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Re: Grounded Experimental Delta Printer - 12 years ago

@MetalButcher Split/cut the .stl into two parts then glue them together. Add alignment notches/holes/pins.

Re: Melzi Hotbed connector fried! - 12 years ago

Lots of vibration solutions for 3d printers on Thingiverse. Maybe there is a problem...

Re: Help and Advice running Reprap in University lab - 12 years ago

Contact Dr. Pearce at Michigan Tech. We are particulary interested in students that either 1) have experience in research on solar PV or 2) have experience in open source hardware/RepRap technology.

Re: ABS purity - 12 years ago

Ask the supplier/distributor for material certification. If they don't provide you with a mat'l cert, assume there is chicken feathers compounded into your filament. There are tests to determine particulate count, and size. A simple test is to dissolve the plastic in a solvent and then filter it. Examine the filter under a microscope.

Re: Melzi Hotbed connector fried! - 12 years ago

If vibration is the cause, consider applying high temp silicone to the screw. I wouldn't use hot melt glue, as it would be a fuel for a fire. From what I have read: Type I silicone reacts with water. I believe type I releases acetic acid during setting (smells like vinegar), and this is corrosive to metals. Type II silicone reacts when water is removed, or is activated by a different means, ("Ox

Re: Anyone know about Cams? - 12 years ago

Search for: Eccentric Cam Bolt, I'm not sure how you would get 3 of them to work together. Wheel Alignment Toe Bolt Kit.

Re: Anyone know about Cams? - 12 years ago

Nylon is a replacement to bronze/brass gears, i.e. it's good for wear and pressure applications. A flat or a spot drilled hole would be beneficial. 3 more ideas: Use a keyed shaft. Use a threaded rod with locking nuts on either side of the cam. Probably the easiest and strongest would be to simply drill a hole in a steel slug slightly off center, this would act as a cam.

Re: Professional Arburg freeformer using plastic pellets - 12 years ago

Do they have a patent or a licencing agreement?

Re: Anyone know about Cams? - 12 years ago

Re: Tri-Polar Bot Concept -- Meet Wally - 12 years ago

Tolerance: What is the X, Y, Z tolerance of a 6" x 6" x 1" plate? Reduce the thickness if that's too much material/time. Any beta testers out there with a working Wally that can provide us with this data? A2

Re: Anyone know about Cams? - 12 years ago

That is a custom turned cam profile. Work around: Print an over sized cam profile out of Nylon. Design a pocket to retain a nut for a set screw. Press fit the cam over a steel rod, and lock it in place with a set screw. Then attach a driven gear to the end of the steel shaft to mate with the stepper motor driver gear as depicted in the video. A2

Re: Sextupteron - 12 years ago

I was impressed with the doubly curved print on the glass bottle. The entombment of objects might be useful for someone. A comment found on reddit: "If anything, the build platform should rotate in the x and y direction so that overhangs and bad angles can print easier by rotating the entire print." Maybe the end effector should be the build platform? This would allow for more complex, and fi

Re: Is there any alternative to Teflon? - 12 years ago

@RP Iron Man Another note: I see you have an "internal" 60 degree included angle leading up to the orifice, and a land of 1 mm. Is there a precedent for this angle and land? For contrast, on some 3D metal printers there is an internal radius (due to pressure feed back), and some maths to determine the length of the land. I've not given this much thought of what the common internal profile sh

Re: Is there any alternative to Teflon? - 12 years ago

Sounds like you got the real deal there! I just looked at your print, that can't be wired EDM, that has to be plunged cut. Just saw your note, it's electropolished...

Re: Is there any alternative to Teflon? - 12 years ago

@RP Iron Man EDM = Electro Discharge Machining. You can get a mirro finish with an EDM machine. But I'm not sure if it's possible in a deep small ID pocket. I've only seen it done in shallow pockets. Can you post a cross section of your extruder? What did the machine shop quote you for the surface finish in RMS? 4 RMS is a mirror surface. What SS are you using, did the machine shop make any

Re: Melzi board question - 12 years ago

I found this in my notes: Melzi + Raspberry Pi combo (LCD)

Re: Is there any alternative to Teflon? - 12 years ago

PEEK Graphite: Graphite loaded PEEK is probably conducting heat into your filament. This added heat I imagine would cause the filament to warm up and stick. Graphite is an excellent conductor of heat, crucibles are made of it. Teflon spray coating: I've designed hotplate fusion welding tooling with a Teflon coating, works great. I've conducted lots of experiments with different exotic coatings,

Re: Sextupteron - 12 years ago

6-axis 3D Printer We just stumbled upon this video by Professor and his students and on a 6-axis 3D printer. The group is from the University of Southern California and their project is called the “Development of a Low-cost Parallel Kinematic Machine for Multi-direction Additive Manufacturing”. That’s right. 6-axes of 3D printing. It uses six linear actuators to move the tool head in alm

Re: New arm design for Simpson style printer. - 12 years ago

Upper arm shoulder pivot looks to be above the print table.

Re: Muxtruder - WIP open source plastic extruder - 12 years ago

I like the direction that you are taking with this project. A2

Re: New arm design for Simpson style printer. - 12 years ago

OK, so there are 3 solution paths available to eliminate the nonlinearity: 1. An infinity of magic loops. 2. Software, (codify the hard maths). 3. Geometric, (but no one has a clue what that might be). No one has indicated what geometric direction we should be exploiting. I think it's time we explore the software solution. If the maths is brain numbing, lets break it up and work in teams and

Re: New light extruder concept out of bolt - 12 years ago

@erylon Heat exchanger: It appears you have drawn it as a thread? Add an undercut at the base so the cutting tool can be retracted. Or make each rib independent. Filament twisting: I envision the filament twisting ahead of the drive nut. This bound up energy will cause problems. I think you need a means of holding the filament straight as the drive nut draws the filament into the hot end. Driv

Re: New arm design for Simpson style printer. - 12 years ago

Thank you Owen, Dave, Nicholas. Problem: In general you are loosing your MA as the gear drive rotates. Idea: Change the pulley perimeter to a cam profile, such that the MA stays consistent. Simple sketch to stimulate ideas. A2

Re: New arm design for Simpson style printer. - 12 years ago

No one has explained what the problem is in a manner that a student can set out and solve. 400 to 230 microns (.016” to .009”) error is not acceptable for my work. Would a simulation like this help? Go to the last post there is a down load video titled: Cable Roll On-Off.mp4 I still don't know what geometry is causing a nonlinearity problem. There is not a schematic of the string routing to

Re: New arm design for Simpson style printer. - 12 years ago

Guitar tuner: “If we put the tuner on the motor arm, we have a perfect proportional response.” I need some clarity again By integrating the tensioner (guitar tuner) into the dual drum the nonlinearity error of 400 to 230 microns (.016” to .009”) is eliminated, is this correct? Or are you saying mount the guitar tuner on the same arm as the stepper motor will eliminate the nonlinearity. I

Re: New arm design for Simpson style printer. - 12 years ago

Spring: I understand the gear binding issue and the need for the spring. I have not seen a picture of the spring, it's placement in the system, or it in action, and can not comment on the virtues of a torsion vs. a coil spring relative to the use of a split drum tensioner, or how the difference between the two spring types rule out my design suggestion. Is the dual independent drum tensioner

Re: New arm design for Simpson style printer. - 12 years ago

Idea: Use a split drum, i.e. two drums mounted onto the shaft of the stepper motor. This will allow you to adjust the tension at the drum by counter rotating one or both of the drums, then lock the drum down with a set screw to maintain tension. Place a spanner wrench into the face of the drum and apply tension, then lock the drum down with a set screw. With this system you can use one conti

Re: New arm design for Simpson style printer. - 12 years ago

“If we put the tuner on the motor arm, we have a perfect proportional response. The question is where to put the tuner and the spring on the motor arm.” Fantastic! OK, I'll integrate the tuner into the drum, give me a few minutes to work out a mechanism j/k What is the spring for, safety, or some thing else? What is the maximum OD of the drum allowed before we loose all our torque? How long

Re: New arm design for Simpson style printer. - 12 years ago

I don't want any error So I'll keep at it. Idea: Center the drum between the two symmetrical pulley systems, and tangential to the string coming off of the pulleys. This arrangement allows for magic loops The tensioner is located opposite the drum on the opposing arm, but could be located on, or within the drum. Smallest O.D. of the pulley = Dia 0.02” x 8 = 0.16” (4.0 mm). A2

Re: New arm design for Simpson style printer. - 12 years ago

“As long as you perform complete loops, the total engagement of the cable on any pulley remains equal. With the half-loops, the engagement length changes with arm angle, per the formula I provided.” Problem: The inability to wrap a whole (integer) number of loops around a pulley (e.g. 2 loops). Instead you can only achieve a fractional number of loops around a pulley (e.g. 1.5 loops). The stri