Calibration instruction by Mircea Russu: https://groups.google.com/forum/#!topic/deltabot/pbLF-FHZoDk

Equation for calibrating steps: The steps you asked it to move divided by the number of steps it actually moved, the total of which timed by the number of steps in the firmware. For example I asked the extruder to retract 100mm. It only retracted 97mm. My steps were 800. 100/97)*800=824.7422

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You’re probably thinking what the hell is dragging out in front of the camera this time. Well it’s yet another 3d printer, but the reason I accepted this one is because I could recycle it into a CNC router machine.

This is going to be big.

Part of the kit includes three lengths of 1 meter long aluminium c beam, and there’s plenty more material as the top and bottom of the machine have been made from thick aluminium which could be milled into new CNC plates. This could come in handy for the machine I’m designing or have been perpetually designing for quite a while now. But for the sake of this supply line of parts to continue to trickle into my cesspit in London, I will assemble and review the Tevo Little Monsta.

Ok I’ve got the other printers running in the background. I’m just going to follow the instructions for the little monster and start assembling this thing. It comes with a nice manual and they haven’t skimped out. It’s really thick paper and colour prints on both sides. It has a parts list here. Some QR codes and an after sell card.

Please remove the blue plate including hot bed from black plate before installation. Ok.

I checked that c beam was square and the correct length, and then began assembling everything. I’m going to make sure the belt is in-between the wheels. And I’m just going to test that. This one’s really well seated. You repeat that with the other two.

I’m using my finger while moving the plate along the c beam, to check that the wheels are turning properly. So they are neither too loose or too tight.

The next thing is to place the top piece on. And you know what way they go coz there’s some counter sunk holes for the machine screws at the top. These are my own washers. I don’t think you get washers in this section here. I’m going to add some anyway. I’ve done all three.

Between my engineers square and Vernier calliper I made sure things were lines up correctly. So for example the belt gear on the stepper shaft or the idler pulley on the opposite end of the belt. It wasn’t clear from the manual which way to position the steppers so the terminals which feed off in a particular direction. I had to change these when I put the power supply unit on the top but overall it was a pretty simple assembly process. Not too confusing.

I’m going to fit the titan extruder. I’ve already put the PTFE tube in. It’s about 150mm long.

I think I’ll probably change these at some point something a bit more springy and rubbery.

Ok I don’t have the Tevo tarantula anymore but one thing I’ve noticed with Tevo machine is that their cabling is always atrocious. They just literally bung everything in and cut everything the same length. It’s where they save I guess the most amount of money on their builds. It’s definitely a feature. Some people don’t mind messy wiring, or will rewire stuff up themselves or just live with it.

Anyway I think this collection of wires goes through that there.

Make sure you set to the right voltage for the region you are in. So over here it’s 220 or 200-240.

So I put the terminals for these two stepper motors facing inwards where the power supply is meant to be attached so I’m going to have to undo the tension on the belt and flip these around.

This is the wires for the heated bed.

Ok this the last stuff that was in the box. I don’t know where this went or was attached too or where it should go.  But I don’t think I’m going to use it. There are two SD cards slots and two USB slots. You have a Tflash or micro SD and a larger one or normal SD card on the LCD display. There’s a USB there type a and a usb type b there and then you’ve got the Ethernet port which is described as WAN there. I’m just going to tidy up and then it on. I was just about to turn this on and looked at the spatula. The plastic has been put on the blade and then the handle was put on afterwards. You can’t just pull it off. You’ve got to peel it like a banana.

Ok I just had to retention the suspension of the extruder as I couldn’t get the filament through. It was a bit too tight and I couldn’t take this off now it’s all ok and has reached the bottom.

So this is where the video get a bit complicated, as the monster in the name rears in ugly head. As I did the self-levelling protocol I began to notice some smoke coming off the hot bed. Ok I need to turn this off because I can see a bit of smoke coming off the bed.

Ok that was really confusing. When I did the calibration on the manual it said the bed would go to 80 Celsius and it went instead to 160 Celsius which was bloody hot. I could see a bit of smoke starting to come so I turned it off and I’m leaving it to cool down. That said now it’s on, the temperature is just creeping back up again.

Something is not wired correctly on this machine and now I have to investigate to find out what it is. Something has been wired incorrectly here and it’s resulting in the hotbed just going to the max temperature. I just waste my time with these bloody machines. Look at it. It’s still going up.

I’m just making sure that the positive is going to the positive and the negative to the negative. Look alright there. It’s a bit worrying that it heats the bed so. If one bit is not present it would just keep heating up and really it should be wired up differently so that if thermistor is not connected properly it won’t heat up at all. I just find these little errors phenomenal.

They haven’t even used normal tape. They used fucking double sided tape. Who sticks stuff down with double sided tape. This is disgusting.

Ok this looks neat but something is definitely wrong here and also there’s an excessive amount of wiring here for whats actually here.  It makes it a bit difficult to see whats going on.

I’ve just turned it on while open to see what’s going on and the temp is still heating up. It’s already at 60 degrees so I’m going to turn it off again. I definitely think this has been wired back to front so I’m going to rewire it. That doesn’t look right. It’s completely sunken in. Yep. Shit.

The pixies just farted their noxious yellow fumes. God know show poisonous that little puff of smoke was. I got the fan on and tried to disperse it as best as I could. Open the windows and got out of there for a little while. I manged to borrow a similar solid state relay from Nathan, and re-wired everything. This ones from Taiwan. At least this ones made in Taiwan. Aaaah.

So. So. We have life. So essentially this is just turning on and off until this gets to 21 degrees. So this is what you would call bangbang by the look of it. I mean it figures why they wanted a solid state one rather than a mechanical one because it could go very rapidly.  So now it’s working, it’s doing what it’s meant to do. That whole section was wired incorrectly and the relay looked damaged as well. It was going to 160 Celsius and actually I touched the hotbed with my hand as the laser temperature thermometer wasn’t working and I was like that’s hot. Yeah you could fry an egg on that.

So this is a 25 Amp relay as opposed to a 40 Amp which I’m borrowing from Nathan. Lights are working. I’m going to have to re-watch the footage to see if I had accidentally swapped those two wires around, but my hunch was right. It was the relay that was the problem.

I also brought some thermal fuses which I was adamant I would install but still has not go around to it. Anyway this was just the beginning of a long process of getting this machine to work. The calibration protocol didn’t seem to work properly. I could print smaller object but not larger ones which would un-stick from the bed. I later found a good step by step instruction which involved performing a slightly edited calibration process.

I was having loads of trouble with it over extruding, and there’s more in the bin. And it was something quite simple in the end. In the smaller SD card at the top, there’s two basically. There’s one in the control panel, and then one plugged directly into the controller itself. You can access the configuration files to edit and adjust how the machine runs and there’s also a config override file. I did the bed levelling manually using some instructions I found on the internet, and I’ll link to those when I get around to it. And later I noticed that there was a couple things missing on the config override file. The first thing was the diameter of the filament wasn’t actually specified and also the extrusion steps weren’t set correctly. And what I had to do was measure how much filament actually moved buy putting a bit of tape and using the calipers to check the distance after I had set it to move a certain distance. So for example I set it to move 100, it only moved 97mm. I worked out the equation and then put that information as the steps back into the config-override file. A combination of doing those two things and now suddenly the thing is printing better. I did a quick test print of the spindle mount. I decided to make a version of my CNC machine which would hold a slightly cheaper easier to use and access hand router or trim router. And essentially there’ll be two of these, thicker and I’d bolt this thing on… waffle waffle…

So a few more things to add, I edited those parameters in NotePad ++ and the last thing to mention was despite carefully following the calibration instruction I still decided to also add a manual levelling to the machine bed in the form of wing knobs and springs. However I’m going to edit that as a separate video so I’m not going to go into that now. Anyway credit where credit is due, that calibration process was really informative and well written, and researched by someone called Mircea Russu. I’m hoping I’m pronouncing that correctly and the link will be in the description bellow. Anyway I’m going to write up my verdict – the pro’s and cons for this machine on the Top 3D printer that I’ve used which is available as a link to my website in the description bellow. Along with the revised callibration process. I was pretty shocked with the solid state relay problem on this machine, and it’s quite a dangerous problem to have. I think any 3D printer or CNC machine should never be used unattended. And from what I’ve read a lot of people who get this machine eventually upgrade the controller and software and electronics to something a bit more reliable by a company called Duet. I’m not sure if that’s something I’m going to do. I don’t particularly want to spend over £100 on doing that just yet but I think if you were to consider buying this printer you should also be aware that you may have to spend a bit more money to really guarantee it’s going to work properly because hardware wise it feels well made, but electronics a little bit scary. Anyway thanks again for watching and I’ll catch you in the next one.