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Re: Gen 2 OnABoard (was Gen 2 BackPlane) - 15 years ago

I'm trying to decide which connector to use for the heaters and fan. I don't like the screw terminals used by the PWM board because they sometimes come loose. The .156" connector used by the stepper boards has served me well. It stays put and is easy to remove when I want it to. So, I used a 2 pin version of this in my first draft. Now, I'm thinking about switching it to a .100" 3 pin connec

Re: help with electronics - 15 years ago

Re: A call for help/ideas to develop the Heated Bed - 15 years ago

This could be a good idea to return to the idea of multiple heated zones. Print a part in zone 1, then let it cool while printing in zone 2. If you have a large part, it can cross multiple zones and use the entire bed, but you will have to wait for it to cool before you can print something else. The other benefit is that if you are just printing one part, you don't have to heat the whole bed.

Re: Gen 2 OnABoard (was Gen 2 BackPlane) - 15 years ago

I'm working on the BOM now. You can see it here. This includes everything on the board, but does not include the connectors you need to connect to the headers. If the ATMega you have fits the socket I wouldn't be surprised if you can get it to work. The big issue is that all the ground power and oscillator pins are in the right place. If not, you could modify the circuit before making it.

Re: Most helpful, Extruder or Mendel? - 15 years ago

What I am planning to do is to build a mini-Mendel and lend it out to people who want to print a RepRap. That solves the problem of the person who has a working RepRap has to spend enormous amounts of time in order to propagate.

Re: A call for help/ideas to develop the Heated Bed - 15 years ago

> Yesterday I printed a relative big piece for Mendel Z axis. It was very hard to remove it from Kapton tape... and I used 110ºC on Heated Bed. Did you allow the part to completely cool before removing it? As I remember, Forest did this and the ABS shrinks as it cools, breaking it free from the kapton tape.

Re: Cheap Reprap Electronics - 15 years ago

The Pololu stepper driver costs $13 instead of the $35 for the stepper driver at MakerBot. The downsides are that you have to add your own connectors and it needs to be cooled with a heatsink or possibly a fan.

Re: extruder/pin 0 conflict - 15 years ago

The Sanguino hardware page shows pins 8 and 9 as connected to the USB2TTL header, which I assume means these two pins are used for communication to the host. Pin 0 is connected to the debug LED, but I don't think that would cause much of a problem. You should be able to verify that the dir signal is correct by watching the debug LED. Also, look at this thread for a bug with the DC extruder on

Re: Gen 2 OnABoard (was Gen 2 BackPlane) - 15 years ago

I've created the board layout in PCB Designer. I still want to spend some time inspecting it for mistakes before I send it out. I've updated the Wiki page with new images and a new project archive. The project archive contains the gerber files. You can load them with an open source program called Gerbv and print them out to scale or convert them to other formats.

Re: Decoupling Capacitors - 15 years ago

When you say small capacitors, does this refer to capacitors with a large value, like 100 uF, with 0.01 uF being a small capacitor?

Re: Decoupling Capacitors - 15 years ago

I recently read an article about decoupling capacitors. It recommends, as a rule of thumb, one .1uF monolithic ceramic capacitor for each IC, and possibly others for long wires.

Re: A call for help/ideas to develop the Heated Bed - 15 years ago

Maybe the thermal blank could be some pieces on the sides of the bed sitting on rails than can be pulled over the section that won't be used. If there is a hole in each piece and the software knows where they are, the nozzle can pull the pieces into a precalculated position. I'm thinking about four pieces all on one side that slide parallel to each other. If you need only 25% of the x axis, yo

Re: "mendell" mcmaster carr part/order list (US) - simply paste into website - 15 years ago

Actually, it is 0.0625 mm smaller than 8 mm 0.0625 mm = 0.00246 inches, which is less than 1/32 inch They are close enough that it doesn't matter. This isn't true of the threaded rod, which has a different pitch.

Re: Gen 2 OnABoard (was Gen 2 BackPlane) - 15 years ago

I added an image of the schematic to the Wiki and also uploaded my project directory, which should be loadable into gEDA.

Re: Gen 2 OnABoard (was Gen 2 BackPlane) - 15 years ago

I've updated the pin assignments. I'm hoping to be able to use the existing firmware with only a modification to pins.h and parameters.h. For this reason, I'm avoiding doubling up the min and max pins. My assumption is that most people won't use the max sensors and those pins will be available for something else. I have the exact same 4 pins available for RS-485 as the gen 3 motherboard uses.

Re: Gen 2 OnABoard (was Gen 2 BackPlane) - 15 years ago

I'm redoing it with gEDA so that I can make the board 4" x 4" and include all the suggestions I have gotten. Right now I am about half way through the schematic. I'll post printable images when I get to that point. I've realized that D8 and D9 are used to communicate with the host PC. So, the free TX and RX used for RS-485 will have to be D10 and D11. I'm also thinking of making an encoder c

Re: Gen 2 OnABoard (was Gen 2 BackPlane) - 15 years ago

I've come up with pin assignments. The last 7 items are not used on the board, and I will likely bring those pins out to a header so that an expansion can be added. I attempted to choose these pins in such a way that they could be used for RS-485, an SD card reader or a second extruder. I'm not sure the specific requirements of operating these devices, so it might not work. AUX will be connec

Re: Gen 2 Backplane (looking for comments) - 15 years ago

Update: I haven't had a lot of time to work on this in the last week. Today I tried to replace the Arduino mini with the ATMega644P in a DIP package. There was not enough room on the PCB for it. I was using the free version of Eagle to do the PCB layout, which has a size limit. I'm going to redo the board in geda, which doesn't have that restriction.

Re: Is there need for Mendel Extruder be flexible? - 15 years ago

How is your extruder mounted to the CNC? In the Mendel, the extruder is mounted between two steel rods. If the nozzle gets stuck on something, the rods will flex and the extruder will rotate around the X-axis. The result is that the nozzle moves up and clears the obstruction (if it is small). I've been having trouble with my Darwin because the extruder hangs outside the two rods. If the nozz

Re: Differing shrink factor of ABS.... - 15 years ago

I ran with natural ABS for a while and then attempted to use some black ABS I borrowed from someone else one day. The black ABS had different properties and I never tweaked my settings enough to get the same quality prints.

Re: Gen 2 Backplane (looking for comments) - 15 years ago

I'm going to get a Pololu driver to run some tests on. I plan to connect it to a stripboard with a block of aluminum attached to the ground pin. This will be a partial simulation of the way it will be mounted in the new board. I'll hook up the stepper motors I have to it and see if I can overheat it. I'll also run it in my RepRap to see if it can keep up to actual working conditions on each a

Re: Heated Print bed? Not this print thank you. - 15 years ago

Why can't you use a random (or changing) starting position for each build.

Re: Gen 2 Backplane (looking for comments) - 15 years ago

There is now a Wiki page that will contain the most up to date design notes and will eventually hold the assembly instructions. I'd like to come up with a different name for this board since I just discovered there is another active project that is calling itself a backplane. I'd call it a motherboard, but that name is used as well. Any ideas?

Re: Gen 2 Backplane (looking for comments) - 15 years ago

rocket_scientest, Do you think the ATmega644P would work. It comes in the same 40 pin DIP package and has 32 IO pins. The advantage is that it is the same chip that is used in the Sanguino. Any firmware that works for the Sanguino will work for this board and someone has already figured out how to make it work with the Arduino host.

Re: How do I add images to posts? - 15 years ago

The [ img ] tags didn't work. I tried with another image I saw someone successfully included and it worked. Maybe there is some restriction on image size I am not aware of.

Re: Gen 2 Backplane (looking for comments) - 15 years ago

I think I can use one of these as a fuse. It has low resistance as long as the current is less than 1 A and then it gets very high resistance until the current drops back down. That should be sufficient to make it impossible to damage the traces by drawing too much current through any connector, and it won't have to be replaced every time you mess up.

Re: Gen 2 Backplane (looking for comments) - 15 years ago

rocket_scientist: I'm not using the ATMega128X because I couldn't find a DIP version of these chips and I'm trying to avoid surface mount. I use the ATMega328 in my RepRap now and it is sufficient for the job. It does not leave many extra pins. I haven't priced out what it would cost to build an Arduino into the board using a DIP socket. That will likely be cheaper than the Mini breakout boa

How do I add images to posts? - 15 years ago

I was trying to add images to a post here. I used the img tag, but the images didn't show up when I previewed the page or after I posted it. I ended up putting a link to the image, but people will have to click on it and it won't be so easy to follow the post with the image on another page.

Re: McWire Successor - 15 years ago

I created a separate thread to discuss my electronics. My goal is to have a clean and easy to build board. I expect that since I am going my own way, I will end up spending a little extra. Where do you plan to get the PCB from? Or is it just going to be much smaller? If it is smaller, how are you going to accomplish that? I know the breakout boards I am using waste a lot of space, but I sti

Gen 2 OnABoard - 15 years ago

I've been designing a single PCB to handle all the gen 2 electronics that does not require any surface mount soldering. My main reason for doing this is to reduce the rats nest of wires that make a mess and sometimes comes loose, but it also ends up being a little cheaper than having many boards since there are fewer connectors and less PCB space is used to support the connectors. This first im