Christmas is near, so we slow down a bit.

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Dec 152019
 

This time of year other things need my attention, so I’m a bit slow at the moment. I’m still working on the tail side plating near the stabilizer of the SA750.

However, something as mundane as ‘a bit of plain 2mm iron strip’ proves hard to come by at the moment. Everywhere I look I can get stainless steel, but I need the lowest, softest iron I can get. I need it to make those small pesky tags to attaching the plating. This means drilling the holes at the right size for a 2 mm tap, without braking everything. As these things go, the first side went without a hitch, repeating the other side has wipes out my stash of properly sized drills. I am now waiting for Santa to deliver more.

So, in the meantime, I got a request for some multi cylinder gadgets. No problem, he says optimistically, after all the printer prints nice and smooth, at a reasonable high speed, what could go wrong?

Nothing, just that my standard slicer (the one I cursed before) did not want to know. So again back to Cura. At least we are on talking terms, it’s just a matter of dialing in all these variables.

And so you discover that PLA does shrink. Most parts I have printed never had any issues, but this one was challenging. No matter what I tried, it kept warping and popping loose from the bed. At 140 mm diameter, a 1 % shrinkage is 1.4mm. And it does shrink more then that.

Anyway, he who wastes a lot of plastic, will succeed. One of the ”secrets” I discovered was a special magic substance for coating my super duper sticky bed. (as in, I never got to stick large parts to it). There are stories around about using pva based hairspray and such. Then one dark night the lightbulb went on: I’ve got loads of PVA, it’s called wood-glue. Squirted a bit in a container, added a bit of water, mix and apply. (I’ve seen suggestions for a 10-15% ratio water/glue.) And to my astonishment, my very unwilling parts stick. No more warping, no more popping loose.

Printer doing it’s job.

If that was all there is to the story, I would have been finished long ago. But Murphy had a good time!

  • My extruder stopped at random times, mostly when I was not watching.
  • The feed tube at the top of the filament heater popped out at midnight.
  • The filament escaped from the extruder
  • Of course a blocked nozzle to make it more fun.
  • My printer can print quite speedily, but that proves its (my) downfall.
  • Printed parts started cracking after a day.

The extruder problem was caused by a broke wire at the connector motor. Why now? Why not now? It took a bit of searching to locate that problem.

Feed tube is held by an Festo connector. It just got tired from being moved around continuously. Fixed that.

Filament guide had to be remade, including better alignment of feed rollers and tubes.

spaghetti, but not as like it!

Blocking nozzle, obvious some cr@p in there.

Printing too fast: oops, actually, that is fine for small parts, where shrinkage is nu issue. Bigger parts, contrary to gut feeling, need to be printed much slower, so that the hot plastic does not cover more than 2-3cm in length.

So after all this was overcome, I have now printed multiple parts where the print-times are in excess of 18 hours. As always, the end result is much experience gained, a much better printer, and plans for a much larger volume version are being hatched!

The result is a nicely printed 9 cylinder dummy engine, printed at 0.1mm layer (with variable layer thickness at the top) speed of most sections ca 60 mm/sec. Bed is 45 C, nozzle at 215 C. GCODE file is approx 75Meg.

in the end, all is well 😉

Is this a gamechanger?

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Nov 052019
 

There are many CAD programs, almost all of them require a large investment in time and ofter money.

I just discovered shapr3d. It looks awsome. I don’t say this lightly. But it looks to me like this is going to be a gamechanger.

I managed to create this cowling as a test-object.

Is there a downside: yup, it needs an ipad. So far I’m lucky enough to be able to use the one provided by my boss.

It ain’t working the way I want it to..

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Oct 082019
 

I’ve come to a grinding halt with OpenSCAD. Pity, but so is life. I learned a lot, and maybe, just maybe there are tricks to do what I want, but since my maths-magic is not that strong, I have decided to stop using it for this project. For quick jobs it certainly does work great. But as soon as you want complicated surfaces, it no longer has the ability (I don’t have the ability) to make it work for me.

But there is an alternative. For too long I have put off using Freecad. Mostly because it takes a lot of learning. So as always, jump in and stick with it. I generally know what I wanted to do. Trace an image (scale it of course) and create a form that can be manipulated. Some tracing something usually involves lots of not so straight lines and curves, the magic words are B-Splines. But between ” it can do that’‘ and something that can be used by me, takes a few hours of hard labor.

Anyway, before I loose it, here is the first ”thing” I made, basically the front part of the fuse, extended backwards. Next I need to copy that to a similar shape, but with slightly different bottom section. It sounds easy. Yes, in a few years I will say that.

The shape I created peeking through the image I used as template.

..and in between I had a pc that blew up, not sure if it is hardware or software, time will tell!

 Posted by at 6:45 pm  Tagged with:

This part time retirement is fun!

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Oct 012019
 

Another day of shed-time, life is good! Continued cleaning up, while the print-slave does it’s printing. (don’t want to leave him alone, in case the dreaded grey electronic smoke escapes. As is well known: All electronic equipment works by the grace of the grey electronic smoke contained therein. As soon as it escapes, your system stops working!)

Anyway, as I said yesterday, I’m not having much luck with Simplify3D, maybe it always was like this, maybe I just forgot. Whatever, Cura in it’s present incarnation does the job very well indeed. Never a bad thing to have another slicer to fall back on. So today was undercarriage day. Got one legwarmer printed properly, weight is 30 grams. 2 walls, and 8% infill. The 1st one had 4 walls with weight to match (60 odd gram)

The next step is designing the cuffs between legs and fuselage. It looks complicated (it is) but if you start with simple forms, and add on from that, it should all be ok in the end. It’s just a matter of stacking the right size of cylinders, cubes and various other bits of magic together. (Hey, I have to convince me-self that it is simple.)

The end result is sitting in front of the screen, but this black PLA is impossible to photograph, so take my word for it, it’s nice 😉

multitasking!
Cura sliced the Openscad design on the right, finished object in the front.

..and no, I have not stopped working on the SA750, this is all part of the fun. I need to make that turtledeck, and the nose-cowl, and various other bits. So, it’s all part of the same game! (oh, and who knows, a driver?

 Posted by at 6:16 pm  Tagged with:

A few 3d print notes

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Sep 302019
 

As always I manage to find the bugs.. Just do quick test for the PT-17 legwarmers.

The design was easy, so what can go wrong. I have been using Simplify3D for a long time, always did what I asked it to do. Until now. I asked it to print this very simple structure, but for reasons only known to it’s inner self, it prints the outline and infill and ignores the internal tube. Ok, well if you don’t want to play, there’s always Cura. And lo and behold, Cura plays nice. Ah well, so I let Cura do the slicing and upload the result directly to the Octopi, and all is well. Pity this is, because I really like(d) Simplify for other reasons. I guess I’ll have to dive into the interwebs to find out the why..

Meanwhile, my Printslave is doing it’s bestest.

important bits of code are there, so that I don’t loose them!
..always fun to let others see glimpses of the workshop 😉

yeah, I need to add some lights at the back of the camera, now where did I put those leds again?

oh, yes the link to the original code: https://github.com/ErroneousBosch/OpenSCAD_airfoil

Openscad again.

 3D print, Acroduster  Comments Off on Openscad again.
Sep 232019
 

3 reasons, Ed asked my if I could do something for his latest project, and I really fancy those 1970’s looking flared undercarriage pants as well. So, bite the bullet, and do some thinkings. I found what appears to be a good starting point on github, so let’s see if we can do this. The greatest hurdle for me is the design phase, once I have the .stl file it’s simple.

The 3rd reason is that I am knackered from working in the garden today, SWMBO decided that the path that runs around the garden needs moving.

The program as is does allow multiple profiles sections, but it does divide then equally along the span. Not what I need. So we have two options, fix the code, or make the pants into multiple sections. The first method will require brain-cell activity, we go with that!

28 sept: It’s a bit of a slow week with other jobs taking priority, but things are progressing. Taking the road less traveled is definitely keeping the braincell entertained. I learned a lot the past few days. I managed to get the turtledeck drawn, and I thought it was then only a matter of printing. Oh the folly of innocence..

it really looks great, measurements are correct, just print it..
of course it does not fit in my printer, but I knew that.

..so what is the challenge? When I import the .stl the ‘skin’ is either to thin, so that the printer does not see it. (less then the 0.4 mm orifice of the printhead.), or if I make the part thicker is starts to complain in a language I do not want to repeat..

/*
Construction of the turtledeck for the SA750.
Date: 28 sept, 2019
Inspiration: https://openhome.cc/eGossip/OpenSCAD/lib-bezier_surface.html
OpenSCAD 2019.08.04
All rights as usual, do as you please, it's open source. 
*/

include <bezier_curve.scad>;
include <bezier_surface.scad>; 
include <function_grapher.scad>;

t_step = 0.01; // smoothness, might be too much for real life printing.
thickness = 0.1;
width = 0.1;
inch=25.4; // is an inch
scale=0.33; // my scale

// refer to fuse stations on full size. 
sta75= 0; 
sta100=25*inch*scale; 
sta120=45*inch*scale;
sta125=50*inch*scale;
sta129=54*inch*scale;
/*
Draw the approx formers on a piece of grid paper, and take the coordinates from there. 
*/

formers = [
//former at sta75
    [[-109,0,sta75],[-100,36,sta75],[-80,82,sta75],[-60,105,sta75],[-40,124,sta75],[-20,136,sta75],
    [0,140,sta75],
    [20,136,sta75],[40,124,sta75],[60,105,sta75],[80,82,sta75],[100,36,sta75],[109,0,sta75]],
 
//former at sta100
    [[-75,0, sta100],[-60,55,sta100],[-40,92,sta100],[-20,105,sta100],[-10,120,sta100],
    [0,150,sta100],
    [10,120, sta100],[20,105,sta100],[40,92,sta100],[60,55,sta100],[75,0,sta100]],

//former at sta120
    [[-55,0,sta120],[-30,30,sta120],[-20,43,sta120],[-10,46,sta120],
    [0,50,sta120],
    [10,46,sta120],[20,43,sta120],[30,30,sta120],[55,0,sta120]],

//former at sta125
    [[-44,0,sta125],[-30,30,sta125],[-20,43,sta125],[-10,46,sta125],
    [0,50,sta125],
    [10,46,sta125],[20,43,sta125],[30,30,sta125],[44,0,sta125]],
 
// and a fake one to get the rudder blended in.
  
    [[-44,0,sta125],[-30,20,sta125+6],[-20,30,sta125+12],[-10,40,sta129-14],[-5,65,sta129-6],
    [0,250,sta129+inch],
    [5,65,sta129-6],[10,40,sta129-14],[20,30,sta125+12],[30,20,sta125+6],[44,0,sta125]],
];

//here the magic happens.
            
    function_grapher(bezier_surface(t_step,formers),thickness); 
    
// that's all there is to it. (if only!) If only I had the knowledge I will have in 5 years today, this would be easy.

After a lot of pulling the hairs, I got the code down to the above, it works beautiful and it ‘should’ be simple to build other variants, if, but only if I can get the code to play happy with the printer. I normally slice with Simplify3D. Since I have Octopi (cura slicer) running on the printer, I want to try if that will eat it.

The other slight issue is of course that I will have to chop up the part in 2 or 3 sections, but that should not be a problem. In the end it will be covered with a layer(s) of light glass to keep it from falling apart. The whole idea is of coarse, that modelling in software is ”easier” then producing lots of dust.

That’s the theory..

29 sept: after a good nights sleep I woke up to realize I have a lot of the good stuff from Stefano. Why oh why did I not think about that? The other option is to try with Freecad, import the .stl, make it a solid and take it from there. Options, options. Then there is Solvespace, and of course all the paid for stuff that I can’t afford.

30 sept: ok, this is the reason why this does not slice well: the code likes the shape to bend in certain direction. At the tail end I try to be smart and diverge, creating a bend in the other direction. And that is what is causing the problems for the slicers.