Experiences with building machines in South Africa

Hello… there are quite a few people interested in (and in the process of) building these machines in SA. This topic is to serve as a platform to share all the trials and errors I’ve had in adapting Dave’s machines to be built within South Africa and where I’ve had to diverge from the blueprints…


Starting with the Shredder:
The first problem arose with the laser cutting of Stainless steel. Due to our standards, we do not stock any 5mm material… it is only available in sheets of 3mm, 4.5mm, 6mm and beyond (or less). I tried my hardest to work around this issue by resizing the ‘middle’ sheets to accommodate for the shrinkage, unfortunately there was a manufacturing defect in the 6mm parts and I could’nt afford to re-cut in SS. I proceeded to have parts cut from Mild Steel as we do stock that in 5mm (and it’s half the price) – no alterations were needed and everything came out fine. However, there was slight movement with the blades which meant I needed to insert two extra spacers next to the bearing of 0.5mm – (http://onearmy.world/community/forums/topic/shredder-alignment-issues-2/#post-96218). I’ve envisaged a human powered shredder from my first exposure to Precious Plastic as there are so many places where that alone could create positive change. So I’ve spent my time trying to achieve that… you can see some results here: http://onearmy.world/community/forums/topic/human-power-shredder-v2/ Otherwise sourcing a motor hasn’t been a problem, there’s a great chap by the name of Lionel who builds and sells motors to spec from Chazen’s Electromotor’s. The rest of the shredder is easily fit to local standards and materials… But I should mention that our nearest sized square tubing is 32mm which varies a bit from the original 30mm.

You can view the shredder here: http://onearmy.world/community/forums/topic/human-power-shredder-v2/

Next the Injection:
While the Injection machine looks to be the most ‘simple’ to build, I’ve had some trouble in building it here. Firstly… our nearest, easily accessible extruded pipe to that of the original plans is Schedule 80 plumbing pipe with an OD of 33.4mm and walls of 4.55mm. This pipe is often slightly bent and rusty unless you specify brand new stock. If it is bent, you will need a perfectly flat surface and some way to apply pressure to tweak the barrel until it is straight (or as straight as possible). Thereafter finding a standard corresponding pipe to fit within is a tricky task… In my first attempts to build the plunger I used 25mm round tube and shaved that down on the lathe. However due to the thinner wall it bent and buckled rather easily. I then sought out some 25mm MS round bar, which of course is not straight either… so a lot more time went into bending it as straight as possible. After it was straight I could then turn it on the lathe until it fit inside the barrel. On the machines I had available it was a tough task attaining a perfect surface finish so my final solution was to have the part made from Bright MS bar and have it shaved to size with a process called Centreless Grinding. Building the frame, apart from the slightly larger tube of 32mm, was easy going and so was the hopper, barrel attachments and nozzle parts. During the welding of the tabs onto the barrel I found that the barrel would warp slightly where the cutout is located (and where you’re welding)… there seems to be a very fine line between having enough power to penetrate the metal while being cool enough to prevent warpage.



**Finding an old functional oven in a SA scrapyard is quite the task, as they have mostly already been found and re-purposed by someone else. Gumtree, OLX and JunkMail are the places to look and they are loaded with ovens at good prices. If you’re building your machine to the V1 blueprints it can be quite a finicky process aligning the plate and assembling the thing… I’d suggest going with the V2 blueprints. If your oven works and has a temperature gauge then you’re already halfway there. I used a 2t car jack found at a local Midas and the frame welded up from 32mm square tube.


As for the **Extrusion:

**No progress has been made here… I’ve found it very difficult to source a barrel and screw that fit flush and are the correct lengths. My best bet at the moment would be to order a beefy custom extrusion screw and barrel from the Bazar 🙂



Finding correct electronic components locally for a price as good as those on the internet has been a struggle. This has lead to ordering the parts from ‘bidorbuy’ (a local “ebay”-like store). However, the parts are still shipped from China and take quite a while to arrive in SA. Wiring wasn’t too complicated but it did take me a fair amount of time to get my bearings using the diagrams provided.


This post is a while overdue but I hope that it can help those seeking to help themselves… skip the learning curves and hurdles I’ve experienced

Hey, awesome intel there @timslab !!

Hope it will help out others in SA wanting to launch a Precious Plastic project !!


ps : i am curious about the last photo in this thread, would you mind explaining to me what the 2 differents zones are for ? (upgraded oven i imagine :))

You nails it @timslab.

We use general profiling for our laser cut , one of the biggest in South Africa. Our motor are bought at principal power. Great quility motors and gearboxes with great service aswell.

Great build! Which parts do you do with it?

Hi, I also encountered the problem of fitting pipes for an injector! My solution to this problem: I welded another pipe cut in half and tightly pressed to the main pipe. Based on the dimensions of the heaters, we cut the necessary length and weld it at the location of the heaters, as a result we get not 33.4 mm, but 35 mm. This is for the injector, and for the extruder there will be a problem with the selection of the auger! I did the injector under 25 mm. I apologize for the English language, I use the translator.

Hey thanks @imuh!


This oven was actually a beautiful find… it’s a Kelvinator made in SA some 30 years ago. The bottom section is just a second, smaller compartment used mainly for baking cakes, rusks and other tasty goods… also works really well for those large flat plastic sheets! :stuck_out_tongue: