Koko, Good points. I had not thought about arcs and other non linear shapes. I also did not think that a PC could have the same degree of timing control that a microcontroller can have. With very fast response time to internal or external interrupts, and built in 8 bit and 16 bit timers running off crystal controlled clocks I would have thought the stepping control would be more solid. But I aby rocket_scientist - General
My first thought is to use ABS cement, since that is very close to the same application you have. I have not tried it for bonding a broken ABS part, and I do not yet know where to get cement that is not black. But I have used it to mount ABS tabs that I heat formed from ABS pipe to other pieces or pieces of pipe, and the odd shaped joins seem quite solid. If anyone finds a cheap source for clearby rocket_scientist - General
Spacexula, I looked more closely at the parts list, and now I am back to wondering about the total build cost. There is plywood (fine, thin multi-layer marine or model grade plywood) used in the construction, but not listed in the parts list. Also no stepper motor drivers or control electronics. I suspect that the gen2onaboard will work for controlling this, and the firmware would only take soby rocket_scientist - General
This one claims only simple tools. Using the match drilling that he mentions takes care of the most critical measurements. This does indeed look like a simple, easy to build small CNC mill. I also want one for making PCBs, and in particular, to drill the through holes. I think my work list just got longer! Mikeby rocket_scientist - General
GCALman, I have been thinking about 3D cameras both to scan a new object in, and to verify that the current piece is coming along as designed. A simpler, cheaper solution that might do well for your Dissertation in Electronics would be structured light approach to partial 3D. Have one or more LED lasers scanning the beam slanted at an angle attached to one side of the extruder, and a ccd cby rocket_scientist - General
I was trying to track down USB output digital calipers. From US sources, they are expensive, especially if you want a build platform bigger than 6". Then I ran into a site that mentioned DRO digital scales from China on eBay for cheap. The interface is not USB but more like the synchronous serial that the microcontrollers a used to. Some send multiple nibbles in BCD, others 24 bit binary. Some reby rocket_scientist - General
Well, I have two taps on their way from mcmasters, so that should solve part of the problem. I think I understand your worm gear cutting setup, so I will try to duplicated it here. I have a cheap lathe/mill/drill combination that is current buried behind some storage shelves and partially un-wired. I was trying to convert it to 220, but decided the included wiring diagram was not detailed enoughby rocket_scientist - General
Koko, While I have little experience as a machinist, I have a strong background in physics and engineering. I understand that coating only affects the sharpness and how long it remains sharp, it is the quality of the metal underneath that keeps it from breaking in the whole, or failing underneath the coating. However, I did think that the coated would have an easier time of getting into the steby rocket_scientist - General
I did not realize that brass was strong enough. I will pick up some brass bolts and try again. When the TiN coated taps come in, that should shift the advantage in my favor. Thanks for the reply. Mikeby rocket_scientist - General
I traded Wade some experimental glass nozzles for some wade geared extruder parts, and am now trying to build a complete extruder to help testing the various glass nozzles I make. The bearing went in fine, a second bolt cut off in the no thread portion nicely holds the idler bearing on its separate block, the 4mm bolts are long enough to go through the base, gap, and idler block, the springs areby rocket_scientist - General
I have also thought about a pressure sensor connected very close to the tip. When extruding, the pressure should go up, when you stop or reverse the gears, it should go done. If the opening gets jammed, the pressure will become very high. If the melt zone gets too big and a plug forms, the pressure will drop while the extruder stepper is running. Mikeby rocket_scientist - General
Fantastic progress Jacob! I have been wondering how to snip the fiberglass strands at the end of a fiberglass, or combined fiberglass in plastic extruder. How are you doing the cutting here? I see a solenoid, but it is not down at the tip. It looks like you would have to cut the wire a little in advance of when you place the last of it in the plastic. You would need software that checked for whenby rocket_scientist - Wire and Thread Embedded Extrusion
Lucky fellow! Still, it must have been popular to see one being built. Or was it more popular putting frosting on bread?by rocket_scientist - General
The photos of a makerbot kit being opened and assembled on site made me think they had starter packs for the audience to build themselves. Then I decided that they were only building the one and doing it themselves as a demo, which makes more sense considering the costs of parts. Then I saw the PVC make something on the spot and that got me to thinking. You can make almost anything out of PVC tubby rocket_scientist - General
I still think my glass nozzles, by eliminating the PTFE, will eliminate that kind of problem. Yes, the extruder base and structure must be made of higher temp materials than PLA. I have not operated on yet, but I think the ABS based ones are more reliable. Wood or aluminum might make something stronger still, but can no longer be made by a reprap or repstrap. Also not having used an extruder yby rocket_scientist - General
buback, the link on you post did not work, but I found you image in the wiki recent changes page. Here is a fresh link: Using nuts on the bolts to hold the stack together will make it stronger than taping threads into aluminum, but will also extend the bottom of the stack and cause more of a clearance problem for the nozzle tip to extend past. Taping threads into the bottom layer and keepby rocket_scientist - General
No, the solder has no elasticity, it will deform once with thermal change and forever after be too small. The best gasket material would be the same thing used for cars. Cork board or fiber board would both easily work in these temperature ranges. Also O-rings. McMaster-Carr lists silicone and PTFE O-rings with high enough temperature ratings. I have been puzzling over how to make an extensionby rocket_scientist - General
Koko, Nice to hear that there is an expert here. I have been learning as I go, and making more mistakes than progress some times. The current process to make a simple nozzle is so easy that anyone with a MAPP torch can make one, so if I settle for something that simple, I am thinking of trying to make a video of the process so anyone can make their own. Andrew, yes, borosilicate can easily hanby rocket_scientist - General
#3 instead of #5 clip ones, because they were out of #5 and she said only people who spend all day at their torches need #5. And yes, it does make it easier to see the glass temp. I use oxy-acetylene because I already had a used torch. I have looked at hard-glass torches, and they start a a few hundred bucks and go up. One I priced out including pre-mixer, stand, 3 basic interchangeable tips, oxyby rocket_scientist - General
I stayed up late last night and ran a test on the good one. There is no wire wrapped around near the tip, so it took a LONG time and way over powered to get enough heat to the tip to melt the plastic and produce a strand. But once the pre-melted plastic reached the tip, it flowed fairly well. After getting the tip unstuck from some projection, the strand came out long, thin, and straight. Yank teby rocket_scientist - General
Nophead, If you look at the data sheets for thermocouples, the voltage difference at the cold ends varies by a fraction of a millivolt per degree C change across the length of each wire. That means that a very sensitive differential amplifier is needed to boost the signal and make it easy to read. And that probably means that if it is grounded or shorted to anything else is may interfere with gby rocket_scientist - General
New experiments. A fresh shipment of new glass rods has added some new possibilities. Even larger outside tube can fit over the 8mm nozzle with some stuff on the outside. 7mm thin wall to test later for passing the 3mm filament better than the 6 which is just too tight a fit. And capillary rod with a really tiny whole down the center. I thought first of using the capillary rod to surround theby rocket_scientist - General
Pica, I know of that as 'grey code', and it is a simple binary sequence setup up so that every step has only 1 bit changing. That way you can have very fine resolution (16 bits on rotary encoders is usually the max) and it will tell you exactly where you are without any problem from missed codes. It is the way that absolute encoders work. But absolute encoders are much more expensive. In this cby rocket_scientist - General
John, yes, optical mice have an excellent optical encoder pickup. But of course they lack a corresponding scale. Simply measuring mouse movements against a textured surface will not be very accurate. You need a scale that is accurate over distance. Also, don't be distracted by the low price of optical mice. An linear optical read head, with capacity to read 360 LPI is only $8 in single unitby rocket_scientist - General
Depends on the type of encoder wheel you use. The less expensive ones that we used on the FIRST Robotics Challenge steering controls were incremental encoders. They are great for telling you how much you have moved, or rotated, since the last time they were calibrated. But just like stepper motor slip, a lost few pulses or extra noise can through the count off, and you would never know it withoutby rocket_scientist - General
That would be fine for normal operation. No valves or solenoids or other controls needed. It simply would not help much for overhangs and horizontal free spans. I think that the simple, two nozzle approach will eliminate the need to extrude slowly, and might help to bridge small gaps, but without bending the strand 90 degrees to come out horizontally without anything under it pushing it up, I thiby rocket_scientist - General
The pieces I have seen where people have tried to build parts with a long horizontal free span have had lots of dropping lines and loops and other problems. This is a basic limitation of fusion deposition of thermoplastic material. However, I was originally thinking about greatly slowing the extrusion rate, so that the plastic can cool and harden just after coming out of the nozzle. That woulby rocket_scientist - General
garak, I agree wholeheartedly with your ideas. Try reading this thread Team Open Air I was thinking that the position sensing can go in several ways, and can even start with some simpler steps. One goal I agree with you, feedback on the quality of the current piece being laid down. This is especially useful when the controlling computer is on a local network, and you want to monitor progressby rocket_scientist - General
Tony, I should also add that I have never used an Arduino of any type. I have the STK500 development and programming board, so instead of buying $65 Arduinos, I buy $8 dollar ATMegas. So for me, it is spend $8 for another ATMega, of which I already have about 2 dozen laying around waiting to be used, or $50 a pop for something I haven't needed yet. I only mention the Arduino because many peopleby rocket_scientist - General