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Re: Single leadscrew non-cantilevered bed: possible? - 5 years ago
QuoteEgonVLCHaving a second thought, if I mount the motor centered under the bed, with the leadscrew "looking down", I could use just that one, but the printer height should accommodate that double z height... But it's not practical nor elegant, and I don't really know even if it would work. Stratasys does something like that but it is certainly wasteful unless you need an airtight heated chambeby 691175002 - CoreXY Machines
Re: Beware : Extruded profiles can be bended or twisted, while remaining standard ! - 5 years ago
Although the allowable tolerances are quite broad, extrusions are often straighter than they are rigid. I've put several lengths of Misumi extrusion against a surface plate and I've never been able to get a feeler gauge below it. A length of 2020 extrusion is probably moving >0.1mm under load, so bend or twist of that magnitude will probably blend in with a slew of other misalignments. Mostby 691175002 - Extruded Aluminum Frames
Re: Tap and Die set - 5 years ago
If you are only hand-tapping plastic and very occasional aluminum then get a super cheap set, maybe even ebay/aliexpress. Cheap taps are often called "thread repair" taps to imply they are not actually designed to cut new threads. You do not want to use these in steel. Depending on the type of work you do, it might be worth getting a plug + bottoming set so you can do blind holes as well, but tby 691175002 - General
Re: GT2 vs 2GT belts/pulleys?? - 5 years ago
QuoteArtemKuchinArghhh. God, help us all. Pretty much. Its best to assume that unless the listing contains the words Gates PowerGrip® it is actually the circular profile. Misumi refers to all Gates parts as MR on their webpage to reduce ambiguity*, but that just makes it confusing in another way. I have a roll of real Gates timing belt and it is loose in circular pulleys, although maybe if yoby 691175002 - General
Re: GT2 vs 2GT belts/pulleys?? - 5 years ago
Timing belt nomenclature is an absolute disaster. Misumi has a table here that might help: You can also browse Gates part numbers to get a better idea of their various parts. I suspect that the cheap components are the Asian circular profile and not a Gates curvilinear, but to test it you would probably need to scan a genuine and off-brand pulley at high resolution and compare.by 691175002 - General
Re: How to improve print quality at higher speeds? - 5 years ago
If you want clean surface finishes, it becomes hard to cool the extruded plastic quickly enough. High powered fan ducts help but printed geometry redirects airflow. Identical layers that have received a different amount of cooling will display a different amount of smearing. I've found that if you care about detail there is a fairly low hard limit on PLA print speed (40mm/s?). Lower acceleratby 691175002 - General
Re: run inverse kinematics calcs prior to runtime? - 6 years ago
Your idea isn't really compatible with the purpose of g-code. You need to know the absolute coordinates of the toolpath in order to calculate the inverse kinematics, but a g-code file does not have that information. It doesn't know where the homing switches are until they are found, and doesn't know the shape of the bed until it has been probed. Complete g-code is closer to a programming languby 691175002 - General
Re: A few general questions about printer design. - 6 years ago
Printers are often designed to meet cost and size requirements, so you buy what you can afford and hope it performs well enough. A particularly motivated designer could do the math to verify the parts will perform acceptably before committing to the design. If you've built a few printers and studied other peoples work you will have an intuitive idea of how a design will print. To be honest, fiby 691175002 - General
Re: Cable management and other noob questions. - 6 years ago
In essence you want to distinguish between power-carrying and signal-carrying conductors. Cables that carry power (power wiring, motor wiring, heater wiring, fan wiring...) are generally noise-producing, and are not sensitive to EMI. Cables that carry signals (limit switches, sensors, thermistors...) produce negligable electrical noise, but might be sensitive to interference and should be keptby 691175002 - Reprappers
Re: Staged heating extruder - 6 years ago
If your goal is simply to melt plastic as fast as possible, limiting the melt zone is counterproductive. Plastic is a poor heat conductor and the limit to extrusion flow rate is almost always getting heat to penetrate to the center of the filament without burning the surface. MIT likely has the fastest printer at the moment, and they heat their filament by passing it through a laser in a mirrorby 691175002 - Mechanics
Re: Limitations and work arounds for Stratasys heated build chamber patent - 6 years ago
QuoteBill ClarkFortunately I do have access to a 900MC to study and they do use a cellular type barrier but don't know the material. I plan to run chamber temps over 200c as they do to print Ultem 1010 The required chamber temperatures are much lower if you use a heated bed. IIRC Stratasys prints ABS at ~70c in the chamber, whereas hobby printers do a 100c table and 45c chamber. I've seen reporby 691175002 - General
Re: Limitations and work arounds for Stratasys heated build chamber patent - 6 years ago
QuoteBill ClarkHave you given any thought to what type of material or a source for the accordion thermal barrier separating the motion system from the chamber? I'm designing a similar machine. The first iteration will use regular fabric way covers from China. They are not particularly well suited for this application, but are reasonably cheap, look nice, and can be customized. I expect them toby 691175002 - General
Re: Limitations and work arounds for Stratasys heated build chamber patent - 6 years ago
While the patent itself describes a very specific arrangement of parts, in practice they can apply quite broadly. For example, piping cold air to shrouds surrounding the extruder and motors could be a violation of their patent, as cold air has been separated from the build chamber using a flexible barrier. I suspect it would be virtually impossible to develop a practical commercial printer thatby 691175002 - General
Re: NEMA motors turn both ways with single direction command - 6 years ago
It sounded to me like one of the two coils was unconnected, so the motor would make a random 180 electrical rotation. Without a multi-meter you are just guessing though.by 691175002 - Reprappers
Re: Flexible build plate suggestions - 6 years ago
I've been most intrigued by PEI on a vacuum table: You don't need to worry about demagnetization and can cheaply rotate a bunch of sheets. I suspect an aquarium pump with the valves reversed can produce sufficient vacuum, but you might also want a reservoir and switch so the pump doesn't need to run continuously.by 691175002 - General
Re: Belt tensioning ideas? - 6 years ago
I've found that moving the tension adjustment mechanism to the stepper motor(s) makes sense. If your carriage is sufficiently compact its very hard to design an accessible adjustment/locking mechanism, and there is no real reason why it has to be part of the carriage. You no longer need to worry about weight/compactness, but your motor mounts will either be asymmetrical (one adjustable, one nonby 691175002 - CoreXY Machines
Re: No-leadscrew, single-motor, precision Z-axis design - 6 years ago
Exact Constraint formalizes a lot of intuitive ideas, but also takes it a step further by meticulously avoiding overconstraints. This is a very application-specific way to design. The preface talks about how Exact Constraint was refined at Kodak for handling high-speed feeding of paper. An overconstrained paper web might fold or bend, causing disastrous misfeeds. Optical designs are another pby 691175002 - General
Re: Are my new rods defective? - 6 years ago
Calipers aren't great if you are measuring small differences since jaw pressure starts to affect the reading. You can check the relative dimensions of your rods by arranging three of them in a row on a flat surface: small - large - small. Then place a second flat surface on top (like the printer bed) and see if it rocks back and forth.by 691175002 - General
Re: Are my new rods defective? - 6 years ago
Its unlikely the rods are inaccurate because ground rods have more or less become a commodity item. The chances are that your old shafts were a different diameter. Shafts come in a variety of tolerances ( ). I would have expected g6 to work, but if it doesn't then the bearings were probably designed for something else. If you have a part number for the bearings the datasheet will tell you whby 691175002 - General
Re: A plea to firmware developers to use common GCode standards - 6 years ago
I'm not a huge fan of everyone adding and claiming g-codes. In an ideal world the firmware and slicer developers would agree on an efficient, minimal set of standard commands. I don't think M codes past 100 or so need to be standardized. Random configuration codes like "M588: Forget WiFi host network" are never going to be called by the slicer; and when you start including that kind of stuff fby 691175002 - General
Re: Change gcode to stop oozing at startup - 6 years ago
If you want no ooze the filament needs to be retracted before you heat the nozzle, otherwise the thermal expansion/offgassing will push a bit out. I retract 2mm at the end of every program. At the start of every program I extrude 1.8mm and do a long skirt to prime the nozzle. It works as long as you make sure the retraction actually happens. If you cancel a print you need to manually G91 G1 Eby 691175002 - General
Re: Inductive sensor question - 6 years ago
The sensing distance is reduced for non-ferrous metals. The datasheet should have a table of metals and their sensing distances. Aluminum is generally detected at 11-30% of the nominal sensor range.by 691175002 - General
Re: RAMPSSB: Closed Loop DC servo drivers for RAMPS - 6 years ago
The idea has been brought up, but AFAIK nobody has actually tried it. The easier kinds of closed loop control get brought up far more frequently and yet servos in 3d printers are still vanishingly rare. FWIW I suspect that the performance of a double loop bowden controller would be rather poor. This is pretty much an absolute worst case control problem - highly nonlinear, noisy, and the plantby 691175002 - Developers
Re: Dual Direct Drive Extruder with one Motor - 6 years ago
As mentioned, this kind of thing is very common in clocks. I've never seen one in a nema form factor though.by 691175002 - General
Re: Thoughts on a beginner CNC - 6 years ago
The problem is that most useful CNC builds require access to a manual/cnc machine shop to begin with, plus years of experience and several months of free time. Hobbyists generally have to bootstrap though iterations of progressively more capable machines. When machinists talk about machine accuracy its a shorthand way of describing the full system. A machine that holds +-0.001" has many propeby 691175002 - General
Re: No-leadscrew, single-motor, precision Z-axis design - 6 years ago
QuoteMKSA Perfect to demonstrate how to properly constrain, just that the "We assume we are using perfect wheels, no play bearings, non stretch cables, perfect flat and square surfaces..." foreword is missing. To be fair, the anti-racking properties of CoreXY rely on those same assumptions.by 691175002 - General
Re: Comparing worm gear drives- any ideas? - 6 years ago
You typically don't use a dial gauge to measure absolute distances because if the plunger is at an angle the measurement will be off. A more accurate way to measure a displacement is to zero the dial gauge on the bed, jog it down X, then insert an X gauge block and verify that the gauge still reads zero. That being said, you've measured a fairly large error so its possible that the bed is movinby 691175002 - Mechanics
Re: Digital Calipers - 6 years ago
There are now Chinese counterfeits for most of the reputable brands. The fakes are quite obvious if you've used the real thing, but purchasing online is more of a risk. Cheap digital calipers perform fairly well, the main inconveniences are that they drain battery quite quickly and use an incremental encoder. The incremental encoder forces you to zero the calipers quite often, and if you moveby 691175002 - Reprappers
Re: My coreXY design is progressing to the build stage - 6 years ago
They carry other brands of worm gears as well, but I tend to avoid third party products on Misumi since the lead times are longer and the documentation is less detailed. For example looks plausible but has no description.by 691175002 - CoreXY Machines
Re: My coreXY design is progressing to the build stage - 6 years ago
Misumi has graded worm gear sets for ~$30. High speeds and zero backlash are the most expensive requirements for a gearbox, and this application requires neither.by 691175002 - CoreXY Machines