Surely the incremental cost of adding the JDM to the powercomms board is much less than $13. Sub $1 I would have thought.by nophead - Controllers
Why does it need modifying? I have reprogrammed PICs with flash over a serial link before without any extra hardware. The PIC did it all internally. I just sent packets with 64 data bytes and the PIC wrote them to flash and then sent an ack back. The flash was twice as big as the program so I wrote it to the second half and then told the PIC to reset. The first sector of the PIC contains a smalby nophead - Controllers
The drive chip on the RepRap controller board drops up to 4.9V at 2A so you will need to start from more than 3.3V if you use that device. Also looking at the datasheet the supply voltage of the chip needs to be 2.5V greater than the logic one voltage so I think you are stuck with using the 12V rail. You can use open loop PWM to limit the current provinding it is switching quickly compared to thby nophead - Mechanics
Why not use the 3.3V output on your PSU. That way you only need 0.5R 7W resistors.by nophead - Mechanics
Dean, The driver chip is a ST L298 bipolar device. It has a saturation voltage much higher than 0.2V. At 1A the total voltage drop is typically 2.55V. The outputs will be Darlington pairs. Here is the datasheet Chrisby nophead - Mechanics
SOI, You can always drive a unipolar motor from a bipolar drive, but not vice versa. You have the choice of using the coils in series by ignoring the centre tap, or just use half the coil. When in series you have to reduce the current rating by root two to give the same heating effect (I^2 * R). This can give root two times more torque provided the magnetics don't saturate (twice as many turnsby nophead - Mechanics
The page you linked says 0.42 Ohm coil so I would guess it is lower voltage than 7.2V otherwise it would take 17A.by nophead - Mechanics
I plan to mill mine so it's easier for me to leave out if it's not required.by nophead - Reprappers
A question for Adrian or Ed: Does the filament guide half of the extruder still need to have the sloping channel now that the motor is offset? I thought the idea was that the filament path would be straight.by nophead - Reprappers
The big difference between CNC mills and FDM is that a mill needs to be extremely rigid to handle the lateral force generated when the tool meets the workpiece. I learnt this the hard way. Darwin can get by with a cheap skeleton of rods because there is no force through the extruder barrel. You can turn a CNC mill into an FDM machine by changing the head, but not vica versa.by nophead - General
Small problem, the rss feed shows the RepRap site to be at which gives: Internal Server Error The server encountered an internal error or misconfiguration and was unable to complete your request. Please contact the server administrator, root@localhost and inform them of the time the error occurred, and anything you might have done that may have caused the error. More information about this eby nophead - Reprappers
The pixma is an inkjet printer so I think you would need to replace the ink with something thicker that sets.by nophead - General
Although I am not using the RepRap electronics on my system I have used a scheme on PICs and other micro controllers that encodes 10 states with two pins which are either tied high, low, left floating or connected together. I can post circuit and code in C if anybody is interested.by nophead - RepRap Host
I can see a couple of problems with the parallel head idea: Two heads in parallel reduces the work area by the distance between them so you need to keep that small. But if you make an object bigger than the distance between them then the inactive head will skate over the freshly laid down filament. Not sure how big a problem that would be. My plan is to have multiple heads mounted around the ciby nophead - Reprappers
Eric, The short answer is yes 50% PWM should be about right. In the steady state voltage, current are resistance are related by Ohms law: I = V / R. So your 2A 3.2V motors must have a resistance of 1.6 Ohms. If you connected them to 7V DC you would get over 4A flowing though them. Not only would that overheat the motor but it would more than likely fry the drive chip. You could fix it by puby nophead - Reprappers
Eric, Looking at the stepper driver schematic it appears to be a constant voltage drive rather than constant current. The driver chip will lose about 5V at 2A leaving 7V for the motors. This means that you will need to limit the current in software by using PWM. I am not familiar with the PIC firmware because I am not using it but I think it has a PWM capability.by nophead - Reprappers
I think the most flexible scheme is to split the RepRap Java (BTW does the program have a name?) into a slicer and dicer and a separate machine controller with an XML file in between, i.e., the scheme Forrest uses. It should then be possible to convert the XML to G code with an XSLT transform or a Python script. I am not sure which route I will take for my machine. I can either hack the comms paby nophead - Reprappers
I had a look at EMC2 yesterday and my undestanding is that it needs G code tool paths as input. I.e. you still need a CAM program to convert from 3D model to toolpaths. This is the main function of the RepRap Java code. I.e. it slices the 3D model and works out the extruder path. It also does the job of EMC2 in that it controls the machine, but some of that work is delagated to the PIC microcontrby nophead - Reprappers
Yes, there is an example atby nophead - General
I believe everything can be made with one head. I read somewhere, that I can not find again, that the corner brackets have tear shaped holes and other clever features that allow them to be made without support.by nophead - General
No the bugs I am refering to are small areas of screen that don't get redrawn when they should. My machine has Nvidia onboard gfx. Its not a big problem just slightly irritating.by nophead - Reprappers
There seems to be minor display bugs in AOI and Kicad also. Is this a Java library problem?by nophead - Reprappers
Impressive! I have not seen home made PCB's with solder resist before. What technique did you use? Regarding the stepper motors, if they are 2.5A per winding then I think that exceeds the maximum for the driver chip which is 2A.by nophead - General
There is a free Windows version of Kicad. I have it running here.by nophead - General
So far there is a a handfull of people willing to make parts as soon as they are able and about two handfulls of people requiring them. That means each person only needs to make two or three sets of parts to meet the exponential growth. It reminds me of when I was a kid and somebody gave me a ginger beer plant. After a week of feeding it ginger and sugar you made beer and divided it into two toby nophead - General
I too will be willing to make parts for people, when / if I get my machine working. I don't think I am far (a week or two) away from being able to mill an extruder body, probably a month or two from being able to do FDM.by nophead - General
I have done some experiments with a paper shredder. I think if I keep recycling the shards though it they will come out pretty small. It might not last long though. The motor is not rated for continuous use. I will add a fan and see what happens when I get round to having another go. I have some pictures but they are too big for this forum so they will have to wait until I blog them.by nophead - General
Wow, that's very impressive. Surely it deserves to be featured on the RepRap wiki.by nophead - Reprappers
I just spent an evening cutting aluminium and I can definitly say that paraffin makes it a lot easier to cut.by nophead - Reprappers
You can get HDPE filament via e-commerce here in the UK but it costsby nophead - General