QuoteZavashier 691175002 you're rightn that 20 module extrusions can bend under load, even if it won't conform as easily as you think. Hopefuly we don't load them with a pound or two V-wheel guides are much better than you thing through. You should give them a try someday. Derlin wheels are strong, low friction and more durable than rubbish LM/SBR series bearings. In some configuration they allby 691175002 - Reprappers
I don't think you will ever get a straight answer. Extrusion is not a particularly accurate process and the numbers, when given, are normally awful. In my experience I've never seen a piece of extrusion with nearly as much bend or twist as allowed in the datasheet. I would generally be more worried about extrusion bending due to gravity/loading. The stuff isn't particularly rigid, especiallyby 691175002 - Reprappers
The current smoothieboard has quite a good following and is pretty feature-complete. They recently posted a picture of a proposed version 2.0: Its pretty ridiculous. Intel edison, cortex M4 and an LX9 FPGA. It also has 7 stepper drivers and sensorless stall detection. I'm not even sure the word ridiculous is capable of conveying the sheer overkill in that board.by 691175002 - General
The idea of using an optical mouse sensor has existed for a while but has never gained traction. Reprap even hosts a few datasheets ( ). One problem is availability. There is no point developing this feature if people need to buy and dissect a specific model of optical mouse to build one. There are also some questions regarding performance, especially for absolute positioning. An encoder baby 691175002 - Developers
Also note that print quality requires repeatability much better than the nozzle diameter. The human eye can perceive inconsistencies well below 0.01mm. For good looking prints you must be able to perfectly line up successive layers.by 691175002 - General
The problem with rotational axes are very simple. In a linear system, mechanical errors are directly reflected in the position of the extruder. If the belt is out by 0.1mm, the extruder will also be out by 0.1mm. In a rotational system, any mechanical errors are multiplied by the length of the arm. A tiny error at the motor shaft becomes a major problem 6 or 12 inches from center. I have attby 691175002 - General
QuotepineappleWhat do you mean by delta's not having an efficient build volume? Just the ratio of build volume to overall printer size isn't particularly great. They are more space efficient than a moving (x and/or y) bed printer, but worse than a fixed or Z-bed cartesian. Delta printers also become ridiculously tall as build volume increases. I'd also consider a rectangular working area moreby 691175002 - General
None of the methods are intrinsically more or less accurate for particular geometries. Any form of approximation made in software is orders of magnitude smaller than the physical resolution of the printer. By your logic (polar being bad at lines, cartesian being bad at curves), delta should suck at everything because any motion requires approximation using all three motors. Polar can immediateby 691175002 - General
QuoteEmbedI'm planning on milling only small acrylic and pcb boards, not metal. The thing about CNC is that even really shitty machines can look okay at first glance. You don't realize just how frustrating they are until you actually use one. I'd consider a machine like this to be pretty trashy and it uses 16mm rods with very small travels.by 691175002 - Reprappers
It depends on what you are expecting from the machine, but I have been extremely disapointed every time I use unsupported linear shafts for milling. Milling and 3d printing are mostly incompatible processes in a single machine. If you use belts you won't have enough rigidity for milling. If you use screws you won't have enough acceleration for printing. Nema17 stepper motors are unlikely to bby 691175002 - Reprappers
Machine shops are dual units everywhere, even in metric countries. Try getting metric bar stock - it pretty much does not exist. In many metric countries it is still very difficult to get metric tooling as well. Most cutting tools such as slitting saws, drills and unusual endmills are considerably cheaper and more common in imperial. Even if you think you are all metric, the chances are a tapby 691175002 - General
I'm skeptical that additional axes will be useful for a 3d printer. Milling machine tools can be long and thin, but an extruder is extremely bulky and would have a hard time with many geometries, especially close to the build platform. You have the heater cartridge, heatsink, fan, and sometimes a mess of tape and wires as well. There are arguably some strength/asthetics advantages to be had wiby 691175002 - Developers
The standard shape of a timing belt is a loop. Flat lengths are actually pretty hard to find for some profiles.by 691175002 - Reprappers
If you are buying high quality belts there will be full lifespan calculations in the technical data based on temperature, RPM and power transfer. Most timing belts will last 6 years or more in a car.by 691175002 - Reprappers
QuoteAndrewBCNThank you for your refreshingly honest post! There is a lot of FUD being spread here in this forum about using the ubiquitous Arduino Mega 2560 + RAMPS 1.4 combo to control linear delta printers. Something I always thought was quite odd was that when Johan Rocholl designed first the Rostock and then the Kossel lines of printers, he was using 8-bit MCUs so I couldn't understand why pby 691175002 - Developers
I was actually really skeptical of this modification. Why would grounding a pin reduce vibration, and if its so helpful why not make it default behavior? It turns out that this mod is for real, and confirmed in the datasheet. Note that in a 3d printer the stepper motor is almost exclusively low speed, especially in pulley systems that have low mechanical reduction. The default behavior switby 691175002 - General
Their revenues are up 60% year over year, so Stratasys isn't hurting that bad. I'm not sure how their FDM line of business is supposed to grow though. I feel like Fortus is going to get squeezed pretty hard since the incremental quality and reliability no longer justifies a six figure pricetag. I'm also not sure if they can make much headway at the consumer level. Makerbot has an extremely baby 691175002 - General
QuotejtoombsAlso, I came across this design and was wondering if it could be applicable at the 3D printing scale. Wow, I'm compelled to comment on how misinformed that guy is regarding harmonic dampers. He does not understand the purpose, method of operation, or proper use of a harmonic damper, and has no idea what causes a stepper motor to make noise. He is literally planning to glue a rattleby 691175002 - General
Quotenikolaos Y. here And there is the link printing with 750mm/s I'm just going to point out that he is not printing anywhere close to 750mm/s. He can type ten billion mm/s into the printer configuration for all I care, that doesn't mean its actually happening. Just look at the video... 750mm/s would imply 30" of movement every second. If you watch the clock, that printer can't even hit 150by 691175002 - Developers
The simplest truth about manufacturing is efficiency of scale. Making a million of something will always have a lower unit cost than making one of something. I do not expect this to change for at least 30 years. For this reason, I cannot imagine 3d printing ever replacing a significant portion of conventional manufacturing. A machine designed explicitly for small quantity prototyping simply caby 691175002 - General
I'm not convinced heat-break insulation is currently a limiting factor in hot-end designs. No matter what exotic material you choose, there will always be a comparatively massive volume of regular plastic right in the middle. The coating may be effective in traditional all metal designs though. Right now it seems friction and surface finish is very important for reliability.by 691175002 - Developers
Quotehaskinsl I have a very crude concept for an active mixing extruder... Leak-free mixing is really the hardest part. I suspect a direct mechanical linkage to the stirrer will be required which would require a dynamic seal that does not leak at high temperatures and pressures. Alternatively we could emulate existing processes and use a long screw whose geometry forces the plastic forward. Tby 691175002 - Developers
There are multiple types of anodizing. Any aluminium designed for sliding or rolling contact will be hardcoat, which is substantially thicker, harder, and less colorful than type 2. Anodizing does not materially alter surface finish. Mcmaster sells several coatings on aluminium linear shaft and lists their compatibility with various linear bearings. The anodized coating is compatible with linby 691175002 - General
QuoteSkypuppetSo after shopping McMaster Carr again (no this is not an advertisement), I found some reasonably priced "type 17-4 ph stainless" precicion ground rod. Not cheap, but not horribly expensive either. I'm not trying to make margins on my machines either, so a few extra bucks is money well spent. Note that if you want to do this properly (aka as the datasheets recommend) you are not looby 691175002 - General
QuoteEzrec Yes, and optical encoders and a good control system takes all that backlash out. I have a gear motor with a rubber grommet driving a fishing line belt system, and I get 250 micro resolution on that axis without even trying hard - it's all about the encoder when working with DC motors. Even though your system will maintain positional accuracy when moving in a single direction, the motby 691175002 - Developers
Velocity will never be a problem. Just do the math - a 14 tooth pulley will move the axis 28mm per rotation. Even at a blisteringly fast 200mm/s print speed the motor is rotating at a paltry 400rpm. If you ever need more speed (unlikely given extrusion limits) just swap to a larger pulley. The improved acceleration provided by servos could eventually improve print speed and quality, but rightby 691175002 - Developers
Standard threaded rod is horrible compared to belts. You get awful backlash, cyclic errors and extremely slow speeds. Multistart ACME with zero backlash nuts are great, but things start to get expensive. There is nothing inherently wrong with belts, its just that most implementations suck. If you actually read the engineering documents on designing linear belt systems they explain you need subby 691175002 - General
QuoteFeignIn terms of G-forces, it's about 8.15G, or roughly 1G less than a rocket bound for the ISS. Not impossible, but not reasonable. Unreasonable is one way of putting it - I'm pretty sure that if you tried to accelerate a metal extruder at 8G the heat-break would snap in half. Especially with a long melt zone and multiple heater cartridges. I haven't done the math but that kind of impulsby 691175002 - Developers
There are several challenges to high speed printing, and I think you are focusing on the wrong ones. I'll start with the mechanical limitations of a cartesian platform. Velocity is rarely an issue for 3d printers because they do not have enough time to reach maximum speed. Sliced 3d models generally have many short linear segments, and a zigzag infill pattern that requires many direction chanby 691175002 - Developers
The human eye can perceive minute irregularities in a consistent pattern. I'd personally treat xy deflection as a percentage of extrusion width, and z deflection as a percentage of layer height. More than about 5% will probably be visible. Note that as long as the printer deflects the same amount on each layer there will be no visible finish problems (just dimensional inaccuracies). That situby 691175002 - Mechanics