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Re: How should i deal with the vertical force of my Z-axis screw drive? - 7 years ago
Aluminum foil or shim stock wrapped around the shaft will work well. I've started using Kapton tape to shim non-critical fits because it is much easier to work with and doesn't creep as much as other tapes.by 691175002 - Mechanics
Re: How should i deal with the vertical force of my Z-axis screw drive? - 7 years ago
There are many strategies for mounting leadscrews. Since a 3d printer bed is preloaded by gravity, a single bearing is sufficient to eliminate axial play. You should be most concerned about introducing wobble if the screws sit off-center in the bearing, or if the unsupported end is free to whip around. The extent to which your bed is vulnerable to wobbling will depend on how it is connected toby 691175002 - Mechanics
Re: Any experience with this hotend? - 7 years ago
QuoteDjDemonDIf it's in the heater block why isn't this considered a mixing hotend? If you extrude multiple colors at the same time they will remain seperate while leaving the nozzle producing a "toothpaste effect". The print is just two colors sitting next together, not a homogenous mix. I think the term mixing extruder is slowly being used only for hot ends that can actually produce a blendeby 691175002 - General
Re: Is this too much for a A4988 Stepper driver? - 7 years ago
I'd just like to point out that I find it extraordinarily unlikely that stepper motors weighing 9g each are intended to survive the currents being talked about in this thread. I could not find a PM15S-020 motor with 10 ohm coil resistance, but the other motors of that series are designed for 100-150mA.by 691175002 - General
Re: Is this too much for a A4988 Stepper driver? - 7 years ago
The coil resistance is effectively irrelevant as the a4988 will regulate current itself. I would probably start with all four motors in parallel and set the a4988 to like 0.2A. Go up to 0.6A if they need more power to turn, and you can keep increasing the current if they are still cold. I am not confident the motors are suitable for this application. They have an 18 degree step angle (regularby 691175002 - General
Re: Conductive build plate? - 7 years ago
QuoteDjDemonDAs an argument against direct electrical contact as a probing method this is a weak, lazy argument. I'm not so sure. I assume most high end printers produce enough force to snap a heat break, so probing the bed with an unreliable sensor seems like a high risk play.by 691175002 - General
Re: Flexible build plate suggestions - 7 years ago
Buildtak sells a magnetic plate system:by 691175002 - General
Re: Need Advice - Heating and Cooling a Digital Fab Lab - 7 years ago
You should roll your questions into one post and head to practicalmachinist.com. I don't think a hobbyist 3d printer forum is well suited to provide the advice you are looking for.by 691175002 - General
Re: Can we make extruder return home after every layer to check for missing steps? - 7 years ago
Virtually every type of switch is repeatable <0.001" over short time periods. Limit switches, inductive switches, and photointerruptor/optical sensors are frequently used in CNC builds. The problems arise if you need a repeatable position over long time periods. If you show up a year later with a different temperature, humidity, atmospheric pressure, and supply voltage; it is very difficultby 691175002 - General
Re: Poor Man's Digital Dentist Core XY build - 7 years ago
My printer is 100% ATP-6. [3.bp.blogspot.com] Note that if you are ordering from Midwest Steel the bottom of the plates will be mangled by forklift marks. I'm not sure if other suppliers also have that issue. Stress cracking is more of an issue for ships and bridges. A print bed has virtually no load so there really isn't any chance of mechanical failure.by 691175002 - CoreXY Machines
Re: Tracking Axis movement with Rotary Encoders - 7 years ago
The advantages of servos are much more constrained than people think. A servo and stepper of equivalent torque will fail in the same situations, and in practice you should not "recover" missed steps even if it is technically possible to do so. If a servo is loaded to the extent that it is missing steps, something has gone wrong. Maybe a bearing alignment has failed, maybe your cables are caughby 691175002 - CoreXY Machines
Re: A new 3D printer design - 7 years ago
What velocity, acceleration, and jerk/juncdev are you using? I've been thinking about how extruders might perform with instantaneous velocity changes. Obviously maintaining constant speed while printing is good, since the extruder pressure can remain constant, but is there a point where the printer starts and stops so quickly that extruder pressure lags behind the printer motion? As far as I'mby 691175002 - Developers
Re: I am working on my portable 3d printer again, is it still worth it? - 7 years ago
I have a bit of a soft spot for portable machines since I went to an out of province university and currently live in an apartment. My most complete attempt at a portable device was a cnc router: It suffered from rigidity problems (too much Z-travel + unsupported rail) which more or less constrained it to plastic, however it saw considerable use at school and even travelled it through airport sby 691175002 - Developers
Re: Are multiple extruders the future of 3D printing? - 7 years ago
My feelings on independent X are mixed. Being able to print multiple copies of a part in one cycle is an massive advantage, but taking advantage of that feature requires identical hotends on both carriages. I find that being able to use different nozzle diameters to speed up a print is perhaps even more compelling than printing multiple copies of a part. I'd also need to really think about howby 691175002 - General
Re: What's your minimum build volume? - 7 years ago
I think rectangular beds have some promise. I'd consider something like 200x100 more useful than 150x150. 100^3 is okay but 150^3 is probably a more realistic minimum since you lose a bit of space for the skirt and such. Most of my prints are less than 80mm high.by 691175002 - Reprappers
Re: A4988 heatsink issue - 7 years ago
Thermal tape will work, but glues are also an option and are easier to find. Thermal epoxy is designed for this application, but I'd probably use silicone adhesive as it is a decent thermal conductor and is often used for mounting LEDs (and I have a tube of the stuff on hand). Just be sparse with the stuff so it doesn't bridge any connections. Even if the glue is an insulator sometimes sensitiby 691175002 - Mechanics
Re: Extrusion based bed level compensation - 7 years ago
This is actually a pretty neat idea, but its very hard to actually implement because it crosses the machine/slicer boundary. The slicer doesn't have enough information to do this unless you probe the bed and send that that heightmap back to the slicer (and then reslice and export g-code). The 3d printer board really does not want to do this because its would require duplicating a huge amount ofby 691175002 - General
Re: Requesting Opinions on Mechanics on my Next 3D Printer Build - 7 years ago
Very high temperature heated chambers haven't been well explored by hobbyists. You can look to stratasys for guidance, but they tend to go for the highest quality/most expensive solution everywhere so its hard to figure out exactly what is necessary. I'd be very hesitatnt to place the extruder in the heated chamber. Stratasys either seperates the extruder from the heated chamber with insulatinby 691175002 - Mechanics
Re: Design Thoughts - 7 years ago
I replied to your other thread but this is a pretty good topic. I think and tell people to reduce BOM as much as possible, but looking back personal my projects always seem to end up with a lot more part numbers than I'd have liked. Design intent matters a lot, a one-off for personal use can make some concessions but if you are releasing instructions or kits you really want to be efficient. I'by 691175002 - Reprappers
Re: thoughts on hardware (nuts and bolts) - 7 years ago
Naturally fewer is better. I will design a part to use an existing screw whenever possible, unfortunately sometimes you just have no choice. When you say three types do you mean three total part numbers or multiple lengths of three different diameters? Three total part numbers is really good. For what its worth my current project has 9 seperate fastener part numbers plus M3/M4 nuts. I wasby 691175002 - Reprappers
Re: Core XY vs Hbot Build - 7 years ago
Quoteprot0typ1calFor a moment, imagine what a dual carriage H-bot looks like, then compare it to as you stated "complexity to be almost universally undesirable". Thankfully, I live in a different universe, the CoreXY. This would just be my first intuitive approach to the problem, but I can't see any immediate disadvantages of this layout. The "primary" carriage is connected to red belt, with thby 691175002 - CoreXY Machines
Re: Core XY vs Hbot Build - 7 years ago
QuoteSo why not build a coreXY with more than one block? Because you could build an H-Bot instead, and the H-Bot will be simpler and have a lower part count. I think where our opinions diverge is that I greatly value simple designs with few parts, especially in applications where accuracy matters. When designing a printer you should be constantly looking for the weakest link in the design. Atby 691175002 - CoreXY Machines
Re: Core XY vs Hbot Build - 7 years ago
I can't provide any definitive answers since there are so many other choices that need to be made. My view is that too many people consider H-Bot to be an inferior predecessor to CoreXY. Both designs have their place. Any system with a single block per rail is unquestionably better as a CoreXY. If you are running two blocks in an H-Bot, the cost of a few extra inches of rail is negligible, anby 691175002 - CoreXY Machines
Re: 3D Printer Design Guides for Custom Machines - 7 years ago
I'm not aware of any 3d-printer specific documents, but positioning systems in general are extremely well studied. For our purposes linear motion is a solved problem. There might be some room for creativity in the low cost space, but people have been building vanilla cartesian motion for a long time. The requirements of a 3d printer are not particularly different from those of pick and place,by 691175002 - General
Re: linear rails advice for a 200x200 design - 7 years ago
What do you mean by noughts and crosses? Is that like the ultimaker arrangement? Linear guides are traditionally selected based on the forces the blocks can withstand. Even MGN7 can survive roughly 600lb of force so when designing a printer we select on other factors. MGN7 is too narrow to easily mount in 2020 extrusion (plus standard nuts only go down to m3) so it typically gets avoided. MGby 691175002 - Extruded Aluminum Frames
Re: Junction Deviation Explained and Visualized - 7 years ago
I was able to follow your explanation well, the charts were very useful. Do you have any opinion on the performance of junction deviation? I've always viewed it as an awkward hack since it requests moves that are physically unlikely and expects stepper motor compliance to smooth it out. Traditional trajectory planners keep velocity and its derivatives within the configured limits at all times,by 691175002 - General
Re: Is a stepper motor the right choice for my project? - 7 years ago
Given your size restriction I think gear motors make a lot more sense. I'm not convinced you can find a stepper that size with sufficient torque. For example something like this is highly unlikely to swing a prop at 20rpm: A stepper with an integrated gear box should have no problem, but is larger: Should you find apropriate steppers, controlling them will be no problem. You can connect foby 691175002 - Mechanics
Re: Belts - Whats the best you can buy? - 7 years ago
QuotenewbobI'm curious why shock handling is an issue when you write that 3D printers don't handle high forces? I just noted it in a general sense, its not a drawback for 3d printing so fiberglass is a good choice for us. In general I'd assume that overall frame and stepper compliance contribute significantly more error to the average printer than its belts.by 691175002 - General
Re: Core XY vs Hbot Build - 7 years ago
QuoteQdeathstar Mr Numbers, You are saying that for a given result, the coreXY costs less that an HBot. Doesn't that make the coreXY objectively better? CoreXY is better for low cost builds, but if your build has no risk of racking then it has no advantages. A coreXY build requires twice as many inside idlers, tensioners, and anchors in the belt path. Not a problem if you are using skate bearby 691175002 - CoreXY Machines
Re: Belts - Whats the best you can buy? - 7 years ago
I've been using genuine belts (Misumi/McMaster/SDP-SI/Gates) just because they are pretty cheap and these suppliers keep a wide inventory of belt lengths. I have noticed that open lengths of belt are quite unusual in industry and are sometimes quite expensive - You can only buy genuine 3mm/15mm Gates in 100ft rolls and they list for >$400USD. Steel core belts aren't really ideal for low forcby 691175002 - General