Hot-End and Extruder Choices

Topics Related to the ORD Bot Printer

Hot-End and Extruder Choices

Postby flickerfly » Sun Apr 28, 2013 11:41 pm

I'm doing research to put together an ordbot for 3D printing. What are you guys using and why?

I like the idea of bowden type system, mostly for aesthetics. Do I need to be careful about what hot-end I get and why? Would mounting the extruder on the back by the controller be a problem?

Should I skip the whole bowden idea?
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Re: Hot-End and Extruder Choices

Postby blah_59 » Mon Apr 29, 2013 12:38 am

I like the compact nature of the direct drive extruders (cold end) but I'm not sure buying one is the way to go. I would get the mk7 gear from the guy in denmark on ebay, get the nema stepper motor, bearing and spring locally and print the 2 part arm lever/block. (or buy it from Bart if you or a friend don't already have a printer)

After suffering through the QU-BD fiasco, I can't say enough good things about the J-Head hot end from hotends.com. I've been looking into the chess hot ends which are very similar to the J-Head but about 10mm shorter.
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Re: Hot-End and Extruder Choices

Postby cozmicray » Mon Apr 29, 2013 1:04 am

I am using an mBot mK 7 extruder
It is all metal, uses a heater (vs a resistor), has a good hobbed gear direct drive
from stepper motor, has fan to cool top section.
I switched from thermocouple to thermistor so I could directly plug it into RAMPS.

Bad situation was when using nylon, It blobbed up around hot end for an hour print
and I had to melt off the nylon (with a torch) and rebuild the entire hot end and
replace the thermistor. I still need to replace the 0.35mm nozzle which seems to be
partially clogged.
It works great with PLA and ABS.

I take it apart and put it back together a lot -- very easy disassembly / assembly
except for perhaps mounting on baseplate.

http://www.mbot3d.com/collections/toolh ... -mbot-cube

It appears the newer ones use a plastic part around hobbed gear.

I have a QU-BD extruder in stock that I will also try out
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Re: Hot-End and Extruder Choices

Postby flickerfly » Mon Apr 29, 2013 3:34 am

I've seen a lot of good stuff about the J-head hotends. Thanks blah_59.

cozmicray, I hadn't seen the mbot extruder yet. Thanks for sharing that. Is it based on the MakerBot design?
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Re: Hot-End and Extruder Choices

Postby cvoinescu » Mon Apr 29, 2013 10:01 pm

I'd like to endorse the the J-Head too. You won't print nylon and polycarbonate with it (you need an all-metal hot end for that), but it's incredibly reliable with PLA and ABS.
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Re: Hot-End and Extruder Choices

Postby roberlin » Mon Apr 29, 2013 10:40 pm

Anybody using the .35mm nozzle j-head?

I had started with the .5 and it was working great. Hasn't jammed up even once.
Then I tried the .35 and it is not working so well.
I am using a Mk7 direct drive setup and wonder if I need more torque.
(getting ready to move so I haven't had much time to play with it and troubleshoot)
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Re: Hot-End and Extruder Choices

Postby cvoinescu » Mon Apr 29, 2013 11:20 pm

My J-Head has a 0.35mm nozzle. I've had no problems with it whatsoever. Granted, I'm using it with a geared extruder, which gives a mechanical advantage 7-8 times better than direct drive with a MK7 gear (about 5.2x from the gears, and about 1.5x from the smaller effective diameter of the filament drive "wheel"). I plan to try direct drive too, at some point.
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Re: Hot-End and Extruder Choices

Postby flickerfly » Tue Apr 30, 2013 3:08 am

Anyone have thoughts if a Bowden type is a bad idea on this platform?
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Re: Hot-End and Extruder Choices

Postby bloomingtonmike » Tue Apr 30, 2013 3:30 am

I am using a QUBD MBE with their nema17, PTFE teflon tube installed in the barrel, minimalistic MK7/bearing tensioner, and the MK7 gear from Denmark.

I am going to try one with stock parts except the PTFE - I think it is the magic fix for the MBE.
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Re: Hot-End and Extruder Choices

Postby flickerfly » Tue Apr 30, 2013 12:34 pm

What is the MBE acronymn? I haven't figured that out yet.
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