Well the crossed version lasted about 20 mins before it broke. The solder didn't really penetrate into the castellations much as it doesn't wet the SS it's probably a surface tension thing.by nophead - Mechanics
Well no surprise it did break again after extruding about 300mm of HDPE at 200C. I switched the motor off and left the heater on. When I switched the motor back on the filament would not move so I tightened the springs and the joint broke. I will try Richards idea of cutting a cross in the top of the screw next. I read that it is possible to solder stainless steel with ordinary tin lead solderby nophead - Mechanics
JB Weld is supposed to be good up to 315C. I have had my extruder heater up to about 250C and it has changed from gray to dark brown. Is this to be expected or have I got some inferior counterfeit product?by nophead - Mechanics
Thinking out loud here but putting a resistor in parallel with the thermistor probably helps with making it a bit more linear. It would certainly tend to cramp up the high resistance low temperature end where the resistance is changing rapidly and have negligible effect at the high temperature end.by nophead - Controllers
Well my thermistor goes from about 2K at 20C to 20 ohms at 200C. To cover that range with a 10 bit A/D only gives you 10% accuracy at the 200C end. If you are measuring time, as long as your timer is fast enough to get good resolution at the high temperature it is no problem slowing it down with a prescaler to get similar resolution over a very wide range indeed. I suppose in this case we are noby nophead - Controllers
Forrest Higgs Wrote: ------------------------------------------------------- > Oh Lordy! You're right! I remember now. Struck > me as a lot of bother to go through at the time so > that you wouldn't have to change PIC chips. There > are, after all, a lot of inexpensive 16F's that > have A/D. Actually thinking about this while measuring the thermistor englewood sent me it isby nophead - Controllers
If you have an index then the end stop only needs to have a precision of less than one turns travel. When you see the index you round your count to the nearest whole revolution. When you see the end stop you take the remainder of the count divided by a revolution. Once you have seen the index once and the end stop once you should always know you position absolutely to the resolution of the encoby nophead - Controllers
The connector on the powercomms board uses those three but it also loops 4 to 6 (DTR-DSR) and 7 to 8 (RTS-CTS). I.e. it effectively converts a straight through cable into a null modem cable.by nophead - Controllers
You can avoid missing pulses by either polling faster than the inputs change with a timer interrupt or have one or both of the quadrature pins on an input that can generate interrupts on both edges. I have used both techniques in the past and had no problems with absolute accuracy, it's just standard engineering. Whenever you see one input change you look at the state of the other to determine whby nophead - Controllers
Well actually I made tapped knobs just the right size using my milling machine but I figured that the tension is not critical enough that you could afford to leave all the wingnuts you were not adjusting in the vertical position. I.e. at most one quarter turn away from the ideal position. I think then you would have room to spin the nut you are adjusting. I couldn't find any dimensioned drawingsby nophead - Mechanics
To make the extruder less fiddly to put together and take apart again I would recommend putting shake proof washers between the nuts and the plain washers. Once you get the bolt finger tight the washer bites and hold the nut. That allows you to tighten them with just an allen key rather than an allen key and a spanner in the other hand. I would also recommend using wingnuts to replace the nutsby nophead - Mechanics
BTW, I think I have worked out why the RepRap extruder is thermally insulated. I think it is because it has a fan cooling the workpiece so the barrel needs covering to stop it being cooled as well.by nophead - Controllers
That is if your logic is sensitive to ringing on the edges, asynchronous comms is not. What will happen is that the signal will bounce up and down the cable a few times because it gets reflections from each end that is not matched to the characteristic impedance of the cable. Traveling at around half the speed of light it can bounce up and down this length of cable many times and will dissipateby nophead - Controllers
He does the A/D conversion by charging a capacitor through the thermistor and timing how long it takes. The erroneous values are caused by the timing measurement being interrupted.by nophead - Controllers
There could be a short from the TX pin of the PIC to an adjacent pin. That way the loop test would work without the PIC fitted because the pin the short is to is no longer driven. However, you have tried two boards so you would have had to have made the same mistake twice. I am really grasping at straws here, I can't believe we have got so far, done so many tests, and not been able to narrow itby nophead - RepRap Host
All the 7.5 deg motors I have are 12V. I don't think they go much faster than two or three revs per second with CV drive. I have never come across low inductance ones but if they do exist that might be an idea. The type I have are known as tin can construction and are relatively cheap compared to the stacked lamination type. They have less torque and less accurate pole piece alignment.by nophead - Mechanics
The only explaination I can think of for that is that you are actually monitoring your mouse! Do you have a serial mouse on your PC? Does it happen with the HT window in focus when you wave your mouse about?by nophead - RepRap Host
I think you will find that at these sorts of baud rates all the reflections will have died down long before the mid bit position where it matters.by nophead - Controllers
Yes I too had been assuming 18W for 8 ohms as I use MOSFETs for switching but actually the UCB uses a darlington with a 2.5V max drop at 2A. If we assume a more typical figure of 1.5V then that reduces the power to: 14W @ 8R and 18W @ 6R.by nophead - Controllers
Sorry my comments earlier about 7m should have said 7ft.by nophead - Controllers
So 12 characters in 5 minutes. Did they all arrive at once or one every 25 seconds or did they arrive irregularly?by nophead - RepRap Host
Electronic parts are always much cheaper in volume. My company gets Ethernet sockets with magnetics for 1$ / 1000 off and PHY chips for less than $2. I think once the projects reaches critical mass the RRRF will be able to take advantage of volume discounts to sell remarkably cheap kits fo electronics parts.by nophead - Controllers
I think it started at 12 ohms, went to 8 and now 6. I made mine when 8 was recommended and it rapidly gets to 200C, and would get hotter if I left it on, and that is without any insulation, so I am not sure why it needs to be as low as 6. I think Forrest's Tommelise has 6 but that has a large plate at the top end acting as a heatsink as well as no insulation.by nophead - Controllers
1. If you coil up 7m or wire and place it anywhere near a stepper motor or DC motor I would not be surprised if you got comms errors due to it making a parasitic transformer. 2. More time consuming than making a few crimps and a much messier result. Feel free to put the video of the RepRap site if you think it will help anybody.by nophead - Controllers
So a loop back through the PIC pins echoes OK but when the PIC transmits the data is corrupted? Other than a very poor ground connection between the PCOM and UCB I am starting to run out of ideas. Can you send a screen shot of what the garbage is when running emf's transmit test?by nophead - RepRap Host
Well it makes a bit more sense using a 4 pin connector to handle three signals but how do you buy them at the right length? The link Zach gave is 7m long. Making them yourself is no longer an easy option because you need an expensive tool and it is quite tricky to use. I made a video of how to put on a crimp and it only took me 1 minute 40 seconds even while taking time to explain how to do it.by nophead - Controllers
I don't think the voltage on pin 11 is well defined with nothing connected so I don't that is anything to worry about. When connected to the UCB it should go to around 5V. So a loopback test in HT works but emf's transmit test fails. Are you sure HT is set to 19200 baud 8 bits no parity?by nophead - RepRap Host
The polarity of small electrolytic capacitors is usually marked by a stripe down the side nearest negative connection. The board marks the plus connection with a square pad and a + on the silk screen. If you look at the picture in the wiki all the negative pins are those facing the camera. If the caps are wrong that could be your problem, otherwise it looks like the MAX232 chip is faulty. Measurby nophead - RepRap Host