Hot-End and Extruder Choices

Topics Related to the ORD Bot Printer

Re: Hot-End and Extruder Choices

Postby rickmellor » Sat May 04, 2013 9:10 pm

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


Methinks it is for MakerBot Extruder. The Qu-Bd extruder was an attempt to bring the Mk7 Extruder to market for less than the $199 MakerBot Industries asks for it: http://www.thingiverse.com/thing:11734 http://store.makerbot.com/stepstruder-mk7-complete.html
Last edited by rickmellor on Sun May 05, 2013 6:42 am, edited 1 time in total.
rickmellor
 
Posts: 89
Joined: Sat May 04, 2013 4:15 am
Location: Brooklyn, NY

Re: Hot-End and Extruder Choices

Postby flickerfly » Sat May 04, 2013 9:54 pm

That makes sense. Thank you rickmellor!
flickerfly
 
Posts: 247
Joined: Sat Apr 27, 2013 10:04 pm
Location: Allentown, PA

Re: Hot-End and Extruder Choices

Postby cozmicray » Sun May 05, 2013 4:03 am

I don't understand these j-head and mega magnum all metal extruders

QU_BD_extruder.jpg
QU-BD Extruder


I have been using a mBot MK7 for a year now
It's all metal, sort of like QU-BD extruder, but with aluminum around the hobbed gear
with the hot end about 1/2" away from the extruder gear, a fan on the cool end
Very little problems
I don't have to heat up the hot end and cool it with a fan.
The motor and mechanism stays plenty cool with fan on all the time
hooked right into 12V supply
It doesn't have 4 inches to clean out if it gets plugged
and it doesn't have to be mounted six inches above the X-axis.

Please help me understand why you go thru this agony with these J-head/magnum extruders

Tnx
cozmicray
 
Posts: 168
Joined: Thu Sep 20, 2012 4:32 pm
Location: Blue Bell, PA

Re: Hot-End and Extruder Choices

Postby rickmellor » Sun May 05, 2013 7:05 am

cozmicray, I'm not sure exactly what the differences are since I don't have a stepstruder to compare with, but in looking at the images there seem to be two key differences between the two. The qu-bd appears to use a longer stainless steel tube between the hotend and coldend. Also, the qu-bd build instructions call for nut spacers between the mounting bracket and the cold end block. If what you're saying is that the stepstruder uses a metal block between the motor and heatsink whereas the qu-bd uses an acetal block, that could be another crucial difference.

If you take all these differences the qu-bd would likely have the following problems that the stepstruder doesn't: 1) more waste heat from the stepper motor being transferred across the coldend which would cause heat creep on long prints, 2) the qu-bd would sink less heat to the mounting bracket and to the printer structure from the coldend, 3) the longer ss tube on the qu-bd would have more of a temperature drop across its middle. I can imagine all of these differences adding up and when combined with variations of filament quality, humidity, friction of the tensioner set screw, and the very poor grip of the raptor gear, you'd see the types of issues that I and most others have had with the qu-bd.

I think the main issue with the qu-bd is that we really want it to work. It's so pretty and well-made, and well-priced that it's a shame it sucks so bad. $200 is a big chunk of cash and if with a bit of elbow grease we can get our qu-bds to work, then it's worth it. Mine is working pretty well now that I've got the PTFE mod and bdring's idler bearing in place (printed by shapeways so it was $$, but awesome). It was pretty simple for me to do since I have a lathe ... however, it sure would be great if qu-bd would just fess up and fix the darned thing. Unfortunately I think they're swamped having bitten off more than they could chew releasing three printers and a mill at the same time.
rickmellor
 
Posts: 89
Joined: Sat May 04, 2013 4:15 am
Location: Brooklyn, NY

Re: Hot-End and Extruder Choices

Postby cozmicray » Sun May 05, 2013 4:02 pm

My mBot Mk 7 may be unique

mBot Mk 7 2.jpg
mBot M7 all up

mBot_Mk7.jpg
mBot Mk7 insides


with the hobbed gear enclosed in metal and the bearing opposing the gear.

I don't have to heat the hot end then cool it with a fan.
My fan (in duct) is to cool PLA after it is extruded.

I would like to find better insulation for hot block.
It uses a heater (not a resistor -- not designed to be a heater).

The fan on upper block keeps it cool and the motor gets warm on long prints
(I suppose I could put a thermal radiator on it or a fan)

and it wasn't $200 --- $150 from mBot cheaper on eBay

But it really seems to me all these are experiments --- none truly engineered

Tnx
Ray
cozmicray
 
Posts: 168
Joined: Thu Sep 20, 2012 4:32 pm
Location: Blue Bell, PA

Re: Hot-End and Extruder Choices

Postby orcinus » Sun May 05, 2013 4:55 pm

@Cozmicray

Didn't you use to have issues with that Mk7 as well? And, by the sound of it, pretty similar to what the QU-BD has:
viewtopic.php?f=27&t=1581
orcinus
 
Posts: 720
Joined: Tue Feb 14, 2012 4:03 am

Re: Hot-End and Extruder Choices

Postby peter_ » Sun May 05, 2013 5:53 pm

cozmicray,

If I can ask, which fan duct are you using? I'm also using a MK7, and all the fan ducts I'd found or printed so far dont look quite compatible with the RD Bot/MK7 without some modification.

thanks!
peter_
 
Posts: 9
Joined: Tue Feb 14, 2012 4:49 pm

Re: Hot-End and Extruder Choices

Postby flickerfly » Mon May 06, 2013 3:41 am

Thanks guys for sharing. I'm hearing the QU-BD is great once you modify it properly, but I'm rather inexperienced so am concerned about messing up the drilling out of the nozzle to add the PTFE. Also, I need to do more research to figure out where to get the proper info on all these mods.

Steve's extruder from SeeMeCNC is $75 + a NEMA 17 and with all the mods, the QU-BD is about the same price plus labor and chances of mistakes.

Everything else I have to wonder what I'm getting for my extra $50.
flickerfly
 
Posts: 247
Joined: Sat Apr 27, 2013 10:04 pm
Location: Allentown, PA

Re: Hot-End and Extruder Choices

Postby cozmicray » Mon May 06, 2013 4:11 pm

orcinus

Your right I did have problems in my early months of use
Seems to need to be broken in
and I have found out the difference in filament and filament suppliers

Also a run with nylon which engulfed the whole hot end, and had to be torched off,
has screwed it up royally. Rebuilt it and still not working 100%

If you haven't have had extruder problems you haven't been squirting a lot.

The extruder gear that comes with QU-BD is bad
and the tension adjustment is not to good.

**** anybody using a mBot Mk 7 how's it working

orcinus wrote:@Cozmicray

Didn't you use to have issues with that Mk7 as well? And, by the sound of it, pretty similar to what the QU-BD has:
viewtopic.php?f=27&t=1581
cozmicray
 
Posts: 168
Joined: Thu Sep 20, 2012 4:32 pm
Location: Blue Bell, PA

Re: Hot-End and Extruder Choices

Postby cozmicray » Mon May 06, 2013 5:02 pm

peter

attached sketch up for duct
Sorry I can't remember where I got it to give credit



peter_ wrote:cozmicray,

If I can ask, which fan duct are you using? I'm also using a MK7, and all the fan ducts I'd found or printed so far dont look quite compatible with the RD Bot/MK7 without some modification.

thanks!
Attachments
30mm_air_duct.skp.zip
30mm air duct
(57.43 KiB) Downloaded 686 times
cozmicray
 
Posts: 168
Joined: Thu Sep 20, 2012 4:32 pm
Location: Blue Bell, PA

PreviousNext

Return to ORD Bot

Who is online

Users browsing this forum: No registered users and 5 guests