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Tony Olivo
Reprapper (Thav) in NC
Reprapper (Thav) in NC


This is a new one for me (or maybe an old problem that I never really solved). I have been trying to calibrate my extruder steps. Here's how my process went this morning

M503 reports E1022 steps/mm
Extrude 100mm, get 111.5mm
M92 E916.6 (1022 * 100 / 111.5)
Extrude 100mm, get 93mm
M92 E985.6 (916.6 * 100 / 93)
Extrude 100mm, get 115mm!

So my last extrude was with fewer steps/mm, but got more total extrusion compared to the first. My next test will be to repeatedly extrude with the same steps/mm to see if the rate is self-inconsistent, or if the steps/mm settings are being quantized in unexpected ways and systemically don't match reality.

Things I know:
* Drive gears are not out of round, good meshing all the way around
* I'm driving very slow, and filament is not slipping, grinding or pulling the spool
* Control board is iDuino MEGA (Arduino MEGA clone)
* Shield is RAMPS 1.4, I don't remember the stepper drivers
* Firmware is Marlin, probably 1.4 years behind master.

Hi all,

I am playing with printing STLs exported by my mechanical engineering team at work. They are exports of large (20 ft container large) full assemblies. Solidworks handles the export decently, and besides the problems of thin-walled third party components, everything comes in, and slices well.

The problems are:
1) The slicer, ever dutiful, tries to replicate every screw hole in the model. This doesn't really add anything to the printed model, but takes extra time and offers opportunities for gloppy overextrusion because I'm terrible at tuning my machine (different story)

2) Some components have geometry that's both internal and external (think of a pipe coming out of a wall). I don't care about the internal part, only the external.

The question is, does anyone know a way to take a full STL and sort of simplify it down to a surface representation, filling holes and spanning gaps? I imagine I could do it manually in something like Meshlab, or manually remove the geometry in Solidworks, but I wonder if there's anything a bit more automatic.

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Friday night acid party!
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I'm having trouble with my extruder after changing to an e3d V6 hot end from a J-head I had been running for 1.5 years before its thermistor fell out and turned into a plastic blob. This extruder previously worked reliably with the J-head, only one screw (the far one) in the idler and a weak spring from a pen.

After changing to the e3d V6 I can't get reliable extrusion before the hobbed bolt strips the filament. The video shows about what happens. I have corrected/tried:
* Thermistor set to the Semitec as recommended, instead of my old Epcos 100k (this was wrong for a while, but fixed recently)
* Cold pull of filament was clean, able to see light through the nozzle
* Adjusting idler tension across the whole range I can manage
* Manual extrusion with the hot end out of the extruder body (which felt tougher than I imagined, but I never tried before)
* Turning the nozzle temperature up to 250C with ABS
* Adjusting stepper mounting with respect to big gear, in case hobbed bolt was being pushed by a slightly elliptical gear
* Cleaning hobbed bolt when it grinds (hobbed bolt was bought from Airwolf out in California)

Things I haven't tried/corrected yet:
* Different roll of ABS filament that has been sitting in a bag with desiccant
* PLA and Nylon Bridge filament
* Slight misalignment of hot end with extruder body. Maybe 4 degrees off square with bottom of extruder body

Any other ideas for me?

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Firstly, sorry to my non-US or uninterested followers for the following post on US Politics. Please do feel free to unsubscribe from the collection if this is clutter to you.

Larry Lessig (who you may be familiar with from his work as an open source software advocate and copyright critic) is considering entering the Democrats' primary on a single issue: Citizen Equality. This would include fixes for campaign finance reform, gerrymandering. The promise is then that he would resign, and let the VP take over. This is all pretty wild, but I am supporting it just so he can get to a debate or two and give a national voice to the problem of corrupt government in a way I don't feel other Democratic candidates will (with the exception of Bernie Sanders, who does include it high in his list of grievances).
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I love talking about how to do my job so much, my company is putting my power conversion training sessions on the web. I will caution that I go into these with only a very crude plan, so it may be more disorganized than your common professor.
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Don't Miss the latest installment of Tony Talks!
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Just wanted to show you all a photo showing what inconsistent filament diameter can do to you. A third of this "e" hit a spot of low diameter filament and I've ended up with under extrusion and poor first layer adhesion.

This is easy enough to check for, you just need to take some measurements of your filament a few times over half a meter or so. Be sure to take two measurements at each point in case the filament has an oval instead of circular cross section (which this one also did).

This filament has been a real problem for me, so I'm trying to use it up in giveaways. The vendor is, but I've had this for over two years and their other colors were decent, so I wouldn't take this photo as a general mark of my experience with their quality.

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I've had this Ultimachine PLA sitting around for three years and have never printed with it or any PLA. Today I fully understand why people like it so much.

.14mm layers, sliced with Cura and printed on my Prusa i3. Stuck remarkably well to my ABS-acetone slurry that I use for ABS.
2 Photos - View album

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I'm having some trouble with OpenSCAD. I am trying to modify an STL with some cutouts. Everything looks fine with Compile (F5) but Compile and Render (F6) gives either no output, or just one of the shapes that was supposed to have been cut out in OpenSCAD 2014.03 and 2013.01 respectively.

Files are here, the top level is the _Tony.scad:

I have tried repairing the STL in Netfabb, exporting from FreeCAD and Slic3r with no improvement. The slot() module doesn't cause issues when differenced from say a cube, so I don't think my handiwork with that module could have messed it up.

This is the source of the original STL:

Do you all have a go-to thing for checking slicer settings for fitting parts? Square/circle/hex peg in a square/circle/hex hole kind of thing is my first thought. There are other types of joints that you want to fit, like press fit connectors and such, but I don't know if those are sufficiently covered by testing inside/outside dimensions
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