aviphysics
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Posts posted by aviphysics
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Stepper: SY20STH42-0804A (http://cncshop.at/index.php?a=4076&)
Who do those guys think they are specifying holding torque in g cm? Sort of defeats the whole purpose of the metric system.
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You probably don't want to allow the extruder motors to slip, which pretty much means they would need to remain energized. Thus the necessity multiple drivers.You have to cool the entire heatsink of the E3D hotend or it will clog. It looks like the bottom part of your E3D heatsink is not cooled by the fan. If the heatsink gets warm, then the hotend doesn't work correctly. Also, the hotend fan must be on (full speed) all of the time, never connect it to the print cooling PWM output.
Fyi, that's what the E3D guys say - I haven't tested the E3D myself yet.
About the "more than two" toolheads thought:
H-Bot is exactly the (only) way to go
I didn't realize the problem with the UM gantry and my idea at first, but that's because I was already planning to use this with an H-Bot...
The problem with an H-bot is that it's very difficult to "hack" one together and get it to work properly. You need a very good quality build in order to get it to move accurately and without distortions.
Technically, you don't even need more than one extruder motor driver - just need to be able to route the driver to different motors. That is as long as you don't need to do anything with the idle extruders (like prime them before they're used).
So yes - new (or adjusted) firmware is needed. This is the part where I'll need some time o.O
However, you could still potentially get away with multiplexing several stepper drivers to a single pair of step and direction lines. That would allow you to control 4 drivers with just 4 lines or 8 with 5 lines (and writing some code for merlin to handle that.)
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With sufficient effort, it could be done on a UM2, but it would be greatly complicated by the fact that the UM2 does not have sockets for swapping out the stepper motor drivers.
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You could use a temperature controlled soldering iron at a low setting to melt a bit of plastic on at either end, as a sort of retaining ring. The axial forces should be pretty small, so you just need a little bit of something to stop them from slipping.
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It should not become deformed. It sounds like you should open a ticket to UM and get them to send you a replacement.
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Is it possible your glass plate is not flat? If you put it on a smooth granite counter top (or other very flat surface), does it lay entirely flat?
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Alternatively, can't you take a usb cable and cut the power wires?
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Yes and no. Yes, x and y axis are important but (no) don't underestimate the extruder motor(s). Just unhook it during a print and you will hear the difference.
Just decoupling the feeder from the chassis makes a huge difference. IME, the silentstep stick did not make a huge difference in the sound of retractions, but decoupling the feeder from the chassis did.
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I've been watching this thread with alot of interest. I have a suggestion for an improved geometry for the nozzle cartridge engagement cones. I'm drawing on my long experience in machine tool design with jigs and fixtures. For easier engagement and disengagement and better repeatability, I feel the following geometry is preferable. Cone A marked in the picture is a true conical pin and conical hole and provides a point location in the XY plane and a Z height by the mating of the surfaces. Cone B is a true conical pin and a conical slot which qualifies the joint rotationally in the XY plane around point A and also a Z height. Locator C provides merely a Z height . The apex of the cones are designed with clearance to the bottom of the conical hole & slot. This geometry is more permissive to less than perfect precision. This is akin to what was found with the print bed that 3 leveling screws is preferable to 4. For best stability, place the features as far apart in the Z plane as possible. For a further improvement in location repeatability, the male cones can be replaced with spherical features, however a tradeoff will be made with the longevity of the contact surface.
For this application, I would place the conical features horizontal and as low as possible above the nozzle.
The picture shows 2 pairs of the mechanical joint with one half of each transparent
Hoping to help
I imagine that in time, the design might start to include inserts for the mating surface. Maybe something sort of like the thorlabs design on their KB1X1 part (I hope that their design isn't patented.)
I think the advantage of slightly over defining the coupling is that you have a little more insurance against wear. What I have found in practice, is that PLA will tend to work itself into a perfect fit over time.
edit: Just thinking. For the inserts, on one side you could have a plate to trap the ball bearings and on the other side you could have a precision plate with slots cut for the ball bearing to mate with. Both plates could probably be relatively thin and fit on top of a 3d printed structure.
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Regarding the (pickup) sound:
Greasing the wedge shaped part works wonders! I used "Titanfett".
Retraction:
One of my two (supposed to be identical) hotends shows almost no oozing / stringing with a retraction of 2 or 3mm (direct drive!) when parking. No idea how the 2 or 3mm translates to with a bowden.
The other one oozes with the same settings. :???:
Congratulations for accomplishing this with an almost original UM2 setup!
Could the difference just be the color?
For example, this gizmodorks dark gray PLA filament I haven't been able to do much at all to stop it from stringing. On the other side of things, their clear PLA had almost not stringing at all.
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What layer height do you typically print the hot end mounts at?
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Interesting, but I think imperfections in the mesh might cause problems with retractions, as the secondary drive gear will suffer a small change in phase relative to the primary drive gear when the drive is reversed. This could cause too much destruction to the filament when the print requires many retraction along the same piece of filament.
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No the ones I got were from e3d. Recommend the robotdigg ones?
I don't know. Robotdigg just often gets recommended as a source for cheap parts. No idea how good their linear bearings are.
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Foehnsturm, yea with me design I left a 'skin' in front of the magnets (0.3mm), and pushed them in from the back. The idea of this was to make it so that they could be easily removed and no need for glue. Have you just made yours a tight push fit?
The bearings seems to be the biggest area of play, very disappointed with those. I guess I'll have to use the oem UMO ones; I was trying to avoid ripping the original print assembly apart incase this doesn't work out. Anyone know where I can buy either oem or good quality replacements?
Were the ones you bought from robotdigg?
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That little drill is so adorable. Is it just for show or does it have any utility?
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Very nice.
I really need to get off my rear and build one of those direct drive extruders. Retractions are giving me such a hard time on my current project. Especially with Gizmo Dorks dark grey PLA. For some reason it is much more rubbery than their clear filament.
I also wish that the person that made those would have designed them so each color could be printed standing by itself. Would just be cool to have them apart and together. Might make a good magic prop.
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For the ulticontroller, is it possible the cables are switched? IIRC, plugging the wrong cable into the wrong slot will cause the ulticontroller to display strange symbols.
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Carefull with the QG030-198/14 and UMO+. It worked for arround 5mins but when doing tests of positioning suddenly the power stuck on maximun and now my brand new umo+ fan power it's stuck. I have place a ticket to see what are my options but I suppose I will have to start searching for a new mainboard.
So carefull with pluging non standard fans on an umo+ (um2 board).
Btw this model blows a lot of hair. Even onthe lowest setting. It was (when it did work) working nicely. I even designed a casing (very crude). If anyone need it just pm (it's like a hanger that allows you move it a bit to make a beta test with it. For my the crossflow planit's dead (I won't be plugging any weird fans on my umo+ if the resoult it's a fast board death).
When something like that happened on my UMO board, all I had to do was replace the transistor; though that doesn't do anything about how much current the fan draws.
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I wonder what the repeatability of a capacitive sensor would be. Might change depending on humidity or dust.
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I missed that they are copper. You don't want copper bushing. Copper oxidizes in a messy way. That is why it is normally plated when used in connectors.
However, I bet they are actually bronze. Copper bushings just doesn't make sense. Would still print your own blocks.
Edit: it especially wouldn't make sense for sintered bearings, as the pores that hold the oil (the whole point of sintered bushings) would just clog with copper oxide
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Printing parts is not a problem I do have a Da Vinci 1.0A but it really is ABS only so want to build the UM for other materials.
Are the Reptar blocks better than buying the ones in the link?
I believe so. IIRC, the UM2 design makes it difficult to remove the XY carriage without breaking the XY blocks. Also, they are designed to put tension on the belt, which isn't needed for a correctly sized GT2 belt.
The Reptar blocks are the ones I use. They are lightweight and the GT2 version doesn't put tension on the belts. A lot of people like the Chopmeister Twister blocks, which make it possible to remove the XY carriage without disconnecting the XY blocks from the belts. IMO, they are both good choices. They are also a lot cheaper, if you can print them yourself. Printing them in ABS should be fine.
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I don't know how to change it. I just measured it with an oscilloscope a while back.
I do however have my doubts that changing the pwm freq will resolve the issue.
I was thinking you could at least test an external power supply. If that resolves the issue, than we can put more effort into electrically isolating the pump, while still controlling through Marlin.
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I have decided to build the UMO but still struggling to find a definative set of drawings, I have downloaded about three sets with all different names, but dont know which ones I should use ? is there different versions of the UMO ?
I was going to use these blocks
What area are you from? Maybe you can get someone to print some Reptar XY blocks for you. Also, if you are building from scratch, you might as well use 303 tooth GT2 belts for long belts, which don't require tentioning.
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I know the default UMO hot end fan PWM frequency is 30 kHz. Could you try using a separate power supply?
UM original with direct extruder
in Third party products & modifications
Posted
So, any idea about finding ~30 mN*m or greater Nema 8 motors in the USA? Just about everything I am finding is like this or worse. http://www.robotdigg.com/product/278/Nema8-High-Torque-Stepper-Motor
I wonder if I could get away with putting 0.8 A on that motor.