Sail carts continued
While printing the second cart in yellow ABS I realised that I have much better material for these sail carts.
ABS is way better than PLA which will disintegrate in sunlight and become brittle pretty quick. However, ABS is also prone to UV-degradation and sitting on sailboat mast will expose it to much radiation.
I have PETG filament which should stand much longer. It is the same plastic as used in soda bottles. Food grade, resilient and strong. One I have is black or, second option, milk-white and changing colour when exposed to UV. Nice option to monitor Sun’s activity.
BUT - why not go with the original material these carts were made from?
Nylon, of course. My aged carts lasted 50 years. If these newly made will last equally long then I’ll be gone long before they break.
I picked specially formed nylon, adjusted for relatively easy 3D printing.
I say “relatively easy” to use because last time I tested it few years ago it become a huge mess of plastic spaghetti after overnight print: component has loosen itself from the table and things went wild. I also clogged the nozzle with, apparently, wrongly set melting temperature.
Messy business.
I did some more reading and performed additional tests to adjust printing parameters. I use power-raft option to keep it stable on printing table. One cart takes 4h30min to build. I left the machine working when leaving the factory. Last time I checked things were going OK.
I’ll hope to see finished component tomorrow morning, for strength tests and some finishing touches in the workshop.
POSTSCRIPTUM
Morning after I checked the result. I had high hopes. Turned out - again - that things went wild during the night.
Not too bad, “spaghetti” started close to the end so it would be possible to use this cart, I thought.
I was wrong. I could separate layers with hand strength.
Apparently it got loose from the table. Also - adhesion between layers is too low due to cooling of the previous layer before it melts together with the next one.
I made another attempt. This time with print parameters which should make this more like moulding process: very fast print, high melting temperature and very hot table. Print started OK so I left the machine and went on with work.
Checked the results after 2 hours.
Nope! Even worse.
Last attempt then, before I dump this filament for good. Stronger power raft, slower printing, cooler table: 110 degrees. After 3 hours, when I checked again I could see that it is on the verge of popping out of the build table. In desperate attempt I secured the power raft with silver tape (which started to melt in 110 degrees but held it still all right).
Print finished and all looked well. No cracks on the surface, no warping.
I tried breaking it with my hand and … it snapped! Not good.
I dump the idea with 3D printing such objects in nylon. Apparently it is too sleek to properly bond layers. Objects become nice and smooth but are weak in layers’ direction.
I started PETG print instead. I shall see tomorrow how that goes. High hopes again …