04 Sep

Kossel – some months in

I think a holiday was what I needed to get my head in the right place for this stupid printer!


Turns out the current Marlin forks have removed the probe feature, as its being reworked. I figured this out in the longest way possible – after around two days of calibrating my z offsets with software. I go to probe, nothing happens. I re compile my old firmware, i get the probe, but no soft end stops. Two weeks later, I just accept that, and use my screws as end stop offsets, and I have the probe back.

Other mods have been a new fan bracket thing for the hot end – it kept colliding into the X and Y towers – now they’re at an offset and fits well – what it hits now though, is the probe pillar, the little thing that puts the probe away after it completes its 22 point calibration!

Maybe I should go to FSRs, but that would mean that I have to undo / redo a lot of work – not happening anytime soon!

The fans are too good though, and my stupid heater cannot manage to keep temps. it got to around 180 despite the target being 210. I reached for my e – z fuse tape, and applied it – now its lovely and insulated, looks pretty decent also.


I’m running new filament, after printing a new spool holder, the thing can be left, I’ve gone shopping to return home to completed prints, its a good feeling! The filament looks good, I have printed around a third of the spool so far, and its been trouble free.




I did have some prints go bad, what looks like the z axis got some skipped steps (on a delta that looks like steps skipped in x / y), not sure why, I did some oiling, and then decided its due to the belts being a bit too tight. When the effector was dancing around doing small infills, it would be quite graunchy, so I slackened off the belts a little and that appears to make it nice and smooth. I ran some prints very slowly last night and the loudest thing was the fan on the hot end – its a very quiet machine.

I also got around to printing and installing the LCD cover – which makes things nice and tidy – it isn’t the nicest of models though…


I also had a go at using meshmixer to generate some rather intelligent support structures – unfortunately it fall off mid way through the structure – but due to the wonders of reprap, it somehow fixed itself when it counted!WP_20150831_17_13_42_Pro WP_20150831_17_38_46_Pro

I doubt i’ll get time for many more mods to be honest, but the list is still there


I know Mark uses this model on his i3 so thought i’d do the same.


IMG_3047 IMG_3048

Some more Grasshopper generate forms  – using the same two profile rails, I was able to modify the amount of divisions of the curve, then draw an arc between the two curves along the sub division. Data MAtching Arc with loft



These guys were printed flat, at 0.2mm and 0.3mm

IMG_3050  IMG_3049

I then re oriented them vertically – spiral vase mode. 0.2mm approx 10mm/s!

IMG_3067 IMG_3069 IMG_3070

Grasshopper vase, worked really well – apart from the undersides of the wibbly bits. I think I will re print, but at a much slower speed – you can see the errors just building up from a previous blip.



22 Aug


Some time ago, and I’m not prepared to say long, I stumbled on a project in Make magazine, the Fetch-o-matic, we have a ball obsessed dog and I decided I had to make one. Overall the project was simple enough to make, I made a few modifications, mainly to suit the motor I got, the pictures should make it all clear.


A couple of pipe clips and the end of a broom handle make up the adjustable height leg


Detail of my pivot design. The ‘pusher’ bar was part of the original wiper mechanism, I just has to flatten the bar . Screwed to the threaded motor spindle is a small turned piece, which acts as a nut to hold the pusher in place, a spacer to set the main bar height and a spindle for the bar to rotate around. The top lock nut is not tight against the bar so it can rotate freely


SAMSUNG These show the microswitch and it’s operating lever. I had this switch in my parts bin but the weight of the tennis ball was not enough to operate it. I used a piece of old copper clad pcb and some duct tape to make up a lever


This is the underside. The motor is attached to a steel plate, if I’d bolted it straight to the ply case the spindle would not have projected high enough inside the case


The underside again, the microswitch is held by the small piece of wood but it also needed hot glue to stop it moving. I wasn’t able to bolt it in as the whole thing was about the same depth as the ply. The battery is loose at the moment so I can remove it quickly for charging. I could just fix it in place and add some charging points for it. I have not fitted a separate switch as the microswitch does this job. I guess there is a small chance something might fall into it when it’s stored and cause it to activate, but I can just disconnect the battery.


Another view of the inside, the loose end of the spring attaches to the lid.

I Finally completed it over the weekend, at least to point where I could try it with the dogs.
I’ll start by saying that when I built the dog kennel, it took a good few months before either of our dogs showed any interest in it. I’m hoping the same will happen with the fetch-o-matic cause I had a frustrating Sunday trying to get Rylie to drop the ball into the hopper. I was depending on her ball obsession and her habit of dropping a ball anywhere where I happen to be focussing my attention, If I hang out washing I usually find the ball in the washing basket, If I dig up some potatoes the ball gets dropped in the hole, If I shovel some compost the ball gets placed in the wheelbarrow, you get the idea. No matter how much attention I gave the hopper  the only way the ball ended up in it was if I put there.  Just to make her point, on Monday morning I was drinking a cup of tea outside, Rylie jumped on the table and dropped a ball in the mug.

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Our other dog, Seamus just barks at the machine whenever I put a ball into it but he does that when I throw things for him too. At least he did learn fairly quickly to get out of the way.

There are a few improvements to make still, I think the bar will wear out where it pivots on the shaft so I would like to create a hub for the bar, connected to the shaft using a proper bearing, should be easy enough to make on a lathe. The lever I made to operate the micro-switch uses duct tape as a hinge, this works quite well but I think I need a tape with stronger adhesive. A stronger spring or maybe a weighted bar may also help give it more range.

Update: Made a little bit of progress with Rylie today, got her to drop the ball in the right place a few times but she’s not getting the connection between dropping the ball in the spot and having it launch. Originally the whole thing was painted white but I’ve now painted the hopper a different colour, which may have helped a bit. I’ve gone for Blue hopper which should be a colour dogs can perceive. Seamus, as ever, just barks at it.
Rylie does seem more interested in actual interaction with me than I was expecting, as Jonathan suggested might be the case. We may have to arrange for an event in a local park so we can bring our respective dogs and see what chaos ensues.