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Author Topic: The care & nurture of a 3d printer...  (Read 3540 times)
Techno
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« Reply #30 on: 02 April 2019, 07:34:16 AM »

Very interesting post, Wulf !!  Thumbs up

Cheers - Phil
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« Reply #31 on: 02 April 2019, 09:45:42 PM »

OK, so, Support...

What is Support in 3d printing & why do we need it?
Imagine you have a wall, with a gap to walk through. You want to build an arch over that gap, so you get a pile of bricks, place one on top of the wall at each side of the gap, slightly overhanging the gap. The next bricks go on top of those, with slightly more overhang, and so on until the two piles of bricks meet at the top over the gap. Voila, you have an arch!
Not going to work, is it? The piles of bricks will quickly fall over into the gap. ...unless you use lego bricks...

One way to create an arch is to build a temporary support in the shape of an arch in that gap, probably of wood, then build up the bricks over it, place the capstone at the top, then remove or break up the temporary support. Now you have an arch. In very simple terms, of course.

Support in 3d printing does the same job, and turning it on is usually just a simple tick box in the slicer, but there’s one fundamental difference to the brick arch & wooden support; 3d print support is made of the same stuff as the arch – it’s all plastic filament, and it’s all extruded hot & sticky. If the support comes into solid contact with the arch, the two become one, and it’s a bugger to clean it off. For that reason, the print doesn’t actually print on top of the support – support is printed up to a point just a fraction – commonly 0.1mm – below the first print layer.  That first layer will sag a little, but just enough to contact the support – filament cools & hardens almost as soon as it leaves the nozzle, and the slightest touch of support is enough to let it harden  in place. The next print layer hardens  on top of that, and so on.  Now, support is printed fairly flimsy, usually single line thick according to your nozzle diameter, and you can choose how dense it is, commonly between 10 & 50 percent – I use 15 or 20. Both factors make it easy to remove, but even then it’s not always necessary. Look at this:



That’s a very odd angle to look at one of the basic print tests you’re well advised to print as one of your first attempts at 3d printing. It’s a very poor pic, I couldn’t get the camera to focus. I offset the pic so the 'Photobucket' logo didn't get in the way so much... Normally the bottom of the pic is the print bed, and the arches rise up into empty space – just as you see them, with no support. Look at the arches marked ‘Overhangs’. As you can hopefully see, the underside of the arches is fine until about halfway up, around 50 degrees. After that, you can see droopy filament. But the thickness of the arch, layer upon layer, means the top surface, not seen here, is just fine. If we were only interested in the top surface, we could print this arch with no supports! But normally we’re interested in the bottom of the arch – think of a tank, sitting on it’s tracks. Layer by layer, the printer prints tracks, wheels, suspension, then, suddenly, the belly of the tank stretching from track to track, across open space. It needs support. OK, so most minis don’t even have a bottom to the hull, they’re often hollow, so no big deal? Also needing support are upper track runs, WWI tank gun sponsons, track guards,  and, of course, gun barrels, and everything else that sticks out.

Now  we have  a further complication from our brick arch & wooden supports.  Look at this:



That’s a JagdTiger, Archer, SdKfz 234 Pakwagon, plus turrets for the Charioteer and a Ram. Sorry about the shadows, I was trying not to use the flash as the grey plastic is really reflective. TOG lurks in the background because... I like TOG... Now, the turrets show normal support, all along the length of the barrels. But the vehicles show a Support setting called ‘Touching Baseplate’ (the alternative is ‘Supports Everywhere’ – I’ll get back to that). The barrels are NOT supported while they are printed above the hulls, but only when they extend beyond the hull. Why? Because to support them above the hull would mean printing support on top of the surface of existing printed material – that  nice smooth front plate of the SdKfz, the equally smooth front plate and little detailed headlamp of the Jagdtiger, and all the engine deck detail of the Archer. OK, support is flimsy, but it will mark the surface and does need cleaning off. As you can see, the barrels have quite successfully printed anyway – why? Back to that pic of the test arch. Look at the bit marked ‘bridge’.  The filament has quite happily printed 25mm across open space from one pillar to another because, as I mentioned, it cools and hardens almost as soon as it leaves the nozzle. That’s called ‘Bridging’, and it works lovely on gun barrels. It does NOT work on the belly of a tank, because, unless it’s a damn peculiar tank, the tracks & suspension do not create a solid wall or pillar each side, and the belly is not printed from the top of one to the top of the other! Bridging is quite specific. Note that the turrets are actually also printed with support touching baseplate, it’s just that the base of the barrel is still directly over the baseplate!

Here’s a problem though. Look at these two Rams:



OK, they’re two different models (the one on the left has lovely suspension detail, but the turret shape looks a bit off), but look specifically at the underside of the rear of the hull above the track. The one on the left was printed with support touching baseplate, and looks distinctly droopy.  Because that area of the hull is directly over the tracks, it couldn’t be supported from the baseplate. I could have placed supports  Everywhere,  and that would put supports between the tracks and upper hull. And between the wheels and upper tracks. And... everywhere... It becomes extremely intrusive and hard to clean out, even when it’s not on top of visible details.

Now, look at the Ram on the right. That was printed using Tree Supports. This is marked as an experimental feature in Cura, but it’s in other slicers. Turn off Generate Supports, turn on Tree Supports (don’t turn both on, it gets a bit solid then). Tree support still uses the basic supports options, but, although supporting from the baseplate, tree supports can lean and twist in, like the branches of a tree, supporting more points than standard support while still not touching the printed surfaces. Not sure why it’s called ‘tree’ support though, it looks more like Alien Encrustation to me...



Now, does this mean that Tree Support is overall just better? Well certainly it has huge advantages. But it’s a bit unpredictable. You can prepare the same models in the same slicer with the same settings twice & get substantially different arrangements of ‘tree’. Sometimes it bonds with the print and makes it a damn hard job to clear up. Sometimes it just fails and doesn’t support some bits. It is after all, marked as experimental. Always better to check the preview view in the slicer before starting to print, and carefully run through it from all angles. I tend to still use standard support for turrets and wheeled vehicles.

OK, this went on longer than I thought... Next time, cleanup.
« Last Edit: 02 April 2019, 09:58:45 PM by Wulf » Logged
Techno
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« Reply #32 on: 03 April 2019, 09:02:03 AM »

Not that I can see myself ever getting a 3D printer.....I'm finding this really fascinating ! Smiley

Cheers - Phil
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« Reply #33 on: 03 April 2019, 07:28:28 PM »

Not that I can see myself ever getting a 3D printer.....I'm finding this really fascinating ! Smiley
I try to provide a good selection of tank types to keep the interest up there at least...
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« Reply #34 on: 06 April 2019, 07:19:10 PM »

THere's been a major speedbump in production. The company called Wargaming, who made the online game World Of Tanks, have just made a copyright claim on some of the 3d meshes on Thingiverse, on the legally enforceable basis that they use the 3d files from the game. They demanded that Thingiverse remove all content using their work. THingiverse, having no way to prove which files did or did not use the game files, have removed just about everything tank related...

Other websites do host 3d files, so there may be a future in the hobby as it directly relates to 3d printing historical tanks, but what I already have may have to suffice for a while. Fortunately, I have a lot...
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Techno
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« Reply #35 on: 07 April 2019, 06:51:37 AM »

Oh.

That's a bit of a sod.

Having said that, if Thingiverse had breached copyright, Wargaming had every right to throw a 'wobbly', I suppose.

Copyright and the 'net' must get horrendously complicated !!

Ages ago I paid for the whole 'set' (then available) of Roger Dean artwork as screen savers.
Roger Dean dot com has since withdrawn those images for sale as downloads. I presume folk were being to free in using them on their own sites ? v Undecided

Cheers - Phil
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« Reply #36 on: 07 April 2019, 12:01:21 PM »

That's a bit of a sod.

Having said that, if Thingiverse had breached copyright, Wargaming had every right to throw a 'wobbly', I suppose.
The problem wasn't really the Wargaming code that was being used - there was some, some models even plain said so. The real problem was Thingiverse's response - it just removed anything and everything which mentioned World of Tanks, including Tags, which anyone visiting the site can add whether relevant or not. As a result, literally hundreds, possibly thousands, of files have been removed, the majority - probably the vast majority - of which have nothing to do with Wargaming's code. Some of them most certainly do not, as the models depicted don't even appear in the game, and some of them are fantasy creations!

Now, Thingiverse don't have the resources, the time or, most likely, the knowledge to tell which models actually contain World of Tanks code and which don't, so they played safe. There's nothing that can really be done there. Other files about WWII tanks are still there at the moment, some of the tanks depicted do appear in the game, but the files are not marked as World of Tanks. It's possible they may be removed too.

Some or all of the files may appear elsewhere, one of the contributors is discussing a location on the THingiverse forum, but whether we see them all or not it's changed the 3d tank printing environment.
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Wulf
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« Reply #37 on: 07 April 2019, 12:05:57 PM »

Quick update - looks like some of the models are being moved in to the Wargaming3d website (no relation at all to the 'Wargaming' who own World of Tanks...).
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Westmarcher
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« Reply #38 on: 12 April 2019, 09:59:51 AM »

To augment Wulf's good work, there's now a good introductory video on 3D Printer basics by Steve on Little Wars TV. 
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« Reply #39 on: 13 April 2019, 02:41:46 PM »

OK, back again and, again, a change of plan. No longer a discussion of cleaning up, this is another post about Support, after I had a few recent challenges in that area.

First though I must put forward a delicate topic which many here will find disturbing. There's no easy way to say this so I'll just state my case directly. There is more to life than little toy tanks. In fact, there's more to life than wargaming. There, I've said it. There are, for example, these...

For those of you who have been living under a rock for the last few million years... well, you'll recognise the Ankylosaurus. The others are Princess Leia in the Slave outfit from Jabba's palace, and Lara Croft, Tomb Raider. The outfit is I think, from Tomb Raider: Underworld.

THe first challenge was Princess Leia's... erm... bust... RIP Carrie Fisher, you will never be forgotten. Clearly there are overhangs here that will need support. Her arms, chin & nose especially. You lot at the back can get your coats. I decided to try this with Tree supports. Normal supports would have to be built Everywhere, and that would mean straight over the surface of her skin, which would likely leave a mark. And what you see there is my first attempt with Tree Supports. It worked beautifully, the tree supports started from the baseplate & curved over the model without touching it until they reached the areas in need of support. The only bits that needed cleanup were the underside of the chin and the top surface of the shoulders (which showed some layering effects). It's quite sturdy too. With 20% grid infill, it survived a fall when I took it in to my office to show off. While doing final cleanup before the paint job (undercoat of Halford's Grey Primer, then a few layers of Halford's Rover Cashmere Gold) I discovered a crack across one side of her neck. Her head would have broken off altogether if the structure had been less solid. A little superglue to the neck & all is well.

OK, I thought, this is going well. I'll try the Ankylosaurus. She (I'm sure you can tell the three of them are all ladies) presents a much greater requirement for support, with all those spines, not to mention the fact her entire body is raised off the ground on four legs. Again, standard supports would have to grow on top of her feet for some of the spines. In this case, tree supports failed miserably. Not only did they fail entirely to support some spines, never even reaching the tipe, but in cleaning up I discovered some support pattern had been printed right through both left legs, which broke off in cleanup. In studying the preview in Cura, I can see two or three layers where the support patters does indeed grow right through the legs. I have an add-on in Cura which warns me that some meshes are 'not watertight' - I guess this is what that means... OK, so try again, but this time adjust the X-Y distance so support never gets as close to the legs, and add in the Support Interface option. This adds a 'roof' to the support structure which conforms to the shape of the structure to be printed above it but, as usual, leaving a tiny gap so it's not in direct contact. One leg broke off and a smaller number of spines still failed. The Support Roof worked a treat though, so I decided to try standard supports Everywhere, but with both a roof and a floor. Dinosaur skin isn't as delicate as a Princess's, so I'd deal with that. Worked a charm. OK, took over hour of fear and sweat to clean the support out, but it worked fine. One spine lost a few mm of it's tip. I'll print a carnosaur to blame that on... One big benefit of supports with roofs & floors, you can build far flimsier support - only 10% in this case.

Last challenge, Lara Croft, standing. Standing on two petite feet, with two slim ankles, two arms that, in 3d printing terms, appear out of nowhere as the print rises, holding two Big Guns on two very slim wrists... Tree support only just failed. It supported her legs, shrouding her entire body in support, but her arms were just too delicate. To the software, once it's supported the tip of the gun on the down pointing arm, or the elbow on the bent arm, the rest of the arm doesn't need support, it's at a shallow angle to the vertical. In reality, just supporting those points was nowhere near enough, and they both broke off as the print head moved around on them. Time to add another feature of Cura to my repertoire... You can add Support Blockers. At their most basic, they stop support printing in a specific location. Select the model in the software view, select the feature from the menu, click on the model & you get a little cube, which can be resized & moved where supports will not print. Remember way back in the first couple of posts in this thread, the factory building in the background with the window frames in the window gaps? Here, however, comes the tricky part. You now select the support blocker itself (it's treated as a separate model in the software), and them the menu item Per Model Settings. I'd already been using this feature to have some tanks print with standard supports and some print with tree supports, but it can do more - it can turn the support blocker into a support block. Resize & position so it supports the arms more substantially, make sure it extends down to touch the base. It uses standard support settings, so it'll have a roof and floor, and 10% support. Now, I won't pretend it was a simple cleanup, between the support blocks and the tree support virtually everything below the eyebrows was covered in support. Both hands actually broke off. But everything printed, so a little Superglue sorted her hands out! I took her in to the office too, but didn't allow the same colleague who dropped Leia to hold her...

My decision after these is that Tree Support is very good when curving in from outside the model, like the Princess and Lara, but no good when curving out like Anky (so... not much like a tree at all...). Support with a roof & floor can be really flimsy and still effective, but, looking at the pic above closely, specifically the centre of Lara's base, it still leaves a mark.

Next comes that cleanup discussion, with some reference to these three again!
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Techno
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« Reply #40 on: 13 April 2019, 06:26:48 PM »

Very interesting, yet again. Wulf.  Smiley

Cheers - Phil


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« Reply #41 on: 13 April 2019, 07:50:41 PM »

Looks great sir
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« Reply #42 on: 13 April 2019, 10:18:20 PM »

Incidentally, some of the major collections of tanks are reappearing on Thingiverse, but without any mention of World of Tanks. They never contained any of their code anyway, hopefully people won't add the tags that got them removed before...

(p.s. my spellchecker suggests 'Thingiverse' ought to be 'Inverkeithing'...  Huh? )
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fsn
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« Reply #43 on: 15 April 2019, 07:53:07 PM »

Forget tanks and stuff.

In Israel, they're printing hearts.  Shocked Shocked Shocked

https://www.bbc.co.uk/news/av/world-middle-east-47940619/israeli-scientists-print-3d-heart-using-human-tissue

Just think. we could replace bits of Techno until eventually - a completely 3d Printed Techno.   Cool

Then we could print out more copies of Techno, and more, and more - until we get some Byzantines.   Cheesy
   
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« Reply #44 on: 15 April 2019, 09:59:39 PM »

Forget tanks and stuff.

In Israel, they're printing hearts.  Shocked Shocked Shocked
What really scares me is that my sub-200 printer can print in that material with a 20 modification... Not to the degree of precision needed, admittedly, and the material costs a fortune, but..
Quote
Just think. we could replace bits of Techno until eventually - a completely 3d Printed Techno.   Cool

Then we could print out more copies of Techno, and more, and more - until we get some Byzantines.   Cheesy
I'll give it a go... of course, it would require scanning the original parts. I hear he's started the dissection already...  Cool
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