If the system is reset when one or more axis are already at an endstop then we would need seperate + and - stops, but these can be shared across the 3 axis (and a 4th if needed say for rotary stuff) Backing up 1 step is a bit small, backing up 10mm may be a bit large, but the variability in the detection zone of the opto sensors isnt big (I should hope not, absolute positioning isnt critical soby Lampbus - Controllers
Dylan, the gas lasers use a gas AFAIK sealed in a tube (sorta like a fluorescent lamp). Often they need cooling with a water circuit. The cutting process uses gas too - for two main reasons : 1. A clean gas is blown across the focussing lens. Because it hangs over the workpiece it can be contaminated by solid and gasious material blown from the cut. (optics are very expensive because they are notby Lampbus - Laser Cutter Working Group
Well, in sorting out my bedroom to make a corner of it into a workshop (small house, living room full of electronics already) I found I needed : New feet for my workmate - the rubber ones fell apart & the bare metal scratches the wood floor. New feet for my wardrobe - my house is 250 years old and nothing is flat or upright. So the wardrobe is perched on bits of variable thickness plywood aby Lampbus - General
Dylan - the animation is cool But in my Antiooze3 the nozzle valve is controlled (almost) directly by the melted plastic pressure as follows : As the extruder motor starts to feed filament into the heater, the pin valve is closed so pressure builds. Instead of filament feeding into the heater, the motor & its mounting do an Indian rope trick and climb the filament a teeny bit. This upwardby Lampbus - Mechanics
Viktor, I am basing my ideas on : and the assumption that the tip of the nozzle contains fluid plastic due to being very close to the heater. This will also mean the cross-drilling dosn't have to be very precise or have seals. Seals are also a reason I avoided a sliding nozzle or heater (see peteredworthy's sketch) and slid the whole heater/insulator assembly in option 2. there isnt any molton pby Lampbus - Mechanics
Lego designer is free (but not open source?) and easy to use. It would be interesting to get STL files out of it, but I had a quick google and didnt find anything. The build-from-layers-on-a-baseboard is a good starting point for future non-engineer reprappers. Pro-Engineer (also closed etc) is available forby Lampbus - RepRap Host
Kyle Corbitt Wrote: ------------------------------------------------------- > Richard, I especially like your first concept. It > has the potential to be effective without > substantially increasing the complexity of the > extruder. It's almost a drop-in addition to the > current design. Props. THats what I thought Problem is it will have a pressure drop across it which will cby Lampbus - Mechanics
And another idea : Have a fixed insulator&heater like current design, but allow the extruder drive bracket to float UP a milimeter with the vlave wire connected to it. As the filament is fed, the motor/clamp raises slightly it opens the valve. Gravity and a spring will push it back down. To keep the valve wire short to prevent it buckling on closeure, an actuator rod could be used. THis woulby Lampbus - Mechanics
Nice diagram Peteredworthy. You inspire me to get doodling It would be nice to put the pin inside as you show, but as you say, the plastic is solid at some point in the insulator so gets in the way. THe spring would only be stiff enough to support the weight of the heater/insulator and liquid contents and to overcome any friction in the mount/valve pin. The pressure from the pushing filamentby Lampbus - Mechanics
I have seen the solenoid driven pin valve design to prevent nozzle ooze, but how about a completely passive system - have a spring loaded valve in the nozzle ? It would need tome experimentation to set the spring opening pressure so that gravity and thermal expansion and residual pressure due to 'springyness' of system components is balanced. And then, tuning so that it dosnt put excessive back-pby Lampbus - Mechanics
The endstops issue - why cant they all be wire-ored together ? To find the origin you move each axis individually to find its start then back it away and move the next axis. This would work for both ends of the travel as you know which way you are moving each axis too. Or is the problem with the stepper driver IC itsself and is it actually important that the endstops are done in the IC? (I realyby Lampbus - Controllers
Copper wire magnetised ? or was it a steel braided screened cable ? Interesting and I would like to know more.by Lampbus - Mechanics
Duratec 750 data sheet states a flextural strength of 23 MPa. ABS is 75 MPa, so it is in the same ballpark. How about designing an extruder mounting system that is abuse tolerant? Eg, a mechanical fuse that is easy to replace, or even self resetting. even a small ammount of compliance in the mounting when a load thereshold is reached could save the day in many instances of head collisions that Iby Lampbus - Mechanics
Pellet feeders - I did some googling last month and found that the barrels have vents in htem to vent air. They seem to rely on the viscosity and motion of the plastic to only let the air out - the vents are tangential in the barrel. Also the screw has several sections of differing pitch so pressure along the barrel is varied. The melt is performed in the screw, not after it. (tried looking for tby Lampbus - Controllers
Im thinking of trying Duratec 750 (calcium silicate) rod in place of the PTFE. RS components do it. Machineable, high temp, rigid, thermal insulator. ANyone tried it ?by Lampbus - Mechanics
I am working on a pinch wheel design . . . my current thoughts are to address the drawback of th pinch wheels tried so far pinching the SIDE of the filament (and causing 'dents') as the point of contact is a point. The current feed screw design drives along the axis of the filament but has high friction loading - the filament slide in its saddle and the threads sliding across the filament. My ideby Lampbus - Controllers
Hi, I think there is a student working on this. Some video of a docking operation is somwhere. (sorry, not v useful for my first post)by Lampbus - Mechanics