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An end to jams - blowers are better...

Posted: Mon Jun 17, 2019 10:45 pm
by ocelot27
Finally got the hot end cooling mod done and tested today - works very well - here are some pics of the mod. The three blowers added a total of 30mA to the whole cooling on the carriage - main hot end blower and two part blowers. Bottom fin of heat sink didn't get above 35°C with the temp set to 300°C. I also had thermocouples on the top fin of the heat sink and inside the heat break to record temps during testing. The top and bottom fins only differed by a few degrees. The thermocouple inside the heat break at its narrowest section positioned just above the block and just below the heatsink read 105°C with the block at 300°C and 65°C at a block temp of 220°. The temps within heat break in the area of the heat sink where almost identical to the temps measured on the fins of the heatsink. There's a torrent of warm hair coming out the back of the carriage. Having run both alternative hot ends (Mosquito) and liquid cooling on the standard Raise hot end, I believe this is the easiest, lightest and cheapest solution for jams and high temp printing without doing too much modification. I also used good quality CPU thermal paste between the heat break tube and the heat sink.

I have tested this set up at both high temps and printing PLA for long prints with the printer closed to maximize stress on the cooling - so far no issues with any jams. Retractions and dual extruder prints are better as well with much less if any ooze.

Print the duct out of something that can take some temperature - ColorFabb HT, nylon etc. I also taped the exposed surface of the bottom of the duct with thick aluminum duct tape - so far no warping or deformation even with both extruders going.

Part cooling x 2:
https://www.digikey.com/product-detail/ ... ND/2560687

Hot end blower X 1:
https://www.digikey.com/product-detail/ ... ND/7691033

STL's here:
https://www.thingiverse.com/thing:3691333

-john

Re: An end to jams - blowers are better...

Posted: Sun Jul 07, 2019 6:40 pm
by ocelot27
Here's a torture test I did using Raise PLA - I printed at 220 with the bed at 60 and the printer completely closed using the Raise standard template with a few small changes.

Print took almost 12 hours and was uneventful other than a power outage during a thunderstorm that I was able to recover from.
-john

Re: An end to jams - blowers are better...

Posted: Thu Jul 18, 2019 11:39 am
by KS_Husker
Thank you for posting this. I have recently started getting many jams at the hot end and was getting very frustrated. I was thinking of doing something similar but wasn't sure what the results would be. Looks like you have gotten great results.

I will be doing this mod as well. I like your water cooling idea but I don't have the time to put into all of that.

Re: An end to jams - blowers are better...

Posted: Tue Jul 23, 2019 8:12 am
by Sunshine
I like this solution very much, well done John! Do you have any issues when it is homing in the x-y plane?

Re: An end to jams - blowers are better...

Posted: Wed Jul 24, 2019 3:38 pm
by danderson
I tried this mod, and I found that the left extruder improved greatly at the expense of the right extruder. The left extruder performance was almost as good as the right extruder was before with only a fan upgrade (10mm -> 20mm). Good mod if you really want to use the left exruder with PLA.

Re: An end to jams - blowers are better...

Posted: Wed Jul 24, 2019 8:20 pm
by ocelot27
I haven't been able to measure any significant temperature difference between the two extruders at the various points I measured through a large range - what was your issue with the right extruder? - perhaps it's not cooling related?

Fans aren't designed to generate any pressure - they can move a lot of air with NO obstruction - I doubt increasing the fan size has little if any effect on air flow through the constricted area. It's easy to tell this by just feeling the backwash in front of the fan and no flow out the rear of the carriage. You can look at the PQ curves for the $0.50 Raise fan (which is horrible) and whatever 20mm fan you're using to compare - flow drops to zero pretty fast with obstruction.

I've been torture testing the mod with long dual extrusion prints and have not had any issues with PLA in either extruder - they perform identically. I've done everything with the printer completely closed at temps of 220 and bed at 60. This is the worst possible scenario for a heat creep induced jam. There aren't even any blobs on the wipe wall - I could've printed without it!

I have also tested several complicated high temp prints in various nylons, Colorfabb HT etc with Aquatec support material (printed at 220 from the right extruder) with no difficulty.

-john

Re: An end to jams - blowers are better...

Posted: Thu Jul 25, 2019 7:39 pm
by danderson
I am having severe symptoms of what I believe to be "heat creep" - print failures several hours into a print, only with 3rd party PLA, worse with the lid on, and worse on the left extruder than the right. The filament would stop extruding sporatically, missing layers or part of a layer, until it would finally stop extruding all together. Fortuantely it is easy to recover, but the failure is pretty predictable.

I have two Pro2 printers with almost identical performance. I swapped the center fan on both with a 20mm unit (https://www.amazon.com/2packs-Bearing-B ... B01MTA09QV), and this helped both extruders. I have a long-running support ticket with Raise3D trying to get support but with little luck.

I was hoping this mod would be the solution that I was looking for. It sure helped the left extruder, bringing its performance up to the level of the right extruder.

I believe that there may be more going on than just overheating. Raise3D support had me check the nozzle spacing, heat sink spacing, several software settings, and several other things. I am basically looking at resourcing our PLA with something that is a little less suseptible to heat creep. I will try some of the filaments listed in the "open filament" program listing.

Re: An end to jams - blowers are better...

Posted: Fri Jul 26, 2019 5:44 pm
by ocelot27
Did you use thermal paste on the heat sinks?

What does the filament look like if you cold pull it?

Have you checked the entire pathway for obstruction - stuck filament - PLA loves to stick to metal - especially warm metal.

Re: An end to jams - blowers are better...

Posted: Thu Aug 01, 2019 8:44 pm
by danderson
I will add some thermal paste to see the impact on the performance.

I have not tried a cold pull, but these printers are barely used.

My early testing with Premium PLA filaments (Coex PLA Prime, Coex PLA pro, Raise3d Premium, Polymaker Polylite) show much better performance - even printing successfully on the left extruder where I could get basically nothing on the left one before. I will keep testing these filaments to see if I can get them to fail.

Re: An end to jams - blowers are better...

Posted: Sun Aug 04, 2019 4:25 pm
by ocelot27
Definitely use a high quality thermal paste design for CPU's - you'll probably double the heat transfer.

Re: An end to jams - blowers are better...

Posted: Sat Aug 31, 2019 10:10 am
by Imrageth
can you provide bit more guidance on how and where to apply the thermal paste?

Re: An end to jams - blowers are better...

Posted: Wed Oct 09, 2019 5:48 pm
by KS_Husker
I did this mod on my printer after it got to the point where I couldn't do a single print anymore using ABS. I had luckily already printed these parts out and had the fans just hadn't taken the time to do the mod yet. I did this mod, and it's been printing beautifully ever since. Thank you very much for you work on this. The parts fit great as well. Nice job.