qu-bd Universal 3D Printer Extruder on Kickstarter

[Liberty4Ever]

To avoid hijacking this thread, I've started a separate thread on small scale production 3D printing.
http://www.buildlog.net/forum/viewtopic.php?f=33&t=1353

[Zat German]

Makerbots use cartridge heaters in their extruders but don't they have safety electronics to prevent them from running away in the event of a failure? I don't see any mention of this in the project, that is probably the only thing holding me back from one of these.

[mattrsch]

They do, but since they are a stand alone system, there is nothing preventing you from throwing one on one of these extruders. All you need is one of the thermostats: http://store.makerbot.com/mk6-thermostat.html
and their relay board: http://store.makerbot.com/safety-cutoff-switch-kit.html

It looks like the thermostat just attaches to the extruder mounting plate.

[Halfdead]

Makerbots use cartridge heaters in their extruders but don't they have safety electronics to prevent them from running away in the event of a failure? I don't see any mention of this in the project, that is probably the only thing holding me back from one of these.

The safety is supposed to be built into the firmware, but there's certainly limitations with regards to it's capability.

[Liberty4Ever]

Makerbots use cartridge heaters in their extruders but don't they have safety electronics to prevent them from running away in the event of a failure? I don't see any mention of this in the project, that is probably the only thing holding me back from one of these.

Good point. 40W at 100% duty cycle would melt any nearby plastic parts. 40W is the low side of the soldering iron wattage for typical handheld soldering irons that are actively controlled, and 25W is typical of small soldering irons that are 100% duty cycle and regulate their temperature by convection into the ambient air. With the larger surface area of the nozzle and heater block, I'd guess the 100% duty cycle temperature of the 40W extruder would be soldering iron temperatures. There shouldn't be any combustibles near the extruder, so I wouldn't think this would be much of a fire hazard. More of a self destructing extruder problem.

It's still a valid concern. You could always buy the less expensive version with the 3W resistor, or connect the cartridge heater in series with a temperature switch or a thermal fuse. Thermal fuses are used in appliances like coffee makers, and are small and inexpensive. Even better, have a temperature switch or thermal fuse open to E-Stop the machine when there is this much of a problem.

BTW - I ordered four of these extruders, so I'm betting they're going to be be good stuff.

[bdring]

I have had problems in the past where a controller locked up when a heater was on. I was right there and saw that the printer had stopped so it did not damage anything. I think my problem was due to something on the USB like noise or ESD.

With number of units MakerBot sells I can imagine they had a few over temp problems or even fires.

[Liberty4Ever]

With number of units MakerBot sells I can imagine they had a few over temp problems or even fires.

Another good reason to build 3D printers with aluminum instead of plywood.

PS - I think the PC power supply remote ON enable signal could be used as a cheap E-Stop if wired to ground through a series of normally closed switches including an E-Stop switch and temperature switches on the extruder heads, although it might be better if the temperature switches were thermal fuses so they'd stay latched instead of possibly cycling on and off. The power supply enable would provide more of a kill switch than an E-Stop, as it would shut down everything and not just the hot stuff and the moving stuff.

[dzach]

What is holding me from buying one of these extruders is the fact that, contrary to open source practices, they didn't bother to provide any evidence of a working prototype or any info on the performance of the device, despite the extensive testing they claim they've done.

[Liberty4Ever]

I asked about the weight of their extruder a couple of days ago and still haven't heard anything. Heck, they haven't even told us the dimensions, although we can make a good guess based on the NEMA 17 motor. So far, they've replied to early queries with an assurance that they'd release all of the info when shipping the first units, and they provided some authoritative quote that this date was acceptable according to their chosen open source licensing policy.

On the other hand, I'd rather they finalized the design before releasing the data. Too often, there is confusion in the open source community based on the desire to release information early and often. People are trying to build stuff based on deprecated designs and bad information.

And on the OTHER other hand, it does look like they've done as they said. They appear to have a design based on the best of the existing open source designs, maximized for scaled up manufacturing to get the price down, rather than the price we'd pay for "lovingly hand crafted by artisan hardware hackers in a loft in the Bronx".

[canadianavenger]

Makerbots use cartridge heaters in their extruders but don't they have safety electronics to prevent them from running away in the event of a failure? I don't see any mention of this in the project, that is probably the only thing holding me back from one of these.

The safety is supposed to be built into the firmware, but there's certainly limitations with regards to it's capability.

I wouldn't trust a firmware only solution... having said that bolting a TCO to the heater block would not be all that hard.

oh and save yourself a couple of bucks... the makerbot TCO is only $6.56 at digikey
http://www.digikey.com/product-detail/e ... -ND/306776