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Discuss any sort of mechanical stuff here: positioning systems, gears, extruding methods, etc.
Re: Gen7 DIY Stepper Driver - 11 years ago
Traumflug Wrote: ------------------------------------------------------- > Funnily, > "Gen7" starts to become a synonym for "DIY-able > electronics" Wasn't that the idea?by Annirak - Next Wave Electronics Working Group
Re: Discrete-FET stepper driver - 11 years ago
Hey, that A3985 looks pretty nice. Close enough to prototype my idea, anyway! Thanks for the pointer!by Annirak - Controllers
Re: Discrete-FET stepper driver - 11 years ago
That's a very interesting device, but I don't think it will suit my requirments. I also want to get away from step/direction. What I would like to do, ideally, is to periodically output a step-angle, which the stepper driver will interpret.by Annirak - Controllers
Discrete-FET stepper driver - 11 years ago
Does anyone (other than me, obviously) have any interest in a stepper motor driver built with discrete FETs? It would have the advantage of being able to use powerful FETs and higher drive voltages. It has the disadvantage of complexity, and it wouldn't be practical to use a step/direction input; instead it would use 2x analog inputs (either PWM or DAC). I'll post schematics some time soon ifby Annirak - Controllers
Re: Getting 0.49v drop across IRFZ44N MOSFET on heatbed... - 11 years ago
Gate threshold is pretty low, so you should be fine.by Annirak - Next Wave Electronics Working Group
Re: Attaching heat sinks - glue? - 11 years ago
Oh, for reference, everything I've found on cyanoacrylates in general indicates that 0.1W/mK is normal for all "super glue" type adhesives.by Annirak - Controllers
Re: Attaching heat sinks - glue? - 11 years ago
Traumflug Wrote: ------------------------------------------------------- > ... if you prefer marketing speech, yes. Anaerobic > glue ("Loctite") works just as fine. I suppose that depends on what you mean by "just as fine." Loctite 382 has a thermal conductivity of 0.1W/(mK). Assuming a bond thickness of 0.05mm, and a bond area of 5x5mm (the area of the A4988) that gives a thermal resistaby Annirak - Controllers
Re: MakiBox $200 Complete 3D Printer 
- 11 years ago
Dark Alchemist Wrote: ------------------------------------------------------- > With money all things are within reach and > with money I would be designing a lot as that is > what I used to do as a kid. I loved designing > electronics and electrical things so you can bet I > will be doing that a lot once I get a printer. > First thing I will be doing is suring up the > priby Annirak - General
Re: MakiBox $200 Complete 3D Printer - 11 years ago
@Dark Alchemist, I don't have a RepRap yet either and for similar reasons--well, I had gone back to school about when news of the first RepRap started showing up so I didn't have the disposable income needed to put one together. I'm also interested in improving RepRap and making it more accessible. My ultimate goal is to make it capable of printing electronics into the 3D structure. There areby Annirak - General
Re: Thoughts about printing circuits. Need to bounce some ideas off someone. - 11 years ago
3M doesn't advertise it much, but they have a conductive polyurethane which is compatible with ABS (and presumably PLA). I have 1kg of it in pellet form. I haven't done much with it because the initial results were disappointing: the resistance across a single 3mm pellet was ~1kOhm. With that kind of conductivity, it would certainly need some kind of additive (graphite? Copper dust?) to makeby Annirak - General
Re: Rostock delta robot now moving at 400mm/s - 11 years ago
I would call it a column bot.by Annirak - Delta Machines
Re: Generation 7 Electronics Development - 11 years ago
VDX Wrote: ------------------------------------------------------- > ... uhmmm ... because of this pretty small > 'critical ranges' i've dropped the nonlinear TC's > and use linear sensors and higher measuring > resolution ... @VDX, Given that I have a reel of 500 ft. of type K thermocouple wire, would you suggest using thermocouples instead of RTDs?by Annirak - Next Wave Electronics Working Group
Re: Generation 7 Electronics Development - 11 years ago
nophead Wrote: ------------------------------------------------------- > > For the cost of two resistors, an LED and a > transistor, you can have 100% resolution across > the measurable range. All you need is a current > source to feed the thermistor. > > > The graph of resistance against temperature is > logarithmic, i.e. very non linear. The effect of > measuringby Annirak - Next Wave Electronics Working Group
Re: Generation 7 Electronics Development - 11 years ago
A thought RE: heated beds and PWM controlled heaters in general. For the cost of a coil and a diode, you can smooth out the power drawn by the heater. Simply connect the coil in series with the load, and the diode across both the load and the coil. This turns a normal PWM configuration into a buck regulator.by Annirak - Next Wave Electronics Working Group
Re: Generation 7 Electronics Development - 12 years ago
Traumflug Wrote: ------------------------------------------------------- > Thanks for the hints, Annirak. German Wikipedia > shows an arrangement without this LED: > > it_Bipolartransistor > The most important thing in a current source is increasing the output resistance--that is preventing the current output from varying with load voltage. With this current source design, theby Annirak - Next Wave Electronics Working Group
Re: Generation 7 Electronics Development - 12 years ago
QuoteTraumflug QuoteAnnirak For the cost of two resistors, an LED and a transistor, you can have 100% resolution across the measurable range. All you need is a current source to feed the thermistor. Could you elaborate what you mean here? Sure. You already know this part: half of the problem with using a thermistor is that a variable resistor and a fixed resistor produce a non-linear curve asby Annirak - Next Wave Electronics Working Group
Re: Generation 7 Electronics Development - 12 years ago
Traumflug Wrote: ------------------------------------------------------- > When reviewing the Gen7 circuitry for the supply > voltage change coming with the ARM variant, I came > across an interesting bit: > > > _Thermistor_Voltage_Divider > > To me, this looks like the temperature readouts > can be made a lot more accurate by the simple > change of an EUR 0.01 reby Annirak - Next Wave Electronics Working Group
Re: Generation 7 Electronics Development - 12 years ago
> Back to topic: > > I think hackability is important for the future of > RepRap. Also the ability to make things DIY. This > is what distinguishes RepRap from the big > commercial companies like Stratasys, 3D Systems, > HP. For electronics, this usually means through > hole parts. The exemption is possibly this rare SO > package, a SMT package with 1.27 mm pin spacingby Annirak - Next Wave Electronics Working Group
Re: "Heated Chamber" idea for delta robot. - 12 years ago
martinprice2004 Wrote: ------------------------------------------------------- > I don't really like the idea of hot gas as its > expensive and would be stirred by the head moving > over the part. You need the open top of the box so > the print head can get in. Argon is not excessively expensive; it's commonly used in MIG and TIG welding. I suggested it because it is significantly dby Annirak - Delta Machines
Re: Taking Gen 8 wishlist - 12 years ago
Traumflug Wrote: ------------------------------------------------------- > All SMD, super fine pin spacing, wasteful feature > count, not solderable by mere humans. You see, > people's opinions about what a good controller is, > varies widely. Oh, naturally, but on this forum, it has to be DIP. For example, when I proposed a new generation of electronics based on the LPC176x seriesby Annirak - Next Wave Electronics Working Group
Re: Taking Gen 8 wishlist - 12 years ago
@Chele69: I've been down that road. The conclusion I've come to is this: The STM32F4DISCOVERY is not suitable for mainstream reprap. It's absolutely a great board, it can do the job, no problem, but it's not going to fit the requirements of the mainstream reprap electronics. As I understand it, the requirements are these: 1) No proprietary (non-opensource) boards 2) Hobbyist friendly (no SMDby Annirak - Next Wave Electronics Working Group
Re: Can you help me with Stepper Motor Selection? NEMA 23 - 12 years ago
That is my best guess, provided that they're not too old. It seems that older stepper motors were rated assuming full-step only and rated current in both coils. I can't seem to find any information in any datasheets about what current the torque rating applies to.by Annirak - Controllers
Re: Can you help me with Stepper Motor Selection? NEMA 23 - 12 years ago
nophead Wrote: ------------------------------------------------------- > With these drivers you get exactly the same torque > with full step or micro step, and in any position. Perhaps I'm not being clear. The majority of stepper motors are spec'd with torque measured when both coils have Imax flowing through them (a vector sum of Imax * 1.414). Meanwhile, microstepping drivers use a vecby Annirak - Controllers
Re: Can you help me with Stepper Motor Selection? NEMA 23 - 12 years ago
Traumflug Wrote: ------------------------------------------------------- > Thanks for sharing, Annirak. What does that > frequency relate to? Step rate of full steps? Half > steps? Microsteps? It refers to the full-step rate, regardless of micro stepping level. E.g. if you're using 1/16 drivers then multiply that frequency by 16 for the micro step rate. @Nophead, that's what I meant.by Annirak - Controllers
Re: Can you help me with Stepper Motor Selection? NEMA 23 - 12 years ago
I've done some more research, and it seems that I have an error in my math. It stems from how stepper torque is rated vs. how it is used in microstepping drivers. Microstepping drivers have a maximum torque with one winding energized at maximum current, while stepper motors are rated with both coils energized at maximum current. The adjusted value for K is: K = (Holding torque in N-m / (2 * maby Annirak - Controllers
Re: Can you help me with Stepper Motor Selection? NEMA 23 - 12 years ago
The coil resistance and inductance both seem a bit high to me. I ran the math and, compensating for backemf, you should expect a maximum full-step rate of 152 Hz at 12V, not counting any stepper driver oddities. 24V gives you 384Hz and 30V gives 497Hz. On a 2cm pulley, 152Hz is 47mm/s, 384Hz is 120mm/s and 497Hz is 156mm/s. To find the step rate, I solved the following equation for t, whichby Annirak - Controllers
Re: ARM DIP package at US1,26 to the rescue - 12 years ago
bobc Wrote: ------------------------------------------------------- > I am > planning to use ChibiOS, which is GPL, lighweight > and already has support for a number of ARM chips. > It may also be possible to run ChibiOS on some AVR > parts, not sure the state of that. While I haven't used ChibiOS, I can tell you for sure that FreeRTOS's "support" of ARM chips is a joke. It breakby Annirak - Next Wave Electronics Working Group
Re: Higher Amperage Controller - 12 years ago
redreprap Wrote: ------------------------------------------------------- > from an electronics point of view, the stepper > coils are driven by the mosfet, so if 1 were to > directly dig in to improve output, change the > driver portion with an alternate mosfet. thats the > theory at least in my mind, however, ramp being a > SMD board, it will be really challenging to do > thby Annirak - Controllers
Re: FreeSoC - 12 years ago
In the past, the problem with PSoC's was the compiler, which was quite expensive. I see that they've shifted to Cortex-M3; this makes them much more interesting to me.by Annirak - Controllers