Quotecozmicray I think the glass on my bed is NOT flat to 20 micron??? Of course the first layer should still be thick enough to stick to an imperfect bed, but from the second layer on one may use arbitrary thin layers.by cristian - Mechanics
On reprap.org I read about somebody printing at 5 micron layers. On my printer, the best apparent quality is at 70 microns. 50 is still acceptable, 20 is a mess. I find bridging very tricky at thin layer height.by cristian - Mechanics
QuoteFalloutBe Thanks again cozmicray, for all your help (; I'm going for the cantilevered platform, 4 bearings, 2 smooth rods and a single lead screw. What do you think will be best? (delrin nut) or (motor attached, regular nut) or (motor attached, regular nut, coupler) ? The delrin nut states to have much better resolution, and it is cheaper. The regular lead screws all seem to have an 8mby cristian - Mechanics
Quotethe_digital_dentist There are two types of ball screws- rolled and ground. The cheapos are the rolled ones and specs won't be as good as the ground screws. The rolled screws (which is what the ones in the photo appear to be) might be adequate for z axis lift. You might want to watch for ground ball screws and see what ebay turns up used. There are several auctions for used ground ball scrby cristian - Mechanics
Quotecozmicray or laser measurement of bed movement and full feedback to moving mechanism. May you post some link for such measurement tools?by cristian - Mechanics
QuoteAndrewBCN Apparently, not any time soon. Quotethe_digital_dentist It can't become a consumer product until someone makes it into a reliable process that doesn't require a PHD to get a machine to make a quality print. Great news! Doesn't that make you feel special, then?by cristian - General
My last post on the thread, I do not want to pollute it uselessly. I wish there was such a filament drying expert, not only for nylon, and I wish you the best luck in finding him/her. From what I see, every reprapper has his/her own recipe which works for him/her and may not work for others. So if such an expert does not show up (since he/she probably does not exist), you will have to find yourby cristian - General
QuoteKoko76 In my experience the words cheap and high precision (along with the equally important repeatability) are not found in the same sentence. To me personally if something is worth measuring, it's worth what the right tool to measure it costs. Henry Ford has a great saying about this. But I think it would be simpler to cut a bunch of several gram samples enough to print some test object,by cristian - General
You can measure the drying time by yourself. Buy a cheap high precision scale (0.01g precision over 100g or more, from $10 on ebay or aliexpress), which should be precise enough to get a graph of the 1% or 2% change of the total weight of the filament. Put 100g nylon filament in a very humid environment for some days. Weigh it, then put it in the oven and start drying it. Take it out of the ovenby cristian - General
Hey, thank you all for discussing this. I am also designing my printer and after thinking, reading and discussing a lot, I am converging to a similar solution with the bed moving on Z, so hopefully my questions will be on topic. Until 10 minutes ago I was thinking of using smooth rods and lead or ball screws. However the design with 3 ball screws and no smooth rods linked by FalloutBe is very aby cristian - Mechanics
You may also carve a bit the plastic with a lancet.by cristian - Smart_Rap
Thank you all for your tests. If I understood correctly the remark about the hobbed bolt, the extruder is unlikely to cause vertical stripes, because the periodic under/over extrusion caused by the hobbed bolt (or gears, or whatever in the extruder) would need to be perfectly synchronized vertically from one layer to the next, which is almost impossible even when printing a spiral vase. It may cby cristian - General
With white PLA, I use some medium/fine wet sandpaper sheet to remove those marks, and I never use that sheet to sand other PLA colors.by cristian - General
Once more, many thanks for your detailed answer.by cristian - General
Thank you for the pictures. I see stripes almost everywhere except in the central part of the orange piece. I think it is unlikely that a geared extruder (or an extruder in general) may cause perfectly vertical stripes, they should be inclined and shifted every time the "shape" of the layer changes with respect to the previous one, but of course only a proper test can tell.by cristian - General
QuoteSteveRoy Why someone would buy the cheapest printer kit they can find, then complain of poor support and put up with continual problems is beyond me. One year ago I chose to buy one of the chapest printer kits out there as my first printer. I spent really a lot of time trying to make the printer work properly, solving, dodging or acknowledging countless problems. After one year, I can say tby cristian - General
I read your instructable with great interest, thank you for sharing it. Lately I have been polluting this forum with many questions, trying to get the best out of the printer I am going to build, given the constraints I have in terms of budget and building capabilities. After reading your instructable I have some specific questions on your build or in general on the thoughts you shared, so I hopby cristian - General
Quotethejollygrimreaper Looking at the picture more carefully, I can count at least 16 infill rows on the long side, but not more than 13 ridges on the external surface of the same side: apparently it is not the same pitch. Since the amplitude of ridges depends on speed, it may come from any kind of vibration in the structure of the machine, including the vibration caused by belts teeth. But ifby cristian - General
QuoteAndrewBCN For example, I am much more worried about changing to another spool of filament and the changes in print quality and the adjustments I'll have to make to the printer/slicer settings! Sure, but that is for another thread!by cristian - General
Quotethejollygrimreaper you can see the vertical ridges lining up roughly where in the infil connects to the perimeter, i think based on this that the vertical ridges are a product of (1) the perimeter speed (2) the infil density (3) and also the number of perimeters as more perimeters would mitigate any effect from the infill This is a good point. 45° rectilinear infill with few perimeters mayby cristian - General
QuoteAndrewBCN Even steel is somewhat elastic Definitely true, but several orders of magnitude less than a belt I guess... QuoteAndrewBCN All I am saying is that GT2 belt driven linear motion systems can hardly be considered to be at the top of the list of factors that contribute to a lack of precision of a 3D printer, given the current stage of development of 3d printing / FDM technology. I agby cristian - General
QuoteAndrewBCN I guess I will have to test a couple of toothed pulleys in one of my printers to verify this. Here is a vertical flat surface and indeed, one can see a very faint vertical wave pattern. I confess I never paid any attention to this because the vertical wave pattern cannot be felt by running a fingernail along the surface, contrarily to the horizontal pattern formed by the layers theby cristian - General
Quotethejollygrimreaper what type of belt are you using? and on what size pulleys? I noticed these stripes on other printers besides my own. It does not make sense to talk about my printer (GT2 2mm belts with 24 teeth pulleys, if I counted well) since it is so unreliable that those stripes may even come from the transit of the Moon or some nearby asteroid, and I have currently no access to the oby cristian - General
Quotethejollygrimreaper those vertical stripes/ridges are actually the belts vibrating/ringing on a direction change, (eg on corners and such, ) , it's a side effect of a lot of the high speed printing people seem to like to do these days however the solution i found is rather simple and doesn't involve spending days tuning acceleration values , you just slow down the perimeter speed , on my prby cristian - General
The object seems thinner every 20 layers or so. Is that caused by some slicing artifact or do you have some problem on Z? Are belts tight?by cristian - Smart_Rap
QuoteJamesK Mark's (digital dentist) build uses a ball screw on Y with very impressive results. He posted a writeup If you can't glean what you want to know from there I'm sure he'd be happy to answer questions. Many thanks!by cristian - General
Quotecdru Cost, speed, resolution. Pick 2. Belts enable a cheap stepper motor to move things faster. The same motor enables a lead screw to move things with better resolution. If you want to move things fast and with higher resolution, you'll need something better than a standard NEMA 17 motor as a starting point. Yes there's a big difference in accuracy between belt driven X and Y and lead-screby cristian - General
QuoteJamesK Um, so I don't want to seem argumentative Please be argumentative, I am trying to understand the "state of the art" to avoid naive mistakes in the printer I am going to build, so even Devil's advocates are welcome in the thread. QuoteJamesK but a 1G acceleration equates to 9800mm/s2 - is that considered normal printing speed? I confess to a lack of knowledge, but that sounds on theby cristian - General
QuoteJamesK The weight of the bed isn't supported by the belts, it's supported by the smooth rods (or other linear bearings). On the Z axis the weight bears directly on the movement system, and in many designs is transferred directly to the stepper motors. None of the weight on the Z axis is supported by the smooth rods. It's this primary factor that makes the difference in gearing between XY andby cristian - General
QuoteVDX ... belt drives are been used mostly for higher possible speeds than with spindles. As the Z-axe can be much slower and the steppers with spindles can withstand the gravity with motors off, this is the most practical solution for the standard machines ... To withstand gravity, a lever corresponding to 20 steps per millimeter is more than enough (I tried), which is a resolution 10 timesby cristian - General