I'm getting close to being able to use my reprap! I have two tasks left; adding a chopper/current limiter to the pic electronics and getting filament. I've been trying to literally roll my own from polymorph for a few evenings now and I don't seem to be very good at it ;-) The diameter varies along the length of the filament normally by 0.1 mm but sometimes more. I've been putting them in pileby peteredworthy - Reprappers
I've got the Y axis, the X axis' gantry, moving freely now. In the end it was a combination of factors that were causing the binding. The bars it runs along weren't perfectly aligned. The spacing testers fit at both ends but one was tighter than the other. I'm not sure how significant this was though as fixing it didn't seem to improve the binding problem. I didn't have a method for quantifyingby peteredworthy - Mechanics
No problem, good luck for Monday.by peteredworthy - Controllers
A thought I had about a hot air reflow head vs reflow oven; With a reflow head it would be possible to remove/scavenge parts, to paraphrase Haynes' manuals 'disassembly is the reverse sequence to assembly'. If I had a method of using SMDs then ideally I'd like to be able to harvest parts from old circuit boards, as I currently do with through hole stuff. In rapid circuit prototyping it would maby peteredworthy - Controllers
>Still looking at maybe using lego motors, cant get any good definitoins of there capabilitys yet. That should keep you amused for a few minuets ;-)by peteredworthy - General
I've posted one off this morning. It would be good if at least one other was sent from elsewhere to try and avoid problems with the post loosing or delaying it.by peteredworthy - Controllers
I broke several of 71 as well, but in my case I originally had one of the corners 2 mm to high and another 1 mm out. It doesn't sound like much but it of cause made it impossible to adjust the rods to the right length. Part 71 was just the weak point between immovable object and unstoppable force. After a weekend reassembling it with excruciating amounts of measuring/checking/re-checking the diagby peteredworthy - Mechanics
On darwin what happens when the carriage tries to travel past the ends e.g. does the belt skip, the stepper stall, the motor coupler slip? I expect it is axis dependent with the X & Y being faster but less forceful than the Z axis.by peteredworthy - Controllers
I like that a lot; it's a very clever re-use of a signal that is already there. > LIMIT = (MIN and DIR) OR (MAX and not DIR) I was looking at the logic and how it could be implemented, when I realized that this is actually a 2 input multiplexer. Min and Max are the inputs, Dir is the select line and limit is the output. The 74157 contains 4 2:1 multiplexor's and so should only require a singby peteredworthy - Controllers
I agree that acrylic can be a pain, I've snapped enough bits building mine, but I don't think you will find MDF less prone to breaking. From what I've been able to find it looks like acrylic takes almost 2,000 times more load to break than MDF while still being as stiff. The parts I broke most often were the corner blocks; MDF's higher co-efficient of friction should result in less force beingby peteredworthy - Reprappers
Looking at the circuit it is almost exactly like the example given in both the L298 and L297 Data-sheets. The only obvious alteration is some filtering on the sense lines. I think the filter is a low pass filter with a cut off frequency of 154Hz. I'd imagine that this could lead large overshoots in the voltage at the sense resistor before the voltage at the sense pin on the L297 had risen highby peteredworthy - Reprappers
I think it has come up a few times before but a scissor jack or variant on one could be easier to RepRap. Using steel rod it might not take all that much plastic to make. By building two of the above and placing them so they cross at the non sliding joint a single motor could drive the whole arrangement removing the need to synchronization belts etc. The main problem seems to be non-lineariby peteredworthy - Let's design something! (I've got an idea ...)
The 'Assembly Info' section of the bitsfrombytes web site has been updated and now includes both the Y assembly and a 3d model. There are also some pictures, an updated 'darwin bot.pdf' and a pdf of the top corner blocks.by peteredworthy - Mechanics
1. To go with the laser cut parts you will need some, mostly standard, hardware; Lists in detail all the parts for the main structure and Lists on the first page the parts for the extruder. 2. Are you asking for replication or for building? If it's for building then there is only, AFAIK, one released version of the BitsFromBytes Laser Cut RepStrap. If it's for replication then someone else wby peteredworthy - General
>The shaft of the Z stepper motor does not reach the grub screw inside parts 34 >and 35 of Z_Sub-Assemblies.pdf. Swapping the positions of parts 33 and 35 >seems to solve the problem. One of the motors in my kit has a longer shaft that can reach all the way through the part 33->37 stack.by peteredworthy - Mechanics
Yep I also found 58 too snug and in fact did break a corner off when I tightened it up the first time. I've also found that ensuring that the nuts can sit with the entirety of their sides within the plastic helps with getting everything to line up. Other parts I filed were: 01, 15, 38, 41 (corner blocks) - on some of these the nut would fit only if it was inserted before the rod; if the rod wasby peteredworthy - General
I've been posting about what I got wrong in both of scpmicro's threads Despite myself, my choice of electronics and my cat it is going well. - Test assembly - complete (based on the picture on the front of the bitsfrombytes site, so it could have had a few parts wrong/different); - Final assembly (carefully measured, built following the instructions) Extruder complete Complete up to step 4 oby peteredworthy - General
spcmicro put up an overview of his progress at: I've had a few problems during my build but none of them have been show stoppers. Most of them probably won't occur/be a problem for others but I'll list them here in-case. Problem: Cracking parts through over tightening. I've broken a few of the parts, mostly in the corner blocks, through over tightening. Solutions: - Learning to judge when toby peteredworthy - Mechanics
While it may cause some problems having multiple versions, single and double sided, they are a product of the different priorities between providing a cheap ready made board and a simple home manufactured board. As far as I know the main advantages of double sided PCBs are higher component densities and reduced assembly complexity (by removing wire bridges). When mass manufacturing PCBs, the sby peteredworthy - Controllers
The Full Mechanical Kit Laser Cut Parts BOM PDF Lists the bearings as p/n 008 7150 114 42, which I believe is for www.skiffy.com The vitals are: 8mm inner diameter 10mm outer diameter 7.5mm depth 15mm diameter of flange (brim of top hat) They are apparently black and made of a mix of Polyamid 66, carbon fibre and PTFE.by peteredworthy - Mechanics
Is this what you are referring to? If so using a unipolar stepper does make the electronics simpler, but they tend to be less efficient and so larger / more expensive for the same power output. So I'm not sure the electronics + the motor would work out cheaper, just a different balance of where the money went. If you are interested in larger motors then could I suggest looking around CNCZone.by peteredworthy - Controllers
The Gameboy Advanced makes a cheap ARM7TDMI platform. I believe that the cartridge slot is connected to the ARMs data and address buses. If it is it should be relatively simple to add a memory mapped I/O chip, or two, for controlling the reprap. This site contains a lot of hardware information about the GBA, interfacing with it and programming it. There are also libs around to interface withby peteredworthy - Controllers
The BitsFromBytes silver kit includes: steel rods; threaded and plain. fixings including; bearings, belts, bushes, springs, nuts, bolts, washers grub screws etc, laser cut acrylic parts, all parts for extruder including; Nichrome, fire putty, springs, fan and motor. stepper motors (Suitable for Arduino electronics, pic electronics require modifications to use them). Build jigs, to set the disby peteredworthy - Reprappers
Ah, I thought there should be a single chip way of doing it but couldn't find it. > but it only saves pins for 5 optos or more. True, it could become worth while though if we end up with more switches either for input or safety sensors.by peteredworthy - Controllers
While not saving many pins, we could get more out of those pins. If we used 4 pins as a simplified matrix keypad (8x1) we would get 2 free pins and 2 extra inputs, which I've drawn as switches. It could also be thought of as a 1 bit data bus with 3 bit addressing. On the downside it does require several external logic chips and must be 'polled' to find the state of each device. An interrupt couby peteredworthy - Controllers
joining in the crackpot spirit of the thread; with accurate temperature measurement it should be possible to detect loss of feed. The energy going in to heating the head is known, as it is controlled by the PWM of the heater. The energy out is made up of convection, conduction and radiation losses and in melting the plastic. For a given temperature the conduction and radiation losses should beby peteredworthy - General
For the heater barrel a brass bolt, or cap screw may be cheaper and more available. Hacksawing the head off is very easy with brass and the softer metal should make drilling the centre hole easier as well. My guess as to a problem with any poor heat conductor is it becomes hard to tell what temperature the plastic is at. The thermometer and heater are on the outside which will change temperatureby peteredworthy - General
> Why do you say "wiring leading to the stepper"? Sorry, it was 12am and I actually have the PIC based electronics rather than the Arduino ones ;-}> On the 'DC Motor Driver v1.1' build page the wires are called channel A and channel B, with each channel having two wires. The driver can be used for a number of things other than just dc motors though. It can also be used for operating soleby peteredworthy - Controllers
Clamp diodes on the inputs aren't the same as on the output, each protects different parts of the chip. The good news is that clamping diodes are very simple to add as they can be added to the wiring leading to the stepper. Each of the four stepper wires needs two diodes connecting to it, eight in total. For each wire; A diode is connected between the wire and ground with the white stripe on thby peteredworthy - Controllers