Bondtech BMG upgrade for the N series

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Jetguy
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Re: Bondtech BMG upgrade for the N series

Postby Jetguy » Wed Jul 12, 2017 5:56 pm

FWIW again using the stock extruder on a newer machine with a black BOHONG brand motor, with a folder paper wedge shim to cock the motor, using the above mentioned 0.7V Vref to reduce motor heating, I got:
PLA was 3.95kg before it skipped steps
Ninjaflex was an abysmal 0.35kg limited by the grip of the feeder slipping.

To put this into perspective:
If you use the stock feeder and don't touch it nor any settings, in theory you get somewhere between under 2kg for a slipping extruder up to a theoretical maximum of roughly 5kg of force is everything works perfectly on the best day. Again, that's what the numbers show, there is just a huge variability here and I was actually astonished to see that I had to add the shim to get correct maximum grip. Something I'm sure some users would consider pretty hacky.

If you upgrade to the Bondtech mini extruder that reuses your existing motor, you are supposed to adjust the current down on the stepper driver to 0.6V Vref to make the motor run very cool. As such, it's operating at reduced torque but this is offset by the extreme grip and smaller diameter resulting in more steps per mm or in basic terms, trading distance for force. The motor turns further with more steps to achieve the same distance of filament, that's a force multiplier, net effect, you get consistent 3.60 kg of force with this combination as tested. Now you absolutely could run slightly higher current, accept a little more motor temp rise and probably see more force before it skips. Also note, this printer as tested had the Kickstarter Minebea 17PMK342BN08CN motor. In fact, I just raised my Vref to 0.66V up from the recommended 0.60V and noted I could reach 3.95kg of force repeatedly before skipping steps. Again, the facts are, I've been printing and so have many others using the recommended Vref on this upgrade, and even though it's not the massive 5KG of maximum force, I don't think we need anything that high under normal and even extreme conditions. I'm just saying, don't discount this option just because the raw force number is a bit less. This is a huge improvement in both weight and force over stock even if my numbers testing doesn't make that clear.

The BMG is using smaller and lighter motors, and when compared to stock, it's just insane the weight difference, and yet, the same extruder consistently is just that much stronger. This peak force is what helps clear a retraction based cold end jam, or helps with pain in the neck filament like Ninjaflex that is just flat out hard to extrude no matter what you put it in. Keep in mind, these smaller motors require even less Vref so again, as a system, you are putting less power and heat in and yet getting that much more grip and reliable force into the filament.

This is just one of those things where the numbers fell pretty much where I thought they would for the Bondtech as I new the BMG would produce higher numbers. I was surprised by what maximum force the stock extruder did produce, but when you consider all the other factors of how I got to that number (the hacky shim method, absolute maximum rated current for the motor) I really don't think that test was representative of actual user performance over say 100 printers. I have confidence in the Bondtech upgrades that anyone following instructions, you get the numbers and results I posted.

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JohnSays
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Re: Bondtech BMG upgrade for the N series

Postby JohnSays » Wed Jul 12, 2017 10:14 pm

Fabulous work JetGuy and thank you.

I am now running the BMG on my 2 N2's. I have run into a new problem since the upgrade: I have now developed a consistent problem of ABS melting in the cold end. Note that this happens on several hour prints with the printer cover on and doors closed. Vref is 0.5. The motor gets way too hot to touch. This never happened with the hybrid BondTec setup. My theory is that the motor is overheating the filament and it is getting soft enough to spread out into the cold end. Btw, it happened more using a 0.2mm nozzle than a 0.6mm. Given that this is the case, and that I see your setup does not even use a cover; what is your recommendation to alleviate this heat problem? I am now doing a large ABS print with the cover "cracked" open about 2 inches in the front. My ABS parts are about 3 inches in circumference and must print absolutely flat. That is why I have kept the N2 closed up.

Also I added an aluminum cooler to one motor to see if this helps. I suppose the effectiveness is limited by the means by which it is held in place.

IMG_6785.JPG
- John
2 Raise3D N2 Duals, V2 nozzles, Bondtech BMGs, and adjustable table

Jetguy
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Re: Bondtech BMG upgrade for the N series

Postby Jetguy » Wed Jul 12, 2017 11:13 pm

Honestly best to discuss this with Martin and see if he has additional feedback. He approached me with a European customer also printing higher temp materials with the doors and lid on and experienced high motor temps. Again, maybe they came back with something as I never heard back other than what I presented. viewtopic.php?f=4&t=1709&start=80#p15122

Just some facts, these smaller motors have smaller surface area. That means that coupled with the insulating aspects of the Bondtech overall feeder assembly there is limited motor cooling. If you ALSO have high ambient temp then the motor is going to get warm. That said, the motor never touches the filament in the BMG. The motor drives a Delrin spur gear on a 5mm shaft and that in turn drives the filament. ABS has a fairly high glass transition temp.

#1 You can use a lower Vref and still get sufficient torque and filament force. I mean honestly, a 0.6mm nozzle, and appropriate layer height ratio of 1/2 to 3/4 nozzle size (0.3mm to 0.45mm) you are running almost no back pressure to speak of. Even though I don't recommend to get the motor that hot, again, to imply with ABS filament the feeder is softening the filament prior to hitting the actual intake of the hotend, I find that questionable. To me, your problem is that the Raise 3D is actually too well sealed, and with the massive bed and extruders and motors throwing off heat, you are experiencing an uncontrolled temp rise in the upper part of the lid. This means the ambient around the motors is too high and also the ambient the fans blowing on the cold end of the extruder is just blowing already hot air and thus not controlling the temp.

Again, in all my experience, the problem is the totally sealed lid is actually too sealed and leads to uncontrolled thermal conditions. The system requires an ambient no more than about 55C and if you follow some very smart folks in some other groups who talk about ABS, they recommend ambient of roughly 50-55C. So yes, I'm absolutely saying crack the lid up. But that may not be enough. Again, the problem is warm air rises. So what happens, is the lid becomes this holding chamber that is doing nothing for your print, but is cooking the entire extruder assembly on especially long prints of several hours.

Also note, I have on loan to me a Zortrax M200. It has no lid but does use sides and doors to control chamber temp.
Again, this printer is designed around ABS and in my testing thus far I am blown away with how well it does with no warping.
Also note, it's extruder block and motor ALSO get almost too hot to touch with no lid and I have yet to have an ABS jamming problem.
I cannot stress enough, here is an example of an ABS printer with no lid at all, only side panels and front door and heated bed and thus far has printed some decently large ABS parts without warping.

Here is what I would do:
#1 lower Vref by 0.1V from what you have it set to now.
#2 keep the heatsinks you installed, they do help.
#3 Raise the lid or remove it entirely. I in fact was going to raise my lid by using these printable parts and long thin lexan side windows cut to match. The stock lid will stack on this. https://www.thingiverse.com/thing:980261
By raising the lid several inches, you are now raising this hot thermal zone of trapped air. This may raise it above the extruders such they are not sitting in "hot air" . Control vents in the side panels you make to raise the lid. If you are willing to test it, I might be able to laser cut you side panels to mate to the printed parts and make adjustable rotating vents that you can adjust. If it works and we find a good set, i'll release open source on Thingiverse.
Last edited by Jetguy on Wed Jul 12, 2017 11:28 pm, edited 3 times in total.

Jetguy
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Re: Bondtech BMG upgrade for the N series

Postby Jetguy » Wed Jul 12, 2017 11:21 pm

Also needed to add to that, Long ago I took a remote thermometer I had when I was testing ABS right after these N2 earlybirds shipped on kickstarter. I saw an insane temp rise in the lid that easily reached 70C during a few hour print all sealed up in "ABS" mode. You could smell the printer being hot, I was concerned with the Styrene upper deck and just the machine in general warping. This a huge reason why I backed off from ABS. Again, I know full well a sealed lid on an N2 will exceed 55C ambient in a short time (relative) and everything I know says that is too hot and needs controlled. How you control it is another answer I never fully got to, but again shared my ideas above as a general direction to try. Note that Stratasys machines have massive blowers circulating air throughout the chamber. We have a relatively dead zone in the upper lid area where hot air just sits. maybe a fan still inside the lid to get a gental rotation or mix of air below the upper black deck and above the black deck into some sort of slow circulating pattern. Otherwise, if you do not control ambient, you either pipe in cold air to feed the extruder cooler and extruder motors or go to water cooling both and that's just one more thing to fail in my book- let alone leak water, tubing to flex, dozens of more places to fail.

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JohnSays
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Re: Bondtech BMG upgrade for the N series

Postby JohnSays » Thu Jul 13, 2017 3:23 am

I am totally with you on your thoughts. I knew you would have some wisdom in this area.

I do like the idea of testing the laser cut Lexan windows. However, what do you think of a BBQ style rotating vent in the top of the enclosure? Maybe one in each corner to vent heat. I really like the idea of a fan. A while ago I designed a filter and have bought a high end particle measuring tool to test the effectiveness of a filter inside the N2. It measure down to a nano particle size. The key item of this filter -- and where I see all other after-market filters fail -- is on air temp control. Many filters suck in tons of fresh air. I want to recirculate the internal air up to a certain temp and them mix in outside air to maintain a max temp. Meanwhile all internal air goes through a hepa like filter. Actually it is a finer filter than hepa as it will filter even nano particles.
- John
2 Raise3D N2 Duals, V2 nozzles, Bondtech BMGs, and adjustable table

Jetguy
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Re: Bondtech BMG upgrade for the N series

Postby Jetguy » Thu Jul 13, 2017 12:16 pm

"However, what do you think of a BBQ style rotating vent in the top of the enclosure?"
or
"I really like the idea of a fan."

Sounds like a plan. I have been reluctant to do anything to the top, hence my desire to use the stacker design. Also, I should have been more clear. From what I can tell, the side panels and lid as supplied by Raise are Lexan or some other plastic than acrylic. I won't cut Lexan on my laser cutter due to the yellow smoke and edge discoloration. Apparently it requires even more power than I have and you should use nitrogen assist at the nozzle (both expensive and lethal if not accounted for). http://www.sawmillcreek.org/showthread. ... s-No-Maybe

Again, I'll cut acrylic AKA Plexiglass all day long as it cuts wonderfully with a great edge. If I have to cut Lexan, the best bet is my local makerspace by using the X-carve CNC router. That won't polish the edge cut the same, but won't yellow it either.
The point being, I will test the lid raise kit I mentioned https://www.thingiverse.com/thing:980261 and I have instrumentation I can install to measure before and after temp changes. If it works out, I will definitely share back here. I printed the corner brackets a while back and just have been lazy (well, I also just spent $900 to replace my laser tube) so hadn't cut the side panel strips. Just another tip on the topic, go to Lowes as they have a glass and plexi cutting section in most stores (Home Depot won't cut glass near me). Point being, they always have this scrap bin chock full of usable waste cuts of glass and plexi and Lexan. They sell me a pile of perfectly usable strips and scraps for about $2, often enough for many projects. Again, they are literally throwing this stuff away every couple of days and it's a shame when you need a strip to buy a full sheet. Just saying, a resource many

firesped
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Re: Bondtech BMG upgrade for the N series

Postby firesped » Thu Jul 13, 2017 1:33 pm

from my experience, if you are getting ABS melting in the cold end, your insulated hotends are channeling all the heat up the thermal tube. They are too well insulated. This is why I stopped super insulated the top of my hotends when I do it. We want to protect the print from the heat but the heat still has to go somewhere. I have not had any issues with ABS melting in my cold ends. I've been printing with ABS+ recently.
RL name: Michael Nolen
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Monoprice Maker Select v2

Safaridog
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Re: Bondtech BMG upgrade for the N series

Postby Safaridog » Fri Jul 14, 2017 4:55 am

This has upgrade has gotten my attention. How does this set up work for printing TPU and ninja flex? it would definitely be worth the money if i can start printing those 2 filaments consistently.

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JohnSays
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Re: Bondtech BMG upgrade for the N series

Postby JohnSays » Fri Jul 14, 2017 5:41 pm

Thank you firesped and JetGuy. Btw, I do not super insulate my hot end. In fact, I had no insulation on one of the ones that jammed. Lately my only insulation is to put a hole in a piece of insulation fiberglass and lay that on top of the hot end -- the sides and bottom are exposed. The idea being to stop some of the heat that goes straight up from going straight onto the cold end. My fully insulated hot end actually has the ends open -- the hot end sits in a fiberglas insulation tube. Again, excess heat can bleed off but the fan will not cool the hot end and the heat should not be getting easily to the cold end.

I print a lot of ABS and it is only since I installed the BMG that I have now had several cold end jams. My favorite question for my programmers when things go wrong is, "What was the last thing you changed before this problem started happening?" After they answer that, I ask them, "What did you do just before that?" These two questions usually result in a debug or a plan to debug immediately. It's cause and effect and the questions help pinpoint the cause. So in my case it was the addition of the BMG and from there analysing what is now different if I want to keep the BMG. So, lots more heat -- as in really really hot motors. That is a change.

JetGuy, I kept the lid cracked about 2" and measured the temp after about 3 hours of printing. It was 38C and the motor was about 57C. A significant difference from what it was all closed up -- at least I could easily touch the motor where before I could not. Prints came out very nice too. So I think all I need is a set of hinged clear Lexan/PC slats that will hold the lid up a bit to vent excess heat. Very simple really. Right now I am using a piece of wood. Also, I do plan on trying an ABS batch without using the cover at all. Oh, and I almost forgot, I did put the heatsinks on all my motors. The tape that attaches them is working because the heatsinks were the same temp as the motor.
- John
2 Raise3D N2 Duals, V2 nozzles, Bondtech BMGs, and adjustable table

Jetguy
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Re: Bondtech BMG upgrade for the N series

Postby Jetguy » Fri Jul 14, 2017 7:23 pm

FWIW I did specifically test a dual extrusion Hilbert cube in Dual Ninjaflex on the BMG upgrade.

Not exactly the fault of the BMG, but Ninjaflex leaves some string and ooze normally just because rubbery filament likes to stretch.
Dual extrusion and all the factors that come from dual nozzles, even with a wipe wall results in a less than perfect print.
That said, I did print it (super cool glow in the dark Ninjaflex and black ninjaflex)

I couldn't even dream of doing this with a stock extruder.
Sorry for the absolutely horrible picture, I was trying to catch the glow from illuminating it with a UV source first.
Attachments
DSC04620.JPG

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JohnSays
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Re: Bondtech BMG upgrade for the N series

Postby JohnSays » Sat Jul 15, 2017 4:17 am

I am also now using both extruders at once to print support structures for my ABS with HIPS. It's so easy and clean now. I could never get the Bowden thing working the way I wanted and I took off the stock extruders before I ever learned how to use two extruders successfully. So, until now, I was doing my support with ABS using only the left nozzle. I haven't tried two color print yet. I think I will try embedding a logo in my products.
- John
2 Raise3D N2 Duals, V2 nozzles, Bondtech BMGs, and adjustable table

Safaridog
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Re: Bondtech BMG upgrade for the N series

Postby Safaridog » Sat Jul 15, 2017 4:19 am

Jetguy,

Thanks so much for that and all the testing you have done for the raise3d community.

I ordered my bontech upgrade today.

Dennis

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Re: Bondtech BMG upgrade for the N series

Postby Safaridog » Sat Jul 15, 2017 5:50 am

Jetguy,

Thanks for that and all your work you have done for the raised3d community.

I have ordered my bontech upgrade today.

Cheers
Dennis

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Bondtech
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Re: Bondtech BMG upgrade for the N series

Postby Bondtech » Sun Jul 23, 2017 10:33 am

Rebuild kit now available!

If you have previously bought our Hybrid extruder kit for Raise3D and would like to change to our DualDirect extruder we have now released a kit for this, this kit will re-use the parts from the Hybrid kit (gears & thumbscrews). The assembly process is a bit tricky and requires some technical skills. With the order you will also receive a link to a step by step assembly video that will help during assembly.

You will find the kit here: http://shop.bondtech.se/ec/upgrade-kits/raise3d/dualdirect-version-upgrade.html

If you only have 1 set of gears /thumbscrew available please send us an e-mail to order@bondtech.se and we will create a manual order for you.

/Martin

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Re: Bondtech BMG upgrade for the N series

Postby Safaridog » Thu Jul 27, 2017 6:26 am

Just installed my Bondtech upgrade, pretty straight forward install. However, I did run into 1 minor issue. The teflon filament feeder tubes prevented the new extruder from sitting down far enough to allow the mounting screw to start. I had to disassemble the hot ends to to push the tubes down, mount the new extruder and set the nozzle height again.

Quick background story on my last attempt to print flexible filaments. Last year I had tried to get my N1 with the factory duel extruder set up to print TPU. I gave up after spending countless unsuccessful days tweaking the slice settings and checking the mechanical bits of the printer. I just couldn't get it to print right... until today!

I just wanted to share my first print using TPU with the bondtech BMG with default ideamaker TPU settings. Sorry for the crappy photo, phone has been dropped to many times. 10x20x40 calibration block was bang on.
Attachments
Capture.PNG

Jetguy
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Re: Bondtech BMG upgrade for the N series

Postby Jetguy » Mon Jul 31, 2017 11:22 am

Here are some of the latest dual extrusion prints using the BMG dual.
First up, torture cube printed intentionally small to make it just that much more of a real torture test using Polysmooth as support material. It is currently in alcohol to dissolve the support material away and will update once finished.
https://www.thingiverse.com/thing:2460271
DSC04771.JPG

DSC04765.JPG


Next is a dual extrusion set of pliers that uses TPU and PLA to make hard and flex parts rather than rotating joint.
I used this version by Mosaic because I'm also printing a 4 color variant using the new Palette +, but that's another post.
https://www.thingiverse.com/thing:2433894
DSC04762.JPG

DSC04772.JPG


Here is a video of them in action https://youtu.be/jl7QkK3up3Q

socke
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Re: Bondtech BMG upgrade for the N series

Postby socke » Fri Aug 11, 2017 3:36 pm

I just got the first prints out of my N2 after upgrading from Bondtech mini to the BMG with only one stepper installed.
First, I used the same settings as before but ended always with a clogged hotend. So I tried different things, also reduced the retract from 1.5mm to 1.0mm. This way I could complete the prints. However, this can't be a permanent solution.
Did anyone experience the same?
Maybe I have to change the retract speed, too? It is set to 30 mm/s, currently.

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sgeolog
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Re: Bondtech BMG upgrade for the N series

Postby sgeolog » Fri Aug 11, 2017 7:05 pm

I am printing with it few weeks already. Quality is good
Cones.jpg
but it was clogging also. I believe it is happen because during idle filament keep melting inside and when you unload it, the end of it does not fit in channel above and it does not loaded also. Few days ago it stuck inside extruder. I had to take apart almost everything. In my opinion, hole inside extruder has to be a little bit bigger in diameter. I also have problems with retraction.
Oct2.jpg
Playing now with temperature.

socke
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Re: Bondtech BMG upgrade for the N series

Postby socke » Sat Aug 12, 2017 7:42 am

These cones are looking really nice, good job!
It seems I have to play around a bit more with all the parameters.
But I just didn't expect this, as everything was running smoothly with the Bondtech Mini.

Jetguy
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Re: Bondtech BMG upgrade for the N series

Postby Jetguy » Sat Aug 12, 2017 11:49 am

I find it hard to believe it has anything to do with the BMG VS mini. It's just the feeder. The BMG can provide more force with the 3:1 ratio even with the smaller motor.


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