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Discuss any sort of mechanical stuff here: positioning systems, gears, extruding methods, etc.
Re: Idea: A blacksmith bot based on Simpson - 11 years ago
Dudesom, you might have some success with ultrasonic welding. I think you're going to have difficulty getting the metal to adhere, though. Check out thermosonic welding. It's the process used to bond wires to ICs. Ultrasonic welding is also used to bond plastic cases together.by Annirak - Delta Machines
Re: Grounded Experimental Delta Printer - 11 years ago
I was thinking more in terms of the drive pulley spinning if there was too much resistance. That's the problem that a rack-and-worm drive would fix.by Annirak - Delta Machines
Re: Grounded Experimental Delta Printer - 11 years ago
I'm not sure that Simpson is stiff enough for milling. Generally, mills use threaded rod to guarantee that they can exert a lot of pressure, and the toolhead is mounted to a huge lump of iron to reduce vibration and keep it rigid. In 5-axis milling, they move the toolhead, but again, everything is built around stiffness and maximum force. In a cartesian mill (x,y,z, no funny business), everby Annirak - Delta Machines
Re: Grounded Experimental Delta Printer - 11 years ago
I've looked into the mouse sensors in the past. They're interesting, but I have a number of concerns with them. [*] They're built for non-critical motion detection. That means that they don't care about repeatability. If you drop a frame, it's no big deal. [*] The interface (I'm talking about SPI, not USB here) they use is completely proprietary and specific not just to each company, but toby Annirak - Delta Machines
Re: New arm design for Simpson style printer. - 11 years ago
nicholas.seward Wrote: ------------------------------------------------------- > This. This is what we were looking for. Very nice work!by Annirak - Delta Machines
Re: Grounded Experimental Delta Printer - 11 years ago
I've been exploring feedback too. I think the best option for measuring joint deflection is to build a circular capacitive vernier into the joints. The problem with this approach is two-fold. First, the scale will not be as precise as you'd like--this is an issue of error amplification: an error of 10um around the joint will be around 100um at the toolhead. Second, a circular capacitive verniby Annirak - Delta Machines
Re: Grounded Experimental Delta Printer - 11 years ago
The math will not be a problem on ARM micros. It's only a few more ops than a normal delta-printer.by Annirak - Delta Machines
Re: Six-Arm Simpson - 11 years ago
It's not fully constrained if you have an equilateral hexagon. It is fully constrained if you have a non-equilateral hexagon. In that respect, it has a lot in common with the Stewart Platform. In fact, you could use the Stewart Platform as a model for a Six-arm Simpson There are two ways to constrain it: either make the base non-equilateral, or make the hub non-equilateral, or, even better, bby Annirak - Delta Machines
Re: MatchboxARM - 11 years ago
QuoteIt means, many electronic components work only with 5V signals. Especially ones for handling high currents. That was true in the '80s. It might have been true in the '90s. It wasn't true in the '00s. It's not true now. A tiny fraction of electronic components only work with 5V. In fact, 3.3V is the industry standard for GPIO and parallel, non-differential buses. Even USB is 3.3V for loby Annirak - Controllers
Re: MatchboxARM - 11 years ago
I'm tired of the anti-3.3V logic arguments. What does commodity even mean? Does it mean standard? What does standard even mean in MOSFETs? It's not like there are any standards... there may be long-life products, but no standards. If you mean "cheap" by commodity, here are two mosfets you can drive direct from 3.3V that are under $1 nxp infineonby Annirak - Controllers
Re: MatchboxARM - 11 years ago
@bobc, Having recently gone through microcontroller selection at 1k quantities, I found Atmel was still coming out on top as far as low cost goes. ATSAM, that is. When I added requirements for: USB, PWM, at least 12ADC channels, and 64kB of Flash, the cheapest ones to pop up were ATSAM3S1C at $2.44ea @ 1k (us.digikey pricing. Actual should be lower). And those are 64MHz Cortex M3.by Annirak - Controllers
Re: Six-Arm Simpson - 11 years ago
Here's how a commercial CNC mill with 6-arms works: Six-Arm Simpson would just be this inverted; the Annirak Drive instead of overhead arms.by Annirak - Delta Machines
Six-Arm Simpson - 11 years ago
I've been thinking about 6-dof bots and the Sextupteron. The toolhead rigidity in Sextupteron concerns me, so I've been thinking about other geometries. What about a six-arm Simpson with a hexagonal toolhead? Actually, a hexagonal toolhead isn't ideal, it needs to have three long sides and three short sides to prevent twisting in the toolhead. This would still give a very wide work range, butby Annirak - Delta Machines
Re: Custom Electronics - 11 years ago
I would suggest that you find a low cost microcontroller that's capable of running your PID loop. It shouldn't take much. You can probably use one of these with no trouble. They even come in SOIC which is much easier to solder than QFP. If you write the software for the PID microcontroller so that its inputs are "step" and "direction," you can use an existing controller and firmware with no mby Annirak - Stepper Motors, Servo Motors, DC Motors
Re: Sextupteron - 11 years ago
It's too bad we can't print PTFE. That's really what you want.by Annirak - Delta Machines
Re: Grounded Experimental Delta Printer - 11 years ago
Looking great! I'm looking forward to the demo videos!by Annirak - Delta Machines
Re: A new development option - 11 years ago
This still doesn't solve the problem. You're replacing a $6 part with a $39 part and a $35 part. $6 < ($39 + $35). That is the problem with Raspberry Pi-based electronics. As long as you're trying to compete with Gen7, you're not competitive. Thinkyhead Wrote: ------------------------------------------------------- > Hold the presses. I didn't notice if anyone else > has mentioned iby Annirak - Controllers
Re: Raspberry Pi based electronics ideas - 11 years ago
Coolerooney Wrote: ------------------------------------------------------- > Just a question about the L6470 Driver you mention > (much) earlier in this thread > > Did you actually hook it up? No, I didn't in the end. I'm trying to cost-reduce/performance increase from pololus, and it doesn't really accomplish that.by Annirak - Controllers
Re: Raspberry Pi based electronics ideas - 11 years ago
JohnDH Wrote: ------------------------------------------------------- > Detailed information on the two Beaglebone Black > PRU real-time processors can be found here > > blob/master/Documentation/01-AM335x_PRU_ICSS_Overv > iew.pdf Ah, I had no idea; I hadn't looked into the Beaglebone Black particularly closely. There's still a fundamental problem with any of these solutions: tby Annirak - Controllers
Re: Grounded Experimental Delta Printer - 11 years ago
I love the torsion springs; it looks much cleaner and comes a lot closer to the constant-force-spring that we discussed earlier! I do wonder about the holding torque vs. spring torque tradeoff. There are two limiting factors: on the one side, you have the maximum torque that the motor can exert, minus the spring force decides the maximum acceleration for arm contraction. On the other side, thby Annirak - Delta Machines
Re: Grounded Experimental Delta Printer - 11 years ago
pokey9000 Wrote: ------------------------------------------------------- > One alternative you might consider is an IR LED on > the end effector, and two webcams at 90 degrees > facing the work envelope, with OpenCV to do point > tracking. A couple of IR filters over the cameras > would make this easier. You'd probably have some > dead spots though when the effector hides behiby Annirak - Delta Machines
Re: Grounded Experimental Delta Printer - 11 years ago
nicholas.seward Wrote: ------------------------------------------------------- > I am going for cheap so I will use a cheap webcam. > The bowden tube flexes very gracefully. I was > thinking about getting an 8 conductor ribbon and > spiraling in just like I do it now. We will see. An 8-conductor ribbon is going to give you horrible signal-integrity problems. I expect you'll see fby Annirak - Delta Machines
Re: Grounded Experimental Delta Printer - 11 years ago
Mounting a webcam on the end of the efector will be challenging. Not physically, but isolating it from something hot. It's also going to be a challenge in terms of cabling. A USB cable going through the flex cycles that will be present in Simpson will fail quite quickly, I expect. You might try a high flexibility USB extension cable, which might survive a bit better. This one is rated for 10by Annirak - Delta Machines
Re: Grounded Experimental Delta Printer - 11 years ago
I will answer the question, but it's important to set the stage properly. Gen7 electronics are not fancy. In fact, they're about the polar opposite of fancy. They are cost-reduced and hobbyist-friendly. Traumflug is constantly trying to reduce the cost and complexity; I think he's done a pretty good job. Would I design electronics the way that he has? Probably not. But I know that mine woby Annirak - Delta Machines
Re: Grounded Experimental Delta Printer - 11 years ago
The Raspberry Pi, while an excellent little computer, doesn't really have the peripherals you need to drive a reprap. It has too few GPIO for endstops, stepper drivers, and heater. It doesn't have an analog input for the temperature sensor. You can get around needing a PWM for the heater by using bang-bang control, but that gives you less temperature stability. You can use GPIO expansion viby Annirak - Delta Machines
Re: Grounded Experimental Delta Printer - 11 years ago
nicholas.seward Wrote: ------------------------------------------------------- > @Efxjim. The print head stays true as is. The > geometry dictates that. The offsets on the > central hub could be removed but it would increase > the complexity and slightly reduce the rigidity. > Additionally, software can make the adjustments > for the offsets with some simple addition. Preciby Annirak - Delta Machines
Re: Grounded Experimental Delta Printer - 11 years ago
This sure has progressed while I've been away. It's looking very good! Looking forward to your release!by Annirak - Delta Machines
Re: Grounded Experimental Delta Printer - 11 years ago
alagi Wrote: ------------------------------------------------------- > Hello! > > First of all, nice work! > > I think all this talk about having to have a > simple math is irrelevant. > One can write a script to convert the xyz paths > that the slicer prints out to whatever geometry > before printing, on the computer. (this script > should split straight lines toby Annirak - Delta Machines
Re: Grounded Experimental Delta Printer - 11 years ago
nicholas.seward Wrote: ------------------------------------------------------- > You have been instrumental in this whole > process!!! I would be messing with wheels, string > tensioning, and firmware from hell if it wasn't > for you. Well, I'm glad I could help in the inception of a new architecture. I don't think I can really help in cost reduction of the hardware parts. That'sby Annirak - Delta Machines
Re: Grounded Experimental Delta Printer - 11 years ago
nicholas.seward Wrote: ------------------------------------------------------- > It was > 20 days ago that I seriously started thinking > about making a 3D printer that has no linear rails > and low center of mass. 10 days ago I hit upon > this basic geometry that allows a delta robot to > actuate the elbow instead of the shoulder. 10 > days in the future I hope to have thiby Annirak - Delta Machines