geert_2
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Posts posted by geert_2
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Have you tried these options?
- Keep all model-cooling fans off during the whole print? If you do not have overhangs, it might work.
- Make a custom brim in CAD that is thicker, for example 0.5mm, thus 2 to 5 layers thick, depending on your layer height? That should make it much more stable, but also harder to remove of course.
- When creating a custom brim in CAD, design "mickey mouse ears" around critical corners.
- Use PET / PETG instead of ABS? Unless it has to be ABS because you want to paint it, chemically smooth it, or glue it, in most cases PET might be good enough. PET can withstand the heat of a car interior in the sun (contrary to PLA), and it is chemically reasonably inert for mild products. I don't know about UV-resistance, but PET bottles do survive long in nature... PET can be chemically smoothed with dichloromethane, although it does not work as well as acetone on ABS.
Pictures:
Custom brims designed in CAD for the overhanging supports (pink and orange), and for the hollow cube, because they need it. The rest not. For reference: text caps height is 3.5mm, text leg width is 0.5mm, so these are small items.
Left model is as printed, right model is chemically smoothed with dichloromethane CH2Cl2. This is PET. For reference: the nylon screw wheel is 16mm diameter. I don't remember if I brushed-on the CH2Cl2, or if I quickly dipped the models in it for a few seconds, I have used both methods. But if you do this too long, the models tend to warp after drying, because the solvent softens them.
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For PET, I never use any bonding, I print on bare glass, with cooling fan off or very low. But I do use my "salt method" prior to starting a print: wiping the glass plate with a tissue moistened with salt water.
For PLA, the salt method greatly increases bonding when the glass is hot, and when cooled down, models pop off by themself. For PET, the salt method *reduces* bonding a little bit (compared to printing on bare glass, or glue), but it makes the models pop off after cooling down too. Without chipping the glass.
So, expect bonding to be a bit *less strong*, and carefully test if it works for your models and materials. Stay with the printer, and watch if corners do lift, or if the model comes off while printing, as this could ruin your print head.
For me, the salt method works very well with long low models, like rulers. But it is not recommended for thin tall models like lantern poles.
Try with a test model that is very hard to print. You could print the exact same model multiple times on one print bed in one run, each bonded with a different method: glue stick, dilluted wood glue, salt method, bare glass, hair spray,... And then compare how each of these behave.
I used to run my bondingtests with models like these inverted prisms:
For an old explanation of the salt method, see here:
https://www.uantwerpen.be/nl/personeel/geert-keteleer/manuals/
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That clips seems excessively thick to me? But if it works...
I would rather think the white colar would be the problem, the metal inserts not clamping enough?
But if you expect the horseshoe-clips to be the problem, you could also try my old design. Although its bottom plate has about the standard thickness. If you want it to be thicker, maybe rescale only in the Z-scale? Or edit the design and make the bottom plate thicker. This clip is way easier to mount and remove than standard clips. I remove it every few days to change filament colors and to clean the nozzle with my more gentle "atomic pulls".
Print it slow and in thin layers. Print cool to prevent decomposing from sitting too long in the nozzle, and print multiple models at the same time, to prevent overheating and sagging of the model. I would go for 0.06mm layer-heigt, 20mm/s, and 190°C for PLA or 210 for PET (shown below in red), but your materials may vary from mine.
See my personal page for the CAD-files: https://www.uantwerpen.be/nl/personeel/geert-keteleer/manuals/
If you like any of these, download them to your own computer. It is not sure that I can keep them up here.
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I guess you have a good reason to print in ABS.
But maybe you could find other materials that have similar or sufficient characteristics, and that print better, with less warping and better bonding, and better layer-adhesion too? For example if the model would needs a little bit of flexibility and enough heat-resistance to sit in a car in the sun, then PET or similar materials might work? (Although they can not be painted and glued so easily as ABS, so that would be a good reason for choosing ABS.)
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Probably not what you are looking for, but: what about an elastic cord to hang the glasses around your neck, in grandma style? This will have less risk of dropping the glasses while driving. You can find them in most shops that carry cheap reading glasses.
3D-prints probably won't give enough grip to securely hold the glasses, unless you would use rubber inserts in the design. If you want a 3D-printed holder, I would suggest you first go look for suitable rubber inserts, or pieces rubber piping that fit around the ears of your glasses. And then design the rest of the holder around those rubber inserts? Silicone rubber usually gives very good grip.
If you would go for rubber inserts, you might as well use one for clamping the holders around the bike frame. 3D-printed clamps don't hold very well: they do not have enough friction, and they tend to deform soon ("creep deformation"). So a rubber insert to add friction and buffer the creep deformation could greatly help.
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If you do a cold pull ("atomic pull"), you can see if the teflon piece is worn out:
- remove bowden tube,
- insert a piece of filament into the nozzle,
- heat up nozzle to printing temp,
- push out a bit of material through the nozzle,
- cool down nozzle untill room temp, then wait 10 min,
- heat up nozzle to 60°C, and then gently wiggle, rotate and pull out the filament. (The older methods call for brute force pulling, but I don't like that. I pull very gently, by wiggling and rotating. Fingerspitzengefühl.)
Now you should have a nice cone, showing the inside of your nozzle and teflon coupler. If there is a thick blob or ring at the lower part of the teflon coupler, it is worn out and needs replacement. Otherwise yit will cause underextrusion and uneven extrusion while printing.
Photos:
(The color changes are because I did the cold pulls to clean the nozzle while changing color.)
The orange cone at the bottom is how it should look. The top and middle orange cones were pulled out a bit too soon, before they were fully cooled and solidified.
The blue cone is still acceptable, althoug it begins to develop a ring in the teflon coupler. But the big ring in the white cone shows that that part of the teflon coupler is totally worn out. While printing, filament will get stuck in this area, causing uneven extrusion. So, that teflon coupler definitely has to be replaced.
If the cone would show black sooth, do a few more cold pulls until the cone is clean. Otherwise black flakes will show up in the print.
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22 hours ago, gr5 said:
I've seen people use vacuum after mixing the silicone but skip the part about vacuum after pouring the silicone and they still seem to get pretty good results. I don't have a vacuum chamber so I get some bubbles but not a problem for my applications.
A few things I learned from experience and from tutorial videos:
In very slow curing silicones (24-48h curing time) bubbles generally have time to rise to the surface and pop by themself. Unless the silicone is very thick indeed, then vacuum may be needed to get them out. It depends on the silicone, time, and temperature. Also in complex moulds with undercuts, vacuum is desired: then you can get the air out of the undercuts and pores, and have the silicone being sucked into the collapsing vacuum afterwards. A shaker (similar to those used to make gypsum and cement flow) helps bubbles rising.
Disadvantage of slow-curing silicones is that it takes lots of time, of course, and that the tiniest leak will make the whole mould leak empty: it leaks through microscopic gaps of one micron.
In faster curing silicones, you may not have enough time to vacuum. Then the way to pour the silicone into the mould is critical to avoid bubbles:
- make sure there is no wind in the room, close doors and windows, stand still,
- pour from as high as you can, and still get it in the mould (this is why it has to be windstill): 1 meter is good,
- pour in a thin stream, slower and thinner is better (but don't exceed curing time of course),
- sometimes you can spray the mould or model with stuff that reduces surface tension, to avoid bubbles on the surface,
- do not pour directly onto a model, but pour besides the model, and let the silicone rise around the model,
- with compressed air you can make bubbles on the surface pop, but blow very very gently, otherwise everything will be covered with liquid silicone...
The first items in the list make most of the bubbles pop while pouring, and the latter prevent air from being trapped on the model. Together, this removes all big bubbles and reduces the amount of tiny bubbles a lot.
Storing silicones in the fridge increases working time (for fast curing ones), but risks getting condensation.
Some fast-curing silicones are delivered in syringes with mixing tips, and a pistol: this allows injecting them with some force, so it fills the mould better. Similar to injection moulding. Such as dental silicones, but they are rather brittle, not very flexible, and not very suitable for seals and balloons.
Also, for really viscous silicones, sometimes you can design the mould in such a way that the silicone does not have to flow by itself: you pour it into a thick blob centrally in the mould, and then it is forced with brute force into all cavities when closing the mould. But this obviously does not work for every mould, and not for too liquid silicones.
Some photos:
Dental silicones (quite pasty, viscous) in 50ml mixing tips, and a pistol. Thicker tips indicate more viscous materials. Most of these cure in 5 minutes, but the light yellow in only a few seconds.
Viscous enough to stay in shape without leaking away.
Mould for pouring liquid silicones around a model (here curing time is ca 20min). The red plasticine was used to hang the model on.
A very old mould for pouring silicone around a model, and then casting composites into that silicone mould. the hard shell is to give the mould enough stability. This was before the age of 3D-printing. The silicone mould is cut in zig-zag to make bot halves align well: looks ugly, but works very well. The hard shell also has alignment keys.
This is a mould for pasty silicones, using brute force to make the paste flow into all cavities and corners. This requires carefull design of the seams and air channels, so the air does not get trapped anywhere, and the paste can reach all corners. In addition, I provided lots of holes to inject compressed air into the seams after curing, to break the connection between mould and silicone. And I provided slits to insert screwdrivers to pry apart both halves. Otherwise it would be impossible to separate both halves and get the model out, due to the complex design. It took me some iterations to optimise this. The red area is casted silicone. (But I can't show you the rest of the inside of the mould.)
Hope some of these techniques could help those of you who want to caste silicones.
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Bij kleine prints blijft de hete nozzle op die ene plaats zitten, dus de print kan niet afkoelen en stollen. Je moet tegelijk een "dummy" toren of model printen, naast de eigenlijke print, zodat de print tijd heeft om te koelen. Maak de dummy van vorm ongeveer invers aan de echte print, zodat de printtijd per laag overal ongeveer gelijk blijft. Maar zelfs dan blijven kleine items moeilijk. Print traag (25mm/s), zo koel mogelijk (185-195°C voor PLA), en experimenteer met laagdikte: voor sommige modellen zijn dunne lagen beter, voor andere dikke lagen. De flow door de nozzle moet ook zo gelijkmatig mogelijk zijn, zodat alle materiaal dezelfde temperatuur en vloeibaarheid heeft (dus geen wachttijden gebruiken).
Kegeltjes met en zonder dummy tower ernaast geprint:
Concept van dummies uitgelegd:
Een dummy van een echte print: de dummy is hol daar waar geen extra koeling nodig is, en massief waar de nozzle wel veel tijd op de dummy moet doorbrengen om het hoofdmodel te laten koelen. Bedenk dat dit een zeer klein model is.
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Vacuum and dessicant will help to dry filament, but may not be enough: you might need a bit of heat to shake the moisture loose from the plastic. If you are not sure about heating, don't go above handwarm: as long as you can comfortably touch it, it should be okay.
Maybe a resin-printer could be suitable for your prints? Some resin-printers can print flexible, rubber-like materials, at least the expensive professional machines with polyjet systems. Ask around in your university if someone has such a machine? E.g. an Engineering-department, or Product Development Faculty, or so? Such machines can also do higher volumes and lots of parts at the same time.
I have no experience with printing flexible materials myself, but from all what I have read here in the past, you need to print extremely slow (10mm/s), increase flow rate quite a bit, oil the bowden-tube or use a PTFE-tube, and then still have good luck. Trying to push flexible material through a tube is like trying to push a rubber band into a keyhole...
Concerning casting silicones: I have fast-curing ones that cure in 20 minutes. There do exist even faster ones, but these cure so fast that you can't even mix and pour them out nicely (some cure in 10 seconds and need dedicated mixing pistols and mixing tips...). Printing a mould in PLA at normal speed, then smoothing that mould with dichloromethane or chloroforme, and casting silicone might go faster than trying to print it very slowly in a flexible material. So I would suggest that you also look into optimising your mould-design for easier printing, moulding and de-moulding. Youtube has lots of good tutorials on moulding and casting, mostly from the pre-3D-printing ages, but they do apply to 3D-printing moulds as well. I learned a lot from them.
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I never even heard of a 3D-printer being used as polymer clay cutter. So maybe you could provide photos and more explanation of how it is supposed to work?
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Look at the bottom of your prints: if it shows round sausages, it is not squished enough. If the bottom is nice and flat, it is okay.
Mine usually look like this:
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It looks like you have issues with the print bonding to the glass. So you would need to look into bonding methods, and try various methods.
Room temperature and air moisture have a huge effect on bonding to the glass, if you would not use any bonding method and print on bare glass. In freezing dry air, PLA might bond excellently, but the day after in warm moist air, it might not bond at all.
You also need to look into your glass cleaning method: never use soaps, window cleaners, thinners, and that sort of stuff: these often leave traces of soap, detergents, or oils that destroy bonding. Fingerprints also destroy bonding. Clean with isopropyl alcohol first, and then with pure warm tap water only.
Try a small but very diffucult model, such as an inverted prism, and try various bonding methods until you find one that works reliably on such very difficult models. Stay with the printer and closely watch what happens while printing.
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Silicones are water-tight because they repel water. But they are *not* gas-tight, and not oil-tight either. Gasses, water-vapours, oils, liquid wax, and solvents do leak through. Don't ask how I know... 🙂
This is why you need to impregnate silicone moulds with plenty of silicone oil, prior to casting solvent-containing materials like PU or PMMA in it. So it is totally saturated with silicone oil. Otherwise the solvents seep into the mould, cure in there, and destroy the mould.
So a silicone balloon won't hold air for very long.
If it has to be gas-tight, you would need the materials used in real cylinders and tools for compressed air. I am not sure which materials that are, maybe neoprene rubbers, or some self-lubricating synthetic rubbers?
And indeed, as said above, silicones come in a lot of different hardnesses, ranging from very soft shore A 0...10 (which is almost like flesh) to 90...100, which feels like plastics such as PE and PP.
To print water-tight, you have to print very slow, and in very thin layers. And thus at low temperatures, so the material does not decompose due to sitting in the nozzle for too long. With thick layers, you get water-jets spurting out of hundreds of tiny openings in the side walls. Here too, don't ask how I know... 🙂
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If you want to print horseshoe clips, you could try my design: these are way easier to remove and place back than the originals. I designed them for myself and have been using them for years now. These are for an UM2, so I don't know if they would fit on an UMO too, but I gues so?
You can find it on my page here (then scroll a bit):
https://www.uantwerpen.be/nl/personeel/geert-keteleer/manuals/
As for the nozzle-height, my first layers are well squished into the glass bed, and look like this, seen from below (=touching the glass plate):
If you don't get a similar surface, then or your nozzle is way too high, or you have something else going on, such as a flow problem? Maybe a partially blocked nozzle? Filament feeder slipping? Temperature way too low so the filament does not melt? Or you have set 1.75mm filament while using 2.85mm, so it feeds too little? Or something along that line of thinking?
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Voor PLA gebruik ik geen lijm, maar ik doe een paar druppels zout water op de glasplaat, en smeer dat met een doekje heel dun uit, tot er een bijna onzichtbaar dun laagje zout achterblijft: een vage mist, zoals bij een wijnglas dat een jaar ongebruikt in de kast gestaan heeft. Dit geeft goede hechting bij een warm bed (60°C), maar totaal geen hechting na afkoelen, dus je kan na afkoelen de modellen gewoon los van de plaat nemen.
Werkt zeer goed bij lage voorwerpen, zoals meetlatten. Maar werkt niet goed bij dunne hoge voorwerpen zoals lantaarnpalen: die komen soms los.
Teveel zout is ook niet goed, het moet een heel dunne film zijn, dat werkt bij mij het beste.
Zie mijn oude maar nog bruikbare handleiding op mijn pagina (en dan een beetje scrollen):
https://www.uantwerpen.be/nl/personeel/geert-keteleer/manuals/
Ik zou zeggen: probeer het eens, maar blijf erbij om te kijken of het goed houdt. Test dit met lastige modellen zoals omgekeerde prisma's (=afgeknotte punt naar beneden) zoals op deze foto. Dan weet je waar de grens zit.
Zo ziet het zoutlaagje er ongeveer uit: bijna onzichtbaar als je er loodrecht op kijkt, en een dunne aanslag als je er heel schuin op kijkt:
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I can imagine that it is very expensive if you would buy real microscope grease.
But here in Belgium you can find silicone grease in automotive and hobby shops, among all the other greases, at about a similar price. I also got copper grease, lithium grease, PTFE oils, and others there. Silicon grease is often marketed as "car door rubber treatment in winter", and "keeps rubber in good shape", so should be rubber-safe. But availability might be different in other countries, of course.
Be sure to find pure silicone grease, not mixed with petroleum greases.
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If you use only infill and no wall thickness, you should get a porous model. But I don't know the best settings, nor best infill patterns.
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I think I once read that Rhino visually rounds the models on-screen, but not in the CAD-model? But that was long ago, ca. 7 years... I don't know if that could be the problem today?
Also, try playing with the quality settings for export to STL, OBJ, etc. In some programs the quality can be adjusted from very coarse to very fine. A too coarse setting could also produce this effect.
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For the noisy belts on my UM2, I used a bit of silicon grease. This is the thick grease used in binoculars and microscopes. I only applied a little bit on the edges of the belts, not on the teeth, so it would not slip and skip teeth. The sound came from the belt rubbing against the flange of the drive gears.
You can detect which edge is rubbing by gently pushing the belt aside while manually moving the head, when the printer is switched off. Or gently push the belts aside when printing a small test block in a corner of the print, so you won't be surprised by suddenly moving heads.
If you would try this, be sure to use pure silicon grease. Never use petroleum grease or petroleum oils on rubber, that might damage the rubber.
In my case it was this edge (red arrow) that was rubbing, so I applied a little bit of silicon grease just on that edge. That solved it.
My two UM2 printers (non-plus) are also from 2014, and still working. One of them is getting a little bit of play in the head itself (not the belts), and the display is occasionally locking-up when rotating the button (seems like a hardware glitch?), but the other is still perfect. I use them every second day, on average.
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On 1/21/2022 at 11:13 PM, GregValiant said:
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And this is how I cheated...this time. I did miss a trick on the "Retraction minimum travel". There was some webbing between the small cones.
If it produces better prints, I would not call it cheating, but rather "advanced methods". :-)
Standard supports are good for standard situations, but special cases might be better off with custom supports. Then you can provide features to not damage the underlaying features (like the bottom plate with text here), or to make removal easier by providing holes to insert pliers, or do less damage to the underside of the supported model, etc.
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A lot of my prints are about that size, 100% filled, also with holes. But ususally they print fine without problems.
However, recently I found that on some new "PLA" materials (non-Ultimaker), I needed to increase bed temp to 65°C to make them stick well. The plastic also has a different feel, and a slightly different sound when dropped. Seems like a different PLA-blend? In one case it needed 70°C, which even didn't cause elephant feet, so I am wondering about its composition? Bizarre, since I never had that in 7 years...
Further, if you would be printing on bare glass, without any bonding method, then try one. Moist and rainy weather gives very poor bonding on bare glass, in my experience. Also: dirt, oils, grease and soap (from cleaning) on the glass give very poor bonding. So after cleaning the bed, rinse it with pure warm tap water only, no soaps, no detergents.
I use my "salt method" for bonding: gently wipe the glass with a tissue moistened with salt water. This leaves a very thin almost invisible mist of salt on the glass, like a glass that got dirty from sitting too long without being used. This gives good bonding when hot, but no bonding at all after cooling down, so models pop off by themself.
This salt method works well for long flat models like shown below. But it is not recommended for narrow high models like lantern poles: they tend to get knocked over. Only works for PLA, not for ABS. For PET and polyesters, it tends to slightly reduce bonding, and thereby also reduces the risk of chipping the glass.
Anyway, if you would try this, stay with the printer and carefully watch what happens, to see if it works for your setup and your materials, and so that you can abort if it would cause problems.
Or try different bonding methods like: dilluted wood glue, glue stick, hairspray, 3D-lac or any other bonding method you prefer.
Typical models:
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Is that material PLA? Some materials do string a lot more than others, e.g. the PET I have, because they are more elastic, while molten PLA is more like yoghurt. So, if it would not be PLA, try PLA first, with a fairly standard speed of 50mm/s.
I never played with retraction settings, so I can't say anything on that. Did you enable retraction in the slicer, make sure it is not switched off somewhere (there is a checkbox in my Cura version)? Forgetting to enable retraction would cause the same stringing effect.
Also, it looks like your nozzle is too far away from the glass: normally the bottom layer should be much smoother, more squeezed agains the glass.
Also, not sure, but the vertical patterns in the benchy might be infill shining through?
This is how the bottom of my prints usually looks for normal prints, and for very fine prints:
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Obviously I do have that green model above. It was not designed as a real test model, but rather as a demo model to show people some of the limitations of this printer-concept, in case they come along and ask for impossible prints.
For example: "Could you print an M2.5 screw thread?" No, because that melts into a blob, like the top of the little cones, due to insufficient cooling: the nozzle staying on top of these cones, so they can not solidify.
Or: "Could you print this thing with steep overhangs?" Yes, but only with a support scaffold under it, which you have to cut off, causing an ugly underside. Otherwise the filament sags.
This model answers those questions.
I think it should be this file:
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Is that an Ultimaker coupler? If not, if third party, maybe it is not temperature resistant enough? Or a bad batch? It should not deform that fast. So that could also be a possibility?
The newer couplers (TMF, MTF, or whatever their name...?) do also fit and should be a bit more temperature resistant. They have a slightly different color, a bit more translucent.
If the flow of a fan is difficult to feel, you can often show it by holding a thin paper in front of it: the paper should deflect or blow away, or be sucked onto the fan, depending on its flow direction.
But I am still thinking in the direction of the sensor not right, or giving bad contact. At room temp it could still indicate the correct value because everything is at room temp then. But if it does not give good enough contact, it might not feel the heat. Just guessing of course, I don't have "remote viewing"... If you could find a multimeter with thermocouple that you could insert into an empty nozzle, it could show if the sensor is working correctly. Otherwise I don't know how to exactly verify it?
Enduring long streaks of print failures
in Improve your 3D prints
Posted
Maybe the last one could be a bad power supply? If it is degrading, and "on the edge", it could cause seemingly random problems due to a too low voltage at moments of higher loads? But I am not familiar with hardware-failures, so you better get a second opinion on this.
I still think you need to look into your bonding method too.
Your series of problems reminds me of a guy who always had problems with laser- and inkjet printers (for printing on paper). He bought lots of new printers, correctly installed them. And then they always would fail after a few weeks, and cause endless problems. It appeared to be a spiritual problem: he had a very strong mind, very powerfull. And after the first couple of accidental print failures, he had firmly decided that "all printers always fail on him". And so they did, because they obeyed his command authority. This does not work when weak-minded people try this, but spiritually strong people can do it sometimes, they have control over matter. There have been switches on the market (around 1995-2000) that you could switch on by *thinking* it on, and switch it off by thinking it off. So you could switch the light in your room on and off by thinking it on and off. But they only worked for spiritually strong people, not for weak minded.
In case this would apply to you, you can solve it by going back in your mind to the past, and carefully find all moments when you firmly decided "it would fail", "it always fails", "it never works", or all decisions along that line. Find all of those decisions, examine them, examine all the circumstances of back then, and then remove those old decisions you made, so they stop being active.
Sometimes you find the strongest people are in the technical and artistic sectors, thus among engineers, artists, technicians. That is why they can create things: they have mental and spiritual control over matter and energy.
(Hmm, now that I come to think about it: we technical people should get more pay...)