating element.
The effector also has quite a few things going on, so I took a break to work on the effector.
An important feature of the Kossel Mini is the auto level probe. I have high hopes for this probe as it will hopefully be the end of time and effort spent in trying get the height just right. This probe uses a hex allen key as a probe and a string and endstop switch to detect the bed.
This is when I encountered another issue – the opening on the side of the retractable housing would not allow the allen wrench slide down(shown in green).
I was able to remedy that with the aid a dremel and a cutting wheel (shown in red).
Next, I found that the J-Head nozzle does not fit the opening on the effector. Strange, but no longer hesitant to grab the dremel and enlarged the opening to make the J-Head fit. I just enlarged the hole by shaving the walls of the opening on the effector.
And for the final test fit:
I added the bracket with the 40mm fan mount and noticed that the hole on the effector is not deep enough – but I left it as is, since evenly boring a hole is beyond my capabilities.
2 x M3x16mm screws go on the effector and bracket with fan mount, 2 x M3x20mm screws go through the retractable housing, effecotr, and bracket with fan mount
Now, back to the rods. Each end of the rods require 1 x M3x25mm screw and 1 x M3 (tapped) nylon screw.
Getting back to the auto level – next step requires modifying a safety pin into a spring powered latch to lock the probe.
*note – I bent the wrong leg on the safety pin. 😐
A M2.5x12mm screw goes through the safety pin’s eye and onto the hole half bottom of the auto level housing.
I removed the retractable housing from the effector to install the switch. A quick photo of the components that make up the auto level switch :
The compression string is from a hardware store, cut to 24mm.
The auto level switch needs to be wired up on the C and NC prongs.
Upon test fitting, I noticed that the legs of the switch needs to be bent(this is probably better illustrated on Blomker’s PDF)
Next, I’ll need to trim the lever.
When I cut the lever, it wasn’t a clean cut and a little bit was left bent up. I think I’ll leave that as is.
I reinstalled this back into the effector. I also added a bit of shrink wrap to the handle of the allen wrench.
Back on the retractable housing.
I installed the spring and the euro connector this way. On the locked position(see green on left picture), I fully compress the spring and screwed the euro block facing an angle(see red on left picture). This is so that when the probe is released(see green on right picture), the euro connector is facing out(see red on right picture)
Finally, I got the 40mm fan from a “Chipset Thermal Package” kit and installed it using 4 x M3x12mm screws.
I was able to just screw the pressure fitting ontop of the effector without any problems.
Whew, finally done for the day… The amount of trouble I had with the nylon screws and overall fitting issues was bit unusual.