Did this change your opinion of them as a company?by JohnnyCooper - General
jeffpark_ Wrote: ------------------------------------------------------- > > Let's suppose that I want to replicate a lot of > mendels to sell them or to give them to friends, > does it make sense to buy a hobbyist lathe? > > > Another thing to consider, is most of the parts > (smooth/threaded rod, nuts, bolts, washers, etc.) > are usually cheaper if you are buying inby JohnnyCooper - General
Maybe another option would be to print the tracks in plastic on a metal/glass plate, and then pour/mold a plaster of paris PCB on top of the plastic. Vulcanize away the plastic and pour alluminum/zinc/copper in to form traces.by JohnnyCooper - General
The approach I'll be taking is to have two print beds on a lazy susan, the table will rotate 180 degrees between prints.by JohnnyCooper - Kartik M. Gada Humanitarian Innovation Prize
Why choose? You can use a CNC mill as a repstrap with the addition of an extruder.by JohnnyCooper - General
That looks like a die casting job to me. I say that for this reason: You're not going to be able to compete with that price if you're looking to save money. If you're looking to sell them: 3d printing is a prototyping technology in most situations. Die casting would be the way I would mass produce them in order to try and sell them but then you're looking at potential trademark lawsuits... Ifby JohnnyCooper - General
I forgot to mention, but I think the design looks brilliant. I have some of those ball joints you linked to. They will most likely get the job done, but their range of motion seems like a possible unnecessary restriction. I'm going to use mine for prototyping and switching to a spring, cup, and ball design ASAP. How are you fabricating the plastic parts? Will you be uploading .stls?by JohnnyCooper - Delta Machines
That's exciting! I'd personally love to see it in the wiki. My impression of official policy is "anything but a handgun."by JohnnyCooper - General
Yes, but the answer gets complicated from there. The answer is machine specific. There are overhang tolerances, and if those must be succeeded: there are strategies to cope. If you mean specifically: "can mendel print support material?" -PLA is supposed to be an acetone soluble support material for ABS but this calls for a multi extruder print head. Is the Mendel's official release capable of sby JohnnyCooper - General
It occurs to me that a 3rd joint could be added by simply calculating the trig relationship between Adjacent(needed) and hypotenuse(adjusted) for a given opposite.(Z) Even less complicated with a scara setup. I've been questioning my goal of a Backhoe format when I consider that a backhoe's design is specialized for the wrong plane. (vertical) Seems to me: the most basic polar bot would reseby JohnnyCooper - Polar Machines, SCARA, Robot Arms
I've been most successful with the search terms "Delta Inverse Kinematics". There is a java applet out there somewhere with published souce code I think, but I'm having trouble finding it.by JohnnyCooper - Delta Machines
A "Jiffy mold" design is the simplest. I always hesitate to pile on complexity until I have a working prototype. I'm wary of the temptation to bog down projects with complexity until I've gotten that far.by JohnnyCooper - General
nophead Wrote: ------------------------------------------------------- > PLA works as a support material for ABS and you > can dissolve it with caustic soda. +5 Informative So the question becomes: Does discussion of alternative support materials merit it's own forum?by JohnnyCooper - General
I think the idea shows a lot of promise and lends itself to injection molding more than the original mendal simply because there's fewer molds to make.(the fact that it's virtually 100% plastic is a huge stepping stone towards the Gada Prize... If it can print the parts to a mother machine(mega-Mendel) and a "Mega-Mendel" can produce it: we have a 2 stage approach to self replication that looks vby JohnnyCooper - General
Interesting issue you raise. Begs the question what parts of a polar arm are critical dimensions? If you combine 3 will the error average out? How small of a work envelope is necessary for acceptable accuracy? If you used a jig to drill the pivot holes: I think the dimensions could be incredibly sloppy. Another question being: could photo-lithography be applied for laminated structures?by JohnnyCooper - Polar Machines, SCARA, Robot Arms
My intention was to drive the spool using a hobby servo. My preference is for hydraulics rather than pneumatics for the reason of hydraulic fluid not having the compression issues of pneumatics.by JohnnyCooper - General
I'm skeptical. There are more suitable guns to build a plastic receiver for. Good luck printing a barrel without laser sintering.by JohnnyCooper - Administration, Announcements, Policy
The notes regarding suping up hobby servos seem invaluable. I'm semi-torn on hobby servo arms. They seem like a good stop gap while other servo technologies are tied up in R&D, and allow for Inverse Kinematics work to move forward, but I don't want to get too attached to their mechanical designs because their design considerations are built around an entirely different animal than the R&aby JohnnyCooper - Polar Machines, SCARA, Robot Arms
Here are the files. This is design revision 1. Suggested changes are to double the depth of the spool and valve block allowing for larger holes. 1/8 holes aren't fun to tap threads in to. Material isn't called out, but I recommend brass spools, and a steel valve block, or an alluminum valve block with overbored holes and a consumable sleave be machined from brass. EDIT: ABS should be fine for thby JohnnyCooper - General
SebastienBailard Wrote: ------------------------------------------------------- > JohnnyCooper is working on: > > > Monolithic+elastic sounds elegant, but dozens of > rigid (modular) parts is much easier to get into > for beginners. > > I think Cyberdyne_T-1 is a necessary waypoint for > what you're proposing, Viktor. SebastienBailard Wrote: ----------------------by JohnnyCooper - General
Foundry crucibles are sometimes made of a material with a material of a lower melting point than it's contents. They use water cooled plumbing to wick heat away from the crucible. Same concept as lighting a paper cup on fire.by JohnnyCooper - General
I've seen a jeweler who 3d prints wax for investment casting so I know it's possible. What extruder, or what composition I do not. I imagine any thermoplastic which can be vulcanized would be adequate.by JohnnyCooper - General
Taking a stepper motor apart is a decent hassle. I vote worm wheel or cogged belt pulley.by JohnnyCooper - General
Seems like instead of direct control via EMC or some such, you could wire the paper feeding rollers to a moving platform and use the inkjet head control signals to pulse an extruder on and off. Then you just use the existing drivers and queue up your .stl layer by layer in the printer queue as black and white sihlouettes?by JohnnyCooper - General
Looks great. I'm really happy you're doing development of GM3 motor linear actuators! I think that's very important. What type of tooling are you making the acrylic body on?by JohnnyCooper - Polar Machines, SCARA, Robot Arms
7 DOF open source platform and software: Some libraries that perhaps IK tidbits can be tapped? Big list: IK relevant/spline/motion planning relevant:by JohnnyCooper - Polar Machines, SCARA, Robot Arms
I don't think so. Just thinking maybe they had some PID code in there for servo control.by JohnnyCooper - Polar Machines, SCARA, Robot Arms
Is there anything that can be learned from these guys?by JohnnyCooper - Polar Machines, SCARA, Robot Arms
Looks great! That's Acrylic?by JohnnyCooper - Polar Machines, SCARA, Robot Arms
I see what you're saying, although in the specific robot I've linked to's case: the hobby servos I've played with seem to have decent holding torque simply as a result of the high gear ratio. I can understand why there is a potential for cumulative error, however since the servo's themselves have potentiometer closed loop feedback, I'm hoping that the PID controller's acceptable error will be acby JohnnyCooper - General