It happens commonly enough that I try to keep it in mind when designing parts.by RevarBat - Developers
Quotelivingfractal QuoteRevarBat Adding lots vertexes too close together in an arc can cause shudders and slowdowns in printing, which can add blobs and ripples to the parts as well. Can you elaborate on that? Because STL files are all flat triangle faces, models made with them translate arcs into small consecutive facets. Slicers translate these into short line segments in the g-code output.by RevarBat - Developers
Quotelivingfractal Would there be any benefit to rounding the corners, such as the internal corner between the beams and walls on the x-y motor segment, to reduce stress concentrations? Maybe? Probably? Have to be careful what you round out, though. Rounding out overhang corners can cause bridging issues. Adding lots vertexes too close together in an arc can cause shudders and slowdowns in priby RevarBat - Developers
Correct. You do not need to regenerate the STL models if the printer slop is already correct.by RevarBat - Developers
Regarding the slop calibrator: 1. find the smallest hole that it you can insert and remove the plug from without having to use a lot of force. 2. Take the value of that hole and set the printer_slop variable in config.scad to it. 3. Regenerate all the STL model files by opening each *_parts.scad file in OpenSCAD, use F-6 to render the parts, then export to STL. 4. Print from the new STL filby RevarBat - Developers
Bridging gaps are kept to less than about 25mm. If you have reasonable bridging settings in your slicer, it should make good parts. Even if you get some bridging sag, those are not a critical problem for this design.by RevarBat - Developers
It takes about a week of continuous printing. Maybe more. The STLs/slop_calibrator_parts.stl model still exists for slop calibration.by RevarBat - Developers
I just released Snappy v3 as a working design, and added a Snappy 3 page to the Reprap Wiki. I patterned the page on the one for the original Snappy. The main improvements of the Snappy 3 over the old Snappy 1.1 are: - Replaced the old metal lifter rod vitamins with printed equivalents. - Bed leveling is now adjustable. - Z axis homing is now towards Z-min. - The herringbone gears and raby RevarBat - Developers
Last time I weighed it, my print of the snappy took somewhat over 2Kg of filament, or 2-and-a-bit 1Kg spools.by RevarBat - Developers
While it's not a completely static motor design, the Snappy RepRap printer has gotten rid of most of the standard vitamins, to the point that it snaps together without screws, and uses no pulleys, belts or metal rails, and the frame is completely printed.by RevarBat - Developers
I didn't see this mentioned here, so I figured I would post this as an update. At is this update on the awarding of the Gada Grand Personal Manufacturing Prize: QuoteKartik Gada 1/1/2016 : We have a decision about the Prize results. For the Grand Personal Manufacturing Prize, unfortunately, of the entries submitted, only two were sufficiently impressive, but neither of those two were able toby RevarBat - General
Moving either the X or Y motion up onto the gantry would be problematic for introducing a lot of wobble into the printing process, as plastic isn't as rigid as metal rods. I have been looking at ways to use string to remove one of the Z motors, though.by RevarBat - Developers
Quote_dreamer when trying to pause the operation using: M226 P59 S255 but the line is just ignored. What is the proper method to tell Marlin not to execute any preceding lines until the input of a certain pin is HIGH? Is the M226 being ignored because pin 59 is not set as a digitalRead or analogRead? M226 P59 S1by RevarBat - Developers
The code seems pretty clear that it will ignore M226 if P is undeclared or S is not -1, 0, or 1. If S == 0, then M226 will wait for the pin to go LOW. If S == 1, then M226 will wait for the pin to go HIGH. If S == -1, then M226 will wait for the pin to change from its current value.by RevarBat - Developers
I don't actually know what all constraints injection molding adds. I did a quick google on it, though, and as best as I can tell, this design would need to have thinner walls, and the extruder platform may be problematic.by RevarBat - Developers
The slop calibrator part is indeed what you are looking for. I could make it smaller, but I want the calibration text on the side of the part to stay readable. I'm adding a note about updating the Ubuntu packages to the Make.md and README.md files.by RevarBat - Developers
Yes, all the assembly instructions images are generated by OpenSCAD. Yeah, it took me a while to do that, but the benefit is, I can make changes to parts and the assembly instructions are updated with a simple 'make instructions'. (And a half hour wait.)by RevarBat - Developers
You can now find the assembly instructions for building a Snappy RepRap at:by RevarBat - Developers
As promised, here's some photos of the parts from the 1.1c revision of the Snappy. It's a lot better, but there's still some artifacts in the printing. They are so extremely consistent, though, that I have to wonder if it's viable to make software compensate for it in the G-code.by RevarBat - Developers
The direct drive Z failed in that it just didn't have enough torque to lift the extruder platform against gravity and slider friction. Also its layer resolution was sub-par. It COULD be geared down to work, but that introduces more slop into the system. Sarrus linkages are fascinating, but very complicated and hard to make pin-less without being very wobbly. I do find the printed lead screws iby RevarBat - Developers
I've released Snappy v1.1b, which re-instates the lifter rods, as the direct Z drive just did not work out. You can get the latest files from the repo at https://github.com/revarbat/snappy-reprap, under the release name "release_1.1b". This is a known working release.by RevarBat - Developers
Quotecristian Would these artifacts increase or become reasonably stable generation after generation, if a Snappy printer had to print a second Snappy printer, and this one printed another one, and so on? Unfortunately, I would expect generational degradation.by RevarBat - Developers
For reference, here's photos of some of the first items I printed on the Snappy, before I fixed a lot of the issues. You can see a lot of Z banding due to the vertical lifter-rod misalignment in the v0.93 printer, and from the Z axis motors being held too loosely. Direct drive Z shouldn't be prone to this, I think. Also, tightening up the motor mount and slider spacing should reduce this a lot.by RevarBat - Developers
QuoteEzrec and 2 threaded rods I'm actually experimenting with a direct drive Z axis that will eliminate the threaded rods. Quotefrankvdh I wonder how big a build volume you need to be able to print the parts? Looks like maybe 150x150? All parts should be printable in a 160x150x120 build volume. My main driver for choosing the given part sizes is that it should be printable by the printer itby RevarBat - Developers
Okay, I cleaned up that page a bit.by RevarBat - General
On my home-brew printer, I have a larger 6" x 7" build platform (about 150 x 175mm), so I had to make my own heated platform. I used the following parts: 6" x 7" x 0.25" aluminum sheet 100W 4" x 5" silicone heater pad, 5 W/in^2, self adhesive backing, 120VAC (part# 35765K181 on McMaster.com, $27) Four #6-32 male-female threaded aluminum hex standoffs (part# 93505A112 on McMaster.com,by RevarBat - General