I have had some time to think about several blog articles I recently read about desktop 3D printing. They were about the time and effort (and money) we and the machine manufacturers invest for the results obtained at the hobbyist class machine cost level.
Example, an original project promoted for hobbyist. REPRAP. A desktop machine that can build itself. Really? No… a few plastic pieces of dubious quality, Yes. It helped kick start the hobby interest. It is not the best printer design.
Two products, one made with hobby level desktop 3D printing and the other with professional injection molded parts. I know what I would purchase. A friend and I both looked at recently designed (large) kit DIY printed parts 3D machine. The non-printed components (~$700) were an excellent choice. The self-printed (plastic) parts could make the complete printer a very bad investment.
The elephant in the room is 3D desktop printing as a hobbyist uses it, cannot deliver equivalent consistent output of conventional subtractive manufacturing, injection molding, or profession additive manufacturing. We may pretend it does. I can produce a facsimile of these items. Professional quality production 3D printers are not small desktop sized machines.
I ventured into resin (DLP) 3D printed, Lost Wax Casting models. I used a Wanhoa D7 Replicator. (lead picture) I had some success. But overall, factors beyond the actual printing proved wax is still the most consistent and cost effective method for a hobbyist doing lost wax casting. Making jewelry on a hobbyist 3D printing machine is possible but not practical.
Prototype modeling is a desktop machine's strong suit. Scale model, low volume, specialty, static display components.
What still scares me is some hobbyist using “carbon fiber” PLA and printing propellers for his drone or R/C aircraft engine with his $400 desktop hobby machine. Propeller failure at 20.000 rpm is lethal.
One guy writing about his Moai SLA printer, pretty much summed up what he has. (and all hobbyist have.) A tinkerer’s delight. A good first step in understanding the POTENTIAL of 3D additive manufacturing. The hobbyist grade hardware is basically a toy. A dental lab will not or should not be using a D7 or a Moai.
Technology junkies like myself are attracted to the 3D process and what we and a 3D printer can produce. We invest in our love of things technical and the low-cost desktop printer makes it possible, but so far it is mostly a hobby stuck in “demonstration mode” for me.
I like what I can do… not knocking my interest. Mostly making unnecessary plastic JUNQUE like 50+ plastic owls...
The kid who prints a dog cart, for the pup with no back legs, has not created anything new. The fact it was 3D printed doesn’t make it a better product. What it does show IMHO, is that this 3D print technology is getting these kids (and adults) into tangible, hands on making of things. The story gets press coverage because of the use of the “new” 3D print technology.
If hobbyist desktop 3D printing is anything, it is an enabler for tangible creative effort. It’s the new (toy maker) kid on the block. In an age where home machine shops are extremely rare, it brings affordable manufacturing onto a desktop in a home or a school. That’s what is good about 3D printing as a hobbyist.
What’s actually being printed is not necessarily the best way to make things, but it is a very satisfactory way to see designs come into tangible existance.
Very high-resolution 3D printing is associated mostly with layer height designated as Z in most systems. There is also resolution in the X/Y plane. FDM filament printers control X/Y resolution with nozzle diameter and flow rates.
With SLA resin printers, X/Y resolution is the size of the laser spot or focus point. Laser power levels and slow travel can cause light “bleed” and affect the effective dot size very slightly. Generally, the spot size is fixed by the design of the machine and the laser.
DLP and DLM (Digital Light Projection and Digital Light Masking) resin printer dot size is fixed by the number of pixels and their projected size. One to one is the highest resolution but it is possible and common that the image has less pixels than the hardware. A 1K image on a 4k screen, enlarged to fill the screen, is still a 1k image.
By far the most common and manipulated resolution variable with every type of 3D printing is the Z layer height.
There is a very serious factor to consider when attempting very high-resolution 3D printing. That factor is printing time. Time increase as the cube of the size and in inverse proportion to the layer height with FDM printing. Double the size and halving the layer height (Four time the number of layers) could take 16 time longer!
Large FDM printers (prints) and super fine resolution are just not practical together.
DLP and DLM print time are ONLY affected by height and number of layers, and NOT X/Y size. Doubling the height doubles the time. Reducing layer height by 50% does not again double the time as exposure times decrease as layers become thinner. Rather than 200% longer print time, it may be 190% longer.
Doubling the size and reducing individual layer height by half will be 3.8, say... something less than four times longer print time.
Good FDM printers will produce 100um (micron) layers. I have seen claims for as small as 50um. But doing any print of reasonable size, say... within 64 cubic inches (4x4x4) at 50um will take (just for comparision) perhaps 32 hours. The Resin DLP/DLM printer could probably do it in half the time 16 hours) or better as it does a complete layer at once without X/Y travel.
My general rules:
Large prints, 100um to 400um layers then FDM (filament) printing
Small prints, very fine resolution 10um to 100um then SLA, DLP, DLM (resin) printing.
Otherwise, pay the Zeitmiester (time master) his due.
I just finished building a working prototype laser hand gun (pistol) using 3D printing. The laser is one of those laser pointer sticks used for slide show and teasing cats. It IS a real laser and I built a pistol shaped holder with a trigger to energize the laser beam. The only damage it is likely to do is to someone’s vision if they looked into the emitter when it is turned on.
Also, the fact that it now looks like a gun could get the user killed if they pointed the device at armed law enforcement and energized the beam. It’s almost harmless and makes no gunshot noise, but if I was a cop and saw what looks like a pistol with a red targeting beam coming from it, I might shoot first and ask questions later.
SO, this LASER device is not a TOY and needs to be deployed in a disciplined matter. It could get someone holding it killed.
My plan is to use it to persuade some nesting doves to stay away from my porch. Every year they try roosting, drop their bird crap all over tables and furniture and everything else on the porch, as well as dropping hundreds of nest building sticks.
I think nesting season is over this year but will try the red laser if they try again. It’s a war between me and the two lovey dovies.
Back to the laser pistol. The first prototype worked as intended. It was ugly and square and very hard on the hands to hold because of the square corners and 90-degree edges. I was interested in getting the trigger to function and not the appearance of the case.
The laser pointer has a small push button in an awkward location towards the LED end of the case, so I built a basic version one prototype just to test and find a way a trigger action could be utilized to energize the laser beam. That problem was solved after testing several variations in the first prototype. Version two includes the final trigger design and rounding the sharp corners on the body, making it more comfortable to hold and use.
There is a slight and satisfying audible “click” when the laser is switched when squeezing the trigger pull. Accidental activation is not dangerous unless one has their eyeball peering directly into the end of the laser at very close range. (Again! This is NOT a child’s toy!)
The bands around the front and the handle are to hold the case together. There are no metal parts like metal screws used. All parts are 3D printed PLA plastic. The only metal is the laser pointer.
It’s not designed to be an X-ray non-detectable stealth gun. Someone is going to think about that with all the media negative hyper-propaganda about 3D printed plastic guns. The appearance is that of a 3D printed gun, so it is best treated as if it were lethal. Read again the second and third paragraphs above.
I am considering NOT putting the .stl files openly on the internet. There seems to me to be too much liability with shoot-first cops and child’s play even if it is a low powered device. I watched my pre-teen granddaughter “role-playing” with it. She was totally safe, and maturing from child-hood, but I could see where it might go with a similar group of peers of any age, showing off and passing it around without proper instruction and self-discipline.
WOW! So much concern over human stupidity and ignorance.
I enjoyed the project and working out the simple design. I loved using FUSION 360 for the CAD and printing the prototypes on the Anycubic Kossel (delta) printer.
All parts are 3-layer shells. The trigger and switch are 40% fill and the case halves are 20% fill. All layers are 0.20 MM. The material is PLA plus. ABS would work well if printed with NO warps. No supports are required.
The design and trigger configuration are 100% original. This project typifies the sense of accomplishment creating a product from initial idea to functional operation. Truly making something, starting from nothing, start to finish.
Lovin’ what I can do when I try.
Been messing around for two days trying to figure out how to get decent PETG prints off my A/C Delta printer. Then I remembered my PLA prints were looking a bit crappy for quite a while, too. But PETG is a far fussier material than PLA, so I was thinking, doing a little mental math… 2+2=3.14159265…
Then I looked really close to the printing going on with the top layers on the current test PETG print I was running. “Dang! That nozzle tip looks awful short!” I said to myself. It’s drawing the shoulder of the nozzle across the top of the print!!
AH… 2+2=4!! Now the pie is on my face! The tip of the nozzle is worn off. That hole isn’t 0.4 MM. It looks like at least 1.0 MM!!!!
Of course, I couldn’t see that at that moment, but it was obvious I needed to change out the nozzle.
With the (very) old nozzle removed, I was able to examine it under my photo microscope and grab these pictures.
Lesson learned… Just because it isn’t plugged, doesn’t mean it’s still good… DUH?!
Yeah, that old nozzle probably made at LEAST 100 good prints or more. The quality was dropping but the present PETG really drove the issue home. I’ll be changing nozzles a bit more often now I see how they wear.
I was wondering about how nozzles change with time as I was doing my test prints. I have read the claim that flow through them with stuff like carbon fiber wear the hole bigger, but it looks to me that wear off the end is also a big problem. It depends on if the hole is tapered inside or has a fairly long parallel wall hole. This may be a combination of both.
I also read that some nozzles carbon up inside from overheating and the effective hole diameter gets smaller. I bought an expensive steel nozzle months ago and have never installed it. Not even now. I have run a lot of wood PLA through the old nozzle, but it says wood does not wear out the nozzle. That old nozzle has seen PLA. ABS, wood, and PETG. After a good purge, they all flowed fine.
Months ago, when I was playing with printing test parts for a U-Build-It 3D printer, the same spool PETG was not printing quite like I expected. I just blamed it on poor S3D settings. It was probably the point when I should (could) have changed out the nozzle. That old one was in there forever even then.
|A camera microscope is a handy tool for nozzle inspection and photo capture.||The left is the new nozzle. The right was exactly the same, now with at least a 4X bigger hole!|
Now wiser than I was yesterday, this old dog can still learn a few tricks…