30 May

Mini Kossel – it continues!

Will be posting this a bit retroactively as its very very very near completion!

That is, until something goes a bit wrong with the next thing that gets implemented!

I spent the bank holiday weekend putting in the hours – I loaded up a couple of different build guides to assist me – but most of it was pretty straight forward! The printed parts all fit, the only real headache was the sawing of the aluminium extrusions. I would strongly suggest either taking extra care when cutting by hand to ensure that the extrusions are cut to the correct length – or just get a purpose cut  set via ebay for a similar price than straight lengths. as a friend of mine said – you cannot put a price on ball ache!


Assembling the top frame mounts – very minimal clean-up required. The Ultimaker did a great job at printing these parts for me! I didn’t buy the flanged bearings for the belt guides – no idea why – so instead I am using bearings and washers. They are a bit noisy – so will have to gauge how annoying they are when I am printing to warrant replacing them with flanged bearings in the future.


A little bit further along and now the parts are assembled, at least for a dry fit. The colours look great IMHO.


I chose to add some stepper dampers to the build – its typical to get a song played at you by the printer whilst its doing its thing – but it gets old fast. These were about £5 each and more of an indulgence then really necessary. There are other out there made of lasercut cork sheet – but their cost isn’t that much less than these beasts.


Another shot of the top and bottom frame – with motors installed.


To create the rods for the delta I had to assemble the traxxis mounts and then bond them into the carbon rods. Wasn’t too much faff, I brought pretty decent araldite so that it would set quickly – turns out that I didn’t have any time left in the day and had to leave it overnight anyway! The other thing that is crucial is how long they are – I didn’t really focus on that – so will have a bit extra work to do in the calibration….


End of day one – about 4 hours in total as we spent a good portion of the morning faffing about in the car, followed by the eurovision party which stated at 6. The weather was great on the Saturday so started the build outside – I think there are still bits blowing around to be honest :s.


Start of day two – and I realise that the rails I brought only take M3 Cap screws and my extrusion starts from M4 – but really wants M5. So I had to improvise! Lots of M3 caps later with larger washers over a small washers – and then jamming it into the extrusion. I didn’t have much clearance and the nuts were on by a quarter turn, so a couple fell off during install – I must admit – I just carried on…hopefully it wont rattle too much when doing travel moves! I had to use a power drill to spin and tighten the nuts on the fasteners, as there as no purchase or bite on the smooth washers to the inside of the rail – most of them are tight now though! I possibly should have used MGN 15 – but that would have required remodelling the carriages…


The effector for the delta – pretty straight forward to assemble. Once again i’m using slightly longer bolts for no reason other than that’s what I have…


Mounted and installed with the timing belts – all standard. Except I got to use my matching cable ties! There is something to be said here though – and had I known this before (possibly through lack of research!) but I installed the rails where I was instructed – yet it starts several CM from the top frame,  I have at least 2CM extra space there now – surely I could have used that space for extra build volume?

Secondly – I spent a fortune on these rails – 400mm long. But due to the design – I dont have that length to build with.. So either A, I could have brought rails 250mm and saved some cash (they don’t exist as off the shelf purchase) or to extended the extrusion to 900 high, and mount the rails accordingly to get around 350 / full 400mm of build. In theroy its a simple swap – in reality – its a day to do that…so possibly wont bother!


here I am getting the wiring sorted – I brought the wrong size connectors from RS – so that was a bunch of money wasted! I opted to use female headers and solder my wires to those – a much more affordable method (and available to me without any extra purchases as I just raided the bits box).

The means I can slide them onto the pins on Ramps without any hassle!


The motors all wired up (X, Y, Z) – looks like doc oc from spiderman! What I didn’t realise was that now I started with the cable management – I had to continue – and that’s pretty much where the rest of Sunday and all of Monday went!


Its current form – my desk got really messy – and my usable workspace got less and less. I really should go tidy up but that’s not going to happen any time yet! its one of those things though, by front loading this, I wont have to re visit it later down the line, and when that involves a lot of soldering and connecting, re connecting, it worked out better I think in the long run.


One stupid oversight was the lack of mounting for my hot end – I was in a bit of a panic about it really as I don’t have any real tools, let alone material at home to fabricate anything! But, I do have my not yet calibrated Huxley on hand, and I quickly found a part on thingiverse and printed him out. Its a bit on the slide, but fits a treat! Its the white part in the above image. I have since taken it off, as I needed the space for the fan mounts and also, it pulled the hot end into the effector so well it created a very tight interference fit.


This was now Tuesday evening – meaning its eating it my evenings… I had hoped to have gotten it all sorted within the bank holiday – but that  went out the window with the amount of time it took to sleeve all the cables!

The above image is part way through the calibration stages – to ensure the machine knows where the bed is or some other stuff, like how long its arms are or something. The instructions looked very daunting – but I read through them slowly a couple of times and I think its pretty simple – very different to setting up a cartesian printer, also easier as I’m just following someone else’s hard work!

I did think though that it was a waste of time to continue with the calibration as I didn’t have the heated aluminium bed yet – so it would be fruitless – also it was late! I see a lot of videos on youTube that only print on glass – but I am going for the heated bed option. Whilst I don’t have much experience in printing ABS, I do have a couple of rolls of it, so that might save me a few quid in the future. Also, a headed bed on PLA is quite common now.



So I got onto fabbing one at work – I was planning on using the rotary table on the bridport mill – but was advised to use a jigsaw and the linisher to nibble and smooth it out. It didn’t take all that long really and surprised myself how close to the edge I managed to cut! There are only a few flats on the circumference, good enough for my needs that for sure :).


Just a shot to show it all really very close to finishing! I also made a plywood insulator for below the bed – so in all its a 10mm thick bed! I had to do something about that as I want as much build volume as I can squeeze out of it. Also in the above image was a bed holder I d/l and printed – but it didn’t fit my 170mm build area! Also the tongue that supports the bed was about 5mm so that just would not do!

I promptly measured around and figured I could drop the bed into the base of the printer – as the bed is only 170 across.

eds kossel bed

So they clip to the frame and sink below on the inside – and the glass bed will be a mm or so proud of that.They’re installed and look pretty good!

ed 1

I Dropped into an electrical shop on the way home today and grabbed some terminal blocks, this allowed me to get on with the Z probe – something that allured me to the kossel in the first place.  It took a while to figure out how the thing worked, and how long to make the probe – but its all installed now and really cannot wait to see it bopping around the bed to get my prints looking sexy!

Now I just have to find a day to go through the lengthy calibration process – I hope the build went well enough now to attain the finishes that made me want to build the machine in the first place! Maybe I’l do that Sunday… 🙂



Last Updated on 14 June 2015 by Mark