3D Printing

The summer and autumn sort of just drifted away and I didn't get a lot of 3D printing done. To complicate things, I was lured away from my shed by the delights offered by IKEA, in particular "Kitchens". Fortunately everything has been built/fitted/commissioned/ and almost approved by the lady of the house. Perhaps now I can get back to trying to print a model aeroplane. After getting success with the Icon-A5 prints, I read an article on the new lightweight PLA. Unfortunately, the designers of the Icon don't recommend it. So I stopped working on the Icon, and ordered some LW-PLA. This took some weeks to arrive as the stuff comes from Germany. In the meantime I found that an outfit called Eclipson have issued mods to their original files to incorporate settings for the lightweight material. Just for fun I downloaded the Eclipson Model T, it isn't anything spectacular, just a routine sort of aeroplane, but it does have the choice of undercart, wheels or floats. The unfortunate episode with my Lazy Bee at Longham last summer didn't deter me from choosing the float option. The airframe is all lightweight PLA, but the floats and supporting structure are regular PLA. The floats have printed quite nicely, and so have the wings. I haven't weighed the wing assembly yet, but some of the parts, like the ailerons are unbelievably light. If I can remember to charge the camera battery, I'll post some photos of the progress.

The wings for the Eclipson Model T weigh 132g. Quite light for a 1.16 metre span. The parts have printed with a distinct wavy effect on the wing sections, but the frail aileron parts are quite straight. The waves are symmetrical and are the same for the left and right halves of the wing. The wing tips weigh 18g and the aileron 7g, being 4g for the part with the built-in horn. The appearance is quite nice, reminded me of Chinese prawn crackers, but there's a tendency to string with some parts like the location tabs. According to the designers, using lightweight PLA will save 260g. I won't be saving quite that much as the floats are standard material.

Once again a long time has passed since I fired up the PRUSA printer. A Spring and Summer spent on refurbishing three newly acquired models, slopping preserver on fences and erecting new trellis panels, didn't leave much time for other disciplines. Back in the depths of last Winter I was asked to print a figure in wood filled PLA
This took a fair time to set up, but was fairly successful and the printer churned out several items. The "thing" is called Groot, and is something to do with Marvel comics. Unfortunately, wood filled resin is prone to block the small 0.4mm nozzle of the printer. One morning I went to check a print that had been left unattended for a couple of hours, the shed had a definite odour of burned wood, and the printer was busy printing nothing at all at some distance above the bed. The blockage had done more than bung up the nozzle, the complete heater block was a mess of burned on resin. Since then, all I've done is order replacement parts and soon I'll strip out the old block and replace it. Its fortunate in a way, the new parts are of an improved design, so with luck, further prints will be a bit better.
So far I haven't had a lot of luck with my choice of aeroplanes to print. The Joker from 3DLabPrint was easy to print and the assembly method gave an accurate model, but the model itself is rather heavy and I've seen two videos where the model disintegrates in flight. I've tried to print models from Eclipson, but I seem to be unable to understand their complicated setup chart, consequently the prints aren't quite right and aren't usable. I've tried printing parts for models by PlanePrint, once again, the setting up is a bit complex and mistakes are all too easy. However, the test parts were encouraging and I decided to choose a model that would use a 70mm 12 blade EDF. Unfortunately the model needs trike retracts, even more unfortunately these are "available" from HobbyKing. They have been on order for nearly four months, the mains came a few weeks ago, but until the steerable nose unit arrives, there's no point in starting the model, unless I ditch the U/C and rely on hand launching.

Hand launch preferably near long grass initially. This may be of interest to you 70mm EDF retract set ex my old Habu 2. You also may have been better off getting some retracts from Motion RC. EU rather than from China.

Thanks Phil, unfortunately the mounting size of all the "Non-HK" servoless retracts isn't suitable. Pity the designers don't offer an alternative mounting arrangement.

Okay, just thought I could help progress a bit quicker. They are redundant at present and gathering cobwebs in a drawer

Over the past weeks, I've spent some time on the Prusa printer. The blockage caused when printing wood filled resin caused more problems than I thought. Poking the nozzle with a needle produced a puff of smoke and a black blob of molten resin that narrowly missed my fingers. Nothing improved the situation and I had to strip the print head and clean and re-assemble it.
The last prints I made of an aeroplane were made for the Eclipson Model T, I wasn't impressed by the quality and I didn't know what to do to improve it. Took the easy way out and abandoned the project.
Then in November 2021 I found a glider called Riser on the PlanePrint website. The video of the model in flight was quite encouraging, and being easily persuaded, as well as a bit soft in the head, I bought the programs for printing the model. Over the last few days I've spent a few hours re-calibrating and generally setting up my printer. The trial prints were OK, and I went on to work on the Wingtest program recommended by PlanePrint, this is in the form of a small airfoil section, and the general idea is to tweak the printer's settings until a perfect print is made. Sounds easy, but it took a few hours to get it right.
Having a new spool of lightweight PLA resin, and a working 3D printer, I started to print a part for the Riser glider. That was yesterday. The print failed after three hours. Today I modified the program slightly and the first printed piece of wing finished printing at three this afternoon. I was quite pleased with the result until I weighed it. The manual says "68grams", my part weighed just over 100 grams.
Obviously I have missed something between downloading the STL files and generating the G-Codes from them. I only downloaded the build manual today, lots of A4 sheets to peer at, perhaps the clue will be in there...somewhere?
The photo shows the wing part three hours into the print.

Hi Brian
At the last C&Dmfc meeting i attended (pre Covid) there were a couple of members exploiting 3D printing with good success and displayed several good examples including a nice Mustang.
Would you like me to try and put you in contact with these guys with view to reducing your R & D ?

Kevin

There are so many things to go wrong with a 3D print, I stopped everything and reviewed the programs again. I repeated the setup tests, I reprinted the test pieces. This morning it dawned on me that I had used up so much filament that I couldn't finish the prints for the wings. Normally, the PLA filament comes on a 1Kg spool, however, light weight PLA tends to be sold in 500Gram spools. Lightweight PLA foams up when it exits the print nozzle, in fact it almost doubles in size. Hence, in theory, you get the same amount of print output from 500Grams of lightweight PLA as you would from 1Kg of standard PLA. The filament I'm using comes from Germany, and I've found that it isn't practical to use filaments from different manufacturers in a multi part assembly like a wing. Guess I'll have to be patient until sometime next week. Still, I've got the Moonglow project to get on with, and working with balsa is relaxing and very satisfying.

I have at last found part of the cause of the problem I've been having with printing lightweight PLA parts. The downloaded files for printing the model insisted that the various parameters set out for the printer settings must be used. Right! Finally, I did the unthinkable and read the manual. Its a very comprehensive document, details every part and the print parameters. The flow rate I was using was 100%, the manual stated 60%. The temperature I was using was 215°C, the manual stated 250°C, so the resin wasn't hot enough to foam up properly. At last, with the flow rate and temperature suitably adjusted, the parts started to print at the recommended weights.