Tevo Little Monster

2019-01-26 I began unboxing and assembly today.

You have to remove the heating element and the glass plate before you begin. You can place it back into the shipping container underneath the top-level foam cover from whence it came.

Tevo-2019-01-26-004.jpg

The heating pad and heat sensor wiring.

Tevo-2019-01-26-005.jpg

I had to adjust the elliptical nuts on the slider to get a smooth but tight fit so that they move freely in gravity.

Tevo-2019-01-26-001.jpg

I have to stop here for now.

Tevo-2019-01-26-006.jpg

2019-01-27

Tevo-2019-01-27-001.jpg

I was able to make a bit more progress today. The assembly instructions are much lacking and I had to remove the sliders several times to get the belt properly aligned. The heating plate and base plate shipped with one M5x20mm missing screw.

2019-01-30

I am pretty much finished building the Tevo LM but calibration is failing slamming the print head into the printer bed.

I have opened a support ticket. There is also a video attached to this page showing the problem.Update I was able to get it working. I am not quite certain what I did to fix it but I reseated the connectors on the logic board and tightened all the belts in the columns. I am not sure which one helped.

tevo-2019-01-30-001.jpg

Notice te insulation isn't going into the connector leaving exposed wires to break or be damaged. Poor Quality Control.

tevo-2019-01-30-002.jpgtevo-2019-01-30-003.jpg

2019-02-02

I am having problems running filament through extruder. I have been working on this for a couple days.

2019-02-01-001.jpg2019-02-01-002.jpg2019-02-01-003.jpg2019-02-01-004.jpg

2019-02-04

I was able toi resolve the issue with feeding filament through.

Extruder-2019-02-03-01.jpg

2019-07-26 Everything has been going well with this printer. Other than occasionally adjusting the X,Y,Z column belts, adjusting the extruder drive tension, and cleaning a few clogged tubes and nozzles it has gone very well.

I had an issue due to improperly gauging the proper distance between the extruder drive (hanging from spring-loaded straps) and the hot end. It eventually pulled apart somewhat and was catching the filament feeding into the hot end (on the hot end side.)

I had to detach the straps, shove the bowden tube deeper into the hot end side and then re-adjust and re-attach the straps properly. It went quickly and should be fine for a long time.

At first glance it again appeared to be an extruder drive problem with the clicking sound as the filament slipped within the gear/wheel area. Fortunately you could tell when loading a new roll of filament that it was getting "stuck" occasionally right as it went into the hot end assembly so it all became obvious quickly.

Since there is so much movement in this part of the printer, we should most likely expect to perform tasks like this from time to time. Mine became a problem during some extensive print activity recently and you could see the thing literally shaking itself apart.

I am also struggling with keeping the printer level but that is because the platform I have it sitting on cannot be leveled and the BL Touch and accompanying code that tries to compensate for not level build plates works as best it can.

In hindsight and after much retrospection I feel Tevo should have incorporated some kind of bed leveling method into the design.

Due to the leveling situation (for now) I print everything sort of on the left side of the build plate. Since the LM is so huge I can get away with that for now. I love this printer and I hope to have it in production a very long time.

If it does last a long time I am sure I will eventually built some sort of mounting plate so I can place the entire printer on top of that and level the bed perfectly. It has to be heavy duty and withstand vibration so I suspect I will be looking at some kind of massive steel plate that I bolt the LM onto and that gets bolted in turn to some heavy duty table that won't shake, rattle and roll during printing.

2019-08-01 I have had more issues with the extruder and hot end with more bowden fittings failing.

This time the fitting stopped gripping the tube so when the extruder drive was actively pushing filament the tube detached from the fitting and the filament started coiling up near the heating plate and wherever else it wanted to go.

This was the bowden fitting near the extruder drive assembly and not the hot end! I also noticed a groove melted into the bowden tube around the area where the bowden tube had been gripping the tube.
I don't know yet the source of these bowden fittings but they are all from the same source I imagine. These are the ones with the black plastic (vs the blue.)

You must always keep at least a dozen of these fittings and a few meters of the tubing itself around at all times because they become an expendable item.

I am seeing the same thing on the Creality Ender 3 so

I detest ongoing maintenance issues like these but I guess it's the state of current technology.

2019-08-07

I had to replace a bowden tube and bowden fitting AGAIN today, the same fitting failed (on the hot end side) and the tube also seemed to have a melted spot. The fitting would not grip the tube, even a new tube. Again, this is the M4-10 fitting (black plastic.) I have been printing a lot but this does not seem normal. I am not using an inordinately high nozzle temperature. I have been printing all PLA — The first layer is always 210C, then cooling to 205C for normal extrusion.

2019-08-07

THE TEVO LITTLE MONSTER IS DOWN.

It is entirely my fault as I had neglected to obtain spare Volcano nozzles so I have rectified that oversight by ordering a dozen nozzles (steel.) However despite hours of soaking the damned nozzle in acetone, I have still not been able to clean it. I believe what has been happening is that this nozzle was always constricting the filament and creating resistance causing the extruder servo extra load and putting too much stress on the bowden fittings when they are also hot. This is a developing theory but it seems to explain all the failures I have had lately.

I have only ever printed PLA with the LM but despite that it seems whatever the hell is in there will not melt away with heat or chemicals. I also broke my cleaning tool in the process and had to order (10) more of those too. I detest ordering from Amazon but I could not find them anywhere else in North America.

So due to poor maintenance and lack of spare parts the LM is down until I can receive the replacement nozzles. Since I live in the middle of nowhere New Mexico, that will be a week to 10-days that this machine is offline. I needed to print some large parts too, which is not going to happen until later this month.

As an aside, the little Ender 3 is still cranking out parts. I am preparing for a hamfest soon and have a lot of cool stuff to sell and/or trade with other not-stupids like me. Note: See Mycroft's comments to Manuel for reference.

2019-08-07-TevoLM_Broked.jpg

I realized about 8-hours after I wrote the above that I owned a lot of Enkay miniature drill bits and a tool so I got out a #60 bit and started drilling stopping short of the tip. I switched to a #79 to go from the tip inward (flipping it around in the vise.)

I recommend having a set of these bits and the drill just for something like this. There are times when I worry about myself, I seem to forget that I own some things until by some chance I happen to realize I have an alternative. Some might say that is a sign of owning too many things, but I don't believe that you can ever own too many tools.

(some time later…)

Anyway, after trying to print just now it still is restricting flow and underextrudes. I know it is restricted because the extruder drive is "popping" as the filament slips in the drive teeth. The print itself was failing with occasional globs as some filament squirted out suddenly interspersed by underextruded base layer. The brim (10mm) was beautiful until the nozzle slowly jammed up again. I could try drilling out the main body of the nozzle with a larger bit to eliminate more of the built-up plastic.

I could just let it idle for a week or so too, but I already failed the patience test by attempting to drill out the nozzle. I might try to put the nozzle into a vise and then get a propane torch and heat it up while trying to extract extra plastic material. We shall see what tomorrow brings, I am going to let it rest awhile.

2019-08-13

I disassembled the hotend, removing the entire lower assembly from the carriage because I kept seeing the filament clog the nozzle even though I just replaced with new nozzle. That was when I noticed that the hotend was bent, It was bent at an angle that you couldn't notice from the front but I tried to straighten it because I realized that when using the cleaning tool it would always seem to catch at a point before the nozzle but if you rotated it around a bit it would pass and go on to the nozzle tip (coming from the hotend side with the bowden fitting removed.

I remember once in Jan or Feb when I first assembled the printer, it slammed badly into the bed once during initial powerup. I don't remember what was wrong but I solved it quickly. I never noticed the volcano/tube assembly being bent. I've been printing with a bent nozzle assembly since the very beginning. How crazy is that? I straightened it out but somehow I broke the thermistor because at first it was reading 768C constantly and then later it reads 0C so I assume there was a full short then it opened completely. I have not checked it with a meter yet because I know the hotend is completely useless if you care about precision.

Can you believe it is almost impossible to find the 24v version of the hotend heater? It seems all you can find on eBay or Amazon is the 12v version which mystifies me since as far as I know, all the Tevo Little Monsters are shipped 24v.

I had to order from AliExpress and I doubt my LM will be back online any time soon. I love the selection available from AliExpress but the shipping time crushes you, and if you use DHL it is usually at least $20 US added to your order.

I did order (3) complete hotend assembly, one from Tevo directly and (2) from a third party vendor which looked like it is a drop-in replacement for existing hotend including the heater and thermistor cables and connectors. I could only find the 24v version in China. There was nothing compatible on eBay. They look identical so you first get your hopes up but once you see they are 12v only and the vendor says that is the only version they have you suddenly realize you are going to have to order from China directly.

If my (2) third party hotends work well I hope to order a few more as they were less than half ot the "genuine" Tevo hotend which everyone knows is a slightly-modified clone of E3D volcano hotend.

I really don;t know when the Tevo Little Monster will be back in operation. It has been an expensive and very frustrating period with this printer. I will not blame the printer, there seems to have been an early accident that in hindsight was catastrophic. I think it is simply amazing the printer ever produced anything useful in it's damaged condition.

THe filamenet was entering the bent tube and sometimes being restricted and as I started printing on larger parts of the bed at certain angles (parts of the build plate) it seemed to cause underextrusion. The heater and thermistor were working fine before I removed the hotend assembly so it had to have been damaged during that. I was most likely rough on the part at times because the plastic caused threads to seize and I had to use some force , I protected the thermistor when I put the heater block into a vise but somehow I still damaged something.

It is important to look at the heat shield for the thermistor and heater wiring as it enters the heater block making certain that you pull the shield closely into the top of the heater block as it will have to bend and will be very close to the hot metal

Take a close look at an closeup of the lower print head area and you will see the wires exiting the heater block and going upwards to the wiring harness. If I have a chance I will create an image for this but meanwhile you can find many images of that area online using a search engine. Most are professionally-created and are usually quite detailed (heh.)

Once again, you should keep several complete hotends as spare parts. In my opinion the supply chain is far too long especially when you live in the middle of nowhere New Mexico, USA. I don't recommend keeping all the component parts as sooner or later you will end up with a collection of used parts that you saved from all the hotends you replace. I assume you will collect a few volcano tubes, heater blocks, thermistors, etc. that you salvage from used parts. This assumes you don't have the same failures over and over and I believe that to be an accurate prognosis at this time.

Tevo sales were very helpful to me guiding me to a link where I could get the right one. For some reason they alsmo promised to expedite the shipment. I am not depending on it, but if it happens then I will be very impressed with their customer service. I have had terrible experience with their support normally and it was a rough pre-sales and pre-delivery period as well when I tried to purchase a Little Monster. Everything worked out well in the end, though.

Necessity is the Mother of Invention

I got really tired of trying to keep the print head carriage from banging into the bed plate when the power is turned off, or if the printer resets. I noticed (2) holes near the central huge hole at the top. I had some soft aluminum wire, so I bent it into a "U" shape approximately the same width as the two holes. I fed the top ends of the "U" into those two holes and then bent the tops at an 45-degree angle creating a u-shaped hanger. Then I used a small bungie cord to hold the printer head carriage. It works well I have the hotend carriage assembly partially disassembled and the carriage is hanging securely while the work is being done.

2019-08-12-Tevo-Hanger.jpg

I have felt as if I should ry to write up more of my experiences with the Little Monster, hopefully some of it will be useful to others!

2019-08-21 I have the LM working again. I found an ebay seller that had a third party volcano hot end with titanium "V6 Hotend J-Head "Big V" Heater Block for 3D Printer" which claimed to fit and was 24V. I ordered it and it arrived today. There were several problems but I got it working! One problem was the aluminum heat sink/radiator is designed for direct and no bowden fitting works with it. I ended up using the old piece from the original hot end with a normal bowden fitting.

I thought I would end up destroying the new heating cartridge and the new thermistor but they seemed to survive assembly. The thermistor in particular has to be bent at 45-degrees and then mashed as you screw the radiator onto the heat break tube. The heater cartridge like the standard LM design sits in the front and has heat protection near the cartridge end to protect the wiring from heat.

This hot end is not quite like the stock Tevo hotend, the thermistor and the heat cartridge go into separate holes in the heater block.

I am going to keep using it but have several parts coming from China both original and some third party versions, I don't want to have downtime again because I did not have spare parts.

Here are some various items of information from the eBay listing from vendor http://myworld.ebay.com/britech_3d Their advertising says fast shipping but they seem to order the parts and then send them to you which takes a long time. It is still faster than the parts from China will arrive. Fortunately I could use some of the parts to get my LM working again,.

hotend-v6-clone.jpg

2x Heat Breaks (throats) 1 Titanium, 1 PTFE tube (Bowden goes through the throat to the top of the Nozzle, which reduces the chance of clogs).
1x Aluminum heat sink (radiator)
1x Volcano Aluminum Heater Block. Multiple configurations possible.
1x Pneumatic Connector.
1x 30mm 12v Fan With Blue Shroud
1x NTC 3950 1% 100K ohm Thermistor cartridge
1x Bowden tube 1 meter
1x Silicone Sock Insulation
5 Brass Nozzles .4, .6, .8, 1.0, 1.2
12v40w or 24v40w Heater Cartridge

I did not use the fan (of course not.) The Pneumatic connector does not fit the aluminnum throat/radiator. As they ship the kit can only use a direct connection as illustrated here.

This is the image from the eBay vendor of the assembly.

hotend-radiator-ptfe.jpg

2019-08-22 It is down again. I had to disassemble the hot end and reassemble it (had loosened up not printing worth a damn.) When I reassembled it the thermistor wasn't working. At first it read max temp. then after I wiggled the wires it read minimum temp. I guess it is broken. I have to wait until the parts from China come. I did not like how the thermistor attached to thie V6 third party heat block any way, you had to bend the heck outo f the wire to get it to clear the screw-on heat sink.

2019-08-23 I was disassembling the hot end today in hopes some parts show up soon and saw that the heat break and radiator had leaked spewing hot pla (grey) all over things. I checked the thermistor and it is definitely bad, probably broken lead into the cartridge body.

01-V6-Hotend-Joke.jpg02-V6-Hotend-Joke.jpg